Skyting

[Tad Eareckson]

1985/08
*
SKYTING NO.40
AUG 1985
*
1985/08-01

FROM THE EDITOR

Once more I need to apologize for being so late in getting an issue of SKYTING out. But this time it's really my fault. You see, I've been spoiled over the last few months. Some of you subscribers have sent me enough material so that I haven't had to write anything, myself. And my mother - you remember her - she wrote the Wuffo article in #32 - well, my mother visited with us for a spell and typed up the last few issues of SKYTING.

Yep, I really got spoiled - all I had to do on the last few issues of SKYTING was be the EDITOR! It was unreal!

But now reality is setting back in. "Mom"'s gone back to Colorado, and you haven't sent in enough material to fill up another issue of SKYTING, so for me it's back to the keyboard and composition.

Now don't go saying, "Oh, NO!"

After all, I WARNED YOU! It was on the last page of the last issue.

So now you're going to receive an overdose of my babblings. Not only that, but the material is not even going to be original! It's going to be a rehash of what you already know from reading the back issues of SKYTING.

You see, I had this grandiose idea of writing a book on skyting and telling everyone everything they need to know about skyting - or at least telling them everything I know about it. And over the past few months (while the pressures of the Newsletter were off of me) I got everything organized and began writing. The only problem was that nothing I wrote was worth reading.

Oh yes, I was putting down the facts - ALL of them. But I'd fall asleep every time I tried to reread the material.

So after waking up, I would start all over again, trying to get in the "creative" mood for writing. Unfortunately, the information would come out in an unreadable form.

I don't know. Perhaps the project was so big that I could not become excited about doing it. I never did get even a single chapter in a reasonably presentable form.

And now the pressure of the Newsletter is back on me - and still I have done nothing to try to educate the increasing number of tow pilots about the known dangers, problems, and solutions associated with towing.

Every time I learn about another towing accident (such as the fatality mentioned elsewhere in this issue), I can't help but wonder whether or not those involved were even aware of the skyting criteria that they were violating and if not, then whether or not I could have done more to educate them.

I've also come to the conclusion that it is really unreasonable to expect everyone to read all the back issues of SKYTING in order to gain the information they need to tow safely.

Now, if you've been following me this far, you may have noticed where I am heading: Beginning with this issue of SKYTING, I am going to start writing an article each month which deals with one of the aspects of skyting which I feel is important from the safety and the beginner's point of view. Yes, I know that others (for example, Charlie Nordstrom in #14, June '83) suggested my doing this years ago, but sometimes I'm a little slow catching on to a good idea.

In essence, what I will be doing is sending you a very rough draft of the book I was intending to write. This will FORCE me to at least write up SOMETHING each month. And it will at least START getting information out to those who need it.

Of course, it will take about a year or so to cover all the bases, but that's better than taking two years and getting nowhere. (That is the rate of progress I have been achieving lately.) Perhaps when I finish these series of articles, it will be easier to rewrite the material into book form. Who knows?

And by not copywriting the articles, perhaps more copies will be distributed among those who need them.

Oh, yes! There is one other thing I hope to accomplish by presenting this information through the SKYTING Newsletter. And that is to get feedback from you. After all, words of encorragement help keep one working on a long and difficult task; words of criticism help keep one on the right path; and words of advice help guide one toward the proper goal.

One of the reasons I have found it difficult to write is that I feel inadequate to do so. Let's face it, many of you have considerably more skyting experience than I have had, and are much better acquainted with the practical aspects of skyting than I am. In short, many of are better qualified to write this material than I. After all, much of my knowledge of skyting is second hand, having come from you through your correspondence. I am hoping that you will continue this correspondence and correct me when I write something wrong or misleading.

Really, I can take it. I've been corrected before. Perhaps by my putting my foot in my mouth and you clamping down on it, we can work together to save a few lives. What do you say?

Donnell Hewett
*
1985/08-02

THE SKYTING CRITERIA

by Donnell Hewett

HISTORY

The history of the skyting criteria dates back to the earliest days of skyting. They were not always called the "skyting criteria", nor were they always listed specifically by the number and in the form that they are today. But the concepts behind the criteria have always been a part of the skyting design philosophy and the fullfillment of their requirements has always been a goal of the skyting effort. It's just that in the early days, the requirements were not so clearly identified as they are today.

For example, in SKYTING No. 1 (October 1981) the requirements of a skyting system were not called the "skyting criteria" at all. They were called the "elements of skyting". There were four of them: (1) gradual advancement, (2) tension limitation, (3) C-M bridle, and (4) reliable release.

But by July 1982 (SKYTING No. 3) it was clear that some of these "elements" could be further subdivided into more "fundamental elements." Specifically, element 2 (tension limitation) was divided into three parts (constant direction, constant tension, and infallible weak link), element 3 (C-M bridle) was divided into two parts (C-M distribution and C-M attachments), while the other two elements were left intact. These eight more "fundamental elements of skyting" were then grouped together were then grouped together and called, for the first time, the "skyting criteria." They served their purpose well for a period of three years, helping to guide the development of skyting as it was introduced to the world. Even today they are used as guidelines in the design and operation of safe towing systems.

But when I recently began organizing the critical ingredients for a practical skyting operation, it became clear to me that certain essential elements of a safe skyting system were not included in the original eight skyting criteria. These elements were present in even the earliest skyting systems, but they were so obviously necessary in any towing operation - skyting or otherwise. They are included today not because they are PECULAR to skyting but because they are ESSENTIAL to skyting. They are: adequate power, capable crew, reliable communication, and suitable environment.

So today there are twelve identified skyting criteria. Perhaps in the future others will also be found, but in the mean time these twelve should serve as a guide for future skyting development. These twelve current skyting criteria are briefly tabulated in the accompanying box and are are more fully described in the rest of this article.

SAFETY AND THE SKYTING CRITERIA

Many people, myself included, use the skying criteria as a set of safety guidelines for towing. Indeed, I have yet to hear of a towing accident which was CAUSED by the TOWING SYSTEM and which did not violate one or more of these criteria. As an example, consider Cris Bulger's fatal accident described elsewhere in this issue. The lack of a helmet and parachute were not violations of the skyting criteria, they were violations of common safety guidelines applicable to any form of hang gliding. Their PRESENCE may or many not have SAVED Cris's life, but it was not their ABSENCE that CAUSED the accident in the first place, it was the improper weak link, the unreliable releases, the non-constant tension, the non-constant towline direction, and the non-C-M attachment points that allowed things to get out of control, even for these two highly accomplished pilots. It was the violation of skyting criteria that CAUSED the accident, or at least SET THE STAGE where an accident was likely to occur.

Yes, the skyting criteria can be used as a set of general guidelines for safe towing. But that is not, and never has been, their primary purpose. Now please don't get me wrong! Safety is indeed the most IMPORTANT and the most VALUABLE goal of the skyting criteria, but it is not their PRIMARY purpose. If it were, then they should be called the "safe towing criteria" and they should include other important practices for safe towing (such as preflight inspection, hang check, helmet, parachute, etc.). Furthermore, there are conventional water towing systems that have a long established record of safe towing which, never-the-less, flagrantly violate one or more of the skyting criteria. Conversely, there are other systems that fulfill all of the skyting criteria, but which are just as dangerous as the pilots who use them. In other words, the skyting criteria are neither necessary nor sufficient to guarantee safe towing practices.

What, then, is the primary purpose of the skyting criteria. It is to DEFINE specifically what is meant by a SKYTING system, so that skyting can be distinguished from other forms of towing, and so that an ideal goal can be recognized which real towing systems can strive to attain.

Let's face it. The skyting criteria are probably so idealistic that no system can ever hope to meet all of them under all real flight situations. But real systems CAN approximately meet the skyting criteria and the better the approximation, the more appropriate it is to call the system a "skyting" system. The skyting criteria, therefore constitute a gauge which can be used to judge how well a specific towing system approaches a specific "ideal". The skyting "ideal" is not the only "ideal" towing system that could be envisioned, but it is one specific towing system that has been defined. The fact that the skyting criteria have been effective in promoting safer towing suggests that this skyting "ideal" is a worthy goal to persue.

THEORY

Now if what was said above is all you have ever heard about the skyting criteria, you may well have gotten the impression that these criteria are simply an arbitrary set of randomly chosen elements, which just happen to be successful in promoting safer towing. Maybe someone put a few promising ideas into a hat and drew out one or two for good measure. Or perhaps he happened upon some reasonably successful towing system already in existance and simply identified those features that made it unique. Not so! The skyting concept occurred well before any successful skyting systems were developed, and the skyting criteria (at least the first eight criteria) were obtained through pure reasoning. Perhaps if you follow the logic of that reasoning you can better appreciate the principles upon which skyting is based and understand why the skyting concept has been able to produced successful towing systems. You may even decide to adopt the skyting criteria as your own personal set of towing standards against which you evaluate other towing systems and upon which you structure your own.

OVERVIEW

In its purest form, the skyting concept is very simple: FREE FLIGHT UNDER ARTIFICIAL GRAVITY. The idea is to develop a towing system which simulates as closely as possible the situation of a hang glider flying in an artificial gravitational field. Obviously if this can be done, then towing will be just as safe as free-flight hang gliding. The goal, therefore, is to make towing as safe as free-flight hang gliding by making it become a perfect simulation of free-flight hang gliding.

The skyting criteria are simply those identified characteristics that a practical towing system must have in order to be able to accomplish this goal. The twelve skyting criteria may naturally be divided into three groups of four criteria each: The first four criteria insure an accurate simulation of the earth's natural gravitational field; the next four provide for a safe entry to and exit from the artificial gravity experience; and the last four provide for a safe and practical method of implementing the artificial gravity concept.

GROUP 1. ACCURATE SIMULATION

In order for an artificial gravity to accurately simulate natural gravity, it must have the same characteristics as natural gravity, namely the artificial gravitational force must be (1) constant in direction, (2) constant in magnitude, (3) distributed the same as gravity, and (4) acting only through the center-of-mass of each component. The first four skyting criteria are a direct iteration of these properties.

The first skyting criterion requires that the tow line tension remain constant in direction. This, in turn, requires that the length of the towline be long compared to the transverse motion of the glider. In other words, the faster the glider climbs and maneuvers, the longer must be the towline. Generally speaking, a towline needs to be about 500 ft or longer in order to meet this criterion. Most practical skyting systems use towlines from 500 to about 2000 ft.

The second skyting criterion requires that the towline tension remain constant in magnitude. This means that some tension regulation device must be used. Most pilots use a tension gauge at the bottom of the towline to help regulate the vehicle's speed to keep the tension reasonably constant. Some use a payout reel or a power winch to automatically regulate the tension by allowing a spool (about which the towline is wrapped) to slip at a given tension setting.

Regardless of the method used to regulate the tension, it needs to remain constant to within about +/- 25 pounds as long as the glider is on tow. The value of the tension during climb-out is usually about 1/2 g (say 100 lbs or so), although beginners may prefer to tow at about 1/4 g and some experts like to push the 1 g limit. The general rule is to tow at a tension setting that produces a "comfortable" flight and "reasonable" climb rate.

The third skyting criterion requires center-of-mass distribution of the towing forces. If a hang glider were a single unit the towline could be attached to a single point, but because the pilot and glider move in relation to one another, the tow force needs to be distributed proportionally to their respective masses. It is the bridle's responsibility to properly distribute the towline force between the components of the flying system. In practice a 2:1 skyting bridle has been found to be quite effective in meeting the third skyting criterion. (Note: Many modern towing systems tow from the pilot's shoulders. You should realize that shoulder towing may be a better approximation to the skyting ideal than some of the other towing bridles in use today, but it still violates the third skyting criterion because it does not distribute the towing force between the moving components of the flying system.)

The forth skyting criterion requires that the tow force act only through the center-of-mass of the respective components. Violation of this criterion is responsible for lockouts, adverse yaw, and other loss-of-control problems. Most towing accidents are a result of the violation of this criterion because it is this loss- or reduction-of-control which prevents the pilot from being able to make the proper flight corrections to adjust for an increasingly dangerous situation. Ideally a skyting bridle should be attached to the pilot's belly and the floating crossbar of the glider, but most crossbars are not designed to withstand the resulting stress and many hidden crossbars are not even accessible. Therefore most pilots attach the bridle to the keel. Again, the best place is at the hang point, but French connections and pilot head room usually necessitate moving it a foot or so forward. Any resulting reduction in control is more than compensated for by the increased freedom of motion afforded the pilot.

The greatest danger of loss of control occurs when the bridle line is allowed to touch some other part of the control bar or flying wires (such as on takeoff, when topping out, or upon getting turned crossways to the towline). If the pilot cannot correct such a situation within a matter of seconds, he had better release from tow before the situation gets completely out of hand.

GROUP 2. SAFE TRANSITION

Adherence to the above four criteria is all that is needed to accurately simulate free-flight in a gravitational field. These criteria are the heart of the skyting concept and apply as long as the ideal towing phase of operation is in effect.

Unfortunately, non-ideal situations will occur in any practical towing operation and in practice it is always necessary to enter and exit the towing phase of flight. Therefore, in addition to the pure simulation of gravity, any practical skyting system also must be able to handle (5) deviations from the ideal case, (6) pilot release, (7) excessive tow force buildup, and (8) learning to use the system. The second set of four skyting criteria directly reflect these requirements.

The fifth skyting criterion is designed to see that the first four criteria are approximated at all times, even during transitions to and from towing and during fluctuations from the ideal conditions. The easiest way to meet this criterion is to use a long tow line with adequate stretch. Theoretically the more stretch the better, but in practice too much stretch can make it difficult for the driver to regulate his speed properly. (With excessive towline stretch it is hard for the driver to see how his speed is effecting the towline tension. He, therefore, tends to over compensate for tension variations and winds up speeding up or slowing down too much and/or too late to keep the tension reasonably constant.) Generally about 100 ft of stretch under a 1 g force (say 250 lbs) is about right for most towing situations. This is approximately the amount of stretch in a 1500 ft towline made of 1/4 inch polypropylene.

The sixth skyting criterion designed to make sure that the pilot will be able to release from tow whenever he wishes to do so. This is obviously important from the safety point of view. There are many types of releases that may be suitable for skyting, but whatever is used, it must be RELIABLE. Furthermore, the release activation point must be readily accessible to the pilot regardless of where his hands are positioned or where his body has shifted. And finally, double point release systems have been responsible for several very serious skyting accidents, so only single point release systems should be used. One of the most common release systems used today which meets the sixth criterion is a three-ring release located at the apex of the bridle and activated with a pull line looped over the pilot's wrist. After release the bridle stays with the glider and the pilot simply tosses it to the side, out of the way.

The seventh skyting criterion requires an infallible weak link. In my opinion this is absolutely essential for safe towing. Yes, I know that certain water towing systems have established excellent safety records without ever using a weak link. But I contend that there is always the possibility (no matter how remote) that the unexpected can happen, causing the towing forces to build up beyond the limits of safe towing. Furthermore, the limits for a "safe release" occur well before the limits of "safe towing", so if one is going to release from a potentially dangerous situation, he had better do so before the release, itself, becomes dangerous. To guarantee that this is possible, a weak link must be included. To properly serve its function it must be completely infallible, which means that it cannot be mechanical. It should be either a single loop or a single strand of consistent strength line tied with a consistent knot and experimentally tested to break at the desired tension limit. The break point should be appropriate for the weight and the experience of the pilot. It should never exceed one g of force (i.e., the combined weight of pilot and glider) although lower settings are suitable for learning situations and for more leisurly climb-outs.

The eighth skyting criterion requires a gradual advancement method of learning to use it. Obviously professional instruction under a qualified instructor at a certified school is the best way to learn. But whatever method is used, the pilot should gradually advance from one level of experience to the next after mastering each level in succession. The guidelines here are essentially the same as for learning safely and efficiently any other new skill. For example: (1) NEVER try two new things at once. (2) NEVER allow yourself to be pushed beyond your own personal level of comfort, (3) NEVER exceed the limits of your equipment or skills, and (4) NEVER go more than twice as high, fast, far, etc. as you have already mastered.

GROUP 3. PRACTICAL IMPLEMENTATION

The first two groups of skyting criteria constituted the original eight criteria. The third group of four criteria has been added only recently. In fact, these last four Skyting Criteria are so obviously a requirement of ANY safe and practical towing system that they were originally taken for granted, so now that they have finally been identified, they have been added to the list of skyting criteria. They are: (9) adequate power, (10) capable crew, (11) reliable communication, and (12) suitable environment.

The ninth skyting criterion, requiring adequate power, is obviously essential to any towing operation. Without adequate power the glider will never be able to climb properly and there is a high probability that a dangerous stall could result.

Skyting doesn't care what kind of power source looks like as long as it is capable of supplying the necessary power. Generally any power source that can supply a climb rate of about 400 fpm or more at an airspeed of about 25 mph is adequate for skyting. Although any power source can be used, the particular choice of the power source has a dramatic effect upon other aspects of the skyting operation. So much so that the power source should always be the first item considered when designing or selecting a skyting system. Car towing, winch towing, boat towing, ultralight towing, and even people towing each have their own peculiar skills, equipment, and procedures which must be employed if they are to be conducted safely.

The tenth skyting criterion requires that the crew be capable. Unlike foot-launched free-flight hang gliding, skyting cannot possibly be performed without a properly functioning ground crew to assist the pilot during the towing phase of operation. An absolute minimum crew consists of a single person operating the power source. This person (we will call him the "driver" of the "vehicle") must be in direct communication with the pilot at all times. And almost as essential as the "driver" is a "spotter" who maintains direct visual contact with the glider at all times. And almost as essential as the "spotter" is the "launch assistant" who helps the pilot prepare for a tow launch.

The eleventh skyting criterion deals with pilot-crew communication. Direct communication (preferably two-way, but at least one-way from pilot to driver) is essential for safe towing operations. Reliable radio communication (constant-on or voice activated) is required for towlines longer than about 500 feet (i.e. for almost all practical skyting operations) although visual signals can be used for shorter towlines. If no spotter is used, constant-on and constant-chatter radio communication is essential. (Constant-chatter means that the pilot must continuously talk clearly into the microphone and that the driver should immediately stop the vehicle if he cannot hear the pilot talking or if he cannot understand what the pilot is saying. Both pilot and crew should totally agree upon what signals are to be used (whether vocal or visual) before the flight, and rigorously adhere to them through the flight. If either deviates from the agreed upon signals and/or responses, the other should immediately abort the flight.

The twelfth and final skyting criterion deals with the environment. Skyting operations require a runway of at least four times the length of the tow line in no wind conditions. This means that a mile or more of runway is normally required for most skyting operations. Obviously the sides of the runway should be clear of obstructions that could possibly entangle the towline. The weather conditions (particularly cross-wind, turbulence, and wind gradient) should be within the control limits of both the pilot and the crew. Learning sessions should only be conducted in near ideal conditions with a smooth 5-10 mph wind blowing straight down the runway.

CONCLUSIONS

These twelve skyting criteria completely define what is meant by a "skyting" system of towing. Those and only those towing system which meet all twelve of these criteria may legitimately by classified as "skyting" systems.

There are many other towing systems in use today (systems which do not meet all of the skyting criteria), and some of these systems may actually be as safe as a skyting system, but most are not. Unfortunately, there seems to be no known way to distinguish the safe ones from the unsafe ones (except through their statistical safety records, which can be a pretty expensive way to evaluate an unproven towing system).

The skyting criteria, although not really a set of "safety" criteria as such, provide a means of identifying a towing system which is theoretically as safe as free-flight hang gliding and, therefore, as safe as a towing system can possibly be. Of course, no practical towing system will ever be able to totally fullfill all of the skyting criteria in all circumstances and under all flight conditions, but a paractical towing system should be able to fullfill the skyting criteria to a high degree of approximation. And the better the approximation, (everything else being equal) the safer the towing system will be.

At least that is my opinion. I will let you formulate your own opinion about the matter.
+
THE SKYTING CRITERIA

1. CONSTANT DIRECTION

The direction of the towing force must remain essentially constant throughout every phase of the towed flight.

2. CONSTANT TENSION

The tension in the towline must remain essentially constant throughout every phase of the towed flight.

3. C-M DISTRIBUTION

The towing force must be distributed between the components of the flying system proportionally to the masses of the respective components.

4. C-M ATTACHMENTS

The towline and/or bridle must be attached as closely as possible to the effective center-of-mass of each of the components and must not be allowed to touch any other part of the flying system.

5. GRADUAL TRANSITIONS

The transition to and from tow as well as any variations while on tow must be gradual in nature.

6. RELIABLE RELEASES

The release devices and their activation methods must be sturdy, rapid, and reliable.

7. INFALLIBLE WEAK LINK

The system must include a weak link which will infallibly and automatically release the glider from tow whenever the tow line tension exceeds the limit for safe operation.

8. SAFE LEARNING METHOD

The system must include a method for safely learning to use it by gradually advancing from one level of experience to the next.

9. ADEQUATE POWER

The system must contain a source of power adequate to maintain a safe mode of flight while under tow.

10. CAPABLE CREW

The system must be operated by a crew which is adequate in number and competent in ability to see that it functions properly.

11. RELIABLE COMMUNICATIONS

The system must provide a means whereby the pilot can reliably communicate to the rest of the crew.

12. SUITABLE ENVIRONMENT

The system must be operated only within the environment and under the conditions for which it was designed.
*
1985/08-03

POOR RESPONSE TO HOBBS SKYTING TOURNAMENT

Dear Donnell,

My apologies on being so remiss on information concerning the Hobbs Skyting tournament. I will preface any remarks about that, with the fact that the Standard class soaring competition in July was a great success, contrasting our efforts for the first major skyting tournament.

In spite of our efforts to woo skyters here in June, we met with absolutely no success. Mike Haley, from Lubbock, Tx. was our only qualified entrant. Through the Chamber of Commerce, we sent out nearly 100 letters to hang glider shops, and individuals throughout the west and midwest. As indicated on the printed flier, prize money was involved, and even without entries, we (I) had raised over $1000 in sponsorships. To tell you the truth, I was absolutely amazed at our lack of response. I really don't know what the problem was, perhaps the information came out too late; nevertheless, we received no response from even the semi-locals.

I certainly learned a lot about staging an event with the potential that I thought this had. The USHGA office was very helpful in supplying sanctioning, and insurance information. Quite a few calls were made to California, and I know I spent nearly an hour on the phone with Liz Jackson in Colorado on judging a contest like this, and making sure all the bases were covered.

If you might remember, per a conversation we had while I was trying to coordinate this, you stated that Skyting was still rather fragmented and I might have a difficult time getting a good representation for this event. I am sorry to say, you must have been right. When everyone takes a "wait and see" approach to something new, there's not going to be much to see.

Anyway, if anyone else wants to put together a Skyting competition, they can feel free to contact me, because I think I know some shortcuts that might be helpful. The major cause this letter is so late, is because I have been job hunting for the last couple of months, which takes a lot of time and effort. Fortunately, it paid off, and I'll be moving to Grand Junction, Colorado in four more days.

You might want to take note of this new address for your files.

Merlin D. Zimmet
803 Texas
Grand Junction, CO 81502
*
1985/08-04

FATAL AERO-TOW ACCIDENT

Dear Donnell,

Terry and I just returned home from the U.S. Nationals. I'm sorry to report an aero-towing accident that took the life of Chris Bulger, age 20, of Mercer Island, WA. It happened Wednesday, July 17, 1985, on our scheduled rest day, in the middle of the competition week.

Terry and I were heading for the Chelan airport to learn about aero-towing, when we met the ambulance coming out. Talking with some very upset pilots and friends, at the airport, about what happened, it became more unbearable.

I feel that it would not have happened had your guidelines for safe towing been followed. Here is the information I received: (1) No weak link, (2) no helmet, (3) no parachute. There was some speculation that Chris (in the tug) may have broken the release lever ((pedal)) trying to release the line under high tension. There was talk about the towed pilot being locked out to the left and having his release cord OUT OF REACH, tied on the far side of the A-frame. Chris tumbled from just above 1000 ft AGL after the tow line separated. The pilot being towed was not hurt, but had to be sedated.

Bill Cummings
Hoyt Lakes, MN
*
1985/08-05

ADDITIONAL INFORMATION ON FATAL ACCIDENT

(from WIND WRITER, Newsletter of the Houston Hang Gliding Association), Houston, TX)

Chris Bulger was killed on July 17, while piloting a powered ultralight trike. He was towing John Pendry and was at 1000 ft when the glider experienced a lockout above the tow vehicle, forcing the tug into a tuck. According to Hardy Snyman, they had been having problems with the weak link breaking, and so tripled (!?!?) its strength. The tug tucked twice before the bridle was ripped from the glider pilot! The tug tucked one more time (at 300 ft) and Chris was thrown from the tug. He wasn't wearing a helmet or a parachute. Chris was a well liked pilot and a determined competitor. He was the youngest pilot on the 1981 U.S. Team (age 16) and also flew at the next two world championships in 1983 and 1985. He shall be missed by all.
*
1985/08-06

PROBLEMS WITH WATER SKYTING

Dear Donnell,

Had a chance to test the deep water Skyting bridle that we had discussed last winter. I put a ring on the keel rope about ten inches from the apex slip ring. I then tied a rope from the bottom of each down tube after first feeding it through the newly added ring on the keel rope. I then carried the glider into shallow water and had two people hand tow me from the shore using a 130' rope. The newly added rope worked as expected. Next, we put the boat in and hooked to the winch. I moved the glider out into deep water to move out of a shore line produced rotor.

