Skyting demolition

General discussion about the sport of hang gliding
User avatar
<BS>
Posts: 422
Joined: 2014/08/01 22:09:56 UTC

Re: Skyting demolition

Post by <BS> »

Of course, a pilot could deliberately produce a stalled break at 200 lbs...the glider simply drops its nose to the free flight attitude and continues flying.
It works best in a lockout situation... if you're banked away from the tug and have the bar back by your belly button... let it out. Glider will pitch up, break weaklink, and you fly away.
User avatar
Tad Eareckson
Posts: 9161
Joined: 2010/11/25 03:48:55 UTC

Re: Skyting demolition

Post by Tad Eareckson »

To be fair to Donnell - as little as he deserves it - there is a:
But if he is trying to limit his climb rate...
in between.

But as I've noted... TRYING to limit your climb rate doesn't necessarily mean you WILL limit your climb rate. And it's not your climb rate that you wanna limit anyway. It's your angle of attack that you're trying and may not be able to adequately limit - 'specially when you're at a high tow angle with a two rather than one to one bridle. So what the hell.

And that was Ryan 2009/11/03 05:24:31 UTC when Jack's mutual masturbation society was trying to piss all over me and Jack was slightly shy of a week from permanently banning me. And Donnell was hanging out in his Ivory Tower not lifting a finger to do anything about anything so fuck him and the horse he rode in on.

He tended to emerge from the woodwork after fatalities in which his Skyting Criteria were violated and remain conspiculously silent whenever elements of his Skyting Criteria were the obvious causes of the fatalities - Birrenator induced whipstalls for example.

He says:

http://groups.yahoo.com/group/skysailingtowing/message/6744
Weaklinks
Donnell Hewett - 2008/11/05 21:23:39 UTC
6744

Let me begin by saying that I personally appreciate Tad Eareckson's efforts to improve the SOP of aerotowing as well as his suggestion to update the Skyting Criteria. It is through efforts like his that progress is made toward safer towing.
...
I believe that the first of these two conclusions is perfectly consistent with the point that Tad has been trying to make. And I thank him for keeping this issue before the hang gliding community.
He PERSONALLY appreciates my EFFORTS and thanks me for keeping this issue before the hang gliding COMMUNITY then when his fuckin' hang gliding community goes into lynch mob mode he's never heard of me before.

I used to not hate him as much as the Flight Park Mafia crud because he got one thing partially right independently. Now I'm seeing him as a lot more as just another self-serving sleazebag albeit with a bigger vocabulary and a smoother technique for neutralizing threats.
User avatar
Tad Eareckson
Posts: 9161
Joined: 2010/11/25 03:48:55 UTC

Re: Skyting demolition

Post by Tad Eareckson »

http://airtribune.com/2019-big-spring-nationals/info/details__info
http://airtribune-production.s3.amazonaws.com/media/contest/files/2019/07/GTxd6mT4AIn8.pdf
2019 Big Spring Nationals - 2019/07

Weaklinks of 140 and 200 pounds will be available and provided by the organizers. Weaklinks provided by the organizers must be used by the competitors.
Have ya stepped back and looked at the historical pattern?

In the earliest years...
Manned Kiting
The Basic Handbook of Tow Launched Hang Gliding
Daniel F. Poynter
1974

"The greatest dangers are a rope break or a premature release." - Richard Johnson
...the LAST thing you wanted to have happen on a tow - even with uncertified and uncertifiable gliders, frame-only bridles, and easily reachable releases - was a weak link success of any kind at any time.

Then about a half hour later...
Donnell Hewett - 1980/12

Now I've heard the argument that "Weak links always break at the worst possible time, when the glider is climbing hard in a near stall situation"...
...everyone and his dog is using weak links just over sustainable tow tension for lockout protection. They'd successfully calculated that if you only killed twenty guys in stalls for the one weak link that blew during a lockout at two hundred feet or up then that was a good thing.

Hewett comes along and uses the exact same weak link but puts a 1.0 or under G number on it to certify it as Infallible; substitutes "Recovery" for "stall"; puts a tension gauge on the towline to protect the Infallible Weak Link; uses a less lockout prone bridle and pronounces it autocorrecting; dignifies total crap easily reachable stink-on-ice releases with the term "Reliable"; pronounces all imaginable and unimaginable past, present, future problems forever solved.

Through just about all of the Eighties all towing is surface and all surface uses tension gauges:

- because if the tension's relatively low and Constant...

022-04610
http://farm3.staticflickr.com/2809/13746340634_a74b33d285_o.png
Image

...there can't possibly be anything undesirable going on with the glider

- you really don't wanna get up into the ballpark of your Infallible Weak Link 'cause the Recovery is virtually always fatal.

