Anyone actually felt the benefit?
Just slightly concerned about those nasty shock openings if I ever have to throw the chute...
regards all
Simon
Joel Froehlich (TXJoel) - 2012/03/13 15:41:51 UTC
Schertz, Texas
Hi Simon,
Screamers are standard equipment on the WW Covert Harness. I don't know if any other manufacturers are using them.
- Joel
Oh good. Yet another totally useless feature Wills Wing can use to sell something to idiot glider drivers too stupid to understand the physics and too lazy to read the explanation of why it doesn't do anything.
Careful with these suggestions that there might be better ways to do stuff when everyone knows that we attained the absolute pinnacles of safety in everything thirty years ago. Subversive activity like that can get you banned.
Tad Eareckson - 2009/11/28 18:07
Screamers
My heart sank a good bit when I read your last post.
I'd really like these things to work as advertised - and not entirely 'cause I can document that I thought of them first. But I'm really having a hard time getting my head properly wrapped around the physics.
Intuitively it seems like it should do some good. Ya snap that webbing taut fast and hard enough you're gonna do some - finite - amount of damage to the stuff at the bottom end. It just seems that the damage you're doing to the stitching before things max out is damage you're subtracting from Adam's ribs (whoa - just noticed that).
But if this concept is nothing but placebo (like locking carabiners, backup suspension, quick links, and hang checks) then it oughta be shot down good by people like rgold and you.
If you could mosey over to the last place at which I haven't (yet) been completely shut down...
However jjcote says I've got it wrong, just that he's too tired to explain why.
I've been wrong before, about lots of things. I'll reserve judgment on my state of error till I've seen what he has to say
I did pretty much the whole thing in metric and then just went through and put it back into pounds and feet, so I could have got the conversions mussed up too.
So this is my thinking.
The amount of force that a parachute applies to the bridle is purely related to the velocity of the parachute through the air. For instance tie a parachute to a park bench in a ten knot wind and it will provide a force of X. Tie it to a building in a 10 knot wind, same force on the bridle, X. Tie it to the back of a car in still air, then drive the car at 10 knots and it will produce the same force: X.
Works the other way too.
Create a load by putting bricks in a bucket hung on a string, till the force on the string is X. Tie that to the parachute and throw the lot of a bridge. You already know how fast it will sink through the air, 10 knots.
and we can see that a force of 225 lb will drag a parachute through the air at 16.6 fps at 3000 ft altitude.
So we can use that to work out the force that the parachute will provide if you drag it through the air at any other speed because as we both know drag varies with the square of the speed through the air.
If there are any doubts about that axiom of aerodynamics we can check it easy enough with the chart.
Look down lower and you can see the speed of the chute with different loads (or conversely and equally, we can see the force produced by the parachute at different speeds.)
At 325 lb the chute travels at 19.9 fps.
At 225 lb the chute travels at 16.6 fps.
So 325/225 is 1.4444
Square root of 1.4444 is (about) 1.2.
16.6 x 1.2 = 19.92
So I think we can agree that the long held idea that drag is proportional to the square of the velocity through the air is correct (at least in this case it hasn't been disproven).
So how the force that the chute delivers down the bridle is only proportional to the speed of the chute through the air.
So how fast are you falling if like Adam you have to throw your laundry in freefall. Well the *most* conservative projection is that you fall at the same speed as a skydiver who's falling flat to the air. They fall at about 120 mph, which is in the same units as the parachute chart: 176 fps.
That's 10 times faster, no more than 10 times faster than the velocity that produces 225 lb force. Square the velocity... 100 times more. The force produced by a QS 330 dragged through the air at 120 mph is *over* 22500 lbs!!!!!!
Even the heaviest tandem is going to experience over 50 g. A human head weighs about 10 lb. So you will have more than 500 lb pulling your head off. Most people clip in at less than 100 kg. They're going to have over 1000 lb pulling their head off... If they're upright like Adam the pressure of the blood inside your legs will be more than 15 atmospheres! So it's not survivable. You don't live through being subjected to 100 g. Your organs will be so displaced that your aorta will tear off your heart.
Now there is some stretch in the bridle, the parachute opens *very* quickly but it's not instant so perhaps these figures are over estimates...
So add a Screamer...
The Yates site says that they activate at about 550 lb force. There's also the Petzl Absorbica that activates at about 6 kN (about 3 times as much).
So the parachute opens, it weighs very little and it stops (more or less) relative to the air. The bridle pulls tight and the force starts to go up. The parachute moves through the air faster and faster. At 550 lb (or with the Absorbica about 1200 lb) the stitching starts to give way and holds the load on the parachute steady at that level. So the chute will be going through the air at the square root of (550/225) times 16.6 fps. So it will be travelling at about 26 fps.
Meanwhile you'll be falling at 176 fps. You'll also be feeling the limited force of 550 lbs. If you're about 220 lbs hook in, you'll be feeling 2.5 G. Given that the aero load on you was stable and was exactly balancing the force of gravity (that's what terminal velocity is), you will actually slow down at 2.5 G. That's 80 fps.
So the initial speed difference between you and the chute will be 176 fps (your speed) less 26 fps (parachute's speed) so a relative 150 fps. The screamer is 4 or 5 feet longer when it's fully extended.
You would cover 5 ft at 150 fps in 1/30th of a second. There is a deceleration but it's going to be less than the errors in estimation. *Roughly* your velocity would decrease by 80/30 fps. So you would reduce your speed by a bit less than 3 fps from 176. The Absorbica (being a bit stronger) might reduce your speed by 10 fps.
Which is great, but your real terminal velocity in a pod could be as much as twice what I estimated anyway.
Gee that was a long winded way of saying we're screwed if we throw a low speed chute at high speed.
So maybe we should be throwing a high speed chute if we're going at high speed?
will throw a parachuting reserve chute for you if you're travelling at more than 96 mph straight down. I don't know if it would trigger during aerobatics. Might be worth talking to the makers before we put them in a harness.