Here the trouble started! A gust had me backing up in the water. The left wing tip caught the water and started to roll over upside down. I released the tow line then unhooked the harness from the hang strap. I yelled to my driver that I was tangled in the bridle close to the sail and would be pulled under water when the glider finished rolling upside down. The boat then drifted over the tow rope, which wrapped around the propeller and killed the motor.

The observer dove in as I was pulled under. The floats on the base tube stopped the glider from sinking farther when they settled into the water but I was just short of the surface. This had to be Murphy's Law at its best! Just as my-would-be rescuer (Tim Nestler) finished swimming the last 100 miles to get to me, I was able to get free.

For water towing I think it would be best to be able to release the bridle from the glider and pilot. I do, however, like the apex release-type bridle that stays with the glider for land towing.

I guess I'll be Moyes towing over water until we can get the bugs ironed out of the deep water skyting bridle.

Bill Cummings
Hoyt Lakes, MN
*
*

[Tad Eareckson]

1985/10
*
SKYTING NO.41
SEP
OCT 1985
*
1985/10-01

WE SKIPPED A MONTH

You will notice that for the first time since SKYTING began its monthly publication an issue has been skipped. Actually the issues for September and October have been combined into this one issue. The reasons for this are the same as mentioned previously in SKYTING, namely: you have not been sending in enough material and I have not had enough time to write the material myself.

But do not despair. Since your subscription is recorded according to the final issue number and not the final date, you will still receive all the issues you paid for. (They will simply come a month later otherwise.)

Indeed, if this trend continues and I am able only to publish the Newsletter bimonthly, then you subscription will simply be extended to twice as long. Of course, you will still receive the same number of issues.

When I complained in the past that I was too busy to accomplish all that I wanted to accomplish, some of you have suggested that I use this bimonthly approach to reduce my work load. The main reason I have resisted this approach in the past is because of pride. But this time the load was simply too much for me to put out two issues during the time I had available. I hope you are not too disappointed about having to wait twice as long for this issue of SKYTING, but please understand that I am doing what I can to see that you receive your money's worth.

Donnell Hewett
*
1985/10-02

MEETING SKYTING CRITERION #1

by Donnell Hewett

SC#1. CONSTANT DIRECTION

The direction of the towing force must remain essentially constant throughout every phase of the towed flight.

Last month we reviewed the twelve Skyting Criteria and described briefly what features a towing system must exhibit in order to meet them. At that time it was mentioned that in order to meet the first Skyting Criterion the towline had to be long compared to the motion of the glider, and that 500 ft of towline was generally long enough to insure that the criterion would be met. In the space below, we will explore this idea further and try to provide a better understanding of how towline length influences the suitability and safety of towing.

In order to meet SC#1 (as well as several other Skyting Criteria) we need to have a better feel for what is meant by the phrase "essentially constant throughout every phase of the towed flight". It simply means that the property under consideration (in this case the direction of the towing force) changes slowly compared to the reaction time of the pilot and the response time of the glider. In other words, a pilot must have enough time to maneuver his glider adequately to correct a situation before it becomes dangerous.

In order to introduce a quantitative measurement we need to (1) determine a reasonable value for the RESPONSE TIME of the pilot and glider, (2) determine how much an "essentially constant" quantity may be ALLOWED TO CHANGE, and (3) to combine these together to obtain the MAXIMUM RATE OF CHANGE allowed in a quantity considered to be "essentially constant throughout every phase of the towed flight."

RESPONSE TIME

Obviously the time required to correct a potentially dangerous situation depends upon the type of situation, how the pilot reacts, and how the glider responds. If the situation is drastic, if the pilot is slow to react (or if he reacts inappropriately), or if the glider responds slowly, then more time will be required to get things under control. Therefore, it is impossible to define a specific time interval over which the towline direction (or other property of the system) must remain constant. But it is possible to give a ball park estimate.

Close your eyes and imagine that you are free-flying in a certain direction when a strong gust of wind hits you and knocks your glider off course and into an unusual flight attitude. Now visualize how long it will take you to get the glider back on course, flying straight and level. Time yourself.

What did you get for a typical overall response time? If you got 1 or 2 seconds, I think you are a little over optimistic or else you are not used to flying in gusty conditions. If you got 15 seconds or longer, remind me not to fly with you, for you are either too slow in reacting, or else flying in conditions I would rather stay out of.

Personally, I got a value in the neighborhood of 5 seconds for a typical gusty situations and slightly longer for really radical air. I figure that any towing system which is able to maintain constant towing characteristics for up to 5 or 10 seconds will adequately simulate the free-flight situation.

ALLOWED CHANGE

Now we need to ask ourselves how constant the towing characteristics have to remain in order to be considered "essentially constant". In other words, how much can they be allowed to fluctuate before they are no longer "constant". Again, this is impossible to specify rigorously, but a ball park figure can be obtained.

The general rule I follow here is to say that the characteristic is adequately "constant" if an abrupt, unexpected change no larger than a given amount would not disturb the pilot's confident control of the situation.

Close your eyes again, and imagine that you are flying (this time on tow) in typical gusty conditions when some characteristic of the towing system suddenly changed. How large a change would be required to really disturb you, or cause you to lose some control of your glider?

Try this mental experiment using the towline direction characteristic. Assume that everything else remains constant and the bottom of the towline suddenly switches to another location. (Don't worry about the mechanism that causes this, just assume that it happens.) If the direction of the shift is only about 1 or 2 degrees, I doubt that you would even notice it (unless you just happened to be watching the towline when the shift occurred). But if the towline suddenly shifted by 45 degrees or more, you would probably panic (regardless of where you were looking when it happened)! Personally, I would consider the towline direction to remain essentially constant as long as it stays within about 10 degrees of the mean value. (Deviations of up to 20 degrees might even be handled, but that is probably pushing the limit.)

MAXIMUM RATE OF CHANGE

So it would appear that the towline direction may be considered to be constant as long as it changes no more than 10 to 20 degrees in a time interval of no more than 5 to 10 seconds. This means that the towline direction may be considered to be constant throughout every phase of the towed flight as long as it varies no faster than about 2 degrees per second.

Higher rates than this could probably be used as long as the pilot had the necessary flight skills and was careful to stay on top of things. For example, a directional change rate of 5 degrees per second would give the pilot only about 18 seconds to correct for and follow a 90 degree change in directions. This is probably too fast for most pilots to follow. A good pilot could probably handle such a situation, but if he made a single mistake, he would probably be unable to correct it before the situation became critical.

We shall, therefore, assume that the towline direction may be considered to remain essentially constant throughout every phase of the flight as long as it varies no faster than 2 degrees per second.

VERTICAL MOTION

Now that we have a quantitative description of SC#1, let us use it to determine the minimum length of a towline during climb out. Here we notice that a typical rate of climb while on tow is about 400 ft/min which may become doubled if the pilot enters a reasonably strong thermal. Let us use a climb rate of 600 ft/min or 10 ft/s as a typically high rate of climb.

In order to see how this determines towline length, look at Fig. 1. There you will see a glider climbing out at an angle A. During a small interval of time dt the glider climbs through a height dh, swings through the arc ds, and through the angle dA.

From the geometry of the small triangle, one finds

dh = ds cos A ,

and from the large triangle one obtains

ds = R dA ,

where it is assumed that A is measured in radians.

Combining these equations, dividing by dt, using a prime to denote the time rate of change of a variable, and solving for the rope length R, one gets

R = h' / (A' cos A .

If one now sets h' = 10 ft/s and A' = 2 deg/s = 0.035 rad/s, he will find that the towline length needs to be at least 300 ft long for the initial climb out and about 600 ft long when topping out (at an angle of about 60 degrees).

During the learning process, where the pilot keeps his climb rate below 300 ft/min and his tow angle below 45 degrees, he could use a towline as short as 200 ft. But this is approaching the absolute minimum length of towline for safe towing.

TRANSVERSE MOTION

Let us now look at the transverse motion of the glider and see how that affects the minimum length of the towline. Fig. 2 shows the top view of a situation where the glider is towing at an angle B with its nose pointed at an angle C with respect to the runway.

The velocity of the glider through the air is represented by the vector V. Generally the magnitude of this vector is between 20 and 30 mph (or 29 and 44 ft/s) while the glider is on tow. Therefore, a typical air speed for fast towing is about 27 mph for 40 ft/s).

If the glider's nose is pointing at an angle C with respect to the runway (See Fig. 2), then its transverse velocity VT is given by

VT = V sin C

where transverse velocity means the velocity perpendicular to the runway. Table 1 shows the transverse velocity VT for various nose angles assuming that V = 40 ft/s:

C (deg) VT (ft/s):
+
Table 1. Transverse velocities.

05 03
10 07
15 10
20 14
30 20
45 28
60 35
90 40
+
Notice that the transverse velocity remains less than 10 ft/s as long as the nose angle is less than 15 deg, and that it remains less than 20 ft/s for nose angles less than 30 degrees. The worse possible case is for the nose angle to become 90 degrees, in which case the transverse velocity becomes 40 ft/s.

It is the transverse velocity that moves the glider to the side of the runway and changes the tow angle B in Fig. 2. Specifically, the projection of VT along the towline determins how fast the glider swings along the arc s of the towline. Therefore,

s' = VT cos B ,

where s' is the speed of the glider along its arc of swing.

But s' is related to the angular speed B' through the equation

s' = r B' ,

where r is the radius of the arc.

From Fig. 1 it can be seen that the radius of the arc r is related to the length of the towline R through the equation

r = R cos A ,

where A is the vertical tow angle.

Combining all of the above equations and solving for the towline length gives

R = (V sin C cos B) / (B' cos A)

If we make the assumptions that angles A and B are small (or else approximately equal to one another if they are large), that V = 40 ft/s, and that B' = 2 deg/s = 0.035 rad/s, then Table 2 gives the length of the towline required to tow safely as a function of the nose angle C:
+
Table 2. Transverse towline lengths.

C (deg) R (ft)

15 0300
30 0600
45 0800
60 1000
90 1200
+
The length of the towline is clearly dependent upon how closely the pilot is able to track the tow vehicle. This, in turn, depends upon pilot skill and the amount of turbulence in the air. In smooth air a 300 ft towline should be adequate for almost any pilot, in mild turbulence a 600 ft line would be more appropriate, and in heavy turbulence a 1000 ft towline would be required.

SUMMARY

From the above discussions on the effects of vertical and horizontal motion we can now form some general conclusions regarding the appropriate minimum length for a towline to be able to fullfill Skyting Criterion No. 1.

The absolute minimum safe towline length is about 200 ft. The conditions under which such a short towline may be used are (1) smooth air, (2) low tow angles (less than 30 deg), (3) low climb rate (less than 300 fpm relative to the tow vehicle), (4) slow air speed (less than 25 mph, but obviously above stall speed), and (5) perfect tracking (absolutely no maneuvering while on tow).

Since almost all aerotowing is performed on a 200 ft towline in reasonably gusty conditions at air speeds above 25 mph, you can see why both tug pilot and glider pilot must exercise extreme caution to maintain perfect tracking. There simply is no room for pilot error. This is particularly true when a gust tosses the tug one direction and the glider the other, for then the effective towline length is cut in half - 100 ft. At airspeeds around 40 ft/s, both pilots only have about 2 or 3 seconds to get their respective aircraft back into the proper alignment.

Under anything but the mildest conditions, the towline length should be from 300 to 600 ft in length. A 500 ft towline allows a glider flying at 40 ft/s to deviate as much as 26 deg from his tow direction and climb at just about any reasonable rate. Since 26 deg is a fairly large deviation, a 500 ft towline will fullfill SC#1 under almost all reasonable flying conditions.

A 1000 ft or longer towline should fullfill SC#1 under essentially any safe flying condition. In other words, of your towline is more than 1000 ft long you no longer need concern yourself about fullfilling SC#1. Even if you should get turned 90 deg crossways, the direction of the towline will not change too fast for you to handle it. You may have other control problems (such as a lockout due to the bridle pressing against the flying wires), but you should have no problem with rapidly changing towline direction.
+
Fig. 1. Vertical Motion.
+
Fig. 2. Transverse Motion.
*
1985/10-03

OTHER FACTORS AFFECTING TOWLINE LENGTH

by Donnell Hewett

There are other factors besides Skyting Criteria No. 1 which influence the length to be chosen for a towline. Some of these factors suggest that the towline should always be kept as short as possible, other factors suggest that the towline needs to be as long as possible, and probably an optimum length for the towline.

SHORT TOWLINES:

COST

One of the most obvious factors influencing your choice of towline length is the cost of the towline. At first glance it would appear that this cost is directly proportional to the length of the towline.

For example, doubling the length of the towline will double its cost, double its stretch, double the cost of operating the vehicle, double the required ground handling effort, double the turn-around time, and double the amount of wear on the rope. If you placed a dollar amount on each of these items it would appear that doubling the towline length would double the total cost of the towline while doubling the attainable height. This means that the cost per gain in height would remain independent of the length of the towline.

However, the increase in wear decreases the useful life of the rope, so that the lifespan cost of a towline increases faster than its length. Therefore, it simply is not cost effective to use a towline longer than necessary to accomplish your desired goal. If a shorter height on the same runway under the same conditions, then why use a longer line?

Well, I can think of a few reasons. For example, if the conditions are likely to change, or another runway is likely to be used soon, or the system is already set up with a towline of a particular length. Under conditions like these the wear on the extra towline is small compared to the effort required to shorten it. Furthermore, once the line has been shortened, splicing it back together produces a weaker line and one that wears out even faster. Never-the-less, under normal circumstances (where you wear the rope out under a reasonably consitent set of conditions) you should use the shortest towline that will do the job.

How can you tell if your towline line is too long? This is really a complicated question which requires an extensive analysis of your particular towing situation. However, there are two simplistic answers that can be given.

One way to tell if your towline is too long is to take a look at your pocket book. If it is almost empty, then your towline is too long.

Another way to tell if you are using too long a towline is to simply notice the tow angle when you release. If you are consistently releasing at tow angles of less than a 30 degrees, then you can be fairly certain that your towline is too long. (Conversely, if you are releasing at tow angles greater than 60 degrees, your towline is probably too short.) As a general rule of thumb, you should be releasing at a towing angle of about 45-60 degrees near the end of your runway if you want to attain the maximum possible height.

REWINDING LINE

If you have a power winch or reel to rewind your towline, the length of the line is not a critical factor. But if you have to reel it in by hand, you certainly do not want to use a towline which is any longer than absolutely necessary to accomplish your goal.

DRAGGING LINE BACK

Obviously the longer the towline, the more difficulty you will encounter when you drag it back to take-off and set it up for the next flight. Entanglement, weight, wear, time, and overall effort all increase with increasing towline length. Yes, a power reel can make towline retrieval a lot easier by allowing you to quickly rewind the line after each flight without having to drag it back the full length of the runway, but even here the time, the wear, and the effort required to service the towline is proportional to the length of the towline. So regardless of what method you use to handle the towline, you want to keep it as short as possible.

BEGINNERS

Beginners generally require a shorter towline than experienced pilots. There are several reasons for this. For example, a beginner needs to make a large number of short flights, he needs to stay at low altitudes, the instructor needs to stay close to the pilot and glider, and the towling field needs to be as convenient as possible (therefore it is usually small).

Ideally it would be nice if a 10 or 20 ft towline could be used (so the instructor could always be right there to direct and assist the beginner in his early flying attempts) but such a short line is a clear violation of SC#1. So a towline of at least 200 ft should normally be used when towing beginners.

There are, of course, many other important factors besides towline length which must be considered before towing beginners, but a discussion of these factors is more appropriate in an article dealing with "ab initio skyting".

LATO

Landing at takeoff is essential if a large number of flights are to be accomplished in a minimum amount of time. This is particularly important during the novice (or early intermediate) stage of training. Carrying, wheeling, or trucking the glider back to the launch site after each flight (of several hundred hundred to a few thousand feet) can really eat up the time and energy.

What is the minimum length towline which can be used and still allow the pilot to land at takeoff? Well, obviously the answer depends upon the skill of the pilot, the performance of the glider, the weather conditions, and the towing techniques being used. But regardless of the particulars associated with a given flight, it is obvious that in order for the pilot to land at take-off he must have sufficient altitude to complete the equivalent of at least a 360 degree turn.

In free-flight hang gliding 500 ft is generally recognized as being the minimum safe altitude for a pilot to make his first 360 degree turn. To attain this height, the towline needs to be about 600 to 700 ft in length. Of course, if the pilot already has experience in making 360's, he should not need the full 500 ft of altitude to be able to land safely at takeoff. This suggests that the minimum length towline required for safely landing at take-off under typical towing situations is in the neighborhood of 500 ft.

TROLLING FOR THERMALS

In order to begin a cross country flight, it is necessary for a pilot to find his first thermal. If this can be done while still on tow, then his chances of "landing out" are significantly reduced. Obviously, if the runway is long enough, it is to the pilot's advantage to stay on tow until he is able to release in a good thermal. This process of searching for thermals while still on tow is called "trolling for thermals".

What is the minimum length towline that can be used for thermal trolling? Again there are a lot of variables, but regardless of the circumstances, the pilot needs to be high enough for the thermals to be large enough and strong enough for him to be able to climb in them.

In free flight hang gliding pilots have been known to find such thermals as low as 100 ft, but generaly speaking 500 ft is more common. So once again it would appear that the minimum length towline for expecting reasonable chances for success in trolling is about 500 ft.

LONG TOWLINES:

EXTENDED FREE-FLIGHT

If a pilot wants to have a maximum extended free-flight after releasing from tow, then he needs to climb as high as possible before releasing. This means that the towline needs to be as long as possible.

What is the minimum length towline that will result in a free-flight long enough to have a reasonably good chance of finding a reasonably good thermal before having to land? Once more there are a lot of variables that enter the picture, but sail plane pilots generally tow to 2000 ft before releasing.

Since hang gliders can climb in smaller thermals than sail planes and can afford to "scratch for lift" at lower altitudes, they may be able to release at lower altitudes than sail planes and still have as good a chance of catching a local thermal. On the other hand, sail planes have a better glide ratio than hang gliders and can cover more territory in searching for thermals. So hang gliders may have to release higher than a sail planes in order to have the same chance of catching a distant thermal.

My guess is that the plus and minus aspects of the hang glider pretty well cancel out, so that the minimum length towline for a reasonably extended free-flight is about 2000 ft. Of course, if one trolls for thermals while on tow and searches for them after release, then a 1000 ft towline might be the minimum length needed to provide a reasonably good chance of finding that first thermal.

TOWLINE SAGGING

The sagging of the towline is a result of the towline weight and the wind resistance. This bending reduces the efficiency of the towing process by reducing the forward thrust on the glider and increasing the downward load. The amount of bending generally increases with the length of the towline, so that eventually a point will be reached where increasing the towline no longer results in an increase in attainable height. It is obviously counter productive to use a towline longer than this length. If a longer towline is desired, steps must be taken to reduce either the towline weight or the towline drag.

Actually, with modern materials, towline weight is generally no problem. A hang glider can easily support enough towline to reach altitudes of over a mile. Never-the-less, with extra long towlines or towlines made of heavier material, the weight may become significant. If weight does become a problem, please contact me personally, I'll be quite interested in learning what you are trying to accomplish with a 200 lb towline.

Air resistance is probably more of a problem than rope weight, but even this is not a major problem unless unusual heights are attempted. Nylon, polyproplene, polyethylene, and even steel cable have all been used for skyting. All are sufficiently strong so that small diameter lines can be used. Since it is the diameter of the towline that is primarily responsible for air resistance, you should try to reduce the diameter of your towline if you need to reduce towline bending. Of course, there is a limit as to how small a line you can use and still have the strength to tow. But this is a small problem compared to the others you are going to be facing when the FAA catches you towing up to 20,000 ft.

Oh yes, you can also reduce towline bending by simply increasing your towline tension. Again there is a limit - this time determined by the weak link you are using. But if you keep breaking your weak link trying to straighten out excessive towline sag, then perhaps you should consider trading in your glider for a good spaceship. Contact NASA about this.

OPTIMUM LENGTHS:

SHORT FIELDS

Sometimes the most dominant factor influencing the length of the towline is the length of the runway. Obviously you cannot tow with a towline longer than the length of your runway unless you begin your takeoff beyond the edge of the runway. (Here, of course, I am assuming tension gauge towing and not winch or reel towing where the towline can be several times longer than the length of the runway.) If you do begin your takeoff beyond the end of your current runway, then you have only increased the effective length of your runway. Your towline still cannot be longer than the new "effective length" of your runway.

For a runway of limited size, you will have to select a towline length which maximizes your altitude gain by the time you get to the end of your runway. If your towline is too short, then you will top out too early and not reach the altitude you could. If your towline is too long, then you will not have enough runway left to reach your maximum attainable height. Obviously there is an optimum towline length (under a given set of circumstances) which will render the maximum attainable altitude.

This optimum length of the towline depends upon numerous complex factors including glider performance, flying conditions, and towing techniques. We will postpone a detailed discussion or this topic until a later article, but as a general rule the optimum length of the towline is in the neighborhood of 1/4 to 1/2 the length of your runway.

LINE STRETCH

The length of the towline dramatically affects the amount of stretch in the towline. If the towline is too long or too short, then there will be too much or too little stretch in the towline.

Since the stretch in the towline is directly proportional to the length of the towline, then there exists an optimum (or near optimum) length of towline for a given material of a given diameter. Since the stretch is inversely proportional to the square of the rope diameter, one can adjust the optimum length to any reasonable value by simply selecting a line of the proper diameter.

There are so many available materials and possible diameters that it is impossible to specify the optimum line length in every case, but as a general rule, one needs about 100 ft of stretch in the towline. If the towline is 1/4 inch in diameter and made of nylon or polypropolene, then it needs to be approximately 1500 ft to provide the needed 100 ft of stretch before breaking a 200 lb weak link.

CONCLUSIONS:

There may be other factors which influence one's choice of towline length, but the ones mentioned above seem to be the most obvious ones to me. Certainly there are enough mentioned here to convince you that the "ideal" towline length is hard to determine.

Fortunately, the particular choice of towline length seems to have little bearing in actual practice. If you are off by a factor of two in your selection of towline length, who cares? The situation is usually nowhere critical! If the current length of your towline does not bother you in some way, then change it! And keep on changing it until you get what you want.

One final thought. Many of you may think that this whole article has been a total waste of time. Perhaps you are one of those pilots who either (1) use whatever towline you happen to have available regardless of its length, or (2) decide how high you want to go and add 50% to determine the towline length. Well, if you are one of these people, than may I suggest that you save yourself a lot of time and grief by simply not reading this article.
*
WRIST RELEASE CAUSES INJURY
*
1985/10-04

Dear Donnell,

We recently had an unfortunate towing accident in which a student pilot dislocated her elbow. On her 3rd tow flight, she neglected to flare on landing. The wheels dug into rough ground, and she swung through. The wrist release line pulled tight, and caused the dislocation.

To prevent this occuring again, we are planning to rig our release lines a different way. Instead of running the end to loop around the pilots wrist, it will angle down from a point low on the downtube, and be anchored to the base tube. I've tried to draw this below.

The pilot should be able to release with hands on both the downtubes and the base tube. (Note that the arm motions - downward and outward, respectively - are the opposite of the moves with a wrist loop.)

I want to stress - we haven't tried this yet. There may be problems we haven't thought of.

Tom Bushell
Nova Scotia, CANADA
*
1985/10-05

Dear Tom,

I can think of one potentially dangerous situation that could occur with your proposed setup. If the glider gets in a lockout to the wrong side your pilot may have to shift his weight to the side of the control bar opposite your release line. He may then find it impossible to reach the release line without shifting his weight back toward the center and thereby aggravating the lockout. It is rare, but I have heard of very serious accidents occurring because of this one sided release line system.

An alternative to discarding the wrist release concept is to use a weak link in the release line (although I have not heard of anyone doing this). If you do this, you should also attach the release line to the control bar so that if the weak link breaks in flight, the pilot could still take up the slack and release.

Another alternative to discarding the wrist release concept is to loosely loop the release over a finger and hold it in your hand. (See figure below.) I have used this system myself, particularly when I want to be able to discard the release line quickly and easily after release. But I am not too sure how it would have helped in the situation you described. If the student knew what was happening in time to react, she could have discarded the line, but more than likely she would have failed to do so and some kind of injury (finger, wrist, or elbow) would have happened anyway.

Donnell
+
Release Line
Ring
Clamp
*
*

[Tad Eareckson]

1985/11
*
SKYTING NO.42
NOV 1985
*
1985/11-01

LET'S STANDARDIZE

by Donnell Hewett

HELP NEEDED

As some of you may know, Doug Gordon is currently in charge of writing up a set of surface towing guidelines for the United States Hang Gliding Association. He has asked me to assist in this project, and we would also like to solicit your help.