So everyone and his dog has a tension gauge so all weak links are tested to insure they're down to or even safer than the Infallible standard. And the guys with the best tension gauges are the guys with the best tow rigs. And the best tow rigs are platform in which a weak link can't do anything.

Then at the beginning of the Nineties the Dragonfly hits the scene and brings industrial scale AT into existence. AT is the one flavor in which you really need a real aviation weak link but also need to make damn sure you never get into a situation in which it comes into play 'cause if you do somebody's gonna die.

Tugs have total zero use for tension gauges and thus the same number on hand. Not one of the motherfuckers has the slightest clue what they're pulling in the way of tensions until I get up with my gear about a dozen years ago in the latter Aughts. So they get spools of precision fishing line that with the knot properly hidden breaks consistently at 1.00 Gs which is a good rule of thumb for all solo gliders to keep them from losing control authority and getting into too much trouble one out of every four tows. But for even more safety margin - if one can imagine such a thing - they tell the glider to release before there is a problem to really ensure that whatever happens is his fault.

Recovery is changed to Inconvenience 'cause obviously it's impossible for there to be anything from which to Recover. If it's an inconvenience you just land with a perfectly timed flare and stroll back to the head of the line to Inconvenience all the people who came to fly.

And you can't go to 1.01 'cause:
- you'll:
-- neutralize the tugs weak link and release
-- destroy the back end of the tug and kill the pilot
- we all play by the same rules or we don't play

Since there's no Flight Park Mafia affiliate capably of testing breaking strengths any affiliate can assign for any configuration any value or values to it he finds convenient at any given time. Fourteen pages on 130 pound Greenspot in the 1012/06 Towing Committee magazine article but only expectations of its consistency 'cause actual breaking strengths on the ground are irrelevant and in the air are unobtainable.

So at this point we've gone from whatever the hell string you feel like as long as tests to one G for the individual glider to a specified factory tested precision tournament fishing line that breaks consistently at 1.00 in lockouts but holds well in turbulence to minimize Inconvenience. And if does break in real or alleged turbulence it's 'cause the glider (and never the tug) pilot was towing with poor technique.

Then they finally start crumbling with 2011/08/11 Pete Lehmann and hafta double to 2.00 Gs but tell the tug pilot so he can stop fuckin' around with half power takeoffs. And then Zack Marzec inevitably and FINALLY blows up in their faces and they don't know what to do or say for several months and end up and doing and saying just about everything.

Next phase... Say ABSOLUTELY NOTHING in public about weak links.

http://www.hanggliding.org/viewtopic.php?t=36170
Weak Links?
Bart Weghorst - 2018/09/14 17:58:16 UTC

Please understand that the use of weak links does not prevent a lockout. They could help but they really serve a different purpose. I don't like to explain all this here because I think this forum is not a good medium to teach hang gliding subjects like these. When in doubt, consult an experienced AT operator and attend an AT course.
All we know about them is that we've gotta use the ones provided by the organizers.

And good freakin' luck finding out what's on the Dragonfly nowadays. It started out public on the website when the Dragonfly douchebags thought they might know what they were doing and talking about. Then they started looking stupid after Fort Langley. Then they started looking stupid again on 2008/07/20 when Paul Tjaden's Tad-O-Link bent Russell's tow mast and pulled off his towline. Then Jim the-Mouth Rooney blabbed about the three-strand. Then they had to beef back up again when ALL the solos started flying Tad-O-Links. And they finally got smart enough to realize they had to never again allow anything to go into print.

And now on the gliders...

http://airtribune.com/2019-big-spring-nationals/info/details__info
http://airtribune-production.s3.amazonaws.com/media/contest/files/2019/07/GTxd6mT4AIn8.pdf
2019 Big Spring Nationals - 2019/07

Weaklinks of 140 and 200 pounds will be available and provided by the organizers. Weaklinks provided by the organizers must be used by the competitors.
The 140 is obviously 130. Davis never could keep any numbers straight worth shit. He'd done that before with the 130. There are still thousands of AT assholes convinced that the chances of them surviving a smooth air tow up two hundred feet through the kill zone with a loop of 131 are about one in a thousand. But Davis said 140 so we'll use 140 'cause now his lowest allowable minimum for anybody is eight percent over his long-time maximum (and minimum) for anybody.

The 200... Undoubtedly what...

02-00820c
http://c2.staticflickr.com/8/7252/27169646315_9af9a62298_o.png
Image

...we caught Niki using.