I HAD read your Post 13 on "Parachutes and free fall." but thanks much for taking the time to walk me through things slower. Think I finally understand this thing. And it's even worse than you allow 'cause it only elongates from 10 to 22 inches.
On the other issues...
I've talked with skydivers a bit. Their reserves ARE designed to open fast AND to handle terminal. People who hafta use them at worst case report the effect as pretty attention getting but don't hafta check in to intensive care afterwards like Adam did. And they're all happy with eight G ratings on everything.
A good hang gliding parachute is probably gonna perform like a skydiving reserve.
Adam had to have been going like a bat out of hell - pod designed for nothing but offering no wind resistance beautifully aligned with the airflow 'cept backwards. I think it takes a skydiver twelve seconds to hit 120 mph doing everything he can to slow down, Adam was doing just the opposite for something like ten. I don't know if he had hit terminal for his configuration but I'll bet he'd have blown by a maxed out skydiver like that latter was standing still.
Things got ugly when the canopy opened but he was only about a third killed.
Just looking at your numbers and assumptions, if he was going as fast as he probably was he should have been killed many times over so I think there are other things going on. Lemme try some guesses.
As you said, the canopy doesn't open instantaneously. You gotta be getting some drag benefit before it finishes that job.
Maybe the parachute isn't performing as efficiently at high loads/speeds. Maybe the aerodynamics are such that more air spills disproportionally around the canopy until things start stabilizing.
And then you have nothing but nylon in the system - bridle, suspension lines, canopy itself.
You said that hang gliding parachutes hafta be designed to open as fast as possible. Yeah, lotsa times if you're cruising low on a ridge and wanna survive a midair. But for someone who aerotows the Adam scenario is probably more likely, definitely less avoidable, and probably more likely to happen up high. I've always favored the lower shock / slower opening bias. But it's a dice roll no matter how you wanna cut it.
Nuthin' like smart people to ruin everybody's fun.
Jason Rogers was kind enough to walk me through the math and physics and I think it's pretty tough to make much of a case for a Screamer to have a very measurable positive effect on a high speed deployment. And his assessment syncs pretty well with rgold's.
Lemme try this analogy...
Without Screamer...
You're blasting along the interstate at 120 mph with the accelerator stuck and no brakes. Ahead of you there's a fictitious driverless low mass vehicle going 12 mph. When you plow into the back of it you're gonna decelerate so abruptly that you're gonna break half a dozen ribs and your sternum and collapse a lung.
With Screamer...
Same thing 'cept you slam on the brakes a foot before impact. Better than nothing but your x-rays probably won't look much different.
Now maybe if you made one that elongated from one to a hundred feet... But there are better ways to reduce parachute opening shock.
A possible lesson to be learned with respect to the incident at hand...
Our instincts are gonna be to try to fly out of a situation as long as we have something left to fly. But gliders tumble at many fewer rpms than they can spin and I've never heard of anyone's arms being neutralized by G forces in a tumble. And a chute is a lot less likely to be eaten by a tumbler than a spinner.
I'm thinking that it might be a real good idea to chicken out fast and give up on the basetube in favor of the deployment handle as soon as one can get his brain to kick back in after things start going so seriously south.
Jason Rogers - 2009/12/01 04:55:51 UTC
Hi Tad,
I read your summation on the oz report and you said it better in one line than I did in a whole page. Like getting hard on the brakes one foot before you hit. Wow. I can *see* that.
Actually concreted it in my mind better than all the numbers.
I think there must be something that absorbs or spreads the shock of opening that reduces the shock down from what the raw numbers suggest.
Perhaps it's the way the chute opens. It's not instant, but its quick. Tony Barton described it as being like a cannon going off.
There is stretch in the lines and bridle. That has to take some of it up.
Sounds like Adam was very lucky. Having the non standard configuration on his chute attachment, one I've never heard of. Being the correct orientation while falling. Having the harness break in just the right way to separate him from the broken glider. Getting the chute out in time.
I really think that we need to use a skydiving reserve for high flying in *addition* to the normal HG chute. It would have to be built into the harness, but it shouldn't be impossible. Given that it's fitted to the harness, it would be nice if it triggered automatically as well.
But then again, more people get killed in towing accidents and foot launches gone wrong than in tumbles. Have a look at:
Couldn't have said it in one line without first understanding the whole page and all the numbers. And I've been trying to really understand this issue since late March when Fredrik first pointed me to the dissent.
Was kinda hoping to have heard back from jjcote by now. Seems to have a reasonably good brain but I also find him to be a bit of a jerk.
I've thought about parachutes a lot for almost as long as I've been in the sport but in the entire existence of hang gliding I don't believe there has been a single intentional nonaerobatic deployment at any of the DC club sites.
It would be REAL nice if we had some means of bailing out. Maybe a six G weak link that would fail just before the glider. But then you might get a basetube in the throat on the way out.
And an automatic opener would be nice 'cept then you'd need a pilot chute which could hang up on wires.
There was a ballistic chute fad for a while but even when they didn't malfunction on their own the pilots always seemed to figure out some way to make sure they'd be inert when needed.
We could reduce opening shock with a deployment sleeve but that requires a pilot chute (see above).
Maybe some sort of slider would work.
I'm thinking the easiest / simplest / cheapest / lightest / most effective solution would be just to use an oversized (slower opening) chute with a fairly long bridle - and gear yourself to get it out before things deteriorate to an insane level.
Yeah, Adam was DAMNED lucky.
Not saying I'd have done better (probably worse (which in this case would mean dead)) but I think he missed an opportunity to keep himself and his glider from being trashed during the tumble. I think he could have gotten the chute out and away and both of them could have flown the next day's task.
Then he had two wrongs making a right. It's more dangerous to connect to the harness rather than up near the glider and that suspension shouldn't fail. But he got a very fortuitous combination out of the deal.