Now don't panic. We're not asking you to do a whole lot of work. Much of the work has already been done by Doug. The following "Skyting Standards" was developed by taking Doug's ideas, combining them with some of the ideas in USHGA'S Ultralight Towing Standards (Skyting No. 29.), and then sprinkling in a few ideas of my own. What we need now is a few opinions from you. Surely you have opinions, don't you?

By the way, since the purpose of this project is safety (rather than just an increase in bureaucratic regulations), we are not only interested in the opinions of individuals inside the U.S. of A. but also in the opinions of persons across the border. After all, safety knows no national boundaries.

Please realize that we are not asking for your approval, but your critisizm. Do not feel obligated to be kind or gentle, simply to be honest. Look these "Skyting Standards" over carefully and be as picky as you like. If you do not like a word, phrase, or number, let us know. If fact, we are particularly interested in whether or not the numbers (and other specifics) are consistent with what you consider to be the correct values for a minimum safety standard. Ask yourself if your own particular skyting system meets these standards. If not, then which do you honestly feel should be changed, your system or the standards?

We are also interested in whether or not you think certain crucial requirements have been omitted. Naturally we do not want to get so specific that flexibility suffers and safety development is hindered, but we do want to specify the minimum requirements of a safe skyting system.

SEPARATION?

And finally, I, personally, would like to know how you feel about establishing a separate set of safety guidelines for skyting (as opposed to other forms of towing). These proposed standards are specifically designed for "skyting" systems. But the original goal set by USHGA was to establish a set of guidelines suitable for ALL forms of "surface" towing. (USHGA already has its standards for air-to-air towing.) The guidelines requested would need to be general enough to apply not only to skyting but also to the older "conventional" form of water towing (i.e. to "Moyes towing"), because there are still a quite a few influential members of USHGA who still prefer towing on the traditional system.

Now, I can understand why an organization would want a single surface towing standard rather than a different standard for each form of towing. But the more I study the problem, the more I become conveninced that it is impractical to write a set of useful guidelines suitable for all forms of surface towing. There are simply too many incompatible differences between the Moyes towing technique and the skyting technique. Each technique clearly violates some of the essential safety guidelines of the other. If fact, there is more difference between Moyes towing and skyting than between aerotowing and skyting. Therefore, it would be more reasonable to lump aerotowing with skyting than to lump Moyes towing with skyting.

Personally, I believe that a clear distinction should be made between Moyes towing and skyting and that USHGA should establish separate towing guidelines for each. To fail to recognize these differences (not only in system design but also in basic philosophy) is to promote confusion and to court disaster. My major concern is that in trying to make the guidelines general enough both for Moyes towing and for skyting the results will be inadequate safety for either. Or else, the guidelines will be so complex (full of "if" clauses" that it will be both confusing and impractical.

Of course, there are a lot of differences in various skyting systems, too. So much so, that system specific guidelines must also be established if adequate safety is to be attained. Doug suggests that instead of trying to incorporate everything into a single comprehensive guideline, that both general and specific guidelines be developed. This seems like a good idea to me. So the general "Skyting Standard" proposed here incorporates a method whereby any specific skyting system can become "Approved".

ENCOURAGEMENT

I am encouraged. It looks to me like a reasonably consistent skyting standard is beginning to emerge on its own, as everyone voluntarily tries to maximize the safety of their own skyting system. Now seems to be the proper time to identify this general standard and to adopt it officially. Even if USHGA decides to adopt another standard our efforts will not have been in vain, for our goal is not adoption but SAFETY.

On the other hand, I am confident that if we are able to present USHGA with the best possible set of safety guidelines for this form of towing, then they will be willing to adopt them. In fact, I am quite optimistic. Things, finally seem to be coming together to bring about a situation I have long envisioned - a situation where an individual can receive (1) professional quality skyting instruction and training (2) by a Certified Skyting Instructor (3) on an officially Approved Skyting System (4) that meets officially sanctioned Skyting Standards.

With your help, that day may not be far away.

SKYTING STANDARDS
(Preliminary Proposal)

A. GENERAL SAFETY GUIDELINES

Every aspect of a skyting operation (personnel, equipment, and procedure) at all times shall conform to the twelve Skyting Criteria.

B. PERSONNEL STANDARDS

1. Every person (whether pilot or crew) involve in a skyting operation shall have received sufficient ground schooling to pass an appropriate test demonstrating that he understands the general theory of skyting, the particular system he is operating, and the specific duties his is to perform.

2. In order to qualify as being experienced in any particular aspect of skyting (pilot, driver, spotter, winch operator, etc.), an individual must have properly performed the necessary tasks and demonstrated the necessary skills associated with that aspect of skyting (see below) in front of a qualified skyting instructor on at least five (5) successful flights.

3. To qualify as an experienced skyting pilot, an individual must have demonstrated his ability to safely (1) perform a skyting takeoff, (2) handle a weak link break, (3) track straight, (4) correct for turbulence and wind shear, and (5) release before a lockout situation develops.

4. To qualify as an experienced driver (or winch operator, etc.) an individual must demonstrate his ability to (1) properly operate the power source, (2) accelerate properly for a smooth takeoff, (3) maintain the proper tension while on tow, (4) decelerate properly for a smooth release, and (5) react properly in the event of an emergency.

5. To qualify as an experienced spotter an individual must demonstrate his ability to (1) distinguish between normal, unusual, and dangerous flight attitudes, (2) communicate clearly and relay messages between pilot and relay messages between pilot and driver, and (3) react properly in the event of an emergency.

C. EQUIPMENT STANDARDS

1. The glider being towed must meet or exceed the Hang Glider Manufacturers Association's Airworthiness Standard.

2. The power source must be able to supply a towline tension of at least 200 pounds at a velocity of at least 25 mph. The operator of the power source must be able to see the actual takeoff event either by direct line of sight or through a properly mounted rear view mirror.

3. The towline must be at least 200 ft in length and have a rated breaking strength of at least twice that of the weak link.

4. If tension is regulated by an automatic device (winch or reel), that device must be able to maintain the tension to within 25 pounds of an adjustable preset value. If the tension is regulated by a human operator (driver or winch operator), then (1) a tension gauge must be used which can easily be seen by the operator and (2) the towline must stretch at least 30 feet before the weak link breaks.

5. A short leader shall be placed between the bridle and the weak link to reduce the danger of flyback in the event of a weak link break.

6. A reliable single point release system shall be used with the release line or lever located within easy reach of the pilot regardless of his body position. The release shall be designed to function properly even if the bridle lines should be touching the flying wires or the control bar. It must be tested to verify that it releases properly under a tension of twice that of the weak link break point.

7. The weak link shall be tested to break at less than the combined weight of the flying system (pilot, glider, and instruments).

8. Radio communication between pilot and driver shall be used unless (1) a spotter is employed, (2) the towline is short enough (probably less than 1000 ft) for the spotter to clearly see the pilot's signals, and (3) the visual signals to be used are thoroughly understood by both the pilot and the spotter. If no spotter is used, the lock-on, constant-chatter method of communication must be employed.

9. Wheels shall be used on all training flights over land, and appropriate flotation devices shall be used on all flights over water.

D. PROCEDURE STANDARDS

1. Prior to any takeoff, everyone involved in the towing operation must agree upon the general flight plan, the communication signals to be used, and the emergency procedures to be followed. If anyone at any time deviates from any of these agreements, the flight shall be aborted immediately.

2. Prior to every takeoff a check list shall be used to verify that all important preflight requirements have been fullfilled.

3. No more than one new component, inexperienced person, unmastered task, or unproven aspect of a skyting system may be utilized during a given flight and that item must be perfected before another new item can be introduced.

E. USHGA RATINGS, CERTIFICATION, AND APPROVAL

1. In order to receive a special Skyting Rating, a pilot must (1) possess at least a USHGA Intermediate Rating (level 3) and (2) be recognized by a Certified Skyting Instructor as being experienced in every aspect of an Approved Skyting System.

2. In order to become a Certified Skyting Instructor, an individual must (1) possess a USHGA Instructor Certification, (2) have a special Skyting Rating, and (3) have logged a minimum of fifty (50) flights on an Approved Skyting System.

3. In order to become an Approved Skyting System, a towing system must be documented as follows: (1) The particular components of the system, their arrangement, and the operational procedure must be specified in writing. (2) The system must be reviewed, flight tested, and endorsed by at least two Certified Skyting Instructors. (3) The documentation package must be accepted by the United States Hang Gliding Association or its authorized committee.
*
1985/11-02

BRITISH TOWING INSTRUCTION

Dear Donnell,

It's been tipping it down with rain today and the wind has been listing the trees about. The temperatures up until yesterday were in the 80's - almost unheard of in October Britian. The ridge of high pressure kept everything calm and hot and we were able to pass 4 new pilots from towline training. I agree that perhaps teaching beginners on tow may not be financially equal to training on the hill, but - and it's a big BUT - small classes show better and more consistant progress, the result being happy pilots with good airmanship.

Our school is now part of the British training scheme and pilots graduating from tow must do a hill endorsement in order that they become fully rated as "Pilot Ones." (Our provisional licenses to fly.) This is done at one of the regular hill schools.

Find enclosed extract copies of recent Wings magazine. It may seem egotistical, but let the copy decide.

Also enclosed is a schematic drawing of our bridle. This is still the best solution to our problems. I.e. keeping the system clean and easy to operate plus not having to drop onto concrete any important bits. All that drops is the 8 ft threader and 2 inch ring.

Enclosed you will also find a map showing flights for our National League for Cross Country. Any member sends in is or her distance and they are plotted on the map. We have worked for 19 months to get the two lines in the flatlands.

Rona has recently done a 14 mile flight from East Kirkley in Lincolnshire to the coast. She landed at the Skequess light airport. In fact she was glad to get down from strong frontal lift at 2000 ft. ASL.

My claim to X.C. is a short 6 miles made in gently evening lift at tea break during a hard teaching day.

Tony and Rona Webb
Leicester, ENGLAND
+
Fig. 1. Lejair's bridle.

LEJAIR'S SHORT THREADER.
Based on the Skyting Bridle)

King Post
Location strap
Mounting leg strap
"A" frame
Bowden cable
Pull
Aircraft wingnut assembly
Builformed plastic tube as tow leg
Pull cord
Pull cord
Bungee retract
Small Carabiner
Release
Threader
Towline To ring
Billy cord to Ring
Emergency Pull tube release
Rope to harness

LEJAIR'S SHORT THREADER.
Based on the Skyting Bridle)

Using an eight foot threading rope connected to a Bowden cable operated release cord which runs down an upright with extension loop for prone release function, i.e. release in hand at all times einious hands off.

TUBE PULL back up release, in case of threader malfunction.

BUNGIE RETRACT to clear tow leg from pilots vision after release.

Rigging is simple and adapted to any glider.

Sold complete or in kit form to any pilot holding a towing endorsement.

COMPLETE LEG
- + 5.00 inc vat
KIT FORM
- 0055.00 inc vat

pounds

MODIFICATION NOTE

The new tube pull body release is available to existing bridle owners at 3.00 exchange.
+
Fig. 2. British Cross-Country Flights for July 1985.

NATIONAL X-C LEAGUE

First XC Norfolk Flatlands
Weekends Flying
Weekdays Working
*
1985/11-03

TOWING

Ivan Pennell reports on his conversion course.

(from WINGS, the official publication of the BHGA.)

If you want to have the chance of flying when it's nil-wind or your hill is facing the wrong way, you really ought to take up towing. You really ought to take up towing anyway.

The first step in the conversion process is to ring Tony about Tuesday of the week before you want to go and he will tell you "Yes" or "No".

We met at the guardroom RAF Sculthorpe (which is about 20 miles East of Kings Lynn) at 0900hrs. Once on the Airfield we rigged Tony's gliders. Tony showed us how to attach the "Towing leg" to the glider & also the webbing strap required (on a Supp it would attach to your leg loops until you have permanent fittings added). On my harness it attached to the triangle formed by the main risers next to the apron.

The towing leg is, I think, a piece of plastic electrical conduit with a wire running down the centre. The release is (so I'm told) an old type Hercules transport aircraft cargo tie down unit and is an over lapping pincer type unit with the trigger on one edge. It seems to work well although I wouldn't fancy it's chances if it had a clout (i.e. an impact contact with the runway). So I'm glad to report that Tony does teach you to do a good release check under tension using both methods of release.

Release is accomplished by operating a "piece of string" attached to the wire that exits the conduit and is clamped to an upright at the top and tied to a wing wire thimble at the bottom. This keeps it about half an inch clear of the tube so on takeoff your hand is between the string and the upright.

If for any reason you want to release, all you have to do is throw your arm out and you're off the line. Another string is tied to the first on a sliding knot with a loop under your little finger. If you pull this, it will slide to the center of the release string next to the upright and operate it with little effort. This second release string is for when you are climbing out after transferring your hands to the base bar. You just pull your hand over to the center of the base bar and the release is operated easily and safely.

DEMO FLIGHT

Tony Webb then did a demo flight to which my reaction was "What am I doing here?" as it looks all wrong - far too steep and quite scary. Then he sent Edmund Potter up on the towline. Edmund showed us that Magics perform as well on the line as in free flight by thermaling off and trying to repeat his 40 miles to the coast the day before. Then, after a few others had tested the delights of towing for the first time ... it was my turn.

"DEAD EASY"..THE MAN SAID

Gulp! "First we will give you a man tow". 2 or 3 helpers then hooked me up using a rope with a ring after the weak link then another piece ending in a spliced end loop. It threads first through the ring on your harness back to the ring on the line then onto the release. This gives a 2 to 1 pull, twice as much pull through the harness as through the glider. "Don't try to run, let it pull you." Very hard to resist the urge to pull the bar in and try to fly, but I got it right after two goes.

Then came the moment I was dreading. "A short tow to thirty feet or so", releasing on Rona's signal. Rona operates the winch (very pretty). Tony started asking me hard stuff like "What would you do given an emergency?" "Er what?". My mind was blank. (military training?- Wings Ed.) Tony told me patiently again... "Top release off... check it has unthreaded, if not pull pin on webbing to get rid. cable break?...bar in, pull release get rid of line, check it's gone, never pull webbing pin if not released from main point or all the pull goes to the glider, if you want to stop the tow open your legs, if you want the cable cut open and close your legs ... GOT IT?". "Err-Yer".

IT'S NOW OR NEVER

Hook line on... check release twice..."Remember, stay on the uprights and watch Rona, when she waves, pull on, get the line slack then release...OK?" "Err-Yer".

"Take up slack. ALLOUT!" Holding back was even more weird behind a car and I thought "What a time to have your first flight on a Polaris." Hanging back... two steps and I'm flying. Glider is very stable, nice climb, not at all frightening. Rona waves (Still pretty, even from up here), pull in... yank the string and I'm free of line. I found that a medium Polaris with 14 stone on does not have a good glide angle. Down safe I collected my thoughts and could feel that first soaring flight grin start to set in as Tony ran up saying "What do you think?" "Ace" I said. "Right... a higher one this time... Say...200 ft, OK?"

ENCORE!

Same again, checks done then ALLOUT and a lovely climb-out getting to about 250 ft on joke alti. Pull release... off the tow... 2 turns and the Polaris glide was over. Grin again. Brill! As we loaded the glider onto the winch, I asked - "Any chance of trying the Magic on the line?" "Yes, of course" Tony replied. "Great" I thought as we drove back to takeoff. Magic at the ready... ALLOUT and away we went. The climb was stable, into the harness. Easy. Push out when at a safe height and up, up and away. Ace!

Then I found a few snags: Firstly a 5th gen. glider's a lot faster, a lot heavier too. The speed makes the Magic weave. The answer is to push out. When you already have the bar out past your head you might understand why I say it feels weird. Secondly: to turn when on tow (to fly the line upwind on crosswind launches) you mustn't pull on speed. You have to weightshift to one side then jab the bar out suddenly. It works like a charm, also the bridle tends to drag you back on track if you stray, which can't be bad.

I pulled on the tow at about 6-700 ft and enjoyed about 35 mins thermaling about on the Airfield before landing through choice. Two little things surprised me. Because Norfolk and the Airfield is so flat, there are no visual references for landing. You end up flaring 6 ins too high. (Poor excuse Pennell - Wings Ed.) The second is that it's very odd to start thinking about going up when you're so low. I found myself setting up for landing well before I needed to. This very soon passes though.

SUMMARY

Tim, you have known me long enough to know how easy it is for me to get scared. Well this way of flying is just so easy it's untrue. I have done quite a few flights from Graham Geary's winch but because of lack of access to a good airfield we are not really able to make the most of the system.

Things not to do: don't tow behind a LWB Land rover in nil wind, it just cannot accelerate fast enough + the gap between first and 2nd gear can sink you back unto the runway. Wheels would help save the stainless bits on the bottom bar. I haven't found any to fit my speed bar yet, but I will. After eight weaklink breaks you can get a little worried but even though some were very low, none gave me any trouble.

Don't use any gear you don't feel happy about. I did once and had problems releasing. It doesn't make your flying any better.

Graham Geary has two other sorts of release units which I think will be better and safer and more important, simple.

Don't have a pilot who hasn't been fully briefed driving because if he tries to help you by slowing down if you swing on takeoff, which will happen on crosswind launches, you are screwed. I would add a swivel to the line to stop the weak link breaking because of twisting. I had eight consecutive breaks and was dumped on the runway twice by slow gear changes.

Towing really is a lot of fun. Everyone who has more than the minimum requirements (See August Wings!) should have a go. Towing is going to be big.
*
1985/11-04

SUGGESTIONS FOR PROMOTING SKYTING IN THE U.S.

by Denis Cummings
Dights Crossing,
Singleton, AUSTRALIA

I cannot understand how a contest (tow launched) at HOBBS, NM, could possibly be a flop.

O.K. my "Flatlands comp. was not as large as I expected it to be last year. We only had 60 pilots attend (for flying and the seminars) with 25 actually flying in the comp. We also had to contend with the "hot pilots" comp. at Mt. Buffalo (site for the 1987 World Comp.) on the same dates, and offering the greatest prizes ever seen in hang gliding in this country.

This year's "Flatlands" should be one of the biggest comps. in Australia, as the Mt. Buffalo "Classic" appears to have lost its sponsor and possibly won't offer the financial inducement of last year. Also my PR man feels confident of obtaining some sponsorship of the "Flatlands". If any of your readers are in Australia, 21 Dec 1985 - 6 Jan 1986, the place to be is at Parkes, N.S.W. - they will be most welcome.

I'd like to encourage your articles of the style of #40 - The Skyting Criteria. Your analytical mind lets you slip it all together, and the article shows just how far Skyting has developed. I, too, have thought about a book on Skyting, but, really, it is only a small part of the overall hang gliding experience. A sound, practical series of articles like the Skyting Criteria, possibly with some drawings, photos, anecdotes, etc., would be best suited as a few chapters of a larger book on hang gliding as a whole. By cutting down on some of the words and letting sketches and photos tell the story, you may find that your "unreadable" work begins to come to life.

While on this theme, I feel that "Skyting" magazine may be reaching a stage where it should be blended into the overall hang gliding scene. Now that "Hang Gliding" has started a "Tow Lines" regular feature section, it may be appropriate for you and other authors to concentrate on promoting tow launch safety and development via this medium, and possibly phase out the existing "Skyting" over a suitable period.

I feel that one of the major reasons for the acceptance of land towing in this country stems from (a) the lack of suitable LARGE mountain areas, and (b) the extensive reporting of tow related activities in the Australian "Skysailor" magazine.

Which ever way you decide things should go, be assured that you (or "Hang Gliding") will continue to receive tow news from this country, time and good fortune being available.
*
1985/11-05

BOB CASTO'S TOWATHON(S)

by Bob Fisher

(From WIND WRITER, Newsletter of the HHGA.)

On August 3rd and 4th, B Asher, Carl Boddie, Willie Brenner (& boat), Bill and Karen Misiasezek ((Misiaszek)), Ken Rose, Len Smith, Linda Trueblood, and myself accepted Bob and Linda Casto's generous invitation to see their Lakeside weekend cabin and boat as a base for a weekend of water towing. By a happy coincidence, the Houston Post had contacted B a couple of weeks earlier because they are doing a series of "Lifestyle" articles on "adrenaline" sports, so B invited them and they sent a reporter and photographer. Expect the article anytime after you get this newsletter.

Everyone there had at least one tow during the day and most had two. There were no hang gliding accidents and the most common comment was that the tow was not "radical" (as they had expected) and the launch was much smoother in reality than when watching. On the first day, there was a slight breeze which made the launch really easy and predictable. On the second day, there was almost no wind and an attempt to launch any Streak resulted in a 1/4 mile tow at 20 ft followed by a deep-water dunking. Glider and pilot survived unscathed. Apparently, it simply flew too fast for the boat with nil wind.

The tows were up to about 600 ft on a 1000 ft line, Bob's 115 hp boat is capable of about 35 mph with a glider in tow but 15-30 mph are typical tow speeds, depending on wind.

As an example of the ease of towing, note that Ken Rose has only two Packsaddle (top to bottom) flights, and he was fine (although he did seem to prefer the middle of the lake for his LZ!)

All the tows used Bob's Moyes Maxi and Bill Misiaszek's new single point release bridle, with the old top release retained as a safety backup. The bridle stays with the glider. The release is operated with a pull string attached to your wrist.

In addition to the hang gliding, many people tried my windsurfer and quite a few people skied behind Joe's boat. Joe is one of the Casto's neighbors who was as hospitable as Bob and Linda, even though he doesn't fly and was only involved as a neighbor.

Late on Saturday, Willie dislocated some rib cartilage when he fell, skiing, but is now more or less fully recovered. On that Saturday night everyone ate fried chicken and fried chicken and fried chicken..., watched video's taken during the day, and then camped out either in the Casto's dining room or in their front yard. No one remembered to get up at first light to watch the alligators swimming back from feeding along the lakeside.

This was to have been a one time chance to water tow at Bob's but fate had another card to play. The Post photographer's camera had a fault which resulted in white spots on the negatives. They therefore asked if we could do it all over again on Sunday the 11th. Of course, we obliged. It was a different photographer and he admitted he had never had so much fun on an assignment. We didn't actually get him airborne, but he did put his camera on the glider for some aerial shots of B Asher and the countryside. On the 11th there was light wind and everyone was towed in a 3/4 mile diameter circle and released over launch. On this occasion, we towed Esteben (?) (one of B's Brazilian students) who has one Packsaddle flight under his belt.

He was fine, doing 360's on the way down, but demonstrated classic beginner symptoms by trying one last 360 at 100 ft in wind shear (although the wind was light) and stalled in, but caught a tip in the water and was spun towards a wooden bulkhead. Bob's glider was damaged, but repairable and the pilot was unhurt, thanks to a water landing. Three feet nearer the buldkhead would have resulted in serious injuries. B (as his tutor), myself, and Bob were guilty of not ensuring that he knew, understood, and would follow a stated flight plan. This is mandatory for all flights in the first hour of flying.

Finally, thanks again to Bob and Linda, and Joe and Claudine for being such warm hosts.
*
1985/11-06

ACCIDENT ALMOST FATAL

Dear Donnell,

It has been a long time since I wrote to you. This letter is not because you claimed that you didn't have enough material to publish, but because of an accident that happened a week ago.

My idea was to improve the bridle I normally use for towing because we will soon run towing studies for 2 pilots. I wanted to add another release after the front ring. First I tried my old release, but because of its weight it jumped upon the pilot's face each time it was activated. I made a new three-ring release. After a few experiments I made a good one and tested it many times at a load of 140 kg (double what I mean to use). It worked.

Then I attached it to its place and connected the release rope to the base tube on the right corner (my mistake). I tried it a few times on the ground. It worked OK.

My friend connected the release for me to the main rope (my mistake) before I launched. He saw the release before and I watched him doing it. But I'm not 100% sure if he did it right, as he wasn't familiar enough with this kind of release.

I launched into front wind about 10 m/h. From time to time I saw dust devils in the area. When I reached about 30-40 meters (100-130 ft) I got a strong bank to the right. I pulled the release. From that point things happened in a matter of seconds.

I remember I saw the main rope attached and pulled the glider from right corner of the base tube. I looked for my knife. The glider banked 90 degrees and more to the right. I recognized it was a lockout. Then it continued to bank 360 degrees - full turn. The rope failed (my luck). I succeeded to balance the glider only a few meters above the ground and landed very hard. Down tubes and half of the "French connection" broke. Hard to believe nothing happened to me. Thanks to "La Mouete" (Profile) on making such a strong glider.

I found the three ring release locked. I think it happened because the pin that was supposed to be pulled was pushed too much (behind the pin) and could not be pulled.

My mistakes were: (1) The release should have been connected to the harness, not to any part of the glider. (2) The friend wasn't familiar enough with the equipment (I didn't plan to use his help.) (3) I didn't have an observer on the ground in the takeoff area.

I hope no one else will experience something like it any more. Please Be Careful!

I mean to try now to do towing when the rope will be attached only to the pilot. I know that there are a few disadvantages by doing it. But one of the main advantages is that it is less complicated. The release is close to the pilot, and there is less possibility that the rope will touch the glider.

Heber Ytzhack ((Itzhak))
Nahal Oz, ISRAEL
*
*

[Tad Eareckson]

1985/12
*
SKYTING NO.43
DEC 1985
*
1985/12-01

BIRTHDAY REVIEW

Skyting if five years old this month, so it seems only appropriate at this time to review the progress that has currently been made and suggest a reasonable course of action to take during the next year.