We know that none of those assholes have tested these weak links 'cause they've never tested anything, don't have the equipment, don't even know how to. They're just using my/our testing work which found that a loop on a bridle end is reasonably close to the breaking strength on the line's label. Multiply by two for the number of strands then divide by two for the weakening of the knot.

140 or 200. Pick one and put it - presumably - at one end of your long thin pro toad bridle with your easily reachable bent pin pro toad release at the other. No relation to glider capacity, flying weight, experience, skill, conditions, towline tension, tug power, tug or glider safety. If your bridle wraps after:
- you release your weak link will succeed so you won't need a release
- your weak succeeds your release will work so you won't need a weak link

http://ozreport.com/forum/viewtopic.php?t=24846
Is this a joke ?
Cragin Shelton - 2011/09/03 23:57:33 UTC

Nice Reference Citation
Manned Kiting
The Basic Handbook of Tow Launched Hang Gliding
Daniel F. Poynter
1974

"A bad flyer won't hurt a pin man but a bad pin man can kill a flyer." - Bill Bennett
"The greatest dangers are a rope break or a premature release." - Richard Johnson
Do you REALLY think that there has been no progress in knowledge about the practical applied physics and engineering of hang gliding in 37 years? OR that an early, 3+ decade old, information book written by a non-pilot is a solid reference when you have multiple high experience current instructors involved in the discussion?
Yeah Cragin. The advancements we're making - 'specially now well into the Information Age - are truly astounding.
Zack C - 2012/06/02 02:20:45 UTC

I just cannot fathom how our sport can be so screwed up.
How 'bout now, Zack? After another seven years of experience and evolution?
User avatar
Tad Eareckson
Posts: 9161
Joined: 2010/11/25 03:48:55 UTC

Re: Skyting demolition

Post by Tad Eareckson »

http://groups.yahoo.com/group/skysailingtowing/message/6686
Weaklinks
Donnell Hewett - 2008/10/14 00:49:34 UTC
6686

In the case of hang gliders, platform towing is the only mode that consistently pulls downward throughout the whole flight when performed properly. All other forms of towing use forward pull at least during the early part of the flight. Therefore, they should all use a forward-pull weak link. Even platform towing can revert to forward pull if done improperly. I have seen cases where the glider would launch and the vehicle would race forward at high speed to lengthen the towline before the glider could gain significant altitude. This converted the down-pull into a forward-pull even while using a down-pull weak link. The glider climbed out at a 45 to 60 degree angle at low altitude. If the payout winch had jammed for some reason, the down-pull weak link would have broken, the glider would have whip-stalled, and the pilot would have been killed. I was appauled at such an operation. But it was SOP for that group. They had done it many, many times without a mishap.
Tad Eareckson - 2019/10/05 21:13:32 UTC

1. Yeah, I've seen that technique quite a few times. Probably was the subject of it a handful of times.

2. Before the glider COULD gain significant altitude? The whole idea was to get a lot of line out and it was nobody's intention for the glider to gain significant altitude during that phase.

3. The idea, if I recall / can reconstruct correctly, was to get the launch off safely, get a lot of line out, crank up the tension and slow down to slingshot the glider into the headwind gradient and have it climb steeply for the remainder of the tow and maximize efficiency for the limited runway length. And I believe this to be totally valid.

When I flew a lot of platform at Waverly, Ohio the truck would radio up for your release altitude and record it. So I believe they TOTALLY knew what they were doing on this and had the data to back it up.
http://www.hanggliding.org/viewtopic.php?t=36471
Questions about platform towing
KeLe - 2019/09/16 17:51:07 UTC

Hi to all again.
It seems, that we finaly have finished the construction and we are going to test the winch in the following days. We will travel to our friends to Hungary to do this. As I said before, they have a lot of experience on other types of winches but none on a payout winch. We plan to make some training on their winch first and than try some foot launch on our payout winch. If everything goes well, we will try platform towing too. Now I have a questions about the way to apply the towing force on platform launch. Should we apply the total force from beginning, or take off with a smaller force and set it bigger at a certain altitude?
Jim Gaar - 2019/09/16 18:17:09 UTC

Typically, for our system we start at a pre-set force (in our case it's 65-68 psi on the pressure gauge) on the brake of the tow rope drum and increase pressure towards the end of the tow, depending on conditions of the tow and requests from the pilot. We also slow down the speed of the tow vehicle as the drum pressure increases.

For us, the idea is to "pay out" as much line as possible in the beginning of the tow and then "sling" the hang glider and pilot up as the tow nears an end.