But that business of the deployment being compromised because of the harness failure was bullshit. I'm not real familiar with this generation of competition harnesses but that was totally unacceptable. You should NEVER hafta fight anything more formidable than a couple of strips of two inch velcro when the shit hits the fan.
At that point he'd have had to borrow a glider but he still could've flown the next day versus - as it is - possibly never again.
I noticed the "dreadful launch" thread appearing but didn't realize it was you and hadn't read it.
Generally speaking, I'm not terribly interested in such incidents and the discussions 'cause they're inherently complex and dangerous and the culture has long had about as good a grip on the issue as it's gonna get. I can get so much more bang for the buck in the areas in which the culture is totally clueless - towing, landings, and hook in failures.
I've had my share of launches such as you described with worse outcomes - the last one a ground loop which resulted in a broken foot, my only serious injury in the sport.
This Chris Thale / Henson crap really pisses me off. Easiest ramp in the world. What were people thinking! The red line is there for a reason - Windy Cliffs 101. What a waste.
I did notice the rekindling of a little activity in the "Tow Park accidents" thread. How ironic that SlingBlade who knows how dangerous insecure releases and state of the industry weak links have made his flying is seeking counsel from the flock of idiots that's responsible for the lay of the land being what it is.
Thanks again,
Tad
Vrezh Tumanyan - 2009/11/30 03:53:35 UTC
I'm thinking that it might be a real good idea to chicken out fast and give up on the basetube in favor of the deployment handle as soon as one can get his brain to kick back in after things start going so seriously south.
Agree.
I don't see an alternative at this point.
In Adam's case having two chutes wouldn't do any good either.
On the flip side, though, I was able to hold on to the basetube through the tumble and recovered.
The alternative would be a parachute ride from 13K into the dinosaur country in the Sierras.
So DON'T chicken out fast.
But if you lost the bar, DO grab that red handle FAST!
Then you'll have gotten through it and come to an understanding about three days faster than I did.
Short answer though...
It looks good, sounds good, seems like it would do something - but it doesn't.
If you wanna reduce your opening shock - just use a bigger chute and a longer nylon bridle. But we - in hang gliders - really can't afford to get in situations in which we need parachutes anyway so it's not really worth discussing that much.
P.S. Forget what I said about the bridle - that's probably wrong too. (But it'll help get your chute clear of your spinning wreckage a little better.)
Miller Stroud - 2012/03/14 01:03:11 UTC
Arlington, Tennessee
It can't hurt to have one.
It can if you're putting the time, engineering, resources, dollars into something that doesn't work and for which there's virtually nothing in the way of data indicating a need even if it did.
All industries that have to deal with sudden deceleration issues use some sort of device. ( deer hunters, window washers, warehouse workers, cars(airbags),) ect....
The sudden deceleration issue with which hang gliding is most plagued...
Most common HG injury... spiral fracture of the humerus.
...is best dealt with by a good pair of wheels and a landing intended to utilize them. But, strangely...
Gil Dodgen - 1995/01
All of this reminds me of a comment Mike Meier made when he was learning to fly sailplanes. He mentioned how easy it was to land a sailplane (with spoilers for glide-path control and wheels), and then said, "If other aircraft were as difficult to land as hang gliders no one would fly them."
...Wills Wing has never had a whole lot to say on that issue.
Jeff Shipiro has enough insight to know that they can make a difference.
Too bad Jeff Shapiro doesn't have enough insight to tune into the climbing and hang gliding forums and do the fucking math to figure out that they don't.
Here are a few other sudden deceleration issues we occasionally hafta deal with in this sport...
Mark DeMarino - 2010/01/18
Upon reaching 100-125' he released and at this point he slid down downtubes to base. I said to myself "Oh shit, he's not hooked in."
Bille got the glider leveled off and released the towline, started to come in to land, and at about twenty to thirty feet suddenly dropped from the glider. As he was in a semi-prone attitude he came down at an angle of a few degrees, impacted the ground on both feet, and then fell forward on his face.
The impact broke both legs at the ankles and drove his shin bones out the bottom of his feet six inches. He also broke his hips and nose and had other more minor injuries.
I don't have many details at this point, but I just got a call from Scott. Bill Priday launched from Whitwell without hooking in. Scott indicated there was about a hundred foot drop-off from launch. Bill's status is unknown at this time. Please pray for him!
Mark Johnson - 2008/08/31
Then all hell broke loose. "He's unhooked, shit..." Guys yelling at him over the radio to throw his chute, "Kunio don't think, throw your chute - throw your chute". We all watch in horror not believing this was happening.
Larry West - 2012/02/20 14:49:54 UTC
I looked up and he's almost fully prone with his hands still mid-tube on downtubes, his nose pitched way up and about ten feet off the ground. At that moment, the weak link broke. (He was using that lame greenstripe crap and no one had talked to him about weak links as far as I know. He had a thousand foot roll of the stuff in the back of his van. He was just using "what they told him to use".) So the nose pitched forward to dive into the ground and his arms were still fully extended and locked so he went through both of them taking his right arm out as he went.
The weak link broke from the tow plane side. The towline was found underneath the wreck, and attached to the glider by the weaklink. The glider basically fell on the towline.
Doug Hildreth - 1990/09
Immediately after launch, the glider pitched up sharply with nose very high. Apparently the angle caused an "auto release" of the towline from the pilot, who completed a hammerhead stall and dove into the ground. Severe head injury with unsuccessful CPR.
The best option seemed to be to resist the lock out and slowly bring the glider down, even if it was crooked, but another problem arose when the observer had the towline cut when I was down to about fifty feet.
I had no chance. The glider that had been hanging on like a kite dead leafed to the ground. The left leading edge hit first, destroying it along with the nose plates. My body's impact point was the left shoulder and the left side of my head and neck.
