OliShann

Is this a joke or what ? Okay, so I was wondering do people have a problem with french jumpers. would you still jump with me?? See... the whole thing is pointless. There is no issue.

WHAT AN EXCELLENT SUBJECT ! Instead of trying to get an answer in books or websites with obsolete data, I would suggest the following (we need an actuary here) : some people must be maintaining such databases we are looking for : our insurers, their reinsurers, or their brokers. I don't know how this is organised in USA, but I suppose USPA make you pay some mandatory insurance to get the licence. And then a broker works for them to get the best insurance conditions on the market, going to big companies for who will insure the risk (death/loss of income) for the whole association. So the best thing to do would be to contact USPA and ask them who is their broker or insurer (the broker should be Marsh or Aon), and then ask them for stats. What do you think ? Let me know anyways.

I wouldn't say so :( ...but still am curious to hear a specialist about that.

Exactly, and by not detaching from the surface, the flow keeps on going over the control surfaces which in turn keep on being effective. Indeed it is not a problem for us.

Yep... sounds right. I love this topic ;-)

One more thing : The vibration will be divergent when its frenquency hits the natural frequency of the structure. Therefore our problem reduces to : does the trailing edge of our parachutes have a natural frequency ? At first view, if it has any it is when inflated, ie flying. Hence the whole thing strongly depends on the speed of the wing. But then again it is non rigid and of so little weight that I doubt we can get a solution for that. Anyone knows anyone designing canopies, who could light us a bit ? PS : I may be wrong but I don't think vortex generators have anything to do with flutter. They are designed to insure good energy feeding to control surfaces. The only way to prevent flutter is to change the natural frequency of the structure under study, generally by adding some weight to it.

See DT, from now on you will be jumping with a broom handle over your shoulders behind your neck with your wrists draped over it. Have fun.

In my own humble opinion, what you are describing is not flutter. It is just that under these conditions this part of the wing is a bit loose and subject to strong vortices, therefore inducing the observed vibration. Flutter is an aerodynamically induced vibration of a wing, tail, or control surface that can result in total structural failure in a matter of seconds, because the vibration is DIVERGENT. What you observed is not divergent, and the fact that the vibration applies to a non rigid structure of little weight brings up the following question : Can we talk of flutter at all in the case of a parachute ? Bye.