We also watch the speed of the line coming off the drum and attempt to keep it at a relatively constant rotation. You should hear from others as well on their particular methods. Good luck and let us know how you did!
Dallas Willis - 2019/09/16 18:41:18 UTC

I am a firm believer in the "slingshot" method. Set the tension low enough that the truck can tear off down the road at 50mph and the glider hovers around 100-200' above the ground. Once the truck has reached the halfway point of the road, it begins to slow down and continues to slow down until the winch is rotating as slowly as possible but does continue to rotate. The first half of the tow is just paying out line, the second half is when the glider begins to climb. This keeps the tension on the glider constant and low. It produces the same altitudes as cranking up the tension and driving slower but is far easier on the equipment (on both sides of the rope) and the human attached to the glider which is also far far safer overall.
Dallas Willis - 2019/09/16 18:42:43 UTC

Yeah what Blindrodie said Image You can search this forum for "slingshot" and you'll see other posts from the both of saying the same thing in other ways too.
Mike Bomstad - 2019/09/16 18:45:10 UTC

Start with a set tension. Foot launching or using the platform (We can take a rap on the rope and give it a couple of hard jerks to get it to pay out, rough idea of the initial tension if you dont have a gauge or don't know what the pressure means yet)

You dont want it too soft as the glider will lift off then lag behind the vehicle not climbing. (low and slow is no good)
Have an airspeed indicator on the front of the rig with clean air flow.
For us- a single surface flex about 25 mph, topless 30mph, rigid about 35 mph for take off airspeed.

As blindrodie said We also watch the speed of the line coming off the drum and attempt to keep it at a relatively constant rotation.
User avatar
Tad Eareckson
Posts: 9161
Joined: 2010/11/25 03:48:55 UTC

Re: Skyting demolition

Post by Tad Eareckson »

http://groups.yahoo.com/group/skysailingtowing/message/6686
Weaklinks
Donnell Hewett - 2008/10/14 00:49:34 UTC
6686

In the case of hang gliders, platform towing is the only mode that consistently pulls downward throughout the whole flight when performed properly. All other forms of towing use forward pull at least during the early part of the flight. Therefore, they should all use a forward-pull weak link. Even platform towing can revert to forward pull if done improperly. I have seen cases where the glider would launch and the vehicle would race forward at high speed to lengthen the towline before the glider could gain significant altitude. This converted the down-pull into a forward-pull even while using a down-pull weak link. The glider climbed out at a 45 to 60 degree angle at low altitude. If the payout winch had jammed for some reason, the down-pull weak link would have broken, the glider would have whip-stalled, and the pilot would have been killed. I was appauled at such an operation. But it was SOP for that group. They had done it many, many times without a mishap.
In the case of hang gliders, platform towing is the only mode that consistently pulls downward throughout the whole flight when performed properly.
- And in all of hang gliding, nay all of any and every form of towed aviation on the planet, only the great Dr. Lionel D. Hewett, PhD is qualified to determine whether or not something's being done PROPERLY.

- They're not using Center of Mass Hewett bridles. So how can anything in platform towing be being done properly from the instant they start rolling on? Aren't all bets off from the word go?
All other forms of towing use forward pull at least during the early part of the flight.
- What if the forward pull flight locks out immediately upon launch and the pull is virtually instantly identical to a properly performed platform launch relative to the wing? What weak link would we wanna adjust to if we had the ability to succeed soon enough to permit safe recovery?

- Here's a launch with a Koch two stage. One of the safest, most effective release systems ever developed. Been around since at least the mid Eighties and you've never bothered to fuckin' look at it 'cause there's no provision for it in your Sacred Skyting Criteria.

Starts out forward pulling and identical to aero...

06-03506
http://live.staticflickr.com/65535/48250952622_b832a69ab5_o.png
Image

...transitions...

14-04604
http://live.staticflickr.com/65535/48250878351_fa79a21af8_o.png
Image

...to...

15-04610
http://live.staticflickr.com/65535/48250878176_35b2cb57c6_o.png
Image

...downward...

21-04811
http://live.staticflickr.com/65535/48250877516_11538eb058_o.png
Image

...pulling...

26-10206
http://live.staticflickr.com/65535/48250949847_517a14b221_o.png
Image

...same as stationary max (which is what it is) or platform. It would be brain dead easy to have staged weak links. How:
- come you've never advised it?
- many tow pilots do you figure have been needlessly killed because you never advised it?
Therefore, they should all use a forward-pull weak link.
And sailplanes too of course.