I remained unconscious for about twenty minutes with a bloody face from what poured from my nose. The chopper arrived about an hour after the crash. I was already semiconscious but in a lot of pain and having trouble breathing.
Bill Bryden - 1999/06
During the tug's rollout for the second launch attempt, the tug pilot observed the glider clear the runway dust and then begin a left bank with no immediate correction. At that point he noticed that the launch cart was hanging below the glider and immediately released his end of the 240 foot towline. The tug never left the ground and tug pilot watched the glider continue a hard bank to the left achieving an altitude of approximately 25 feet. Impact was on the left wing and then the nose of the glider. Rob was killed immediately from severe neck and head trauma.
Holly immediately had control problems right off the dolly and completed 3 oscilations before it took her 90 degrees from the tow vehicle upon when the tug pilot hit the release and Holly continued turning away from the tow in a fairly violent exchange of force . Holly pulled in to have control speed and then began rounding out , but there was not enough altitude and she hit the ground before she could do so. She was barely 100 feet when she was locked out in a left hand turn. At that time, she was banked up over 60 degrees.
The basebar hit the ground first, nose wires failed from the impact, and at the same time she was hitting face first.
The Herald on Sunday - 2009/01/10
Aucklander Stephen Elliot, 48, was taking part in the Forbes Flatland Hang Gliding Championship in Sydney last Saturday when he landed badly.
Elliot shattered four bones in his neck and damaged several blood vessels that supplied blood to the brain. He was flown to the Royal North Shore Hospital in Sydney and put into an induced coma but died on Monday.
Luen Miller - 1997/07
"At fifty feet Frank got into a left turn for reasons unknown. The operator thinks that Frank may have been reaching for the release. The turn went uncorrected until Frank was 180 degrees from his original flight path."
Then Robin shifted off to the left again getting his right, upwind wing, high again. He was seen reaching for his release. I understand that Bobby also released him.
He kept doing a wing over to the left and dove straight into the ground from about fifty feet. He was killed immediately.
Joe Gregor - 2004/09
The pilot suffered fatal injuries due to blunt trauma. There is no evidence that the pilot made an attempt to release from tow prior to the weak link break, the gate was found closed on the Wallaby-style tow release.
But I'm not seeing Wills Wing do jack shit about any of those.
Oh well, I'll sleep a lot easier knowing that at least one glider manufacturer is at least trying to do something about all these horrible opening shock issues that take such a horrible toll on the members of our closely knit hang gliding community.
These devices are typical of OSHA fall protection gear.
You got some documentation on that?
I would think at a high altitude, being separated for the wing (as in a blown loop or tumble) high G situation this might be the way to go.
I've got a better idea. We're all vulnerable to tumbles in strong enough thermal conditions but nobody's ever been forced to do a loop - which is a prerequisite for blowing one. So if you decide to do one then don't blow it 'cause you really don't wanna be in a position in which your life is gonna dependent on your parachute doing its job.
With a LARA type quick deploy chute, not sure if the extension of the bridle would work adversely to in deployment time vs. altitude situation.
It's a tradeoff. Pick one. Flip a coin. I'm more worried about spinning wreckage eating my parachute than I am about dying 'cause I needed another ten feet of altitude - so I go long.
The harness also works as a shock absorber, but single suspension systems have less of that...
Do they? How big a fucking deal is the couple of feet of whatever's between your harness and your carabiner when you've got twenty-five feet of single suspension nylon webbing between your carabiner and your parachute swivel? And then we can throw in the shroud lines.
...so no doubt that's why Wills would have decided to use the device.
Yeah, no doubt whatsoever. They must've put tons of thought into this. You see a need for something in this sport just screaming for fulfillment, you do something about it. My hat's totally off to them.
Or maybe they just thought they could sell more harnesses to you clueless bozos if they appealed to your totally irrational fears. Checked your backup suspension lately so that you can be sure it'll catch you when your primary fails?
Since, I have been away from the sport such a while one question; what happened to Rocket deployed chutes? I know there were issues with hand deploy options, and traveling on airlines are they used much at all?
- People had enough ways to fuck up hand deployed chutes so they wouldn't work when they needed them. The ballistic jobs just gave them so many more options.
- They weren't very reliable even when the glider pilots didn't fuck them up.
- It's a lot easier and better not to do or blow extreme aerobatics or fly into other gliders than it is to deploy any parachute successfully.
- I've got a theory that we fuck up more people with accidental deployments than we save with deliberate ones.
- The vast majority of people we're mangling and killing in this sport wouldn't have benefited from totally reliable hand or ballistically deployed parachutes and there aren't a whole lot of non aerobatic flyers being saved by them.
I got out of hospital three days ago and tried to put something together about the accident last night. It's a scary incident but the outcome has nothing but positive implications for all of us. We can survive a parachute deployment at terminal velocity after separating from our glider. Best to avoid such an event but if it does happen it need not be a death sentence. I am very lucky to be alive, and extremely grateful to still be here. Hoping what follows covers all questions but have also attached a more formal report too.
It was the second task of the Gulgong Classic and just like the day before the wind gusts and turbulence in the tow paddock were moderate to heavy. It was about 30-35 degrees Celsius at ground level and the conditions seemed stable although the weather report had predicted good instability. Due to the rough conditions weak links were breaking just about every other tow and the two tugs worked hard to eventually get everyone off the ground successfully. The task was 209 km, north, to Manilla Airstrip.
I towed out of the airstrip around 1:30 pm and went to release height behind Pete Marhiene. During the first thermal I noticed several light inversion layers. Eventually I drifted downwind and met up with Chris Jones, Phil Schroder, Oliver Barthelmes, and Dave May and we topped out at 6500 feet before heading NW in a cross-tail direction to get on the upwind side of the course line.
