Jim good to hear your thumb is on the mend. Years ago I damaged two shoulders by hanging too long to both downtubes. My 12 year old glider still has its original downtubes but I vowed to never hang on again in the event of a swing through landing. I also will, if the situation demands, turn diagonal and/or hold to one side of the control frame. My intention is to avoid contact with the keel. If equipped with the rear restraint I will do my best to not touch the downtubes anywhere close to midway. An empty coke can used to withstand 180 lbs unless you touched the sides of the can with your fingers. That is my analogy with downtubes. Most of the whacks that I have seen has left the downtubes intact. We can't expect the rear restraint to do much more than help on a straight nose over. A yawing impact will have the nose and keel out of line with the pilot anyway. I'm not sure how you would go about simulating a blown out downtube but for now it seems too soon in the experiment.
It's high time we stopped to take a look at ourselves and the tech we've adopted, and got out a fresh sheet of paper and started all over. Sounds radical but it ain't.
Okay....I totally botched where the camera should go...totally botched the keel repair (didnt pin it down and it spun)...totally misjudged how far this thing would travel forward without definite stop lines, but its good for a laugh and might even make Rick hurl.... on film I say the pin releases did not release correctly but that is not true. Upon closer examination the trolley separated from the glider perfectly and exactly where I had wanted it too.....I just misjudged everything else....no real damage done....a slieghtly bent down tube. this test was done with 120 pounds. I need better camera placement, need to straighten a few things out and pin them down properly too.....other than that the trolley release system actually worked pretty good..... consider all this merely a backyard budget prototype for whack testing the hang gliding industry should have been doing thirty years ago...maybe this will inspire some companies with actual budgets to do some whack testing someday. Has ANY major hang gliding company done ANY serious whack testing or worked on safe splat devices that you guys know of? Shame on them.
yes, the trolley release worked exceptionally well.....that glider was under its own steam as it hurtled past the camera and not attached to the zipline at all. Also with the new trolley system the zipline jumps up and out of the way of the kingpost completely and does not interfere in any way. HOwever....I am going to re-attach the lines that went to the basetube and set them to go tight after the glider has released and traveled a short distance to force a whack......a really good whack....as if the base tube hit a good sized rock at good speed. I need those lines re-attached to provide a definite stop point. For more than one reason. without the tripod line support to stop the glider on this test it might have smashed into the back of my ford Explorer. it was moving pretty good. I think all I am doing here is....determining the best way to imitate a whack.....After that the real testing starts.
Has ANY major hang gliding company done ANY serious whack testing or worked on safe splat devices that you guys know of? Shame on them.
You imply an obligation on manufacturers that I consider unfair. Hang gliders with gentle landing characteristics have been produced. Do you see these at your flying sites? No or rarely, I think, would be the answer. The faster a hang glider is designed to fly, the greater is the demand on the pilot's skill. He determines entirely his landing risk by the level of performance he chooses in the wing he flies.
Hang gliders are not consumer items like cars. They are a simple, lightweight wing used by enthusiasts engaged in the pursuit of dangerous sports. The design of the wing is limited by aerodynamics, not the manufacturer's whims. The production of gliders is determined by the kind of performance pilots want, not by what somebody else thinks is safer. If pilots wanted gliders that land gently, you would see them everywhere. However, most pilots want robust, strong gliders that fly well and quickly through the air. This forces a compromise. Fast gliders have a more critical flare window. They demand a much higher level of skill. For a lot of pilots flying these models, that skill is lacking.
When a hang glider pilot screws up, you often see him crash with his arms pushing out all the way on the base tube. This is not how you fly a hang glider. It is not even the correct way to crash a hang glider. When a pilot exceeds his level of competence, bad things happen. At that point, it is too late to fix the problem. "Safe-splat" involves one basic strategy: extend the time of collision. You want to take that sudden stop and stretch it out as long as you can. That's the idea behind a compression device as well as the use of wheels or sacrificing tubing. It makes the collision take longer and thereby reduces the force of impact. However, to perform design and analysis in the absence of properly applied crashing skill is self-defeating. Any results are more like an autopsy than safety improvements. For instance, a pilot's first priority in a serious crash is to extend the collision by using the glider itself as a compressible member. The pilot must position himself at impact so that his body flies into the undersurface of the sail, not the ground. He must do everything he can to extend deceleration at impact by letting the glider take the blow. Essentially, this involves grabbing one downtube with both hands about halfway up so that his body will rotate around that point and hit the sail instead of the ground. It is important to note that this can work on any vector whereas a compression device will only be effective on a forward vector. And it makes no sense to me to secure the pilot's mass to the base bar for testing. It should be secured to a downtube in the same fashion a real pilot would grab that downtube in a crash.
Last edited by Rick Masters on Tue Jul 19, 2016 11:19 am, edited 6 times in total.
Rick: ---"Essentially, this involves grabbing one downtube with both hands about halfway up so that his body will rotate around that point and hit the sail instead of the ground.----
Rick, How about one hand near the bottom quarter of the downtube and the other hand near the top quarter of the downtube and avoid halfway up the downtube?
You won't have much time to think about it. Whatever throws you into the sail is good. Wrapping your arms around a downtube also works. Give no thought to preserving tubing. Compared to bones, tubing is almost free.
You want the self-preservation action of grabbing a downtube to be instinctive at the moment you realize all is lost. It can happen very quickly. You'll be fighting for control, lose it entirely, then a split second from the ground let go of one downtube and grab the other with both hands. I have found myself against my sail on several occasions, both me and the glider unscathed, but not being able to remember at all what happened!
The only time I hurt myself on a hang glider was before I realized how important this was. I stupidly stuck my arm out. If I'd been hanging onto the downtube with both arms, I would have been fine. A hang glider is a wire and tubing cage that protects you. Trust in it. Stay inside it.
Instead of quoting everything Rick just said suffice to say....I couldnt agree more As I mentioned early on in this thread. throwing myself sideways just before impact altered everything and saved my bacon in Chelan when my arm was dislocated midair. I really had not thought of holding on to one base tube and being spun around sideways as Rick describes but the result is the same as what I did instinctily. Rick has explained this before but this is the first time I have been listening...sorry. Rick just solved the safe splat problem with zero devices (which always complicate) for a cost of zero dollars. (and I thought I was cheap) Maybe we dont need a device, Maybe we need better training from day one on this important survival technique. my next zip line test is going to be Ricks technique. going to tie off the test dummy to one side with light line equal to the average pilots grip on the DT. Going to take out a downtube for sure but oh well....I want to see it in action. We can call this next one the sidewinder
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