An illustration of how far skyting has come to date, we have included in this issue a "Hang Glider Towing Manual - Skyting Method", written by Mark Mulholland and Dan Marcus. This manual is currently being used in Dallas, Texas, to introduce new pilots to the skyting method of towing and as a guide for local skyting competition. The fact that neither of the authors has previously subscribed to the SKYTING Newsletter demonstrates how well skyting information has filtered down through the hang gliding community. I find this very encouraging because it demonstrated that information is really getting out, and that there are other people besides "us" in the U.S. who are towing with state-of-the-art skyting systems.

You may find a few things in this towing manual with which you disagree or on which you want to make comments. If so, please send Mark Mulholland a letter to that effect. And let me know if there is anything you want conveyed through the SKYTING Newsletter.

I would also like to encourage you to send more comments, information, and articles to Hang Gliding Magazine. My own attempts to get things published there have not been very successful. Perhaps it appears that I am trying to use the magazine as a forum for pushing my own personal form of towing onto the hang gliding community.

In any case, there have been only four towing articles in HG during the last year (12 issues). (Two of these articles were from the Moyes towing point of view and two dealt with aerotowing.) It appears that if our form of towing is going to receive much coverage in HG magazine during the next year, then YOU are going to have to write the articles.

You should also realize that USHGA wants to make some kind of decidion this February on the proposed surface towing guidelines (see #42). Some of you have already sent in some feedback, but if the rest of you want a voice in this decision, you will need to send in your comments immediately.

And finally, please have a safe and happy Christmas Season. And may your next year of skyting be even better than the last!

Donnell
*
1985/12-02

PREVENTING WRIST RELEASE INJURIES

Dear Donnell,

Re the letter in issue 41 on wrist release injuries. In Houston, we have been using a two-ring release made here by Bill Misiaszek and operated by a pull line. We simply attach the pull line to a suitably robust (or weak) rubber band, which is then slipped over the wrist. No dislocations from this and so easy to make.

Bob Fisher
Houston, TX
*
1985/12-03

ADDING AERO TOWING

Dear Donnell,

We've added aero towing to our car towing alternatives. Mario has his tug (currently on a 185 Comet wing) and the Cincinnati group has a Cosmos. The best flights from the Cincinnati site have been 1 to 1 1/2 hours; best flights from our Pike County site have been 1/3 to 1/2 hour, so far.

Had an interesting auto tow flight last Saturday. Bumped through thermal about half way down runway but decided to tow to end. Nothing there. Flying back found it again. After about 6 360's, a buzzard joined in below me and in anaother 360 for each of us, was above me! Buzzard launched off cross country and I stayed with thermal to get 10 minutes.

You know, I can't recall if the buzzard turned with me or opposite - but I think it was opposite. Rude - but I guess it figured anyone dumb enough to tow/fly through a thermal the first time isn't entitled to any courtesy - especially if a dozen or so 360's only gets several hundred feet of altitude.

Well, anyway, I found the thermal first and centered it first. (The buzzard seemed to agree with my centering, circling right up around me.)

So far we've used non-center-of-mass bridles for aerotowing - off harness chest straps. Seem to work OK, but don't seem to offer the lateral stability of our auto towing (center-of-mass Hewett-style bridles). Will try our/your autotowing bridles next on our aerotowing.

Jerry Martin
Dayton, OH
*
1985/12-04

HANG GLIDER TOWING MANUAL
SKYTING METHOD

(REVISED 06/18/85)
Gateway Hang Diving Club

by Mark Mulholland and Dan Marcus

This manual is intended to be a source of information for those persons who wish to become airborne via towing of hang gliders. It represents a synopsis of our knowledge of towing technique as derived from publications, correspondence, and our own trials and errors. We have tried to keep the system as safe and reliable as possible. This manual is not the gospel truth, so (as always) exercise your own judgement. Included is information on the techniques involved under various conditions and a description of the necessary and optional equipment used in this pursuit.

OVERVIEW OF TECHNIQUE

A glider and pilot are attached to one end of a stretchy rope and a vehicle to the other end. The vehicle has a tension measuring device so that the driver can adjust the vehicle's speed to maintain the proper tension on the rope and glider. The rope has stretch to facilitate launch and to absorb gust loads. The rope also has a weak link to prevent overstressing the glider and to try to prevent a severe stall in case of a rope break at high pressure (the weak link breaks at lower pressure so that the glider will not get into a sever stall). The glider and pilot are attached to the rope via a bridle with a release mechanism.

The main feature of the bridle is that BOTH the glider and pilot are attached to the tow line. The pilot is pulled with about twice the force of the glider due to a simple pulley system which is necessary for stability reasons to increase the control the pilot has over the glider.

This towing scheme allows experienced tow pilots to launch in varied wind conditions: up to about 25 mph in line with the tow road, and up to about 15-18 mph in 90 degree crosswind conditions, the more experience is required. Learn with a smooth straight in wind. A one mile road and 2000 feet of tow rope should allow for a release altitude of 1000-2000 feet, depending on wind conditions.

SET-UP OF GLIDER AND PILOT'S HARNESS

The glider needs wheels on the control bar for all learning learning flights and is optional for experienced tow pilots. In addition, an attachment point for the bridle is requluired on the keel 0-8 inches in front of the center of gravity (CG). A piece of 9 millimeter perlon rope (usually 1-2 feet long) tied around the keel and kingpost is sufficient for the attach point (be sure that it cannot slide forward on the keel).

The pilot's harness needs a rope tied (bowline knot) between the main support straps across the front of the harness with a loop in the midpoint for attachment of the bridle via a locking carabiner. Alternately a piece of webbing can be sewn to the harness to attach the bridle directly.

A "hand held" citizen band (CB) transceiver needs to be mounted to the glider with a microphone attached to the base tube. Broom clips work very well as attaching hardward, however, be sure to have a secondary attachment for your CB as broom clips may pop off the downtubes. When mounting the microphone, tilt it rearwards to minimize the wind noise.

PRELIMINARY EXERCISES

After tying oneself to the back of a vehicle with a rope, most people of at least average intelligence will be at least somewhat apprehensive. In order to ameliorate the situation, one should experiment with the system without being strapped in and without a glider. Two things should be tried: 1) attach a handle to the tow rope, grab the handle with gloved hands, tell the vehicle driver to "stomp on it", and feel how slowly or rapidly the tension (of the rope, not your nerves!) develops in the line. 2) Do it again, but dig your heels into the ground and try to break the weak link (as you would do in the event a gust upsets the glider after the "CLEAR" signal). Now you have some idea of how the tow system behaves. You also have some sound reasons to be scared when you hook in.

THE TOW FROM THE VIEWPOINT OF THE GROUND VEHICLE DRIVER

The driver should lay out the rope from the launch area to the vehicle's starting point. Check the rope for wear, check the integrity of the weak link (replace if necessary, usually every five flights whether it needs it or not), connect the rope to the tension measuring device on the vehicle. Signal the pilot that you are ready (get into the car, flash your brake lights, and contact by radio). When you hear "brake check", flash your brake lights. When you hear "Give me twenty pounds", SLOWLY move the vehicle forward until the gauge reads 10-20 pounds. DO NOT KEEP INCHING FORWARD. The pilot will adjust the pressure as necessary. You are only supposed to initially bring up the tension to ensure that the gauging system is operational and to remove slack from the rope. Wait for the "CLEAR" signal from the pilot. When you hear "CLEAR", accelerate as RAPIDLY as you possibly can (like STOMP ON IT!!!) to a tow tension between 90-110 pound range. After the pilot launches, continually adjust the vehicle speed for proper rope tension. Never exceed 150 pounds of rope tension, or you WILL break the weak link. When the wind is strong, you may even have to back up the vehicle (if you do, make sure that when the pilot releases, the release will not hit anyone/anything when it falls).

After the pilot releases, keep driving to straighten the tow rope. After stopping, release the tow rope from the vehicle, turn the vehicle around, put the tow rope around the turn-around pulley, attach the rope to the vehicle, and return to the launch point (never exceed about 20 mph due to rope wear). Release the rope and drive back to the other end, hook up the rope to the vehicle and wait for the next pilot. Repeat endlessly and do not be selfish by asking to fly the glider.

THE TOW FROM THE DIVER DRIVER VIEWPOINT

Set up your glider (with wheels if needed or desired).

Preflight the glider and climb into the harness. Layout the bridle and attach the single-line end to the keel.

Hook into the glider hang strap and do a hang check. Route the double-line end of the bridle under the control bar and connect it to the harness attach point with a locking carabiner. Run the trip cord for the release through the control bar and slip the pilot's hand through the tightly fitting loop on the release line. Then attach the bridle to the tow rope via the release mechanism. Test the release mechanism, then reconnect the bridle to the tow rope. Ensure that the cable on the release has an adequate loop in it, so that the release line cannot hang up on it, preventing a release. Turn on all your instruments and check that the CB is on. Contact the driver and make sure he/she is ready. Ask for a "brake check", then when the vehicle's brake lights flash, go to "transmit". To do this, use some bungie cord to tie down the microphone key (this will allow you to talk to the driver without pressing anything). Ask for another "brake check". When you are ready, ask for "twenty pounds". Upon hearing this, the driver will move forward to increase the tension to 10-20 pounds. Ensure that the rope is straight and not diverted by any brush or bends in the road. Launch is best obtained by using a straight section of road. Once the pressure comes up, the driver will stop the vehicle. The glider should be lifted to make the hang strap taut. Keep the glider pointed into the wind with a slightly positive angle of attack. If the wind is strong cross, turn your body so that you can run down the road in the direction of the vehicle.

When the glider is comfortably under control, signal the driver to accelerate by saying "CLEAR". It will take a few seconds (1-5) for the tension to build. Keep the glider level with a positive angle of attack. When the glider starts to be pulled, stay with it, however do not overrun the bridle. The more tension on the rope, the sooner you will get into the air. However, with increased rope tension, the pilot needs additional energy to hold the glider back, so it becomes a trade-off as to how much energy you want to expend holding the glider back versus running faster and longer on the ground. Usually it is better in light winds to hold back more, than in stronger conditions.

Climb out should be at an average rate of 200-500 feet per minute. You should not push out a lot during the launch for such action may break the weak link and cause a stall. If the wind is cross, let the glider drift off the road after launch, then gradually crab the glider back upwind. This makes handling of cross winds easier.

Climb until ready to release, then pull in the bar to relieve tension on the line, and release immediately (so that the vehicle driver does not speed up to maintain tension). Let the bridle lines sway behind the glider. When you sky out, you may disconnect from the birdle and put it out of the way. Remember, SKY OUT, land glider, and repeat as necessary until air-gasm.

SKYTING WITH GROUND PULLEYS

Skyting can also be accomplished with the use of ground pulleys. This is usually done in front of a soarable ridge that does not have a good launch site but has plenty of room at the bottom.

Basically, one or two ground pulleys are used depending on the situation, see figure numbers 1 and 2 for some possible schemes.

From the pilot's viewpoint, everything is the same as normal skyting, except that there is maximum height you can obtain. Once you get there, you must get off the line or else if the driver keeps on driving forward, the rope will apparently get shorter and try to pull you down. At this point, or earlier, release and head for the ridge. Once you make it back to the ridge, SOAR!! It is also helpful for launches if the glider and first section of rope are lined up into the wind.

From the driver's viewpoint everything is about the same as the in-line towing, however, be certain to accelerate as quickly as possible, and add 10 pounds to the normal tow pressure to adjust for the additional friction. The turn-around pulley cannot be used with this system, so once the pilot releases, stop the vehicle, release the rope, and back up to where you started. Also, if the wind is strong enough for the pilot to skyte, (i.e. hover or fly backwards) you may have to back up the vehicle. If you do, do not drive beyond where you started, else when the pilot releases, the rope with releases will land at launch on people, gliders and anything else in the launch area. The only additional task is that someone must go out onto the field and bring the rope back to launch.

EQUIPMENT

The BRIDLE is illustrated in figure number 3. The bridle consists of a carabiner (attaching it to the keel rope), 22 feet of rope (anything stronger than 1/4" polypropylene that is low stretch, abrasive resistant, and slides easily (ie. 1/4" braided nylon)), rolled non-welded ring approximately 2 inches in diameter ("slip ring" used as a pulley), and a locking carabiner (attaching the bridle to the pilot, "locking" to keep from accidentally connecting the pilot to the glider), and a single ring release half (of a three ring circus release) that attached to the slip ring via a small "hardware store" type of locking carabiner.

The release line is approximately 10 feet long (to be adjusted after first flight in the glider/harness configuration). If the release line is too long, releasing is not accomplished with a quick snap of the wrist, if the line is too short, releasing will be done unexpectedly and automatically (usually at the most improper time and altitude). One end of the release line should have a loop spliced in the end that is just large enough for the pilot's hand. The other end should have a loop spliced in it that is just large enough for a release cable to go through (any larger, and there is a chance that the release line could get hung up on the release cable nico).

The TOW ROPE is illustrated on figure 4 and consists of a two ring release half (of a three ring circus release), 25 foot leader (1/4" polypropylene rope), weak link (#18 nylon twine), 1500-2000 feet of 3/16" braided polypropylene rope, weak link, 25 foot leader, and release (two ring release half). The tow rope is symmetrical about its midpoint, which was designed for use with the turn-around pulley. Initially the weak link should make a complete loop (ie., tied to the leader, looped through the two rope, and tied back to the leader). With increasing experience, it may be found that an additional half loop (ie. tied to the leader, looped through the tow rope, looped through the leader, and tied back to the tow rope) may be desirable. All leaders and tow ropes should have a loop spliced at each end to facilitate attaching weak links and releases. All knots shall be bowlines or double grapevines.

The TURN-AROUND PULLEY was designed to enable quick turn-around of the rope after release. It minimizes the rope becoming entangled with the crops and/or brush that is ever present next to the ideal tow road. It is made from two garbage can lids with a pulley bearing (ie. NICE6286) placed in between each lid as shown in figure 5. The bottom lid is filled with cement and reinforcing rods (coat hangers or old flying wires connected through the lids to keep the cement in). There are two studs (made out of bushing stock) between the lids for rigidity's sake. The turn-around pulley is staked at the end of the road after the first tow. DO NOT FORGET TO PICK IT UP AT THE END OF THE DAY!

The GAUGING SYSTEM consists of a single port hydraulic cylinder (1" bore 2-4" stroke) filled with motor oil (any leakage will be far less caustic than hydraulic fluid) with about a 15 foot line going to a liquid filled 300 pound gauge. The gauge is inserted into a wedge shaped piece of foam which mounts easily in between any vehicle's dash and windshield. Attached to the cylinder is a single ring release half. A release line needs to be run from the vehicle driver back to the vehicle release for emergency use.

The PULLEY SYSTEM is made up from an old downtube, eyebolt, bracket, and a pulley bearing (ie. NICE 6286). Secure the eyebolt into the downtube at the top. A couple of inches down, install the bracket that contains the pulley bearing.

The pulley shown in figure 6 is pulley #2 (as shown in figure 2). To make a pulley #1 (as shown in figures 1 and 2), turn the bracket 90 degrees. To use the pulley, hammer it into the ground, and tie it down through the eyebolt with some rope and aircraft tiedowns.

Below is a list of known suppliers of the unique skyting equipment with estimates of cost (price is subject to change wit out notice). If you can get the same quality for less money, let us know, then go out and buy it!

3-ring release (part number 69, cost is around $35 each)

by

Paragear Equipment Co.
3839 W. Oakton St.
Skokie, Ill. 60076
(800)-323-0437
Mastercard or Visa

Braided Polypropylene Rope
3/16 inch economy braid ($42.99 for 3000 feet (cut in half for two systems)

by

Nylon Net Co.
700 Vance Ave.
P.O. Box 692
Memphis, Tn. 38101
(800)-238-7529
Mastercard or Visa

Gauging System ($160.00)

by

Omega Energy
1805 Woodmont Dr.
South Bend, Ind. 46614
Attention: Marc Magor
(219) 291-1097

Pulley Bearing ($5.95 each

by

Hobby Specialties Division
#3 Castle Dr.
St. Louis, Mo. 63034
(314) 831-5031
Cash, Check or Money Order

Carabiner,
Perlon Rope,
Rolled (not-welded) Rings

Get at you local hang gliding/climbing shop or at:

The Mulhollands
1102 Whitehall Ln
Greenville, Tx 75041

GENERAL RULES

1) All tow pilots must be members of the U.S.H.G.A. and the local hang gliding club.

2) Pilots should bring all the necessary equipment with them:

Glider
Harness
Helmet
Instruments
C.B. with charged batteries and auxiliary antenna
Bridle and Release line

3) First pilot in line has 5 minutes to launch after the rope is returned to take-off.

If the pilot is not ready to launch at the end of his 5 minutes, then he loses his place in line and goes to the end of the line.

If the pilot is ready to launch, but does not want to launch in the conditions, he may pass to the first pilot in line that is willing to try and launch in the conditions. That pilot moves to the front of the line and has 5 minutes to launch. If unsuccessful, the pilot goes back to his/her original place in line, and the next pilot in line that is willing to try and launch in the conditions moves to the front of the line. The process continues until darkness or airgasm, which ever comes first.

4) Prerequisite for beginning tow pilots:

Has had some altitude experience (Hang II rating)
Is smooth on the bar
Has read and understands the tow manual
Knows how to tie a bowline (for all knots)
Has driven at least 5 tows

5) Before entering the line for tow rope:

Have all instruments (vario and radio) hooked up
Have bridle attached to glider
Have auxiliary antenna hooked to C.B. (with radio check)

UNSOLVED QUESTIONS

1) If the weak link breaks under high tow pressure (you shouldn't be here but in case you are) close to the ground (less than 100 feet) and the glider starts to stall, should the pilot:

a) tuck the bar in?
b) let the glider recover by itself?
c) push out?

Answer???

If you tuck the bar, you will probably recover faster (time wise) and with more speed, unfortunately it will probably take more altitude. It is preferred that the pilot not push out on the bar at low altitudes, keeping at recommended tow pressures at low altitudes. Then if a weak link breaks, let the glider recover, unless contact with the ground is imminent, in which case flare as required.

2) If the glider starts to roll severely at the time of launch, and a crash looks like it's developing, should the vehicle driver:

a) accelerate?
b) stop?
c) release?

Answer???

It is preferred that the driver maintain tow pressure unless the glider actually hits the ground. The more pressure, the more likely it is to gain altitude which will prevent contact with the ground. If the glider touches the ground, the contact point will act as a pivot and most likely will be opposing the force from the towline. This will cause the glider to "pancake in" (ie., flatly) versus winging it over in a ground loop with a whole bunch of energy.

HISTORY (UNSUCCESSFUL/UNDESIRABLE DESIGNS)

1) The wild horse release. This release was completely unreliable and would release when you didn't want it to, wouldn't release when you wanted it to and would require increasing pressure to release with increasing rope pressure and as such would store a lot of energy for when it finally did release. It has bitten us, and if you use it, expect to be bitten also!

2) Winches. Winches have too many things that can go wrong, such as birdnesting of the line and mechanical failure. Additional problems with winches are that most people don't use weak links, and the pilot must rely on someone else not screwing up. Look at the fatalities/ serious injuries in towing and you will see our point!

3) Spring Gauges. They tend to be less accurate and less sensitive than the hydraulic gauging systems. The cost of the hydraulic system is worth it. Once you've tried a hydraulic gauge, you'll never go back to the spring gauge.

4) Threaded bridles. There are problems with the end of the rope upon release, traveling at high velocities and either hitting the pilot or wrapping around portions of the glider. Neither case is desirable or necessary.

5) Double Release. This was supposed to eliminate the problem of having the rope that attaches to the keel hitting the pilot's head when a high tow angle is achieved. It consisted of an additional three ring release attached to the bridle at the single ring release with a rope attached from this additional release to the harness. It allowed the pilot to release the bridle and still have a single line attached to the harness from the tow rope. The problem arose when the tow rope was twisted, thus after release of the normal bridle, the tow rope would start to untwist, thus wrapping the release line around the release and tow rope. This made release impossible. Fortunately the vehicle's release worked and the rope untwisted in the air, allowing release of the tow rope. This only happened once (out of two attempts), and once is more than enough. Any failure that prevents release is undesirable, so this method goes to the scrap heap.

6) To be continued when new information becomes available. Please write any comments to The Mulhollands at the address in the equipment section.

FUTURE (UNPROVEN IDEAS)

1) Tandem. This will eventually be developed both for enjoyment purposes and for training. When used for training, remember that the student will not know how to effectively do a foot launch (angle of attack tends to be high on tow, with "Piece of Cake" launches being the norm), so instructors be careful!

2) Alternate Release Methods. Everyone wants to increase performance, so someone will develop a method of having even less attached to the glider/pilot after release. Some people currently use the threaded bridle to do this, however problems concerning the rope that is flying past vital parts of your body at an incredible speed.

3) Tandem Flight Towing. Two gliders, two tow ropes, one tow vehicle for competition, show, or Fun!
+
COMMON ANNOYANCES
-
CAUSES
-
PILOT ACTIONS
-
-
1) Yaw Oscillation (pilot induced)
-
a) roll inputs
b) high line tension
-
a) have driver lower line tension
b) release bar pressure (roll axis)
c) yaw the glider
d) be smooth on the bar
-
-
2) Weak Link Break
-
a) high line tension
b) wear on weak link, replace every five flights
-
BELOW 100 FT
1) release
2) land
ABOVE 100 FT
a) with short end of rope
1) line up for landing
2) release
3) land
a) with long end of rope
1) release
2) land
-
-
3) Premature Release
-
a) too short of release line
-
a) land
b) lengthen release line
-
-
4) CB Wind Noise
-
a) improper mounting
-
a) rotate microphone rearwards
-
-
Weak CB Signals
-
a) weak batteries
b) poor antenna
-
a) replace/recharge batteries
b) use 108 inch single wire auxiliary antenna
-
-
6) Too Many Launch Steps
-
a) new rope
b) lack of wind
-
a) prestretch new rope
b) hold back on glider
c) have vehicle accelerate faster
-
-
7) Release Doesn't Release
-
a) release line is too long
b) homemade release
-
a) lengthen line
b) grab bridle and manually release
-
-
8) Yaw Instability At Launch
-
a) double surface gliders are unstable in yaw with low angles of attack and slow speed
-
a) increase angle of attack
+
Figure 1

Top View
Bluff
glider
wind direction
2000-3000 feet
pulley #1
road
1000 feet
Tow Vehicle
+
Figure 2

Top View
Bluff
glider
wind direction
1500-2000 feet
pulley #1
pulley #2
road
100 feet
Tow Vehicle
+
FIGURE 3

A = NON-LOCKING CARABINER
B = LOCKING CARABINER
C = HAND RELEASE LINE
D = SLIP RING
E = THREE RING RELEASE
F = SINGLE RING RELEASE HALF
G = DOUBLE RING RELEASE HALF

ABCDEFGH

FIGURE SHOWN JUST AFTER RELEASE
+
FIGURE 4

TWO RING RELEASE HALF
25 FOOT LEADER
WEAK LINK
1500-2000 FOOT ROPE
WEAK LINK
25 FOOT LEADER
TWO RING RELEASE HALF
+
Figure 5

Side View

Garbage Can Lids
bolt
washer
stud
washer
Pulley
cement filled
reinforcing
loops

Top View

STUDS
pulley
loops

Bottom View

reinforcing
loops
+
Figure 6

Side View

eyebolt
Bolt
stainless bracket
pulley
old downtube

Top View

downtube
Bolt
pulley
*
*

[Tad Eareckson]

1986/02
*
SKYTING NO.44
FEB 1986
*
6/02-01

THIS ISSUE

You may have noticed that this issue of SKYTING is a month late. The last time this happened, it was your fault (for not sending me more material). This time it is my fault (for relaxing too much over the Christmas Holidays). Sorry about that! (About being a month late, not about relaxing over the holidays.)

I had planned to include in this issue some of the material several of you sent me months ago. But upon hearing about the fatal accident of Mike Dorobiala I decided to hold your material for yet another month and devote this issue to the topic of reporting and analyzing towing accidents.

As you can see from Doug Hildreth's letter, very few U.S. towing accidents were reported last year. This may be good news or it may be bad news. It is good news if no other accidents occurred. It is bad news if other accidents did occur but were not reported.

Since there is no doubt that towing activities are on the increase, it would stand to reason that the number of towing accidents is also increasing. If this is true, then there were a lot of towing accidents that went unreported last year. Bad news, indeed.

But perhaps - just perhaps - the reason more accidents were not reported is that they did not occur.

I hope this is the case. For if it is, then it demonstrates not only that towing CAN be accomplished safely, but also that it IS being accomplished safely. In fact, the safety record for towing may even be better than that for free-flight hang gliding!

The most recent fatality statistics seem to bear this out. Until last year the number of towing fatalities was on the increase. By 1984 there were as many towing fatalities as free-flight fatalities - (four each). The trend at that time suggested that during 1985 there would be more towing fatalities than free-flight fatalities - that there would be approximately eight towing related deaths in 1985.

But apparently the fear of this trend prompted pilots to exercize extreme caution while towing (or else to postpone towing until it was safer). As a result, the trend was reversed.