Image

He starts out pulling forward with his forward-pull weak link and he's fine. Then when he climbs too steeply his Hewett Infallible Weak Link succeeds before he can get into too much trouble and he recovers to get hooked back up and give it another go. I can only shudder to think what might have happened if he'd been using a downward-pull Tad-O-Link.

I rest your case.
Even platform towing can revert to forward pull if done improperly.
If it CAN...
Donnell Hewett - 2008/10/14 00:49:34 UTC
6686

But I still believe, "Anything that can go wrong will go wrong." It is only a matter of time.
...it WILL. It's only a matter of time. So then obviously for an Infallible Weak Link to be TRULY Infallible on platform it needs to be a forward-pull.
I have seen cases where the glider would launch and the vehicle would race forward at high speed to lengthen the towline before the glider could gain significant altitude. This converted the down-pull into a forward-pull even while using a down-pull weak link.
- Then let's dial it down until it succeeds one out of four times - like we do for plain vanilla surface and aero. Problem solved.

- But with a properly done platform the glider immediately starts climbing steeply under normal high tension with a higher tension downward-pull weak link so when you get a line dig the proper Infallible Weak Link will succeed well before the limits of safe recovery have been exceeded so it's physically impossible not to have a safe recovery. What part of that are people having such a hard time understanding?
The glider climbed out at a 45 to 60 degree angle at low altitude.
After they dialed up the tension with lotsa line out and the glider was cruising along at 75 feet. It would've been SO much safer if he'd just blasted off the truck bed at a 45 to 60 degree angle with his downward-pull weak link.
If the payout winch had jammed for some reason...
What reason? A zillion passenger jets a day blast of from runways too short for a total power failure on rotation to be survivable. The engines and relevant systems are a zillion times more complex than the fuckin' payout winch can ever dream of being. Yet such power failures are virtually nonexistent. And when we DO get incidents it was because of negligence somewhere up the line and somebody's head ends up on o platter. We can manage all this OK without Infallible Weak Links but we're incapable of running a drum with some rope on it that won't jam at or near takeoff?
...the down-pull weak link would have broken, the glider would have whip-stalled, and the pilot would have been killed.
Well then. By this point in time they've obviously killed scores of pilots. How do you figure they're running the cover-ups so effectively? And if they're so effective at running the cover-ups then how is it that they so totally suck at keeping their payout winch running smoothly?
I was appauled at such an operation.
And if you were appauled at such an operation it's a no fuckin' brainer that you never hopped on the back of the truck yourself. So how many flavors of towing have you actually engaged in? I'm guessing nothing beyond foot launch fixed and payout with a winch or truck. That's got everything totally covered...
Zack C - 2011/03/04 05:29:28 UTC

As for platform launching, I was nervous about it when I started doing it. It looked iffy, like things could get bad fast. I've since logged around 100 platform launches and have seen hundreds more. Never once was there any issue. I now feel platform launching is the safest way to get a hang glider into the air (in the widest range of conditions). You get away from the ground very quickly and don't launch until you have plenty of airspeed and excellent control.
...under everything defined by the Skyting Criteria.
But it was SOP for that group. They had done it many, many times without a mishap.
But Skyting Theory tells us...
Donnell Hewett - 2008/10/14 00:49:34 UTC
6686

But I still believe, "Anything that can go wrong will go wrong." It is only a matter of time.
...that something WILL go wrong so they need to get out there and do more tows until they're able to achieve a malfunction in which an Infallible Weak Link will kick in to allow a safe recovery. Until that point it can't be considered legitimate Skyting Criteria towing.

Pity you never figured out that your Center of Mass Skyting Bridle...
Donnell Hewett - 1982/09

In addition to the above mentioned roll and yaw tendancies, there is some sideways force on the pilot due to the body line. This is illustrated below:

Image

As can be seen, this sideways force tends to pull the pilot over to the correct side to make the glider turn naturally in the proper direction.
...does the polar opposite of what your theory tells us it will and that you need actual pilots at both ends of the line preflighting equipment, controlling power, pitch, roll optimally at all times, capable of avoiding and/or responding to any of the crap Mother Nature's capable of throwing at us on sane flying days.

Did you ever consider pulling your head outta your ass long enough to see what actually happens in real world towing, what's actually causing actual crashes, what halfway competent operations do to keep things under control?

If you believe - translation: know to a dead certainty beyond the slightest doubt - that anything that CAN go wrong WILL go wrong then that obviously includes the glider/harness/pilot assembly. And I'd rate that as the most complex, critical, fuckup prone chunk of the tow package. If we can manage that the rest of the package is relatively straightforward and easy. If you can't then you have no fuckin' business flying on or off tow. Your Infallible Weak Link doesn't do you any good if your sidewire pops

Did you ever once tow up to hook a thermal and STAY UP for an hour or two? I've given the Skyting newsletter archive a skim and I can't find or remember a single relevant reference. No big surprise 'cause in order to effectively do that you pretty much need to be doing AT or solid high powered platform.

