Jonathan Dietch <<res007jc>>
writes:

http://ozreport.com/forum/viewtopic.php?t=50038

The Wills Wing drag chute is from the same manufacturer I am
currently working with. In limited applications it works fine but outside very
limited parameters becomes unpredictable.

I don't know whether or not Woody Valley is still using the Metamorfosi
Deltastop Drag Chute design.
Http://tinyurl.com/gnjyvv2 
I formerly owned two of this design that were made by Metamorfosi before they
closed and Moyes bought the company.

 I used these on several occasions and it was the reason I went on a quest
for a drag chute that does not oscillate unpredictably. They do work and in one
case it saved my bacon. But in tight, critical landings these would oscillate
badly enough to make it difficult to steer my glider safely. No amount of bridle
extension will stop it from oscillating and if the bridle is shortened it will
collapse and stay that way. Tests done in the 90s on a design similar to the one
I've re-introduced indicated it was the only drag chute that didn't collapse in
ground effect.

There is a certain model rocket recovery chute being marketed as a hang glider
drag chute. I did several tests on it and it collapsed so badly anywhere near
the ground that I nearly flew into a chain link fence on one landing and off the
end of the LZ on another. Due to its flower-petal-like design if any of the 4
lines get snagged it may rotate very fast like a reverse windmill and the total
drag gets so high that the glider becomes difficult to control. Luckily I've
always had the foresight to do my tests with a quick release and I've had to use
it a few times and jettison the test drag chute. I have never had such an
uncontrolled rotation issue with the 6-panel design in spite of installing it
inside out on one occasion or having a bad line-over on another.

Anyhow, I have been a test pilot at risk who has checked out many things and
learned enough to avert trouble and still be able to rely heavily on what I
trust to be a relatively safe and dependable design. Who doesn't want to be able
to perform and RLF like this?
Https://youtu.be/ih6PUKYyERU.

That drag chute is 72" nominal diameter versus 60" and has a big pull for very
steep landings. It's purely a test model. 60" is a very good size for most
applications. I happen to fly in some interesting places.