According to Doug Hildreth's 1985 Accident Review (see Jan 1986 HANG GLIDING), there were eight free-flight fatalities in the U.S. in 1985 (two of these resulted from a single tandem accident) but only one towing related fatality. After Doug wrote his review another towing fatality was reported, so the current total is two.

The first of these two towing related fatality occurred on July 17 during the U.S. Nationals in Chelan, Washington, and took the life of Cris Bulger who was the tug pilot in an air-to-air towing accident. (See SKYTING No. 40, Aug/Sep WHOLE AIR, and Sep HANG GLIDING for reports on this accident.)

The other towing fatality occurred on December 29 near Dallas, Texas, and took the life of Mike Dorobiala while "skyting" behind an automobile. The real cause of this accident is still a mystery.

Therefore, most of this issue of SKYTING is dedicated to the analysis of Mike's accident in the hopes that this information can help us understand what happened and what can be done to prevent similar accidents in the future. If you know anything that can help us understand this unfortunate accident, please share your knowledge with the rest of us.

In the mean time, may the death of Cris and Mike serve to remind us (1) that both advanced and novice pilots can be killed while towing, (2) that glider pilots are not the only ones in danger while towing, and (3) that every possible safeguard should be utilized while towing.

Let us also remember that even though the number of towing related deaths were down last year, they will not remain down this coming year if we allow ourselves to adopt a carefree of complacent attatude toward towing.

Donnell
*
PLEASE FILE ACCIDENT REPORTS
*
6/02-02

Dear Donnell,

I want to thank you with greatest sincerity for all your help with accident review over the last year. I have really appreciated receiving your Skyting Newsletter and all of your correspondence.

In my report for the upcoming magazine, I was again a little hard on towing from the standpoint that I stated I received very few official towing accident reports whenever they have an accident or incident.

I want you to know that what you are doing is very helpful and that I am not being critical in any way of your herotic efforts by my comment in the article... it is just that I get virtually nothing from anybody else and that is the point I am trying to make.

I continue to look forward to receiving Skyting in the next year and continue to encourage you to pursue with vigor the excellent work which you have started!

Doug Hildreth
Chairman, Accident Review
U.S.H.G.A.
1025 East Main St.
Medford, Oregon 97504
*
6/02-03

Dear Readers,

Did you have a towing accident last year that was not reported? If so, please sit down right now and send Doug an accident report. (The January 1986 issue of Hang Gliding contains a report form you can copy and use.)

Remember, accidents are nature's clearest warnings about potentially lethal situations. But if accidents are not reported, then the warnings cannot be heeded.

Please don't let your failure to report an accident doom someone else to repeat it... with potentially fatal result.

Donnell
*
6/02-04

FATAL ACCIDENT

by Warren Richardson
Dallas, Texas

At approximately 4:00 PM on December 29, 1985, ((1985/12/29)) Mr. Mike Dorobiala of Arlington, Texas, was involved in a skyting accident which resulted in his death. Mike was 22 years of age and a member of USHGA, with Novice (provisional) rating, 11 months of flying experience, and 150 logged flights. The accident occurred while he was towing behind an automobile on a Wills Wing Raven. He was wearing a Bell helmet, sneeker shoes, and a parachute which he did not deploy.

This was the pilot's first 2000 ft towline auto tow. (Fourth tow after a three month period on a 500 foot training system.) The glider had a motorcycle brake handle, cable, Switzer type of single release mounted on the control bar and keel. The bridle was a threaded style that I inspected before launch and found to be correct. The weak link was a loop of number 21 nylon twill.

The takeoff was with good form and a normal climb out angle. The wind was at 3 mph straight down the road varying gently to light cross-winds at 15 degrees from the right. Once climbout through the gradient was accomplished, the pilot fully proned out in his knee hanger style harness.He had moved his right hand to the junction of the base tube with the right down tube, and his left hand to about the middle of the base tube. This, of course, swung his feet to the far left side of center line. The glider began to turn slowly left. Mike appeared to push and pull and throw his body about slightly, but no agressive recovery motions were ever seen throughout the next 30 seconds until the crash.

As the lateral motion of the glider began to pick up velocity, I cautioned the driver/observer of the tow vehicle that "He's doing a yaw turn!" by radio. About 20 seconds into the tow, the glider was about 150 ft high, 1/4 mile away, and 75 yards off of the center line of the road. It appeared that the glider was no longer climbing due to the driver easing rope pressure.

The glider yawed back and forth about three times. The pilot was again making weak contortions with his body. Then the glider started to climb again but this time rolled hard left into a lock-out.

When the weak link parted, the glider's nose was pitched up at about a 40 degree angle with the wings about 50 degrees from horizontal, as seen from take-off (directly behind the glider, 1/4 mile distance, clear, cloudless day). Estimated altitude at that point was 150 to 175 ft. When the weak link broke, the pilot appeared to be pulling up ((Pushing down?)) on the right side of the control bar, legs straight down toward the ground.

The glider stalled (tip stall), turned left, and dove at the ground, all the while turning left. The glider completed the first dive at a very high speed at about 50 to 60 feet, pointed back at the launch area, still banked left.

It then zoomed up to about 90 feet and stalled again, with the keel being almost verticle (though the left wing again was slightly lower). I could clearly see that the pilot was fully pushed out and still had his hands at the same points described earlier.

The glider then whip stalled to the left. It stopped forward rotation at about 85 degrees verticle and about 50 feet altitude, at which time it began to recover. The pilot's body was sideways to the control bar and beginning to straighten back out.

The glider began to pitch its nose up as mentioned, while accelerating to terminal velocity. The pilot got his body straight and was fully pushed out when the glider and the pilot impacted with the ground at about 50 mph simultaneously.

I do not think the glider absorbed any of the impact energy for the pilot due to the angle of the keel at that moment (which in full side view appeared to be 50 degrees from horizontal.)

I believe that recovery in pitch was excessively slow due to the glider having to recover from a slip as well as a dive at the beginning of both dives. (I.e. the side slip motions impeded dive recovery until the keel lined up with the direction of motion.

Medical help consisted of immediate first aid by myself and Gary Shear (within 160 seconds) to clear Mike's mouth and nose of mud (from the field), blood, and phlegm as much as possible. Others went for aid when we discovered no one answered channel 9 on the C.B.

A local nurse was found and brought to the scene within 15 minutes. Meanwhile we cut Mike's harness loose and removed the glider in preparation for professional paramedics.

The nurse managed to get blood pressure readings and heart beat by the time ambulance paramedics arrived. We maintained Mike in the exact position he was lying throughout, due to fear of spinal injury, redigging a breathing space each time proxisms seized his unconscious body and he moved. Eventually we also cut his helmet chin strap and removed it without moving him.

The parametics brought a back board and neck brace and got those on him. Then about nine of us got him turned on his back so they could work on him.

We dismantled and tied down his totaled glider with great difficulty as soon as we learned a helicopter ambulance was comming (for fear of it blowing over and hurting someone else.) When air care arrived, they had trouble getting an airway started which was necessary due to massive internal bleeding. Once this was done, he was helivaced out.

Mike died in emergency about two and a half hours after his accident, after an intensive and frantic effort by all to save him. The lead doctor said he had sustained heavy impact truama to his frontal brain, his chest cavity, and probably his internal organs. Officially he died of cardiac arrest, due to the above as far as I can muddle.

I got Mike's dismembered harness out of the truck last night to inspect it for possible clues. I found that his belly band carabiner gate was not locked. I am certain that it was not locked during the flight and crash. I make no conclusions but am noted for being an advocate of having a half turn on the ferrel ((ferrule)) nut of the belly band carabiner as a precaution against catching on the base tube.

There is no direct evidence at this time that Mike was caught on the base tube of his glider, but I AM stating that there is no evidence that he was not snagged on it, either. The fact that he stayed on the right side of the control bar throughout the flight is unexplainable in view of his previous level of demonstrated flying skill and care as a fledgling pilot. Therefore, I state my suspicion that Mike may have been somehow snagged on his glider, such that he could not make full control motions.

Outpoints:

1. Unlocked carabiner on belly band.

2. No radio on glider, opted for visual signals before flight but made none.

3. Three significant opportunities to recover control without doing so.

Suggestions for prevention:

Create a uniform launch check list that includes the following:

1. No radio, no tow.

2. Make sure that carabiner has at least half turn on ferral nut lock position.

3. Threaded bridle to be used by veteran pilots who wish to try out land towing inexpensively, not for Novice entry level pilots, as was inventor's original intention (me).

4. Formal training in land tow basics for all entry level land towers along same guidelines as all other aspects of hang gliding, with dual instruction for Novice pilots to train them to make AGRESSIVE CORRECTIONS when needed if they wish to tow fly as a prerequisite.

The preceding materials are submitted as a sincere effort to illuminate what is for me at present time a very painful experience. No editing or gramatical correction has been done in the interest of spontaneous reporting and before the healing effects of memory loss begin to set in. At least two other witnesses are doing likewise at this time, they assure me. I've discouraged them from telling me what they think I should write, and I've told them nothing of my point of view in the hope that a composite multi-viewpoint recounting might bring out the truth of the incident. That done as a Pilot, Observer.

As Region 11 Director, I have decided that Gary Shear, Mike's Instructor, is without blame in this incident. He, like all of us does share in the responsibility for creating the tow activity. However, many years ago I discovered many fundamental differences between the words (and intent of) RESPONSIBILITY and FAULT (or BLAME if you will).

I suggest any of you who are looking for someone to blame look up the above three words, too. Believe me, this little group is hurting and soul searching far harder than any censure you could think up to insure no future lack of alertness with entry level tow pilots.

However, I would appreciate any constructive training suggestions, materials to research, knowledgable sources on the subject of land towing, Novice skills beyond the suggested reading list in the Novice and Intermediate Pilot Profficency materials.

Let us not waste this gentle young man's life by not learning.

(P.S. Medical Examiner's report should be forthcoming in 6-8 weeks.)
*
6/02-05

ACCIDENT ANALYSIS

by Donnell Hewett

(Note: The above accident report was forwarded to Doug Gordon who is working on the USHGA Surface Towing Guideline Committee. He forwarded it to me and asked for my opinions regarding Warren's suggestions and how the accident might effect the proposed standards. This letter is my response to Doug's request.)

Dear Doug,

Thank you very much for sending me Warren Richardson's report of Mike Dorobiala's fatal towing accident. Sharing this kind of information with others is the only way that similar accidents can be avoided in the future.

Warren Richardson did an excellent job of reporting the accident. Unfortunately, his report did not clearly indicate the real CAUSE of the accident. We simply MUST pursue this matter further if Mike's death is not to be in vain. I certainly hope that the other two witnesses Warren mentioned will take the time to write up their own versions of the accident, and that the medical examiner's report will be forthcoming. Perhaps they can help pinpoint the actual cause of the accident. In the mean time, we can only assume various causes and try to form conclusions based upon these assumptions.

I am writing this letter to you because it is certain that the topic of this accident will come up during the discussion of the proposed Surface Towing Guidelines. Since I will not be present during these discussions, I would like to take this opportunity to express my opinions on the matter.

HEART ATTACK OR SEIZURE

In my opinion, the most probable cause of this accident is a heart attack (or a mild seizure). I know that this seems improbable for a 22 year old, but stranger things have happened. And it would not be the first time a tow pilot died of a heart attack. (See SKYTING NO. 19.)

A heart attack would certainly explain everything reported so far about the accident. Unfortunately, it can only be verified or disproven through an autopsy, and even that may not be conclusive. Furthermore, this assumption is a type of "cop out" in that it suggests that nothing can be done to prevent future reoccurrences.

Well, we could require that every pilot have a recent and thorough "flight physical" before being allowed to hang glide. But this would be difficult to enforce even if it were the LAW, and impossible to enforce if it were not. Furthermore, I dissagree with this philosophy, feeling that it is the responsibility of the PILOT to learn whether or not he is healthy enough to fly.

PILOT ERROR

The fact that the pilot took no agressive recovery actions throughout the whole incident suggests the possibility of pilot error causing the accident. In my opinion this may have been a contributing factor, but I doubt that it was the primary cause. The situation simply persisted for too long and the number of errors would have had to be too many.

But if pilot error was the cause (meaning that the pilot knew better but failed to do better), then there is little that we can do except emphasize and reemphasize the importance of FOLLOWING THE KNOWN SAFETY GUIDELINES and refuse to tow pilots who do NOT follow the known guidelines.

NON-SYMMETRICAL FLYING

Was the pilot in the habit of flying with one hand to the side and the other in the center of the control bar? I doubt it. But if this was the case, or if the pilot simply chose to do so on this one flight, then this may have contributed to the accident.

To prevent a similar incident, pilots should be cautioned not to fly non-symmetrically (unless that is part of their announced flight plan), and spotters should be instructed to abort any flight where the pilot flies this way. Of course, if the reason for doing so is obvious and acceptable (such as when the top bridle line interferes with the pilot's head movement at high tow angles), then the spotter should not abort the flight.

This procedure should be part of the normal tow training program and not part of the official guidelines. To put EVERYTHING like this into the guidelines would simply make them too long and too detailed to be practical.

INADEQUATE TRAINING PROGRAM

Any time a novice is killed, the training program is automatically suspect.

Was the pilot qualified to fly on a 2000 ft line? I would think so after 11 months and 150 flights. Surely he had already mastered the height at which the accident took place (150 ft) even on the 500 ft line.

Was the 500 to 2000 ft towline transition too great? Probably. The psychological effect of such a large transition MAY have prevented the pilot from thinking clearly. The gradual advancement skyting criteria requires that a student be limited to no more than TWICE the altitude (or towline length) that he has already mastered. This is a clear violation of that safety guideline.

Didn't the pilot know better than to fully push out on his last stall? Surely he knew the this would result in a whip stall which could be fatal at any altitude, especially at one as low as this! Perhaps the panic of the previous stall had him paralized.

If this is the case, then more emphasis should be placed on stall and lock-out PREVENTION during this phase of training. Even though a novice may have been TOLD how to recover from stalls and lock-outs, he does not have the EXPERIENCE and REFLEXES to do so in a critical situation. PREVENTION is the only safe practice at this level of training. It should be practiced from DAY ONE!

Should a video recorder have been used in the training program? Yes! (Oh, I know this is not always economical or practical, but just as parachutes SHOULD always be used when hang gliding, so SHOULD video cameras be used during training flights.) PERHAPS Mike should have made better corrections on this flight if he had previously seen his mistakes on other flights. Of course, a recording of this flight would not have directly influenced its outcome, but it would have provided more information about what caused the accident. In other words, even though it may NOT have saved Mike's life, a video record MAY have helped save the lives of others.

TOWLINE TENSION

No mention was made as to the actual towline tension during the fatal flight. The driver apparently accelerated, slackened off, and then accelerated again. Was the tension too much for the novice to handle? I doubt that this was the case because of the non-symmetrical flying and the lack of positive corrective actions.

In any case, only experienced drivers should tow novices and they should be trained to keep the towline tension low (generally less than 1/2 "g") while towing novices and warned about accelerating so hard that the novices may become surprised.

CREW

Was the crew somehow at fault? Again I doubt it.

However, the report suggests that the driver and observer were one and the same person. If this is true, then it was a clear violation of the proposed safety guidelines. There is no way a driver can adequately observe a towed flight (except during actual take-off).

Was the observer watching the glider instead of the pilot? On a 2000 ft line this is quite probable. If so, then he would have failed to see if the pilot was having any trouble or trying to release. (We know Mike was flying non-symmetrically, but when did he start having "trouble" and did he ever try to release.) The cardinal rules here are, "Watch the pilot, not the glider!", "When in doubt, slow down!", and "When the pilot tries to release and cannot do so, then release him from below!"

WEATHER

The fact that the last turn on the towline was so much faster than the others suggests the possibility that a wind gust contributed to the accident. But it is doubtful that this was the major cause because of the mild conditions and the consistent left-turn tendency of the glider.

In any case, pilots should be trained to react instinctively to wind gusts well before they are placed on a 2000 ft rope.

The slight cross-wind seems to have contributed nothing to the accident as the pilot clearly had the knowledge and experience to handle it.

COMMUNICATION

Did the absence of radio communication cause the accident? Certainly not!

Would the presence of radio communication have prevented the fatality? Possibly so!

The lack of the use of radio communication on a 2000 ft line is a violation of the proposed standards (section C.8) because visual signals are inadequate on such a long towline (thereby violating Skyting Criteria No. 11).

However, the use of two-way radio communication would probably have made NO DIFFERENCE in this situation. If the pilot made no attempt to correct his predicament and gave no visual signals (which would have been seen by ground observers even if the official spotter missed them), then there is little reason to believe that he would have acitvated the radio either.

However, if the pilot had been using the LOCC (Lock-On, Constant-Chatter) method of communication, there is the POSSIBILITY that he would have either stopped talking or said something to indicate that he was in trouble before the situation got completely out of hand. If the driver had stopped at that time, then PERHAPS the pilot could have gotten down safely. Yet even this is doubtful because a pilot who was unable to release from the towline and take corrective actions would probably also be unable safely to land a glider dragging a 2000 ft towline.

GLIDER TRIM

The fact that the glider consistently tried to turn left and was slow to recover after the stalls suggests that it was out of trim. Did it perform properly on the previous flights? Had it been damaged in a recent hard landing? Was it improperly assembled? I don't know. Perhaps someone else does.

The only way to prevent this type of thing from happening is to CAREFULLY maintain, set up, and inspect the glider - particularly after a hard landing and before launching.

GLIDER YAW

"Yaw turns" were mentioned several times in Warren's report. Is this a characteristic tendency of the Raven? Was this the pilot's regular tow glider? Had he previously demonstrated his ability to handle the adverse yaw problem on this glider? I don't know. Perhaps someone else does.

In any case, the towing "adverse yaw problems" is real, and it could have been a major contributing factor in this accident. There are two ways to solve this problem. The first is to use a glider (or a properly attached bridle system) which does not exhibit this tendency. The other is to thoroughly train the pilot in the "punch-it" technique of controlling the glider while on tow. For a novice, the first method is strongly recommended until he has sufficient reflex skills to accomplish the second.

SNAGGED BRIDLE

Warren suggested that the body ring carabiner MAY have snagged on the control bar. But if this is true, then how was the pilot able to "fully push out" later in the flight? Did the carabiner somehow become untangled after the weak link broke? And why didn't the pilot release the instant he realized he was tangled? And how did the carabiner get snagged in the first place? Was the glider being towed so fast that the pilot had to pull his body through the control bar? Was there more wind gradient and/or more air turbulence than suggested in the report?

To me the evidence of a tangled body ring seems very weak. But if the body ring did snag, there is no doubt that the situation would have been quite critical.

The only way to prevent this from happening is to use a body ring that cannot possibly snag. If a carabiner is used, then make sure that it is LOCKED! USE A CHECK LIST to make sure you don't forget.

RELEASE SYSTEM

In his report Warren suggested that the threaded bridle may have contributed to the accident. But he have no evidence to support this hypothesis. Did the bridle fail to unthread when released? Did the release mechanism fail to operate? Was the release lever out of reach of the pilot when he needed to release? (I.e. was it mounted on the left when the pilot needed to have his hands on the right in order to control the glider?)

I see no evidence of this in the report. Nor do I see why the threaded release is more dangerous for novices than for advanced pilots.

But regardless of the evidence, it is my personal opinion that the apex-release system (activated by a pull string) is logically the safest way to tow. Never-the-less, the dangling bridle could (and has) caused control problems (especially for a beginner or novice), so until more evidence is forthcoming I would not outlaw the threaded bridle concept.

WEAK LINK

The severity of the stall after the weak link broke suggests that the weak link was too strong. A loop of No. 21 nylon line should break in the 250 - 300 lb range, I would think. Unless Mike happens to have been a very large pilot, this is almost certainly too strong a weak link - particularly for a novice pilot.

The proposed guidelines state that weak links should ALWAYS be tested to see that they NEVER exceed 1 "g" of force. In the case of novices and beginners, I would recommend that even weaker links be used. It is impossible to state exactly how much weaker they should be because of the variety of circumstances, but I generally recommend something in the range of 0.5 "g" to 0.75 "g" for beginners and novices, respectively.

PREFLIGHT CHECK

Would a preflight check have prevented this accident? Possibly, but I doubt it. There is little evidence to suggest that WHATEVER caused the accident would have been discovered through a preflight check. About the only above mentioned potential contributing factor that I see which MIGHT have been detected by a checklist is the unlocked carabiner. (The release mechanism had already been checked.)

A lengthy check list might also have discovered something out of trim with the glider. But how long should a check list be? Some people and towing systems need a long list, while others can safely get by with a short one. Since each pilot is ultimately responsible for his own flying, I believe each pilot should decide for himself which check list is best for his own system of towing.

COMMENTS ON WARREN'S SUGGESTIONS

The rest of this letter contains my own personal comments about the suggestions Warren Richardson make in his accident report.

UNIFORM CHECK LIST

The proposed guidelines require the use of a check list, but they do not specify that it be "uniform". I agree with the proposed guidelines. A "uniform" check list would neither be adequate for, nor applicable to, ALL towing systems and situations. (If the list is too long, it will not be used.)

NO RADIO, NO TOW!

The proposed guidelines require the use of a radio except under special conditions. I believe that these conditions can provide adequate communication for safe towing. Since the real issue here is RELIABLE COMMUNICATION (regardless of the form), we should not forget that there are certain times when visual (and even oral) communication is more reliable than radio transmission.

The proposed guidelines also require LOCC (Lock-On, Constant-Chatter) radio communication under other special conditions. Again I agree with the guidelines.

In short, I do not support the idea of a blanket rule requiring radio communication in all towing circumstances.

LOCKED CARABINER

Locking the body ring carabiner is a system dependent guideline and should be included in the appropriate SYSTEM check list but not in the general guidelines.

NO THREADED BRIDLE

As already stated, I do not see how a threaded bridle is more dangerous to a novice than to veteran pilots. Nor do I see how it is less expensive than apex-release if it uses 11-mm perlon rope and a reliable release mechanism (as it should if it is to be as safe as possible). Therefore I do not believe that threaded bridles should automatically be prohibited for novice training.

In fact, there is evidence that "short threaders" like those used in England may even be SAFER for novice training than the three-ring apex-release bridle commonly used throughout the United States. So each bridle and release system should stand or fold on its own merit.

FORMAL AB INITIO TRAINING

There is no doubt in my mind that formal tow training program should be developed which parallel those of free-flight. And certainly pilots should be trained to make agressive corrections when needed (and also taught not to over-correct when agressive corrections are NOT needed).

But towing is more complex than free-flight hang gliding, and every towing system requires its own special training program and techniques. Since ab initio tow training is still in its infancy in the United States, it should be approached with the utmost caution.

The proposed towing guidelines are silent on this issue, except to specify the requirements of a USHGA Certified Skyting Instructor. It is my opinion that the person most qualified to determine what should and should not be included in a tow training program is that USHGA Certified Skyting Instructor who is implimenting that program.

If we attempt to set up a universal tow training program at this time, I believe progress will be slowed and more lives will be lost in the long run.

PLACING BLAME

I am greatly disturbed about the trend in our society to always try to "place the blame" for every unfortunate incident. It seems that we just have to "hang" somebody in order to "soothe" our own consciences. If necessary we'll even sacrifice a "virgin" to calm the "volcano."

Let's stop trying to find out WHO and start finding out WHAT causes our hang gliding accidents. That's what disturbs me most about this accident. I am not sure in my own mind what CAUSED it. Let none of us rest until its cause is discovered.

TRAINING MATERIALS

In my opinion the best source of training materials for land towing is the complete set of back issues of SKYTING. (Yes, it's over priced.) Although not designed for tow training, they do contain essentially every problem and solution that I personally have ever heard about. Anyone considering tow training should be aware of these problems and solutions whether or not he ever encounters them or intends to use them.

Furthermore, I am always willing to do what I can to help others learn to tow safely, so let me know if you think I can be of service.
*
*

[Tad Eareckson]

1986/04
*
SKYTING NO.45
MAR APR 1986
*
1986/04-01

AERO-TOWING

by Gerard Thevenot

(Article from Gazette la Mouette, Then Hang Gliding Quarterly.)

Towing a wing with an ultralight - a dream as well as the perfect solution to a number of hang gliding problems like flying in flat countries, reaching mountain tops where there's no road to the take off... solutions even to marital problems resulting from unending pilot recuperation hauls...

Now the dream has become a reality with an advanced technology ready to be taken advantage of by even the most humble pilots.

This series of articles on aero-towing destined to appear in the first few issues of La Gazette does not pretend to give towing lessons through correspondence. It is intended rather as the description of a method, a preliminary theoretical basis for a regular course given by any experienced instructor.

THE TAKE OFF

PREFLIGHT CHECK

Aside from any normal preflight check, for a hang glider, the aero-towed take off is preceded by a thorough verification of security mesures:

-Check the tightening of the ultralight's plier clamp by pulling hard on the tow line and testing the release.

-Extend the tow line from the ultralight to the hang glider making sure that: the tug's weak link is more resistant than the wing's, the tow line is in good condition, and the parachute is well set. Also check the wing's weak link and the tuning of the automatic velcro release system.