I was in love with the idea of towing from Day One on - but as a means to get up into sustainable lift rather than to get pulled up and glide back down. And I tried every flavor of towing I could get my hands on.

In the fall of '80 on the dunes we KHK instructors would wrap a tether line a couple times around an Eaglet trainer basetube and fly each other in high winds like big string-kites. On 1984/05/12 I kited on an early Skyting Bridle up a thousand feet in high winds over the dunes on Paul Gibney's payout winch. 1992/05/06 I got hand towed using a truck tow bridle up off the beach into the lift band at Manteo and soared until I got tired of being kicked around in the strong wind turbulence. 1999/04/03 I fixed-line towed behind Paul Farina's van at Waverly to 1.3 K. Platformed off of trucks and trailers. I've flown behind every flavor of tug that ever got within range from a Cosmos 1986/08/01 through 914 Dragonflies with the turbo kicked in. Stupidly ATed foot launch one point the first time 'cause they didn't give you a choice back then and dolly one point a couple times in the later years.

AT - on the Delmarva Peninsula:
- multiple hour single flights, started falling asleep thermalling on one
- XC up to 37.5 miles
- gains to and beyond cloudbase, max 5800 foot gain

So what the fuck have you done? Nothing 'cause you've always been appauled by anything that didn't fit neatly into the Skyting Criteria for safe towing regardless of actual performance and results? Have you ever even hung out at a mainstream platform or AT operation long enough to really see what's really going on and start questioning any of the validity of your assumptions and pronouncements?
User avatar
Tad Eareckson
Posts: 9161
Joined: 2010/11/25 03:48:55 UTC

Re: Skyting demolition

Post by Tad Eareckson »

In the second issue of the Skyting newsletter - 1982/06 - there's a copy of BHGA's "Wings!" 1982/03/15 magazine article on the Brooks Bridle. Bob Fisher has mailed it in and there's a handwritten note across the top of what gets photocopied into the newsletter:
March Wings! - Donnell, I believe this is everything you were trying to achieve, the practical implementation of your theory. - Bob Fisher - 5-19-82
Got that? EVERYTHING you WERE TRYING to achieve, the PRACTICAL implementation of your theory. The implications being that Donnell HADN'T achieved what he'd been "TRYING" to and his implementation WASN'T practical. And it obviously wasn't just HIS theory 'cause these two approaches had been derived totally independently from each other. And by the mainstream at this point it's unknown who started getting their shit together first. And neither of them had actual THEORY down anyway 'cause:
Donnell Hewett - 1982/09

In addition to the above mentioned roll and yaw tendancies, there is some sideways force on the pilot due to the body line. This is illustrated below:

Image

As can be seen, this sideways force tends to pull the pilot over to the correct side to make the glider turn naturally in the proper direction.
Bill Brooks - 1982/03/15

HIGH degree of roll control on tow, that INCREASES with line tension. You can go more than 45 degrees off line and get back on again at full tension, and launch safely 30 degrees off wind. In addition, the bridle tends to pull the pilot over to the correcting side of the control frame to give recovery. Control is again very similar to normal flight and feels more positive.
they both had bogus totally BACKWARDS hypotheses. And that wasn't caught by the mainstream arguably...

http://www.youtube.com/watch?v=uvhzoVC1UqM
Simple Progression for Teaching Hang Gliding
Ryan Voight - 2015/02/22

As with all hang gliding, it's important to encourage a light touch.

069-25104
http://c2.staticflickr.com/2/1572/26142964830_289bc3f2cb_o.png
Image

If you teach them how to pull the glider with the harness they'll learn to steer the glider through weight shift simply by running toward their target.
...EVER.

And Donnell has - in hindsight not the least bit surprisingly - ZERO response to the Brooks Bridle and Bob Fisher. He doesn't even acknowledge the existence of the Brooks Bridle until seven months later:
Donnell Hewett - 1983/01

You are not the only one who has expressed an interest in air-to-air towing (tuging), but as of this date, no one has reported to me their experiences on this subject. Skyting No. 3 discusses my opinions on this topic, primarily from the theoretical point of view. In essence, I believe that there is no reason that "tuging" cannot be accomplished safely by using a skyting system. In fact, I would never attempt ultralight towing with anything except the skyting bridle. (Or possibly the Brooks Bridle. See Skyting No. 2.)
once and in parentheses.