Chris was ahead by two hundred meters and after a five kilometer glide I watched him complete two turns in what looked like solid lift. Eventually Dave, Oli, and Phil would also head for Chris. Before I got there he had already straightened up and was back into a search pattern. This was typical of the conditions for the day; very short lived 'bubble' climbs, mild to moderate turbulence, and generally a stable type of feel to the weather. Way off to the north great looking clouds filled the sky along the Liverpool Range and beyond, we needed to get there but for now we continued to hunt for a core that may be lurking around in the stable conditions of Gulgong.
While Chris, Oli, Phil, and Dave tended to search upwind I turned downwind for about a hundred meters and noticed the air felt much better there, still bumpy and stable but at least it was more buoyant. I fully expected to only gain a few turns out of any climb I might find before it too petered out. Soon I felt some lift ahead and more to the left so I began a shallow turn in that direction and the vario started to chirp at about two to three hundred feet per minute. VG was off except for about one arm's length of rope. I was flying at about fifty kph with a bar position faster than best glide speed.
As I climbed for about a quarter of the first turn the 'G' began to lighten and the nose started to ease over. For that first split second I expected a 'wire slapper' to precede a return into normal flight. This did not happen. The 'G' went to zero and the nose continued over. I braced onto the basebar and attempted to pull in and maintain hang position. This however could not be maintained. The 'G' went negative and the nose went over. I maintained some grip on the basebar and kept the torso as close to it as possible but the leg/boot end of the harness could not and continued to move toward the undersurface and my upper body would eventually follow. The nose-over motion accelerated and then I lost contact with the basebar.
As I fell weightless through the air the glider proceeded to tumble and I clear the wing without making contact as it passed underneath inverted. Just as the glider came around upright I bottomed out with a thud when the hang strap went tight and for a split second I thought the glider might stabilize. However it had more than enough momentum to enter the second tumble.
Again I don't recall hitting any part of the glider as it went over a second time. Once again I fell with another thud when the hang straps went tight but this time the tension lasted for a much shorter period of time. I went weightless as if falling straight down for several meters before feeling the beginning of a rotation/spin in the horizontal plane (like a sycamore seed). We suspect the side wire had broken at this point and the wings began to fold together.
The first spin finished quickly but I entered the second spin with much more speed. I tried to go for the parachute handle but the G force had already built up significantly. Soon my arms (and eventually my head) were forced and held out away from the center of rotation preventing me from reaching the parachute handle. I realized I was in a bad way but my life depended on getting to the parachute. Hard as I tried and with all of my strength my arms remained straight pointing away from the harness.
What followed is something I could never have imagined, a force developed by these rotations, an incredible rapid acceleration in speed and the rapidly increasing Gs. I have watched video of similar motion when a glider folds its wings but on those occasions the rotation seems to reach a maximum after a number of rotations. Not in this case. The G force continued to increase and was transverse to my prone position, pooling blood ventrally in the front half of my body. The eyes sustained advanced hematoma from this force. By the fifth and sixth rotation the load was so severe I knew the equipment would have to fail soon and hopefully before I sustained serious injury. Then in a split second the G force went to zero and I was being thrown through space. At least I could move my arms and hold my head up. I reached for the parachute handle.
I was aware of moving horizontally with a lot of velocity and could also hear the airspeed accelerating very quickly. Motion through the air was like a projectile but soon turned into a freefall. I realized then I had definitely separated from the glider. I located the parachute handle and pulled with my right hand but it didn't budge, and after a few more heaves I was convinced the parachute was going to need a lot more persuasion to come out. (We would discover the back plate had failed catastrophically and the opening of the parachute port was deformed as a result).
As I fought to remove the parachute I was aware of free-falling straight down in a boot-first/head-up/'pencil' position. This would later be confirmed by eye witnesses. Over the next five seconds while I continued to struggle with the parachute the sound of the airflow achieved a maximum and I realized I was at terminal velocity.
One arm was not enough so I reached down with the left and with both hands heaved on the handle. After another couple of seconds I felt the parachute finally come loose. I threw it sideways, let go and waited.
What came next was the most painful and violent impact I have ever felt in my life, like I had been torn in half. Extreme pain instantly filled the body with the worst of it concentrated in chest and upper back. I knew I had sustained serious injury and immediately suspected my back was broken. I looked up just enough to see one of the most beautiful things, a clean circular shape of the front third of the parachute taut, inflated, and intact. The airflow was quiet now and the earth was no longer hurtling towards me. In less than fifteen seconds I had fallen four thousand feet, the parachute and harness survived the deployment and so had I - but not without injury, and the pain suggested I was in a real bad way.
As I was wheeled in through the hospital doors a familiar face in a green medical gown stood there waiting, Conrad Loten, fellow hang glider pilot and head of the Emergency Department, took over my treatment and directed his staff calmly but with obvious authority and competence. After the CAT scan Conrad came over to my bed and confirmed the damage; six broken ribs, a collapsed lung, broken sternum and a flail fracture of the chest.
Jeff Shapiro has planned the incorporation of Screamers in the new Wills Wing harness since the beginning of the development process early this year. He has just sewn and tested a set that will go into the current proto harness. There is also a set going to the testing facility that Wills uses. If I read his email right, the set going in his harness reduces a 25.5 kN deployment shockload to as low as 12.75 kN. Seems like it's about time for a system that you can count on in a freefall.
- Actually Dustin... It WORKED in the freefall.
- How come we're not talking about getting the system BEFORE the freefall?
- How come we're not talking about designing the harness so you don't need to by trying to pry it out of the container with both hands for four thousand feet?
- Would that be unacceptable for a racing harness 'cause it would take a thousandth of a glide point off the harnesses with which you guys outfitting your comp pilots with so you can advertise your T2s as sweeping the events?
- Or is it just a lot easier and cheaper to slap a Screamer into the system than to properly reengineer the harness?
- Hey! Maybe if you get everyone's attention focused on the Magic Screamer that you think/claim will make the terminal velocity opening shock so gentle you'll hafta look up to verify that you've got an inflated canopy people will stop:
-- worrying about the dangerous engineering of the harness; and
-- thinking about the implications of shit hitting the fan at three grand!