-While the delta pilot is in his harness making a hang check, he should take time to test the release. If it is his first or among his first towing experiences, he should repeat the release gesture a number of times to familiarize himself with the system - first just concentrating on gripping it, then with hands on the down tubes, looking straight at the tug he should release right at the instructor's signal.

Only when this maneuver is done precisely, with no hesitation can the pilot proceed to the take off.

TAKE OFF

While the tug motor is running to heat up for at least a minute, the delta pilot should balance his wing on the trapeze and make sure the run way is perfectly clear of obstacles. He then spreads his feet slightly apart and climbs the down tubes somewhat like a weight lifter lifting the handle bars, and when he's ready, balances the wing on his shoulders with the proper pitch. This is the ready signal for the tug. His running acceleration will be about the same as for a regular take off with the lack of slope compensated by the pull of the tow line. From the beginning to the end of the take off run, the nose pitch should remain the same as if he were taking off on a very gradual slope. Too much pitch will cause the wing to stall and make it difficult to control. Besides, it will climb too fast and bring on an automatic release right from the start. If the nose is slanted, the control bar might scrape the ground and result not only in a crash, but in a possible rupture of the weak link, if no wheels are attached to the control bar.

Once off the ground, the pilot has to make a 3 yard shift in order to get out of the propeller's wash. At the very moment that the tug's wheels lift off the ground, the hang glider should make a gentle nose lift that takes it up at exactly the same speed as the tug. If the towed pilot pushes the bar before the tug takes off, this will rob the tug of energy and consequently show it down or actually keep it from taking off. If the control bar is not pushed just as the tug takes off, the ultralight will do a sudden steep climb and as a result, the hang glider will not be able to rise sufficiently and will be stuck in the wash.

It is extremely important to pay full attention to the tug. The running start, nose pitch control, hand shift and positioning in the harness must become absolutely automatic and most important is to remain at the same level as the tug.

The harness might be the cause of certain problems at take off. For example: a pilot who shifts his hands to the control bar late will find himself in the uncomfortable position of being pulled way in front of the bar due to the tension of the tow line. Although it's easy to steer with hands on the down tubes at a low speed, it's very difficult to do the same at a high speed. It is therefore advisable for the pilot to shift hands just when his feet lift off the ground at the very latest.

Another technical problem can occur with both pod and stirrup harnesses that lack adjustable leg straps as they tend to spill forward because of the pull of the tow line over the shoulders. If improperly adjusted, it is very difficult, if not impossible, to catch the stirrup or slide into the pod. If a pilot using a harness without adjustable leg straps has trouble steering when he's out of his harness, then for the first few times it's better that he take off already set in the harness, on wheels, with an aid at the keel.

The take off is the most critical phase of towing; the ground is hard and too close for comfort. Essentially it's easy, but security mesures are absolutely indispensable (velcro, weak link, wheels, parachute, rear-view mirror on the tug, a practical and reliable release) and most important is to give undivided attention to the tug.

1986/04-02

STATISTICS NEEDED

Dear Donnell,

I am interested in the number of hang gliding students who take lessons every year.

At our recent Board of Directors meeting, Dan Johnson showed me an article from the Parachute Association in which they were making their fatality stitistics look really good, because they included all the students, increased the number of "participants", made the denominator larger, and therefore had a lower fatality rate.

As you know, hang gliding fatality rates have always been computed with the denominator somewhere between 10,000 and 20,000, the assumption being that this is the number of participants in the sport.

Nonetheless, if a beginning student gets killed, we certainly count him in the fatality numerator as a fatality. Therefore, one could make the argument that including them in the denominator is "fair" as well. I think this is a good idea, as long as we admit up front exactly what we are doing. It's for that reason that I would like to get a guesstimate of the number of students who pass through hang gliding schools in the course of a year. I would also be interested in any other comments you might have on the subject in general.

Doug Hildreth, Chairman
Accident Review Committee
U.S.H.G.A.
1025 East main Street
Medford, OR 97504

P.S. If we could get some response from towing instructors around the country that would not only give us a better idea about what's going on but also allow us too make our statistics look better.
*
1986/04-03

EAST ANGLIAN XCS FROM TOW LAUNCH
The Frustrated Flatlander triumphs at last!

by Edmund Potter
ENGLAND

3000 feet below me the Norfolk Broads sparkled in the sunlight: deep blue, studded with minute triangular white sails, and etched with herringbone wave patterns.

Dense cloud shadows dappled the lush green countryside and the blue-grey expanse of the North See beyond the sweep of the coastline. I could recognise Hicking Broad and Horsey Mere. The names brought back memories of sailing holidays long past. Somewhere down there too was Catfield, the village of my earliest childhood recollections. As a boy growing up in Norfolk I had always wanted to fly. And now here I was, circling beneath the white clouds over the undramatic landscape for which I have such a nostalgic affection. Was it a dream? Certainly a dream realised. It was no disappointment to be stopped by the North Sea coast. By now I knew that I had flown nearly 40 miles - my best distance so for. And to do this from a tow launch was an added satisfaction. I hoped Tony and Rona Webb, the winch operators, wouldn't feel too envious.

At last I began to relax and enjoy the flight, the first twenty miles had been pretty tense. Cloudbase had no risen to about 4000 feet, the vario wined away between 2 and 6 up, and the shadow of 'my' cloud which had been a comforting companion for the last half dozen miles looked about a mile across. With my camera fixed to the A-frame beside me I indulged in some unorthodox manoeuvres to photograph the scene below. To the southwest the river Bure snaked its silvery way into the cloud haze towards Great Yarmouth where the long stretch of Breydon Water was just visible.

The coast was fast approaching with my westerly drift. Afraid that the moderate wind might have increased to the fresh wind forcast I turned into wind to check that I could avoid being carried out to sea. Then to stretch my distance a little further I left without a qualm and headed south into the sunshine. Keeping a sharp lookout for helicopters on their way to or from the North See rigs, I descended with the help of some sink to land gently in a sugar beet field just just outside the little village of Winterton-on-Sea.

My feet were safely on the ground but my head was still in the clouds as I cast my mind back over the flight and its preparation: studying the airspace maps the night before, but not daring to hope for a significant flight; the tense drive to Sculthorpe airbase that morning; studying the crops on the way for 'landability'; recognising the classic cross country weather, and being afraid of 'blowing it'; crossing the boundary fense at 1300 feet after releasing at 1000 feet; scratching, catching and losing the patchy lift; eventually reaching cloudbase at 2500 feet after 10 miles; nearly giving up hope at 1000 feet over Blicking Hall; and then catching a good thermal that gave my first sight of the Broads and the Norfolk coast beyond.

But the impression which remains above all - or perhaps one might say, beneath all - is the beauty and fascination of the countryside view from the air. Is this why we do it?

Flight details:

Takeoff: Sculthorpe airfield, Norfolk, 6th July 1985.
Landing: Winterton-on-Sea, Norfolk.
Distance: 39.7 miles.
Times: 11.05 a.m. - 1.09 p.m.
Kite: Magic 3 (166).
Harness: Stirrup.
Towing gear: Tony Webb pay-out winch and towing leg.
'Skyting' bridle principle.
Instruments: Ventimeter; Davron 100 vario; Diplex altimeter.
*
1986/04-04

Towing, Learning in Germany
Article from WINGS magazine.

by Mike McMillan

A light mist dampened the air; blurred figures readied the engine. Light snow floated by on the wind as I prepared for the flight. The command "Start!" - a distant murmur - a sudden snatch and suddenly parked gliders floated towards me. I landed in a heap and wondered what I had done wrong.

"Keep the nose down lower on take off" muttered Gibb as I lined up behind the winch once more. I concentrated hard on holding the nose down and controlling the glider. Once more I was snatched from the ground and seconds later flew at great speed towards the distant clouds. This time the glider remained straight, the air rushed by, the vario screamed and I fought for control Eventually the climb levelled out and I was able to move my legs for the release.

Bob Harrison was next but one in line for the guillotine; the look on his face summed up his feelings. Gliders were taking off at a tortuous angle of attack and we both felt the consequences of a line break close to the ground would be horrendous. We were to find out, as the pilot before Bob started his climb. The line broke; Instead of the expected plunge to earth, the glider simply rounded out and landed straight ahead. The light was fading as the control tower closed the airfield, much to Bob's relief! Talking over the day's events I felt decidedly pessimistic about the ability of inexperienced pilots launching behind this system. Gibb and his friends were all experienced flyers intent on record breaking and maxing out each launch. Standing at the winch end it was obvious that we are being towed up far in excess of usual towing tensions by a winch operator who was perhaps rather unsympathetic to the needs of inexperienced pilots! The following day dawned murky and cold as we set off for a club some 50 K's to the south of Neurenberg. The contrast to the previous day was apparent from the beginning.

A new club, typical of many in Germany of which there are a considerable number with relatively small memberships, perhaps 30 or 40. There was a feeling of life about the field as families and friends gathered to watch the day's proceedings. Club members lined up as the winch effortlessly launched pilots skywards. My hopes rose as here was a system that was obviously working well.

Bob looked a lot more relaxed as he readied for flight Wigbert had briefed us well, running through a long check list of procedures that seemed to cover every possible situation. Pilots were averaging height gains of 250 metres from a horizontal tow of 500 metres in a light variable wind. As Bob released and cruised off hunting for lift, German eyes looked aloft for signs of English aerobatics, the usual manouvers on quiet stable days. Bob's wings remained level; the Germans lost interest and prepared for their own flights.

Ten minutes later a murmur around the field directed our attention skywards where Bob was gently turning and obviously not coming down. Wigbert strode forward and announced in his strong gutteral English that "it eez sometimes not goot to be zee instructor". He halted the winch and race to rig his shiney mylar Magic. By the time he launched Bob was a speck in the sky, but not to be outflown Wigbert rocketed skywards to give chase. This was to be an interesting tow, first hand experienced of a "step" tow. Having reached maximum altitude the pilot turns down wind towing the line behind until he reaches the downwind end of the field. Having turned into wind the winchman engaged the clutch and starts a second tow up. This can be repeated several times, the pilot eventually reaching great altitude. Needless to say, the pilot needs good communication with the winchman, and the system is fraught with danger.

Wigbert streaked off towards the returning Harrison who was intent only on landing and thawing out his toes!

The real value of the day lay ahead as Wigbert handed over the winch controls to us. It took about 10 launches to become confident enough to relax and instinctively fly the gliders up. Wigbert gave us his history of winching and the statistics make interesting reading. The club bought the winch 9 months before and in that time had made close to a thousand launches. Most of the pilots were around P.1 standard flying only Atlas and Polaris Deltas. The more experienced pilots were all flying C.F.X. gliders. During this period there had been no winch launching incidents although a friend of Wigbert's had tried to launch not hooked in elsewhere and had broken a leg. The club was following a set safety procedure that pilots checked with each launch.

I believe that the revolution in hang gliding will not come from 6th generation gliders, it will be the winch. The winch will bring hang gliding clubs into a focal centre allowing the sport to expand the social side of its activities. Outsiders will have a chance to come and see what flying is about and schools will have a tool with which to encourage students to continue their flying careers.

Winching has been around a long time and there have been many accidents. With these experiences behind us and the development of new winches and techniques, a set of procedures can be put together so that over the next few years the Hang Gliding revolution can get under way.
+
Twin drum "Koch" Winch
Mike McMillan operates "GROSS CLAUSS" Winch
*
1986/04-05

HELMET MIKE WITH FINGER SWITCH

Dear Donnell,

I've been enjoying the latest discussions on writing a Skyting manual. I do have a few comments on Mark Mulholland and Dave Marcus's article in Skyting #43. First of all, it is far preferable to use a helmet mike (with either a VOX or finger switch) rather than a regular mike attached to the base tube. The reason should be obvious. If you aren't near the mike (as during take off, or if you stuff the bar), then no one'll be able to hear you. Definately not a desirable situation. Second of all, if you have the mike constantly keyed, then the ground crew can't tell you if they have a problem on the ground (such as the rope snagged in the trees, or a broken winch). I know that there's a VOX mike available for Radio Shack CB's from about $110. That seems rather expensive to me. I have a helmet mounted mike with a finger switch which I made, and I've used this successfully off tow at Packsaddle. The finger switch mounts on the middle finger with velcro, and can be easily activated with the index finger without the need to remove your hand from the glider. I am willing to make them for anyone for $30. (Includes shipping). My address is 6327 Dellfern, Houston, Tx 77035.

I do like the idea of a 5 minute launch window, although it hasn't been much of a problem here in Houston. Actually, this is usually an unwritten rule in mountain flying.

By the way, Donnell, has anyone done anything to test the strength of weak link material & knots, and the effects of single, double, and triple lengths in use. I've seen everything from number 14 to number 20 twine (twisted and braided) used and all sorts of knots. It would make an interesting future article if someone has the right equipment to test them.

Hope you have a great new year.

HENRY M. WISE
HOUSTON, TEXAS
*
48 MILE FLIGHT FROM TOW
*
1986/04-06

Dear Donnell,

Here is a short synopsis of my skyting activities here in Southern Wisconsin. Bong Recreation Area located 23 miles west of Lake Michigan is now closed for the year due to Dog Trails and hunting season. The past season for me has logged numerous memorable flights both from tow and foot launch. The best yet was a 48 mile flight from Bong west to Janesville, Wi. Yes! East to west.

The day was incredible with cumies forming from 9:00 am to 3:30 pm. I launched at noon and spent the first hour trying to get high. Eventually I caught a good one and coned it to cloud base at 4000' ATO. The next 3 1/2 hours I flew from cloud to cloud losing an average of 2000' between them before encountering more lift. As the day and the mileage progressed, I was able to get higher before reaching cloud base. the best thermal enabled me and my Sensor 510 VG to reach 5200' ATO. I then glided over Janesville and landed 2 miles west of town. The time was 4 hrs 20 minutes nearly equaling my foot launch best of 4 hrs 30 min. In my first full year of X-C flying I logged 23, 24.5, and 48 mile flights from tow and 8, 29, 11, 21, 21, and 40 miles from foot launch. The tow flights averaged over 3 hrs each and the first two foot launches were from a 300' ridge.

I'd certainly like to commend you for bringing skyting to all of us flatlanders. It has enabled me to double my airtime and upgrade my flying skills.

On another matter, I need information on using cable instead of polypro as a towline. The info in skyting didn't mention size of line, manufacturer, or cost. Possibly you could get me this info and or Bob Faris address so that I might change over to this line. I've found that polypro-ages quickly and after a short period of time (less than a flying seson) breaks too many times to make for a good reliable line.

I've obtained a drag chute for my towline but haven't experimented with it as of yet.

UPDATE ON BONG:

Even though it has a poor location (i.e. 30 miles south of Milwaukee and 50 miles north of Chicago and 23 miles west of Lake Michigan) Bong produced over 500 miles of X-C in about 12 weekends of flying. Watch out next year! The X-C tow pilots assoc. regulates this site. Anyone wishing to tow should contact them about available flying time.

Larry Bunner
Byron, IL
*
1986/04-07

Dear Larry,

The last I heard Bob Faris was still associated with Front Range Hang Gliders in Ft. Collins, CO, (303) 482-5754. Jim Zeiset at (303) 539-3335 also uses a cable for towing. The best I remember, their steel cable is multistranded and about 3/32 inches in diameter.

Donnell
*
1986/04-08

DEEP WATER STARTS

Dear Donnell,

No deep water towing this summer. I took the two months and traveled 12000 miles to fly the USA. A great experience.

Your letter from Bill Cummings indicated he was having problems with deep water towing using the skyting system and was returning to the Moyes hook-up - - - Donnell, there is NO need to do that - we have successfully been doing skyting deep water takeoffs and landing since Sept. 1982. If you send me his address, I'll drop him a line.

Thanks for ALL your efforts in behalf of our sport.

Don A. Boardman III
Rome, NY
*
1986/04-09

SECOND ANNUAL TOWATHON BEING PLANNED

Dear Donnell,

Thanks to Bob Fisher (HHGA) we were able to use the Skyting method of towing at Lake Livingston this past summer. The Fly-In held the first of August turned out great. We are looking forward to the second annual Towathon next August. Skyting enabled several members of the Houston Club to experience towing for the first time. Skyting and water do mix well, the results are lots of fun.

Keep up the great work as we are always looking forward to reading your Newsletter.

Bob Casto
Houston, TX
*
1986/04-10

SOME USEFUL INNOVATIONS

Dear Donnell,

In March of '83 I ordered the first 4 Skyting Newsletters, with these and help from Garry Whittman ((Whitman)) we in central Nebrasky have been getting more air time than ever.

This winter has been nice, I logged a 1750' tow (1 1/14 mile road) on New Years day, and yesterday (Jan 11) we flew in shirt sleeve weather for a nice winter break. 65 deg in Neb. in Jan. is awesome.

Our system is much lide everyone else uses. We use your CM bridle with a Paul Lindquist apex release, 165-175 lb weak link (150 lb for me) as I tow a 148 sq glider and weigh 135. We use 1/8" or 3/16" poly rope depending on the day, and homemade bydrolic monitors which we synchronize 2 or 3 times a year with each other and a 250 lb spring scale so everyone is the same.

Two things we developed on our own was a "sign" protector and a pretty efficient hand line-winding system I call the "Nebraska sidewinder".

The sign protector is used to avoid taking down the low maintenance road signs, the ONLY obstruction on our ONLY usable tow road. It is a 3/4 rigid ABS plastic water line with a 6'x1/8" slot cut in 1 side on a table saw to within 8" of the end of a 10' length. It slips over the edge of the sign and into a hollow stake in the ground.

You probably don't wish to hear this, but it does guide the rope up & over the sign without problems. Removal of the signs is a major fine in Neb.

The Neb. sidewinder line reel mounts on any vehicle in a few minutes, it THEN goes off & on in seconds, works best with 0-3000' of line.& will hold up to 5000' or more 3/16" so spare line can be stored on the reel. A variable torque bar makes winding quick & easy about 1000'/min, about the same as electric winders, without the expense & time of wireing each vehicle it may be used on.

We have used hand winding for 2 1/2 years and like its cost and portability. I have been marketing the last design for $60 + shipping have sold 3 and will make more if the present users like them as well as we do.

I can't really make any money unless I mass produce 10 or more at a time, so if I can't develope a market I may send skyting news the plans so people can build their own when I make that decision.
+
MINIMUM MAINTENANCE Road
-Drive-
Tow Hang Gliders AT YOUR OWN RISK

Wind Streamer
Duct tape to sign after pushing sign into the slot in the plastic tube
tow line will slide up & over the sign without cuts or abrasions to the line or the pilot and no one gets charged with distruction of county property or tampering with road signs.
10'x3/4" ABS Rigid Water line With 1/8x6' slot cut in side
leave 8" to 12" at the top uncut
Hollow steak
Smash 1 end of 1" conduit or old down tube.
+
BOB HLADKY
217 E 23rd St.
Kearney, Neb. 68847
*
1986/04-11

SKY SAIL PROGRESS

Kirkland, Wa.

(Ed: The following report describes the progress that has been make in developing a "Sky Sail" - an ultralight glider design to be used as a sail for a boat.)

We made 20 test flights during the summer of '85 but failed to achieve stable flights. We suffered a major crash after a structural failure on flight #4 which resulted in a stronger, lighter bird. The most successful flight was flight #3 which lasted over a minute. Coz & Lee were reasonably comfortable aloft during that time, although the power requirement taxed the capability of the 125 hp tow boat.

In reviewing the flight test data, it appears likely that the sweep and dihedral were the primary sources of stability The most stable flight had jibs and not a horizontal tail. Removal of the jibs caused nose dives, as the lift was too far aft. Sweeping the wings forward solved that, but created forward CG problems on the floats as well as the stability problems.

Failure of the keel beam on flight #4 caused inadvertent reduction in dihedral. We never went back and tried with more dihedral. Trimming the jibs was also difficult, and study of the photos indicates that tightly sheeted jibs of flight #19 & 20. Most rotation may also be a significant factor, as mast stall may have caused the nose dives.

Although it would probably be easier to work with a rigid wing next year, we stand to learn more by continuing with the slotted airfoil. The early success of flight #3 indicates that stability is possible, if we can just get the sail adjusted properly. I don't think the weight difference between flight #3 and flight #20 was significant. Let's try adding 2 deg. dihedral and rotating the masts 10 deg. nose down. We can sheet in the jibs and add tell tales to enhance flow visualization, especially for the photo coverage.

One of the reasons we will stick with the soft rig is the weight reduction potential, especially for scale-up versions. We should probably enlarge the tail and incorporate rounded leading edges to prevent stall. It is entirely reasonable to go for a 50% weight reduction by substituting graphite/epoxy for aluminum in this stiffness critical application.

CURRENT PROPOSED
Spars-------Alu--70--G/E/T1---40
Floats--Plastic--30--H/C------20
Sail-----Dacron--40--Dacron---40
Wires-----Steel--10--Kevlar---05
K. Tube--G/E/T1--10--G/E/T1---10
Battens---Glass--10--G/E------05
Tail----G/Nomex--10--G/Nomex--20
King&Dwn----Alu--10--G/E/T1---05
Harness--GL/Nom--10--Nylon----02
----------------200----------147

The potential weight reduction is insignificant compared with the cost, so we will keep existing materials, just improve load paths & improve workmanship.

THE REST OF THE STORY
TILLICUM DASH '85

"Sky Sail" was late to the starting line due to crowded elevators at the Space Needle at noon, 10 min wait for Paul Priebe at Shilshole, and trouble with dynafoil carburetor at Dunamish Head. Our first flight was at 2:05, and the second about 2:15. Joe & Lee finally got underway about 2:25, and they did not know where they were going.

"Dynafoil" circled the Bremerton Ferry, which was making 14 kts, and identified the finish line only when "Roland" and "Meridian" were bearing down on "Tranquility". This is an indication of the potential advantage of 20 kt craft over 10 kt craft in a race. The 20 kt boats like Sky Sail '86 may literally sail circles around the likes of "Meridian" & "Roland". (By the way, "Dynafoil" crashed on ferry wake, restarted, & still won.)
*
1986/04-12

COMPETITION RULES

by Mark Mulholland and Dan Marcus

(Ed: This is a continuation of the towing manuel published in SKYTING No. 43.)

The format for the monthly meets will be a Total Elapsed Time (T.E.T.) meet. The official timer has responsibility for logging start times for each flight as well as confirming this time with the meet director after pilot launch. Units of time will be awarded (or subtracted) for each of three categories:

T.E.T.
Mileage
Landing

Time will be determined by the official timer and confirmed by the meet director) less the launch time (as given by the official timer and verified by the meet director). The units will be in hours and minutes. Mileage will be awarded for any distance greater than 5 miles from launch. The mileage will be divided by 10 with units in hours and fractions in minutes. A 10% bonus will be given to all flights ending inside the designated landing spot (same size as Hang 4 requirement) in which the pilot lands on his feet and does not touch any part of the glider to the ground. A 5% bonus will be given to all flights ending inside the designated landing spot in which a pilot lands on his feet and the glider touches the ground (but does not bend, tear, or break). If the glider is "tweeked" then the pilot gets 0 time for that flight (the pilot forfeits that round). If the glider has to have some tubing replaced or if the pilot is injured, the total time for that pilot for the day is decreased 50% per incident. At the end of the day, the pilot that has the most time wins. An example of a score sheet is enclosed at the end of this manual.

The number of yearly points awarded is the inverse of the place for the monthly meet. For example, if you came in first with ten pilots competing, you would receive ten yearly points, second place would receive nine points, third gets eight, etc.. The pilot with the most yearly points at the end of the year is the yearly winner. The more pilots there are in a meet, the more points the meet is worth. An example of a score sheet is enclosed at the end of this manual.
*
*

[Tad Eareckson]

1986/06
*
SKYTING NO.46
MAY JUN 1986
*
1986/06-01

KEEL TOWING

by Tommy Crump

I have spent the last couple of evenings looking through our past videos trying to determine exactly when I became exposed to the center-of-mass tow system. My first exposure was the middle of June 19, 83 doing some hand towing at Gordon Iveys in a field. We were using a three-ring release.

The Sylvester's Kite Team first tried the center-of-mass system or skyting method with a belt around the waist the last of July 1983 on the James River. The same day I flew with my version of a release mechanism, a modification of the other methods. Other people were using three-ring releases and horse releases. I had a good in-line release from John Williamson and I had it as an apex release with a pull line on it to the base tube. It was a two-to-one system at that time. Sometime thereafter, late 83 or early 84, I got away from the two-to-one system and went to the one-to-one system. The one-to-one system consisted of a rope tied to the keel out to the apex and then back to the arrangement encircling the flyer. The bridle had a spreader bar with a ring in the front so that you could be towed without any side pressure. I used this system up until the middle of August 1985.

Some weeks after Bill Moyes was here in July 1985, we did some experimenting with a boom release that he had had success with in Australia. He had described it to me on the phone and when he came to Virginia, we used it successfully. The boom stuck out past the nose with a bungee that pulled it up. After we tried it in Virginia, John Williamson experimented with it in Maryland. The point that Bill Moyes made about the boom are: the boom offers a stationary plate to mount the release, not dangling on a rope. The release mechanism handle is on the base tube where you can put your hand on it without letting go of the base bar to release yourself in an awkward situation without letting your body fall out of control.