In DonnellLand you need to split the tow force proportionally according to the relative masses of pilot and glider to the Centers Of Masses of the pilot and glider. The Brooks Bridle does NEITHER. It just hooks up to the suspension between the two elements right about at the Centers of Mass and Drag of the plane taken as a whole - just like an ATed sailplane. It never has anything interfering with the control bar, the way the Hewett Bridle in violation of the Skyting Criteria ALWAYS does for surface tow launch, and instead of a Reliable Release in uses a BULLETPROOF Release the pilot can blow without making the mandatory easy reach. And thus it doesn't include an Infallible Weak Link to Infallibly release the glider from tow well before the limits of safe recovery are exceeded.

LEGITIMATE tow people - few and far between though they may be - are ALWAYS inventing and/or looking for ways to maximize efficiency, effectiveness, control, safety margins, benefit:cost ratios, turnaround speed. And a fair bit of reasonably to pretty good stuff has emerged over the decades - gold standard platform rigs, Appauling Payout Tow, Koch two stage, Heuvelstraat Koch two stage, zilch stretch towlines and bridles, Cosmos Trike, Dragonfly, Kaluzhin Release, Multi-String Shoulder Release, Fallible Weak Link...

Donnell - to beat the horse a bit more dead - was only ever concerned with having been 99.9 percent right about everything when he mailed his articles in 1980/12.
User avatar
<BS>
Posts: 422
Joined: 2014/08/01 22:09:56 UTC

Re: Skyting demolition

Post by <BS> »

Image
Really glad the point of view is specified.
User avatar
Tad Eareckson
Posts: 9161
Joined: 2010/11/25 03:48:55 UTC

Re: Skyting demolition

Post by Tad Eareckson »

And for those of us who wanna see how this dynamic looks from the forward perspective...

Image

Hope that helps clear things up.

This Skyting newsletter series - 47 issues from 1981/10 to 1986/10 - is a MASSIVELY critically important element of world hang gliding history. And history is extremely dangerous threat to all the commercial interests controlling and profiting from the sport. That's why they erased Donnell from the Wikipedia entry.

I have the text archived and up here on Kite Strings but I need to get the newsletters themselves up as PDF attachments for all the illustrations, tables, graphs...

And what I have are photocopy scans of all the pages from Henry Wise. And the newsletters that Donnell mailed out all over the planet were photocopies of his masters which included photocopies of other materials. So what I/we have for the Brooks Bridle entry for Skyting 02 is Henry's photocopy of Donnell's photocopy of Bob Fisher's photocopy of his Wings! magazine.

FORTUNATELY for that one we can go to:

http://www.british-hang-gliding-history.com/magazines/wings/no-86/no-86.pdf

(Thank you Mark Woodhams.)

Ideally we could get the masters from Donnell and do some real high quality scans but that would probably hafta be through a non hostile entity. Maybe Zack C could get a Houston clubber ol' buddy of Donnell's to make the approach. But you'd think that Donnell himself would've been most motivated to move on this. The same way I want all my photos on all the AT gear I developed to live beyond me eternally. Go figure. Oh well, stated up front that Skyting was forth on his list of priorities.
User avatar
<BS>
Posts: 422
Joined: 2014/08/01 22:09:56 UTC

Re: Skyting demolition

Post by <BS> »

Hope that helps clear things up.
Yes, now I see the importance of not labeling this as a front view.
Image
User avatar
Tad Eareckson
Posts: 9161
Joined: 2010/11/25 03:48:55 UTC

Re: Skyting demolition

Post by Tad Eareckson »

Gil Dodgen - 1983/05

Editorial
A NOTE ON TOWING

The early days of hang gliding were marred by numerous towing accidents. During this period this aspect of our sport established a hopelessly bad reputation. And, indeed, last year, as you may have noted in Doug Hildreth's recent accident review, there was a towing fatality by a totally inexperienced Texas pilot.

Some time ago I received a series of four articles on a new towing system from Texas experimenter and inventor Donnell Hewitt. I ran the first in the series of four articles. Editors learn from experience and if I could roll back the calendar I would run all four at once in condensed form. In fact, what happened was that the first article - which made seemingly outrageous claims without outlining the actual technique or hardware - inflamed the then towing establishment. It seems that today's innovators become tomorrow's conservatives so I was bombarded with calls, some from the USHGA Board, telling me that this Mr. Hewitt was totally inexperienced, that he didn't know what he was talking about, and that I was contributing to the possible injury and death of unknown multitudes of innocent hang glider pilots.