Jeff Shapiro - 2009/11/27 19:18:05
Missoula
One of the other factory pilots, Dustin Martin, sent me a link to this thread and although I have never posted on this site previously I wanted to respond in relation to the developments being made while designing the new WW comp harness.
Knowing Adam and hearing about his separation from his glider after what appears to be a side wire failure and subsequent free fall deployment, I really wanted to concentrate on improving the safety and effectiveness of my deployment system to include rare circumstance such as being detached from the wing before having to deploy. I was also in OZ and was racing and witness to Andy Ogler's unfortunate death in a similar (practically identical in many ways) accident.
As a climber for most of my life, I have had extensive experience with load limiters (Screamers) and know first hand their effect on a Factor 2 fall. I have wanted to incorporate a Screamer into my deployment system since the beginning of development of the new WW harness. It's ironic that this accident has brought this discussion forth because less than one week ago, I tested my load limiting connection (what a pilot will connect his/her chute bridal to the internal structure of the harness with) and based on my calculations, not only did it work properly but displayed the potential to decrease the shock load almost in half over a 25 foot Factor 2 fall. I am (as I write this ironically) sewing up two more load limiters to be sent to WW's testing facility so that we have accurate numbers to compare to my calculations. I plan for this system to be integrated into the production phase of our competition and XC harness line after extensive testing and the determination of it's effectiveness is complete.
It is my intention to design the safest, most structurally redundant harness on the market so that WW customers can be flying in equipment that ecceeds saftety standards being currently recognized. I am not in any way making the statement that other harness manufacturers are building sub standard products in terms of saftety or quality. Only that I am acutely aware and will do everything in my power to address possible scenarios to improve industry safety standards in relation to harness design.
Sincerley,
Jeff Shapiro
...and although I have never posted on this site previously I wanted to respond in relation to the developments being made while designing the new WW comp harness.
And you'll never post again on this site so we won't hear any updates in relation to the developments being made while designing the new WW comp harness.
...after what appears to be a side wire failure...
The sidewire failure was a consequence - not the cause - of the tumble.
...I really wanted to concentrate on improving the safety and effectiveness of my deployment system to include rare circumstance such as being detached from the wing before having to deploy.
- Are you gonna concentrate on improving the safety and effectiveness of your deployment system to include the rare circumstance of a backplate that doesn't fail catastrophically and deform the parachute port BEFORE the pilot is detached from the wing?
- Are you gonna concentrate on improving the safety and effectiveness of your deployment system such that the pilot can get it out of the port using ONE hand?
- Exactly when was it that Adam "had to deploy"?
- If he had been able to deploy when he first blew out of the glider what would the opening shock have been like?
- Do you think he'd have scored six broken ribs, a collapsed lung, a broken sternum, and a flail fracture of the chest if he had been flying a traditional pod with a chest mounted parachute?
- Are you gonna concentrate on improving the safety and effectiveness of your deployment system to make it as safe as the configurations we had thirty-five years ago?
I was also in OZ and was racing and witness to Andy Ogler's unfortunate death in a similar (practically identical in many ways) accident.
Whoa! Dude! TWO glider tumbles with the pilots ejected to freefall with nearly and totally fatal parachute system failures in New South Wales glider comps well under two years apart! And here I was thinking these were rare events!
Adam Parer - 2009/11/25
Approximately eighteen months ago during the annual January competition at Forbes that I witnessed a very similar incident to the one described above.
An Austrian team pilot sustained two tumbles and then departed from his glider and entered a freefall. His incident did not include the sycamore rotation and therefore he was able to immediately deploy his parachute. Unfortunately his rescue chute was not certified for freefall/terminal velocity deployment. His parachute 'candled' for approximately two seconds before opening violently and failed catastrophically.
Say Adam... I'm a little confused here.
- If Andreas was able to IMMEDIATELY deploy his parachute how could he have been anywhere remotely close to terminal when it hit the air?
- Any chance his backplate also failed catastrophically and deformed the port like yours did? Or was the impact so severe that the harness manufacturer could blame everything on the parachute?
- If the parachute was such a piece of crap how did it get certified and how come I don't remember any advisories?
- Here are the specs for my parachute which I picked up used thirty years ago last month:
Embury Sky Systems, Inc.
Date Mfg'd FEB 1979
S/N 0873
Caution
Maximum Opening Force 3000 LBS
Emergency Hang Glider Use
Limit 200 LBS at 120 MPH
Seems like a newer one shoulda been OK.
As a climber for most of my life, I have had extensive experience with load limiters (Screamers) and know first hand their effect on a Factor 2 fall.
Yeah? Exactly what IS their effect on a Factor 2 fall?
I have wanted to incorporate a Screamer into my deployment system since the beginning of development of the new WW harness.
And I have wanted to incorporate gold stripes on the sides of my new WW harness.
...I tested my load limiting connection and based on my calculations, not only did it work properly but displayed the potential to decrease the shock load almost in half over a 25 foot Factor 2 fall.
- Did you determine that it worked "properly" based on anybody else's calculations?
- Define "properly".
- So it displayed the POTENTIAL to decrease the shock load almost in half over a 25 foot Factor 2 fall.
- Exactly how did it DISPLAY this potential?
- So what did it ACTUALLY display to decrease the shock load over a 25 foot Factor 2 fall?
I am (as I write this ironically) sewing up two more load limiters to be sent to WW's testing facility so that we have accurate numbers to compare to my calculations.
- Yeah. Ironically.
- So you're just doing calculations and have zilch in the way of bench testing data.
I plan for this system to be integrated into the production phase of our competition and XC harness line after extensive testing and the determination of it's effectiveness is complete.
- So at this point you really don't have any actual indication that this device actually does anything.