Skip Springer and I were trying to develop a different release mechanism that would not involve the boom and also do away with the apex release which was released by taking you hand off the glider and reaching for a line or rope to get yourself released. So fooling with or experimenting with some releases we already had at Moore's Brick Cottages, Sylvester's Tow Kite Team came up with a variety of different ways that a release could be secured to the keel. At that time I experimented with a Moyes A frame release that I had. The overhead release on the A frame was turned around backward so the rope ran down through permanent rings on the side of the harness and out in front. The first bridle had a spreader bar in front with a short V pull or a bridle with an overhead or front rope that went through some tubing under the keel and then back to the release through the A frame. The method seemed to work successfully that first weekend, the middle of August 1985, that we tried it.

I have experimented with the system and have modified it and am using it at this time. The modification is a keel release mounted in front of the A frame with the bridle going through the harness rings and up to the release. When the rings on the harness are in the proper position and the release is hooked on the keel in its proper place, no pushout or pull in is necessary under tow. The overhead or front rope of the bridle comes up to the same release. When the flyer releases all the ropes go clear, the overhead rope drops clear away and the two back ropes or body ropes or lower ropes fall or are pulled straight through the harness rings and are gone clear of the flyer. You have an unhampered flight immediately upon release. The system has been released under tow, shortly after take off and at peak altitudes, under tension; and all have released properly. Most releases, naturally, are made after the boat has stopped.

Because of the long bridle, fifteen feet long, there is no pressure on the flyer and the tow flight up is as close as I can imagine to free flight. The one thing that keeps it from being the same as free flight is that as you near the top or as you are peaking out, the overhead rope comes down to the base bar and you have to move your head off to one side to get away from it. Other than that, it is a very comfortable smooth and reliable tow arrangement. It could or may replace all the different types of tow arrangements that exist whether it be three-ring releases, dog/horse releases or a variety of number one releases, apex releases and number 2 releases, etc., etc..

Some things I have noticed in some of the center-of-mass release mechanisms are: breakage or failure of dog/horse releases, three-rings are somewhat of a hassle to hookup and may prematurely release or snag on something causing them to come open. Some of the threaded releases I have seen, where the release is on the keel or a jam cleat type of release will whip around and smack the flyer on the leg, between the legs or in the face or it may wrap around the base tube or hand up. These releases or arrangements all have their pitfalls, but as I can see the particular release mechanism that I am using does not readily surface any pitfalls.

In a release system, simplicity is important. In the keel towing system, you must be careful to thread the bridle line through the rings on the side of the harness and not through the harness straps and hook it on the release. The bracket that holds the release is simple in design and fits right on the Moyes A frame arrangement. A similar bracket could be adapted to most any hang glider A frame. The particular bracket and release I have folds up with the hang glider and the release folds up when you take the A frame apart it folds right up in the bag and zips up nice and neat so you don't have to hook up the release separately when you set the kite up.

Advantages and disadvantages of the Sylvester's Kite Team Keel Towing System: The disadvantages of the system are few. You have to keep 15 feet of bridle rope straight. Three lines must be separated and hooked up. If the bridle arrangement drops in the woods, it could get tangled or snarled. The advantages are: The system slides on a carabina. If the system malfunctions, you can, when the boat stops pull yourself free using the carabina. When you release you are totally free of all lines. There is nothing to hang on any bushes or anything on your landing approach; nothing for you to step on or trip on. Once you release there is no time involved in pulling up release ropes or bridles and hanging them on the wires, once you release, you are done. You are totally free as in the old method of towing the Moyes system. In a tight situation or shortly after take-off, if you have to release you don't have any ropes to be fooling with.

Some points that were left out previously were a ring or a float is put on a the bridle in a certain place to prevent the kite from nosing over on take off because of the inertia of the pilot wanting to stay behind as the kite takes off. A float also doubles as a device so you won't lose your bridle in the water if it comes loose from the carabina. A fortunate safety feature is if a bottom line breaks the bridle will thread through the carabina at the tow point and leave you standing there rather than jerk the nose of the glider over as in the old days. If the top rope breaks you will probably just take off and fly away. The tow bridle does not hook to the harness in any way that would create additional pull on the harness or harness straps which is another point of safety.

The release that I am using works every time and is mechanically sound. You need not have an additional release somewhere in case this one fails. A good mechanical release under probably most all circumstances is going to release every time. There are some things you must rely on or you can rely on that will work every time, hundreds of thousands of times without failure. A release mechanism that is so designed can do that. This particular release that I am using tow is a modified Moyes release that if for some reason it does malfunction in some way you can reach up and push the gate open with your hand and release the ropes.

Back when the center-of-mass system was first observed in our area, I was still flying the Moyes double release A frame even while other people were using the new system. I became convinced the center-of-mass system was effective and the way to go and was very much pleased when we had several aborted take offs with Skip Springer on the tow bar system on his beginning flights and then after several of those we switched to the center-of-mass the week after and away he went with no more problems towing or losing the bar.

One of the problems that is mentioned that some skyting bridles or release mechanisms solves is if a pilot fails to hook in the arrangement will release him from tow. Our solution or what we have been doing for a number of years is when you set your glider up at the beginning of a day, you hook your harness in to the glider hang straps and backup and you don't unhook it anymore. You crawl in and out or step in and out of the harness. You never unhook it and in this method you are less likely to have your harness unhooked.

On our keel towing system we don't actually tow the pilot, we tow from the keel and the pilot is between the body bridles but the body bridle does control the pilot in reference to pitch position but not as much in roll position as your skyting systems.

YOUR COMMENTS PLEASE.
+
Body Ring
body Ropes
CARAbiNA
Tow Line
+
Tommy Crump
P.O. Box 913
Chester, VA 23831
804-748-7886
*
1986/06-02

SYLLABUS
SKYTING TRANSITION COURSE
(8 hours)

by Donnell Hewett

(Ed: Ron Kenney of Elkhart, Kansas recently asked me if I had a syllabus for a Skyting Transition Course. Since I did not have such a syllabus, I quickly wrote up and sent him the following. Although this outline has never actually been used, I believe it contains approximately what should be covered in a professional course for instructing experienced hang glider pilots to skyte safely. Your comments and criticism of this curriculum are quite welcome.)

Purpose: To provide an experienced hang glider pilot (Level 3 or better) with the knowledge and experience needed to skyte safely and to meet this USHGA Special Skills requirements for a Skyting Glider Pilot (ST).

Prerequisite: Intermediate (Hang 3) Rating

A. GROUND SCHOOL (3 hours)

1. Introduction (15 min)

Purpose: To introduce the student to the general concept of towing hang gliders and to aquaint him with the various methods that are being used today.

Teaching method: Video tape or lecture.

Topics covered: Advantages of towing, history of towing, conventional water towing, aero-towing, skyting, truck towing, center-of-mass bridles, shoulder towing, tension gauges, payout reels, power winches, step towing, moored kiting.

2. USHGA Guidelines (45 min)

Purpose: To familiarize the student with the USHGA Towing Guidelines, their purpose, their importance, and their use.

Method: Handouts and discussion.

Topics: USHGA Towing Guidelines, Skyting Criteria, Skyting Standards, Critical Reminders, Approved Skyting Systems.

3. The system and its operation (45 min)

Purpose: To aquaint the student with the components of the particular skyting system he is going to be using, to explain how the system functions as a whole, and to clarify the duties and responsibilities of each person involved in the towing operation.

Method: Video, lecture, handout, discussion, and demonstration.

Topics (Adjusted according to the system being used): System overview, skyting bridle (its operation, attachment, and release), weak link, towline, tension gauge and bottom release, vehicle, driver, spotter, launch assistant, launch site director, towing instructor, wuffos, radios, signals, setup procedures, launch procedures, turn-around procedures.

4. Potential Problems and Emergency Procedures (45 min)

Purpose: To make sure that the student is aware of the more dangerous and most probable problems that may arise during the towing process and to see that he understands the accepted procedure for avoiding and correcting these problems.

Method: Video, lecture, handouts, and discussion.

Topics: Stall, lockout, adverse yaw, hook-up, hook-in, take-off, cross-winds, wind shear, wind gusts, climb-out (tracking, speed), flight plans, radio failure, release failure, entanglement, weak link break, topping-out, etc.

5. Written Exam (30 min)

Purpose: To verify that the student has learned the above material and is qualified to begin actual skyting flight training.

B. FLIGHT SCHOOL (5 hours)

1. System Setup (1 hour)

Purpose: To provide the student with hands-on experience with the towing equipment and to see that he is able to set it up properly.

Procedure: Set up equipment, read tension gauge, test bottom release, inspect towline, break and replace weak link, attach bridle, test bridle release.

2. Demonstration Flight (30 min)

Purpose: To allow the student to witness an actual skyting flight from beginning to end, to calm certain apprehensions he may have, and to demonstrate the actual flight plan he will be following during his first few flights.

Procedure: An experienced pilot should demonstrate the exact procedure the student is expected to follow on his first few skyting flights (i.e. preflight checks, hook-on, hook-in, hang check, launch, climb-out, release, free-flight, and landing at takeoff). An experienced tow crew should also demonstrate how the ground operation should be carried out in order to maximize safety and to minimize the turn-around time.

3. Ground Handling (30 min)

Purpose: To gradually aquaint the student with the "feel" of being towed, to reduce the level of fear his is likely to experience on his first skyting take-off, and to provide some experience in controlling the tow forces he will encounter during actual flight.

Procedure: Tow-launch without glider (hook-on, hold back, run, release), ground handle glider in the wind under moored conditions, run into the wind with glider under people tow, run with glider under vehicle tow.

Note 1: If a student has trouble controling his glider during these ground handling exercises, he should be given assistance. One or more persons holding a nose line and/or a wing or two can provide the stability and safety needed to help build up the student's confidence.

Note 2: This exercise can be exhausting and may even prove to be counter-productive for certain individuals (by increasing their fatigue and anxiety instead of increasing their skill and confidence). It is the instructor's responsibility to determine how much and what form of ground handling is productive in the training of a given student.

4. Flight Experience (1.5 hours)

Purpose: To provide the student with the flight experience he needs to skyte safely on his own.

Procedure: The student's first flight should be on a forgiving glider into a light head wind under low tension to a safe altitude. (I.e. fixed cross-bar glider, 8 mph wind, 75 lbs tension, 700 ft towline, 300 ft altitude, and following the flight plan demonstrated earlier.)

On successive flights, the student should gradually advance until he is using his own glider in typical cross-winds under a good climb rate to a top release.

5. Crew Experience (1.5 hours)

Purpose: To familiarize the student with the duties of the other crew members and to provide the experience he needs to perform these duties safely.

Procedure: Assist in the launch of other pilots, act as spotter, drive vehicle. Repeat each of these aspects as needed to become proficient in all phases of the towing operation. At the end of the training session, clean up the site, reinspect the equipment, and put everything away.
*
SKYTING IN POLAND
*
1986/06-03

Dear Donnell,

Some months ago I got occasionally "Hang Gliding" - June 1981 and I read an article about your towing system. From this time I am crazy about this idea. I spend all the time preparing the whole equipment and thinking of it. I designed and built very handy electronical dynemometer with the scale and three positioned audio alarm.

I already have made first flights with my friend, who is member of Polish National Team. They were very successful and exciting. But now I have a problem. In my country towing, after some accidents, is not practised and it is impossible to get informations on this subject. I would be very glad if you sent me some informations about towing, about your experience, news, etc. Perhaps you can recommend me some books, magazines and ordering addresses.

I hope that there are many new discoveries and expriences from June 1981. In German magazine "Drachenflieger" I saw interesting photo of your bridle system. It seemed to me simplified, the bridle was divided into two not into three parts, as it was shown in "Hang Gliding". But I am not sure because there was no description and the photo was not so good.

Would you be so kind to write some words about it.

Lech Balcerak
POLAND
*
1986/06-04

Dear Lech,

I am sorry to hear that your country does not currently allow towing.

Several other countries outlawed towing on the old system, but many of them have changed their policy to allow towing on the new "center-of-mass" or "skyting" system. Usually this was accomplished by one or two individuals collecting the information necessary to convince the authorities to allow them to tow on a "temporary" basis. After they had demonstrated that towing COULD be accomplished safely, certain guidelines were written up to insure that it WOULD be accomplished safely and these guidelines were approved by the authorities.

Personally, I have not been involved in any of these proceedings, but several are mentioned in back issues of the SKYTING Newsletter. I suggest that you locate other individuals in Europe who have had experiences similar to yours, and then contact them for help and information. I would be glad to do what I can from this end, too.

Now concerning the bridle you saw in Drachenflieger magazine, of course I cannot be sure what you saw, but I suspect you saw a double-line bridle which attaches to the pilot's harness at his shoulders. The two lines are of different lengths, with the short line going through the control bar and the long line under the base tube. During take-off the pilot uses the short line through the control bar. As he gains altitude, this line eventually begins to interfere with the movement of the control bar and is released. Slack in the longer line is taken up and the pilot then flies with the line passing under the bar until he finally releases it for free-flight.

This set-up is an adaption of the "shoulder towing" concept discussed extensively in SKYTING No. 26. In short, shoulder towing is commonly used in air-to-air towing and in certain parts of Europe (particularly Germany). However, it is not as good an approximation to center-of-mass towing as the "skyting" bridle and therefore violates skyting criteria 3 and 4. I do not recommend it unless you really know what you are doing.

Please let me know if I can be of further service.

Donnell
*
1986/06-05

THE TOWING P1

by Kathleen Bodie

(Ed: This article was first published in WINGS magazine.)

I am a P1 pilot of four months standing (passing last Sept), belong to Eastern Airsports and Nottingham University Hang Gliding Club and have just purchased a Clubman CFX 140 after flying a club Gypsy since passing. At Nottingham I am a second year mathematical physicist and being on the club committee organise the training of club members at Peak Hand Gliding Ltd in Leek.

My first taste of the thrill of hang gliding occured one Sunday afternoon numerous years ago, an enthralling television programme about some very brave guys soaring the cliffs on the Isle of Wight. I was determined that one day I would join them, but the yellow pages didn't yield anything and it wasn't until I came to Nottingham that my dream was realised.

During the first week of term all the clubs set up stalls in a large building to attract members. I was only looking for one stall, not to be easily missed or standing on it's keel in a corner was a real live hang glider, much bigger than I had ever envisioned. From that moment I was hooked!

So one crisp October morning I set off for Leek and after the form filling session it was off to the hill, bag and equipment carried down and total confusion as a mass of wires, aluminum and sail transformed themselves into a Skyline. Preflight check, ropes attached, hang check, pick up glider on shoulders a short run, hands transformed to bottom bar and I was flying!

After what felt like hours, but was only seconds, I was back down again and on my stomach where I was to spend many a happy landing. The next day I crawled out of bed only to be thwarted by the weather.

This was to be the story for the following eight months, one odd days flying every three months - I not only had to contend with the weather, but numerous other uni. members also wanting to fly. By July I was determined to pass my P1 after exams, - surely there would be a few flyable days in two weeks? No chance, one days flying and the end of the term arrived. It was back home to Suffolk, hardly a hang glider's paradise - or so I thought. As I flicked through past Wings! magazines I came across an advert for a towing school in Norfolk, just down the road. So a short phone call to Tony Webb of Lejair and the next Sunday I was off to RAF Sculthorpe near Fakenham, but the wind was to strong.

The next Sunday conditions were perfect and I was back to the old routine: rig glider (this time a vary lagre Stubby), hang check and ropes on wing-tips, but there was also the tow rope to consider. It is attached through a ring on an umbilical cord (attached to your harness) over the base bar (only low flights when first training, tow rope and finally clipped into the tow leg. Release check, clip back in, and pick of the glider. My first few flights were hand tows where a couple of volunteers grabbed the tow rope and charged off across the grass as fast as they could run. I only gained a few feet of height but it accustomed me to take off on tow - the bar is eased out a little as you pick up speed instead of holding the bar in with a hill take off. Very soon I was behind the car; Tony uses a pay-out winch mounted in a trailer attached to the car, and after the car had taken up the slack rope I shouted "All out!". The car accelerated up the runway pulling me along. "Ease bar out a bit", yelled Tony as he charged along beside me an up I went. However, I forgot to put my feet under me as I landed - you soon learn to land on your feel when towing, the concrete runway is not very forgiving.

My first impressions of towing as a training method were excellent - I gathered as much airtime in tow sessions of towing down the runway than I ever had when training on the hill.

Each flight was longer giving you more time to settle down and experiment more with pitch control, one mistake with pitch on the hill and your flight ends rather rapidly. Also, once at the end of the runway, just load the glider onto the back of the trailer and the car takes it and you back. At the end of the day Tony suggested a dual flight on the Stubby with him and up we went to 450' releasing for my first flight in prone.

Everything had shrunk and I could see the yellow circles on the runway below us (I'd never noticed them before). It was an amazing feeling to be so high after only being 30' maximum for eight months. We completed a circuit and came in to land - on our feet of course! Away I went feeling very satisfied with the days efforts and more determined than ever to fly.

I went from strength to strength releasing for the first time at 70' and then up to 450', four ninety degree turns and into land. However, I still didn't land quite right either flaring too late or not hard enough. I'd always flared from the bottom bar so on my next flight I tried flaring from the uprights in budgie so as to push the bar out farther and presto my landings were greatly improved. Suddenly the holidays were drawing to an end and I could see myself back in Nottingham with tow half P1's.

But it was not to be and the next weekend I completed my three P1 flights - tow up to 1000' release, one circuit of four ninety degree turns flying back to take off and stand-up landings. I also progressed to a medium Polaris for may last two flights and arrived back to take off with 500' of height to spare, the cars had looked rather small!

Once the written test was done I finally had my long awaited P1, eleven months after first leaving the ground. Any students out there worrying about the length of time it took me to pass, don't worry this is not typical. Last year was bad weatherwise and I always booked the wrong weekends. Although towing is an easier way to learn to fly and certainly less strenuous, there is still the transition to hill flying. A tow P1 pilot has to obtain a hill endorsement from a hill training school, but even experienced purely tow-pilots are not comfortable with the problems of hill launching and top landing afterwards. I appear to have had the best of both worlds and had no problems transferring back to the hill. I have no regrets about taking so long to P1 as I enjoyed every second of the past twelve months training and shall be enjoying many more years to come!
*
1986/06-06

STEP TOW AND SUN
OR FLYING ON THE ISLAND WITH MIKE AND THE BOYS

by John Pendry

(Ed. This article originally occurred in WINGS, the official publication of the British Hang Gliding Association.)

Shortly after arriving from the World's and Como, Mike McMillan invited me over to the Isle of Wight to try out his new winch and attempt the first step towing in Britain.

The local TV were to be there to film the event, so we went out the evening before to get familiarised with the particular procedures and equipment of this system.

The static winch is built in Germany and is basically a VW engine with automatic gearbox, mounted on a trailer with a drum on each axle for the tow line. Two drums mean that one line can be pulled back down the field while the other one is towing somebody up, so making the turn round fast.

The winch operator sits behind the engine looking down the field and sets everything going when he sees the signals from the signalman standing close to the glider. He then controls the force that the winch exerts on the glider, and for step towing, puts the drum into free wheel when he sees the pilot turn off downwind. When the pilot releases, a drogue chute opens at the end of the line and enables the line to be wound in before it touches the ground. The line is a thin cable which is easily repaired by swaging and offers low drag, which becomes important when you get thousands of feet of line out. There is also an emergency guillotine which can cut the line rapidly should any emergency occur.

The line is attached solely to the pilot but has two attachments, one goes over the bottom bar, the other goes under. The line going over the bottom bar is shorter than the other one and therefore takes the load at the start of the tow. This keeps the angle of attack of the glider low when it's close to the ground. When the pilot feels high enough the first line is released and the load comes onto the second line under the bottom bar. The pilot is then able to let the nose up much more and climb more rapidly.

The release mechanism is attached to the harness and mounted wherever is convenient for the particular harness between chest and stomach on the pilot. It comprises of a double release operated by levers, one which you pull and the other which you push. The second lever does release both lines so if need be you can release completely at any stage of tow by operating one lever.

The evenings towing went well with quite strong NW wind and a severe wind gradient allowing me to simply kite up to 2000' ato without the need for any steps. First impressions were very favorable the system seemed simple and effective. The angle of attack after releasing the first line was somewhat alarming at first, feeling like the nose was pointing almost vertically upwards (although obviously it wasn't), but I soon got used to this and although I didn't experience it. Mike reckons if you do have a line break at these high angles of attack, there's so much energy in the system that the glider simply rides over the top and doesn't stall badly. The releases I didn't find particularly easy to locate and didn't really like having to let go with one hand to release the first line when quite low. Initially I was in favor of doing away with the first line and simply towing off one line under the bottom bar, out on reflection I think it's better for safety reasons to ensure low angles of attack at low levels and leave it as it is.

The next day was very similar except that the wind was slightly lighter, better for trying out the step towing. The TV crew rolled up, eventually managed to mount cameras on the glider and we did a few normal tows for them.

Next came the step towing (gulp!) - "It's easy" said Mike, having witnessed it in Germany. "Just make sure when you turn off downwind you make a well pronounced turn so as I know to slack off the line".

So I did and all went well, nothing to it. The strongish wind actually made things easier since I was able to turn not completely downwind but slightly crosswind as well and then turn back into wind and drift back across in line with the winch again. This made things seem a lot better since the line wasn't trailing out directly behind me but slightly to one side as well. After about 4 steps I was at 3600' ato and the winch was starting to look very small. "Now how much line did he say there was?" Cloudbase was about 4000' asl, so one more step and I should get there, since I was losing about 300' everytime I went off down and gaining 7-800' on the next tow, I made the next step a big one going even further off downwind, turned back into wind and nothing happened. "Come on Mike, wind it in"! Still nothing. I'd pulled the line off the drum. So what do you do with 5-6000' of line dangling beneath you? I flew back into wind towards the field for a while trying to decide what to do with it and eventually decided to drop it. Luckily it dropped over fields and hedges and not over any power lines or houses, and was not difficult to retrieve.

Having retrieved the line, I had another couple of tows but didn't bother going so high since it was really just a matter of time to get high and there wasn't a great deal of future in going XC from the Isle of Wight with a NW wind!

My only reservations with the system were that you need a good winchman since you are really in his hands, especially when you start step towing. Also I think there's a need for some form of automatic release that will release under even a small load from behind so that if the drum did jam up when you were going downwind you would be immediately released. The gullotine could easily be too slow and if you did receive a load from behind things could go very wrong, very quickly.

I liked towing solely through the pilot since you could feel all the loads that were being receive, but if this is going to become commonplace the harnesses should be load tested just as the gliders are to ensure their strength.

All in all I was very impressed with the whole system. Can you imagine being able to have 3500' or more to play with whenever you want?
*
*

[Tad Eareckson]

1986/10
*
SKYTING NO.47
JUL-OCT 1986
*
1986/10-01

THANKS FOR THE SUPPORT

As of this issue, the SKYTING Newsletter if FIVE (5) years old and has completed the equivalent of FOUR (4) years of publication.

Now in case you are having trouble following this kind of reasoning, let me try to explain:

The first issue of SKYTING was published exactly five years ago (in October 1981). But since that time there have been several months in which no issue of SKYTING was published. As a result, this issue is only 47. But SKYTING No. 1 was twice the size of a regular issue so it should be counted double, bringing the total to 48 issues. At a normal rate of 12 issues per year this would be "equivalent" to 4 years of publication.

Any way, that's how I figure it.

But regardless of how YOU figure it - whether FOUR years or FIVE (or even SIX if you begin counting from the time the original skyting articles were first WRITTEN) - regardless of how you figure it, a lot of time and effort has gone into the publication of this Newsletter.

Much of this time and effort has been on your part. For without your encouragement and contributions, SKYTING could never have accomplished what it has. And without your support SKYTING's editor would long ago have discontinued this publication in total frustration.

Therefore, allow me this opportunity to express to you my greatest heart-felt appreciation for all you have done to help make this Newsletter a success.

And, indeed, SKYTING has been a success - a success even beyond my greatest expectations.

Look back at SKYTING No. 1 and re-read the list of goals that I had hoped to accomplish through the SKYTING publication. These goals were (1) to inform whoever is interested about the current status of skyting and the progress made in its development, (2) to encourage others to share their knowledge, opinions, and experiences concerning hang glider towing techniques, (3) to provide a vehicle for communication between persons doing independent research related to hang gliding in general and skyting in particular, (4) to provide myself with a means of exerting at least a little influence upon the future development of skyting, and (5) to encourage myself to continue the development of skyting beyond my own specific needs.

Every one of these goals has been fully realized. Today skyting is a recognized and accepted method of launching hang gliders, and it is safely practiced by numerous people throughout the world. Even more important, the introduction of skyting has been accomplished with a minimum loss of life.

It would appear, therefore, that now is the time for the SKYTING Newsletter to step aside and allow its contributers (myself included) more time to work within the established hang gliding community.

After all, there is no doubt that more can be accomplished by working THROUGH the established system than by working OUTSIDE of it. (Other countries are now far ahead of the United States in skyting development precisely because they have applies this truism. Look at the outdated articles in this issue on the Australian and English towing if you doubt this fact.) Yes, at one time it was necessary to work outside the United States hang gliding establishment in order to be able to promote safer towing, but this is no longer the case. Today there is no point in working outside the system - indeed, it is counter productive to do so.