I am not a tow pilot, and although Donnell's system made sense to me I was forced to discontinue the series. The essence of his system was a double bridle that connected to the glider and to the pilot. This system would thus pull the pilot back on line in the event that the glider was inadvertently turned off course from behind the vehicle. This would produce a self-correcting system avoiding the infamous "lockout" the factor which seemed to make towing so dangerous.

Well, it appears that Mr. Hewitt's system not only works but, as I've been told by pilots who have made literally thousands of land tows with it, it works beyond all the most optimistic expectations. One pilot told me, "It is virtually impossible to lock out even if one tries."
So we fixed the lockout. Donnell mailed his articles in 1980/12 at which point the autocorrecting Center Of Mass Bridle had rendered the lockout history.
Donnell Hewett - 1982/09

In addition to the above mentioned roll and yaw tendancies, there is some sideways force on the pilot due to the body line. This is illustrated below:

Image

As can be seen, this sideways force tends to pull the pilot over to the correct side to make the glider turn naturally in the proper direction.
Gil's comment is three and a half years later and Donnell NEVER...
Donnell Hewett - 1984/01

Hang Gliding Magazine has just completed a series of four articles about "Skyting," a relatively new method of towing hang gliders (April, 1981, August - October, 1983). These were the original articles on skyting and described the theoretical foundation and practical aspects of skyting as it existed back in December 1980. Since the information in these articles is now almost three years out of date, I am sure you are wondering how much of it is still valid today and how much is totally obsolete.

Actually, very little of this material is totally obsolete even though significant advances have been made in skyting since these articles were written. The fundamental principles and theory of skyting are just as valid today as they were then, and most of the equipment and techniques described in these original are also being used today.
...disabuses himself - let alone anyone else - of his roll autocorrecting Skyting Bridle.
Doug Gordon and Donnell Hewett - 1988/03

5) Avoid low altitude stalls.

For towing as well as for free-flight, low altitude stalls are responsible for the vast majority of accidents resulting in serious glider damage, bodily injury, and/or death. Never forget that stalling on takeoff or when landing is statistically the most dangerous maneuver you can perform on a hang glider.
Stalls - at any altitude - are virtually ALWAYS consequences of Infallible Weak Links or drivers making good decisions in the interest of your safety. And by the time we had HGMA certified gliders with washout struts and reflex bridles we could handle stalls given enough altitude and if we didn't let things get overly ridiculous. If we say fuck the pro toads - as we should - we're not much worried about straight and level AT stalls after we've cleared the cart. Standard inconvenience crap.

http://groups.yahoo.com/neo/groups/skysailingtowing/conversations/messages/4597
Weaklinks
Donnell Hewett - 2005/02/08 23:28:13 UTC
4597

The sole purpose and function of this weaklink is to limit the towline tension to a manageable level, i.e. a level such that the pilot can still maintain control of the aircraft in the event that the weaklink breaks.
Donnell Hewett - 2008/10/14 00:49:34 UTC
6686

In my opinion, the sole purpose of a weak link is "to allow the aircraft to recover safely when the weak link does break".
He's not talking about the garden variety LOCKOUT...
Bill Bryden - 2000/02

Dennis Pagen informed me several years ago about an aerotow lockout that he experienced. One moment he was correcting a bit of alignment with the tug and the next moment he was nearly upside down. He was stunned at the rapidity. I have heard similar stories from two other aerotow pilots.
The one of which we're all scared shitless every time we launch in thermal conditions 'cause we've all heard about them and lots of us have experienced at altitude. He's talking about textbook straight and level but steeply climbing STALLS. And he's gonna use his Infallible Weak Link to address them.

And we all saw just how well that worked with Zack Marzec and the 0.79 G focal point of his safe towing system.

The pro toad configuration has always been a fair bit problematic for us 'cause that costs us an asterisk. But let's deal with that by not watching the tape until the glider's a fair bit into the climb. Now we can call it a surface tow. And in a surface or worst relevant case scenario aero the steeper the tow angle the less relevant any keel trim connection.

This surface tow gem (lost the turnaround pulley anchor at normal/intended tow tension):

10-00704
http://c2.staticflickr.com/2/1527/25000631815_67393621b6_o.png
Image

comes damn close to a tumble.

If you're rolled in a classic garden variety lateral lockout and you have enough altitude you WILL recover safely. If you're just a bit worse off than Reidar Berntsen here your glider may well become wreckage within the next several seconds regardless of altitude.

It boggles the mind how absolutely clueless this guy was in 1980 and remained until at least Lemmy Lopez 2010/10/13.
Post Reply