- Why does it hafta be integrated into the harnesses anyway? Before I found out that these things don't actually DO anything I just installed one between my swivel and bridle and stowed it in my deployment bag.
- Well, I guess you guys could sell a lot more harnesses if you got your idiot customers to believe that this needed to be integrated into the design.
It is my intention to design the safest, most structurally redundant harness on the market so that WW customers can be flying in equipment that ecceeds saftety standards being currently recognized.
- Great! We can finally see the light at the end of the tunnel with respect to all these needless deaths we've been having because of people's harnesses blowing apart. Where would we be without people like you who identify the serious problems we're having in this sport and do something about them!
- Oh. And while we're on the subject...
A bit under two months ago there was a guy named Roy Messing flying one of your Falcon 3 195s he had just picked up from your Whitewater dealership/school at which he'd gotten up to Hang Two level.
And he was towing up behind a Dragonfly in calm morning air using one of those nice releases that your dealership/school at Lookout sells - and isn't warranted for towing anything.
And he got into a bit of a turn, was a little late getting off, slammed in kinda hard, and sorta died a few days later. Now his harness held up OK - even if it was one of those pieces of shit with no integrated Screamer from Betty - but that particular release...
If you watch Zack here flying one of your Sport 2 155s (he also flies one of your Falcon 3 170s) - plus the same release that Roy got killed on...
...he's having a bit of trouble getting it to work just in straight and level flight.
And if you jump to quarter after four on Outback here - flying one of your Sport 2s with the same release at your Kitty Hawk dealership/school... Ya notice...
...that when he gets into a turn the release gets REALLY hard to blow and he ends up REALLY rolled. Notice the way the horizon kinda goes beyond vertical at 4:20 when he finally pries himself loose?
Ya think maybe these things could be made a little easier to use? Or would the R&D required cause a setback in your efforts to get the harnesses up to safe capacities? I'm good either way - you guys are the pros and I know that all your dealerships are doing the best jobs they possibly can to provide safe, top notch equipment to all your customers.
After Adam's free fall deployment in Australia a few weeks ago, I am exploring the idea of using load limiting "screamers" for a connection between the harness and chute bridle. My hope is to reduce the impact force and make a safer deployment situation without reducing opening time. I've used Screamers for years while climbing ice or any time the gear is "light" and believe in their effectiveness from experience. Pearson has had interaction with the folks at Yates over the years and after I built an example of the Screamer I would like to use in the harness, he sent it to the Yates facility who were extremely gracious, agreeing to test it for us and to give us the valuable information derived from a test to failure.
Even after I sent it off, I couldn't resist building one to test myself with a five foot static drop. The Screamer did exactly what it was supposed to, reducing the impact force on a fall that would have normally broke me in half ;-) After some laughs with Gibisch, I jumped and responded to the result with one word... Cool!
My hope is to reduce the impact force and make a safer deployment situation without reducing opening time.
Yeah Jeff. We also might wanna look at ways to INCREASE the opening time. That would limit your exposure to enemy ground fire.
OK, I know what you meant.
Yeah, Jeff... Ya definitely don't wanna increase the opening time beyond four thousand feet. Just wouldn't be very safe.
I've used Screamers for years while climbing ice or any time the gear is "light" and believe in their effectiveness from experience.
- Great, Jeff. Thousands of people who've been flying Wallaby over the course of the past couple of decades believe in the effectiveness of the 130 pound Greenspot Standard Aerotow Weak Link in breaking if you fail to maintain the correct tow position (centered, with the wheels of the tug on the horizon) before you can get into too much trouble.
- So do you have any actual NUMBERS yet to support your BELIEF in their effectiveness from your EXPERIENCE?
- Did you use a perlon climbing rope to do side by side test drops - with and without a Screamer, blindfolded and with earplugs - to see if you could tell the difference?
Pearson has had interaction with the folks at Yates over the years and after I built an example of the Screamer I would like to use in the harness, he sent it to the Yates facility who were extremely gracious, agreeing to test it for us and to give us the valuable information derived from a test to failure.
- Oh. So you sent an example of the Screamer you built and would like to use in the harness over to the folks who make and sell Screamers and they very graciously agreed to test it for you and give you the valuable information derived from a test to failure.
- So... Exactly what WAS the valuable information derived from the test to failure of the example of the Screamer you built and would like to use in the harness the folks who make and sell Screamers very graciously agreed to perform? I can't seem to find it anywhere.
Joel Froehlich - 2012/03/13
Schertz, Texas
Hi Simon,
Screamers are standard equipment on the WW Covert Harness. I don't know if any other manufacturers are using them.
Ryan Voight - 2012/03/14
Ditto.
Wings Over Wasatch
Authorized Wills Wing Dealer
Miller Stroud - 2012/03/14
Arlington, Tennessee
It can't hurt to have one. All industries that have to deal with sudden deceleration issues use some sort of device. ( deer hunters, window washers, warehouse workers, cars(airbags),) ect.... Jeff Shipiro has enough insight to know that they can make a difference.
-
ATOS VQ, Easy Riser, Fledge II, Fledge III
Hang 4, 100 Mile Club
Covert, Flytec 6030
Tennessee Tree Topper Member
The Wills Wing Covert harness is the next step in optimizing performance for serious competition and cross-country pilots. Designed and developed by Jeff Shapiro and Steve Pearson, in collaboration with Dustin Martin, the Covert takes drag reduction and harness function into an entirely new realm.
So Jeff Shapiro, Steve Pearson, and Dustin Martin...
- I can't seem to find any mention of Screamers here - integrated into the harness, available as an option for the parachute bridle, or recommended as an add-on.
- What kind of numbers did you get back from Yates?
- If I get tumbled like Adam did will I need to burn up four grand and be going boot-down in pencil mode in that streamlined harness at about 240 miles per-hour before I get the parachute pried past the port which has been deformed by the catastrophic backplate failure which occurred when the situation with the glider went tits up?