Therefore in the future it is my intention to spend more time and energy working within the United States Hang Gliding Association. Let me encourage you to do the same within your own national organizations.

As far as the SKYTING Newsletter is concerned, this will be its final issue. But because of your continued support and contributions to this Newsletter, I feel that SKYTING has completely fulfilled its purpose. So instead of ending its publication with a feeling of frustration, I am able to end it with a sense of accomplishment.

Once more, thanks for your support.

Donnell Hewett
*
1986/10-02

REFUNDS

I know that some of you who subscribed only recently to the SKYTING Newsletter did so with the understanding that it would continue for another full year and include many useful articles and much updated material. I am sorry that this will not be the case, and can certainly understand how you may feel that you have not received "full value" for your subscription price. Please realize that it was not my intention to defraud you of anything.

All I know to do in this situation is to refund to you part or all of your subscription price. But not knowing which of you feel "cheated" or to what extent, I do not know how much to send to each of you.

I considered sending everyone a check for the remaining portion of his subscription, but I am certain that some of you may feel that anything less than a "full refund" would be inappropriate, while others of you have already received "full value" for your investment and are not particularly interested in getting a refund.

Since it is impossible for me to know how each of you feel about your own particular situation, I honestly do not know how much to refund each of you. Therefore, I am asking each of you who feels that a refund is appropriate to simply let me know how much you feel should be refunded to you.

I know that this in an inconvenience on your part, but it is the only way I know to be fair to you as YOU see it. If I do not hear from you, then I can only assume that you do not consider a refund to be very important and would rather contribute that money in memory of the SKYTING Newsletter effort.

Now in case you do not remember when your subscription is due to expire, look at the mailing lable on this issue. The number occurring in the upper right hand corner is the last issue of SKYTING that you have paid to receive. If you subtract 47 from that number, you will get the number of issues you have paid for but will not be receiving. Multiply this number by $1.00 (U.S., Canada, Mexico) or $2.00 (Other Foreign) to determine the "legal" amount you should be refunded. Then adjust this amount as you see fit in order to determine what you consider to be the "fair" amount you should be refunded.

Let me know what you decide.

Donnell
*
1986/10-03

AUSSIE FLATLADS TOW LAUNCH CHALLENGE - THE WORLD'S MOST EXCITING HANG GLIDING EVENT

Lindsay Ruddock reports on Vacation
(From "Wings", the BHGA magazine.)

There's one emerging annual hang gliding meeting that everyone should know about, where future records will be set again and again. It's a meeting for competition pilots and fun flyers alike. It has suddenly emerged as the world's most exciting hang gliding event. It's the AUSTRALIAN FLATLANDS TOW LAUNCH CHALLENGE held annually at Parkes, NSW from Dec to 5th Jan.

Fun flyers had great flights. Competition pilots had great flights. The world TRIANGLE distance record was broken by Denis Cummings flying only a Magic 3! Denis carries a barograph, so the new triangle record will be official.

In the old days we sought ridges - always bigger and better, higher and longer, in France, Europe, East Africa and California.

NOW? - Flatlands...

Now that all has changed. Not only has tow launch been now proven to be safer and easier than mountain take off, but flatlands flying is being shown to have more potential than mountain sites and without the hassle. The tow is merely a means of launch which is giving us access to the flatlands thermals. The general opinion at Parkes was that, strength for strength, flatlands thermals were less turbulent than mountain thermals. the ground is flat and empty so you can continue to thermal down to 200 ft without landing worries. No risk of landing in a canyon if you blow it. If you fail to hook on anything on a tow launch, you simply glide back to take off for another try, but the better pilots at the Parkes event were consistently getting away with just one or two tows.

Take off space at Parkes in the Australian semi-outback is virtually unlimited. The local farm owner is friendly and the local council is friendly. Any number of gliders can take off simultaneously allowing fun flyers and competition pilots to mix without disagreement and fly the same tasks. Compare this with a typical mountain take off site, or, indeed, a UK league event!

Tow launch takes place in small groups each with a tow car plus tension gauge, and allocated tow strip. Tow lines are provided by the competition organisers, but each pilot provides his own bridle (Donnell Hewett style). The tow method widely used and accepted in Australia is the car tow system. I was a bit apprehensive about car towing having been converted on a winch. In fact, one is as safe and easy as the other, but the car tow needs twice the length of tow strip (i.e. 1 km), not a problem at Parkes.

I was also apprehensive about the safety of tow launching in extreme thermic conditions. You certainly need a concentrated approach, but that goes without saying. Suffice to say that fifty pilots performed two thousand tow launches in ten days with hardly an incident and no injuries.

The competition location, Parkes NSW, about 200 miles west of Sidney, was chosen from research data accumulated by Denis Cummings. Boomer thermals can be expected as a rule, with cloudbase 8000' to 14000' or more. Take off is 800' ASL. During the competition, better days saw pilots at 13000' ASL, 12000' ATO. To fly height gains like this in the Owens valley is possible, but you would need oxygen. As the summer season goes on towards Easter, the air becomes drier and cloudbase rises higher but that's another story.

"Charles Redtruck" met tracer!

Competition organisation is very thorough. There are hang gliding related lectures before each daily pilot briefing. Scoring is fair, rationalised and computerised.

Each morning at sunrise (6am), "Charlie Redtruck" flies his microlight to 10000' taking a temperature trace on the way down. He also records wind direction and speed. This information together with a ground level humidity measurement enables a prediction to be made for thermal depth and expected cloudbase as the day progresses.

Consequently, realistic tasks can be set with confidence, or the day called off immediately if prospects are poor.

Although fun flyers take part and are welcomed at the flatlands challenge, the competition is no club flyers affair. The average task race distance was over 100 Kms and this includes turn points, dog leg and a TRIANGLE!

The Brits?

How did the British fare? Well, they weren't there. Australia is a long way away, but that is not the reason. A fair number of British hang glider pilots migrate to sunny Australia for the Christmas period. Big names like John Pendry, Jess Flynn, Robin Rhodes and others chose instead to go flogging dead horses at the Mount Buffalo XC Classic being held unfortunately at roughly the same time, mistakenly thinking the traditional XC Classic to be the most valid competition event. (The press and TV cover the FLATLANDS CHALLENGE too, and there are substantial cash prizes).

Mountain take offs and mountain flying will always hold a romantic appeal, but new records will be set over the Flatlands, attracting competition pilots, the sociable, and those who just want good flying at exciting locations and the best in hang gliding experience.

Last year's event ('58/'86) attracted over fifty pilots, including four women pilots, and next year will see a big increase. I will certainly be there.

So save up your pounds and look out for dates etc. for next year. You can ring or write to me if you want to know more about next year's event and how to set about it, or need to know about flying or travel in Australia. There's a lot more to see and do besides hang gliding.

Lindsay Ruddock
Fairhaven Cottage
Ridgemead Road
Englefield Green
Surrey, ENGLAND
TW20 0YG

PS. The chief Tow Launch Challenge organiser is Denis Cummings, Dights Crossing, Singleton, NSW 3220, Australia
*
1986/10-04

TIP TOWING TO THE FUTURE

by Bob Harrison
(From "WINGS", the BHGA magazine.)

At long last after 10 to 15 years of tearful strife, method has been found, copied, altered and now employed to achieve take-offs away from hills.

Valley bottoms and flat plains are the new alternatives to hill and mountain slopes. With these alterations comes a new technology and different flying skills, that need to be learnt before they can be safely and successfully used.

So, you want to be part of this latest craze in Hang Gliding but you're not so sure how to join the ranks of the trend-setters.

Well, sit back, put your feet up and let's have a look at the current revolution in our sport.

If, as an individual you want to have a go to see what all the fuss is about, then scan the adverts in "Wings!" and enroll on one of the many "Tow Pilot Endorsement Courses". Or send an S.a.E. to H.Q. who will return a list of towing clubs and syndicates. (Not all of these will be able to train you but at least you may witness towing first-hand.)

If, however, you, your clubs, or a group of friends want to get involved and utilise the benefits of towing then this article will remove the uncertainties of "what to do next?"

The BHGA have provided a "Bible" for people just like you. It is called the BHGA Club Towing Guidelines and it is available for a fee of 5.00 pounds. The fiver covers the cost of reproduction and postage along with future mailshots which will include addendum and errata notices, further guidelines, and information.

At the moment the manual has over 25 pages, but it is expected to grow to approximately 50 pages as more sections are added to it.

Some of the sections contain rules and regulations that govern towing. They may at first seem a little daunting or even off-putting, but in actual practice they are not. They have been devised to achieve two main objectives;

(a) To cater for good fun flying without the need for unnecessary hassles and red tape.
(b) To satisfy our responsibilities and liabilities to people like the CAA, members of the public, insurance underwriters etc, for the safe control of hang gliding.

As with everything else, a balance between total freedom and total control must be sought. By employing our traditional method of self control by concenus we have ensured that these rules and regulations are realistic and necessary so as to achieve safe and trouble free towing.

A group applying for approval and adopting the standards set for towing will help to strengthen the hang gliding movement, lessen the chances of accidents and incidents, enjoy the benefits of insurance in case they are needed and help standardise the procedures involved with towing.

Anyway, less of the propaganda.

WHAT TO DO FIRST

The first thing to do is to identify the type of tow group you intended to run. Tow Groups are divided into two main types:

(a) Those wishing to tow purely and only on a club, member to member basis.
(b) Those with a commercial interest. It is necessary for these groups to apply for BHGA registration.

Tow groups falling into this last category can be subdivided again:

(i) Those hang gliding schools associated with ab initio training.
(ii) Those groups running endorsement and certificate courses etc for pilots already qualified beyond the basic levels.

Approval for any type of tow group is subject to minimum standards being met in the three areas below:

(a) Pilot and Crew approval.
(b) Towing Procedures and Signals.
(c) Hardware approval.

In other words, you've got to ensure that the right people are involved, in the right way, and on the right equipment. Let's have a brief look at each of these three areas.

PILOT AND CREW REQUIREMENTS

Any pilot flying on tow must either have a tow rating or hold a towing endorsement. This will qualify him to fly on any approved towing system.

The Crew must obviously be qualified also, but what or who does the crew consist of? The answer to this depends on the type of system being used. To date (February '86), there are three approved systems - the dynamic or payout winch, the static, and the fixed line method.

DYNAMIC TOW LAUNCHING needs a: Winch operator; Driver; Signaller is recommended; A coach must be present and may be one of the above.

STATIC TOW LAUNCHING needs a: Winch operator; Signaller. A coach must be present and may be one of the above.

FIXED LINE TOW LAUNCHING needs a: Driver; Observer (Winch Operator); Signaller. A coach must be present and may be one of the above.

As you see a tow coach must be present during any towing activity. The coach is the king pin to operations. He should be sensible, knowledgable and of course have a wide towing and flying experience. He is responsible to ensure that the group is towing safely, and that everyone is being properly looked after. (New pilots will welcome this!)

The chances are that no one in a newly founded group will have the experience to become a full Tow Coach immediately.

As a means to get groups established and so encourage towing a group can start off by having one or more Temporary Tow Coaches. Then, as they gain the required experience they can apply for their full rating.

As only Coaches may take charge of operations now's an appropriate time to find out how to become one.

QUALIFICATIONS FOR A TEMPORARY COACH are:

Winchman
Pilot of Tow P2 level or P2 with towing endorsement.
Minimum age of 18 years.

His duties include:

Responsible to the BHGA for his group's safe towing and the following of procedures.
Responsible for the location of towing operations.
His normal winch duties.
Can only operate with BHGA guidelines/procedures.

But he:

cannot personally operate for hire or reward
cannot teach new winch operators
cannot teach pilots to tow launch

FULL TOW COACH

In addition to the above qualifications a Full Tow Coach needs:

Total of at least 100 person towed flights
Have been a winchman for at least 300 high tows
Have a first aid certificate
Attend and pass a BHGA Tow Coach Seminar (These will commence after 1st March 1986)
Experience as a Signaller and Driver.

After gaining a full rating he obviously will have less restrictions placed on him. The biggest advantages to him and his group is that he can now train new winchmen and convert pilots (Tow Pilot Endorsements). The group can therefore look forward to growth and self perpetuation.

So much for Coaches.

There isn't the scope here to spell out the requirements for winchmen and pilots, so I suggest that you buy the "Bible"!

The second area needing satisfying is that of Procedures and Signals.

PROCEDURES AND SIGNALS

These are already laid down. They are of the same type and standard as found in other aviation sports in this country and abroad. Standardisation is obviously very desirable and it helps to remove the possibility of confusion and accidents.

A full description is given in the manual - a bargain for only a fiver!

SATISFYING THE HARDWARE REQUIREMENTS

This depends upon whether the group has either:

(a) bought an already approved system, or
(b) making part or all of the group's system.

(a) Buying a complete system that is already approved.

If the group's winch/fixed line and bridle systems are approved and are the genuine articles then hardware approval should be automatic.

It is therefore only necessary to clearly list the equipment involved and source/s of purchase.

(b) Making part or all of the system.

In this case the BHGA will needs a written description of the system and have it inspected and test flown.

This obviously takes time but if you are organised delays should not occur. By contacting the BHGA early means that we can put our wheels into gear whilst you are completing the hardware.

It is hoped that the Airworthiness and Tow Committees will soon have concrete details and advice for the would be winch builders.

SETTING UP THE APPROVAL FOR YOUR GROUP OR SYNDICATE

The Training Committee will issue group approval once it is clear that all the requirements have been met in the three main areas. When you have tied everything up send a final letter asking formally for approval.
*
1986/10-05

CAR-TOWING OPTIMIZATION

by Donnell Hewett

Towing hang gliders is like most other human activities which cost money and/or time - once you have done it for a while, you start looking for ways to get the maximum amount of investment.

In the case of towing hang gliders, this usually means trying to get the maximum amount of effort. And this, in turn, usually means getting as high as possible under the conditions that currently prevail.

Of course, the height you are able to attain depends upon what type of towing you are doing. With a power winch you can step-tow to just about any reasonable altitude (even from a limited size field). But most other forms of surface towing limit your altitude to only a fraction of the length of your runway. So if your runway is limited, you may want to optimize your operation in order to have a better chance of gaining sufficient altitude to catch that ellusive thermal.

Efficient optimization, of course, requires a thorough understanding of the system being used. This depth of understanding can only be acquired through a combination of practical and theoretical analysis of the operation.

In the case of the pay-out winch, a rather complete theoretical analysis was published by Edmond Potter of Burwell, England, in SKYTING No. 34, 35, 36. But so far, no one has seen fit to publish a similar analysis of the car-towing situation. This article attempts to perform such an analysis.

SEEING THE OBVIOUS

Let's begin our analysis by pointing out the obvious. If you car-tow with a towline that is too short, then regardless of the length of your runway, you will never attain an appreciable altitude. Similarly, if your towline is almost as long as the runway, you will not have enough room left to tow to an appreciable altitude. Somewhere between these two extremes there must be an optimum towline length which allows you to attain the maximum possible altitude for the conditions under which you are towing. The question, then is, "What is the length of that towline?"

RUNWAY LENGTH

The answer to this question obviously depends upon the length of your runway. (The longer the runway, the higher you can tow.)

In the following analysis, I have assumed that the runway is 5000 ft long (approximately one mile). If your runway is different (as it almost certainly will be) you will need to make some conversions. This is most easily accomplished by expressing everything in relative distances by measuring everything in units of your runway length.

For example, a 1000 ft towline on a 4000 ft runway has a relative length of 0.25. Similarly, a relative height of 0.4 on a 1000 meter runway is equivalent to 400 meters.

To help you make these conversions, most of the figures in this article are scaled in both absolute units (from 0 to 5000 ft) and relative units (from 0 to 1.0).

THE PROGRAM

The analysis in this article is purely theoretical and is based upon the result of computer simulation. The program used in the simulation process is a modification of the one written by Edmund Potter for his analysis of the pay-out winch towing system. The major difference between the two programs is that Edmond's towline changed lengths while mine remains constant.

The primary assumptions of this program are that (1) the glider starts at one end of the runway (not beyond the end of the runway) with the towline stretched out toward the car, (2) there is no stretch, bending, weight, or air friction associated with the towline, (3) the speed of the vehicle is always appropriately adjusted so as to maintain a constant tension in the constant-length towline, (4) there is no wind gradient or cross-wind, (5) there is no turbulence, thermal action, or other vertical air movement, and (6) the glider has the same properties as the one used in Edmund Potter's analysis.

The basic program use to analize the car-towing operation is illustrated in Fig. 1. Its output is shown in Fig. 2.

As you can see, the program illustrates a 1600 ft towline used on a 5024 ft runway in no wind conditions to tow a 210 lbf pilot-glider at a tension of 100 lbf to an altitude of 1009 ft. At the beginning of the flight the glider is climbing at BETA = 19 degrees and at the end of the flight the towline makes an angle of GAMMA = 37 degrees. The ratio of the height gain to the length of the runway is YK/XR = H/L = 0.2 which tells us that the glider reaches an altitude of 1/5 the length of the runway. (The towline was 1/3 the length of the runway.)

OPTIMIZING THE HEIGHT

It is not obvious from the previous result, whether or not a different length towline could have been used to attain a greater release altitude. (A shorter towline would have allowed more room for towing, while a longer towline would not have pulled down so much on the glider.)

The only way to determine the optimum towline length is to run the program again for various length towlines on runways all of the same length. One could then plot the altitude gain versus the towline length in order to determine the optimum towline length.

Fig. 3 illustrates such a plot for various towline tensions. The dashed line shows where the maximum height occurs for each curve. Careful analysis of the curve for 100 pounds shows that the optimum towline length is 1520 ft. Therefore, one could tow slightly higher on a 1500 ft towline than on the 1600 ft line used in our example. But the curve is so flat near its maximum that this difference in altitude gain is really negligable. (Namely, on a 5000 ft runway one can obtain 1007 ft on a 1500 ft line and 1004 ft on a 1600 ft line. This 0.3% difference has no practical significance since the theory has so many assumptions that it would not be expected to approximate reality that accurately.)

Fig. 3 is a fairly useful instrument. It tells you how high you can climb in no wind conditions with any length towline tension. For example, suppose you are towing with a 1000 ft towline on a 2000 ft runway with a tension of 150 lbs. Using the scales on the top and right of the figure you see that a towline 1/2 the length of the runway results in a height of 0.25 for the 150 lb curve. For your 2000 ft runway, this height becomes 0.25 x 2000 ft = 500 ft.

But you could have gone 60 ft higher if you had used a shorter, optimum length towline. (The optimum length towline for 150 lb tension is 0.37 x 2000 ft = 740 ft. And the corresponding altitude gain is 0.28 x 2000 ft = 560 ft.)

WIND EFFECTS

Fig. 3 assumes that there is no wind blowing. Generally this is not the case. And the presence of wind can dramatically affect the towing situation.

Fig. 4. shows how dramatic this effect can be.

A head wind allows one to use a longer towline and reach higher altitudes than are possible in calm conditions. In fact, 100 lb of tension with a 15 mph head wind is approximately equivalent to 250 lb of tension with no wind at all. But remember, 250 lb tensions violate the skyting criteria (being beyond the 1 g weak link limit for the 210 lb system) while 100 lb tensions do not. So the 15 mph wind transforms an impractical situation into a practical one. (Assuming the pilot is qualified to tow in a 15 mph wind.)

As an illustration of the use of Fig. 4, let's calculate how high one could skyte on a 1 km runway in 20 mph winds. Again using the scales on the top and right, one finds that the towline needs to be 0.656 x 1000 m = 656 m, and the altitude gain is 0.54 x 1000 m = 540 m.

This altitude is 54% of the length of the runway! Under stronger conditions, even higher altitudes could be attained!

Of course, under strong conditions it is also possible for one to break one's arm or worse! So I do not particularly recommend that you fly in these conditions.

GENERAL RESULTS

Fig. 5 gives the optimum towline length for any tension in any wind condition. As expected, the optimum line length increases with tension and with wind velocity.

As an illustration of the use of this figure, let's determine the optimum length of a towline for a 2000 ft runway when towing with 150 lb tension in a 10 mph head wind. The 150 lb curve at 10 mph head wind. The 150 lb curve of 0.5 x 2000 ft = 1000 ft.

Fig. 6 shows the corresponding maximum altitude gain. To illustrate its use, let's calculate the altitude that could be attained in the above example. From the 150 lb curve at 10 mph one finds the altitude gain to be 0.39 x 2000 ft = 780 ft. Not bad for a 1000 ft towline on a 2000 ft runway.

THE X-COORDINATE

So far nothing has been said about the horizontal position of the glider at the time it is released. Fig. 7 provides this information for the no wind situation and Fig. 8 provides it for the 100 lb tension situation.

In both cases the curves are reasonably flat on top. This means that the towline can be either shorter or longer than optimum without appreciably affecting the altitude gain. But the shorter towline will release the glider farther up wind of where the longer towline will release it.

Therefore, if you are interested in using most of the runway to look for thermals before releasing, then tow with a line slightly shorter than optimum. Conversely, if you want to climb as fast as possible and release as far down wind as possible, you should use a towline slightly longer than optimum.

FLIGHT PATHS

So far we have not talked about the actual flight paths of the glider. This information is not critical in determining the optimum flight conditions, but it is important from the point of view of understanding the general flight dynamics of car-towing.

Fig. 9 shows the optimal flight paths for no wind conditions and Fig. 10 shows the optimal flight paths when towing under 100 lb tension. These figures also show the release position to the towline so you can get a feel for the towing geometry.

As in the other figures, the vertical and horizontal scales are equal so there is no vertical distortion. But when you get out to the flight field, you probably will experience a strong psychological distinction between vertical and horizontal distances. (After all, 4000 ft doesn't seem so far on the ground, but 4000 ft vertically seems a long way up.) Therefore, even though the figures many not seem to emphasize it, high altitudes can be attained when car-towing (even on a limited length runway). This is especially true if there is any significant head wind.

Talking about the head wind, an interesting phenomenon occurs when the wind is above 24 mph. In this case, a towline equal to the length of the runway can be used.

During the first part of the flight the vehicle must back up in order to keep the tension equal to 100 lb. But once the glider starts leveling out, the car can creep forward until it eventually returns to the end of the runway where it began. The altitude gain with a 25 mph wind is 4700 ft - that's 94% of the length of the runway!

By the way, remember that all of these calculations are idealized, so there is no wind gradient in the above illustration. In a real situation, there would be a wind gradient and it would be very difficult to keep the line tension constant. In practice, the car probably would not back up and then creep forward. It would probably have to creep forward on takeoff (to prevent a stall) and then stop (or back up) after the pilot climbs above the wind gradient. But even though the details of the theory may differ from reality, in both cases the pilot could gain high altitudes on a short runway.

CONCLUSIONS

As you can see, there is a lot of information contained in the program supplied with this article. By adjusting the parameters in the program, one can theoretically determine the optimum towline length for any car-towing situation.

Unfortunately, few pilots know the actual flight parameters for their gliders, and even fewer carry their computers along with them to the flying field. So in many respects this program is not as useful as it could be. To improve its usefulness, perhaps a few generalizations would be in order.

If you look back over the material in this article, you may notice that, although there are exceptions, the optimum towline length under typical towing conditions is generally about 1/3 to 1/2 the length of the runway. And the maximum attainable altitude is roughly 0.7 time the length of the towline.

So what does this mean? Well, for one thing it tells me that in the past I have generally been using a towline that is too short for my runway. And although I can't be sure, I suspect this is also the case for quite a few other pilots.

Conversely, it also means that those pilots who make it a practice of NEVER towing above a GAMMA = 30 degree angle are almost certainly using a towline that is too long.

Of course, there are a lot of pilots who have no interest what-so-ever in attaining the maximum possible height while on tow. They are only interested in getting high enough to catch a thermal and release. Such pilots generally like to tow with a 1000 ft to 1500 ft towline regardless of the length of their runway.

Isn't it interesting that their preferred towline length is very near the optimum for typical car-towing situations (i.e. for towing on runways from 1 km to 1 mile long)?

Isn't it a shame! Such pilots are getting the right answer but for the wrong reason!

Think of all the fun they are missing by not calculating the correct optimal towline length for every one of their flights. And think of the fun they are missing by not cutting and splicing their towline every time the flight conditions change.

Poor guys! I certainly feel sorry for them!

Hey, I hope you're not one of them!
+
Fig. 01. Gauge Towing Program.
Fig. 02. Output of Gauge Towing Program.
Fig. 03. Release Altitude versus Towline Length for No Wind Situation.
Fig. 04. Release Altitude versus Towline Length for 100 lb Tension.
Fig. 05. Optimum Towline Lengths.
Fig. 06. Maximum Release Altitudes.
Fig. 07. Release Positions for No Wind Situation.
Fig. 08. Release Positions for 100 lb Tension.
Fig. 09. Flight Path for No Wind Situation.
Fig. 10. Flight Path for 100 lb Tension.
*
1986/10-06

FINAL FAIRWELL

I hope that you have found the material published in the SKYTING Newsletter to be interesting and of value. Please write me a letter from time to time to let me know how things are going.

Good luck, and good skyting!

Donnell Hewett, Editor
*
*