- Think I'll be able to hold the number of broken ribs down to six?
- How 'bout lungs? Any chance of collapsing two of them? I'll be OK with two 'cause that's when the third one will kick in, right?
The Covert is a race style harness incorporating a carbon fiber backplate supported by a single suspension main. A specially designed backplate insert, CNC machined from a solid billet of aluminum and hard anodized, provides the basis for a low friction slider mechanism that allows for an easy transition between prone and upright attitudes.
- And there's no chance of it catastrophically failing like Adam's (and maybe Andreas's) in a tumble?
- Well of course not! I'm sure you'd let us all know if the case were otherwise.
- So what did you do on this design that was amiss with the 2008 Skyline Zero Drag job that almost killed Adam?
- Any older Will Wing harnesses that really need a retrofit?
- Any harnesses from ANYBODY on which an advisory needs to be issued?
The Covert harness has the option for one or two side-mounted parachutes with an innovative deployment design. The closure and containment system has been carefully designed to produce a system that allows quick parachute removal with either hand while retaining a secure closure.
And there's no chance of that closure becoming a bit too secure?
Zack C - 2010/12/13 04:58:15 UTC
I had a very different mindset too back then and trusted the people that made my equipment. Since then I've realized (largely due to this discussion) that while I can certainly consider the advice of others, I can't trust anyone in this sport but myself (and maybe the people at Wills Wing).
Timeline...
2007/11/23
A bit after the end of the 2007 I start thinking about Screamers, believe what Yates is saying, think that this is a no brainer, install one in my system, plug it on the Capitol Club rag:
Now all the sudden I'm not getting ignored and pissed all over as much. Even Rooney is interested.
2009/03/23
I get a disturbing post from Fredrik in Norway that relays that the smart people in the climbing world are saying that Screamers don't actually do anything. I start clearing my turns a whole lot more frequently and carefully.
2009/11/16
Adam Parer's deployment system jams and the opening shock half kills him...
...and the geniuses at Wills Wing - instead of doing shit to fix the problem - start trying to duct tape in a patch for the symptom using a device I had implemented before anyone else two years prior...
Miller Stroud - 2012/03/14
Jeff Shipiro has enough insight to know that they can make a difference.
...and fourteen days before I'm gonna understand that the people who've been saying for years that it doesn't do anything are completely right and remove mine from the configuration.
2009/11/30
After Jason Rogers (gasdive) takes me through the physics I fully understand the issue and explain on the Davis Show:
that Screamers don't work and why and get ignored as usual and the visionaries at Wills Wing continue their efforts to push the safety envelope to hitherto undreamed of heights.
- With the competition harnesses comes a performance/safety tradeoff.
-- You're supported by a frame instead of an array of suspension lines. That's a lot cleaner but it means that you can't ball up - pull your knees to your chest - to get as much weight as possible forward when you're recovering from a severe stall and attempting to prevent a tumble.
-- If you move the parachute off of your chest to the side you can hang closer to the basetube and decrease your control effort but you no longer have all that lovely padding between your chest (heart) and the rocks. And I'd hazard a guess that parachutes in the chest container prevent more death and destruction than parachutes in the airflow.
-- Furthermore... Moving the parachute off of your chest to the side introduces a failure mode in that load damaged internal CG adjustment hardware can make it undeployable.
The first two are acceptable compromises. The third ISN'T.
- But, in any case, we don't get told any of this by the harness manufacturer - we just get sold expensive, fantastic comp harnesses.
- In response to a near fatal incident occuring because of harness design compromises and defects, Wills Wing descends from its ivory tower to enter the ooze of web forum discussions just long enough to:
-- distract everybody away from the core issue that comp harnesses designs are inherently dangerous and the specific engineering is unacceptably dangerous; and
-- offer a phony patch to the symptom of the problem rather than fix the problem. (Our release won't actually function as a release - especially in an emergency situation - and, anyway, it's impossible to engineer one which will (if it weren't we'd have done it already). But don't worry, just buy one of our hook knives and you'll be fine.)
- Rather than advise everyone to just install the third party placebo mechanism on the downwind end of the bridle they create the impressions that:
-- it's something that needs to be built into the harness; and
-- they're the only ones who will be building it into the harness.
- They independently determine that the placebo is nothing more than a placebo but do NOTHING to reverse the perceptions that they created that:
-- the placebo is something more than a placebo; and
-- they can only benefit from this miracle device by purchasing a Wills Wing Covert racing harness.
- They don't even bother cluing in their dealers and their dealers are pushing this nonexistent placebo as a big selling point.
Way beyond maximum rated speed
Laragne-Monteglin, France
I received the following on my smart phone from an apparently Australian phone number:
Mart Bosman broke his Airborne C4 on final glide at the Belgian Nationals here in Laragne on Thursday. He deployed his parachute without a problem. He didn't break any bones, but was in the hospital overnight.
It looks like the crossbar broke. He was overtaking a British pilot flying an ATOS that was doing 115 km/h (71 mph) which is far beyond the design VNE (50 mph) when the glider folded up. The side wires were okay as was the pullback. I haven't checked the VG yet.
Mart Bosman - 2012/07/20 17:55:23 UTC
Bit of bruising of body and ego. I flew with a Covert and the Screamer worked well. It was very hard to throw the chute due to centripetale forces.
We'll have a look at the Aircotec for my speed at the time of the disintegration of the glider.
- WHAT Screamer? Wills Wing makes no mention of it in their harness specs.
- Let's assume that you WERE using a Screamer. What the fuck do you mean it "worked well"? Compared to the other guy of the identical flying weight who blew his cross spar at the same instant right next to you, and fell at an identical acceleration an identical distance before popping his identical parachute?
What a total bullshit statement.
Hey Wills Wing,
Ya gonna say anything?
Or are you gonna let this crap stand so people will talk some more about the really great equipment you guys are always developing?
