Some concern over the "collapsing canopy"

[Ruffles 0]

Been reading the incidents posts and there seems to be a rash of "canopy collapsed" reports. I understand the physics of the canopy collapse (I think): turbulence or wind shear causes air to escape from the cells instead of filling them, one side collapses, canopy spins, etc. My question is, are the cross-braced and very small (<100 sqft) ellipticals somehow more prone to this abherrent collapsing than say a 210 semi-eliptical? I try not to worry over things I can't control, but I'm wondering if this is something I can.

[billvon 2,989]

> My question is, are the cross-braced and very small (<100 sqft)
> ellipticals somehow more prone to this abherrent collapsing than say
> a 210 semi-eliptical?

Six of one, half a dozen of the other.

In general a smaller canopy will be more resistant to collapse than a larger one, since it takes a larger gust to topload the canopy or cause a stall. However, the same amount of turbulence will affect a faster canopy more violently than a slower canopy, and the results of even a minor collapse at 100 feet are going to be much worse if you have a Xaos 98 vs a Spectre 210. Crossbracing and airlocks make a canopy _slightly_ more resistant to turbulence. They help in some cases, but not even the best crossbracing/airlocks in the world will help if turbulence causes a downward force on the canopy - no ram-air flexible wing in the world can withstand that,

[FrogNog 1]

Are there enough incident reports to see if the canopies involved figure statistically above or below where we expect them to based on their composition of all jumps made?

There are a lot of other possible factors. The pilot is one - people with certain canopies are more likely to jump them in weather conditions that can cause these problems.

-=-=-=-=-
Pull.

[Samurai136 0]

Failure to maintain line tension can result in the canopy spinning up and or collapsing. A high performance canopy can be flown into this state by the pilot in no wind conditions by reversing direction after an aggressive turn input.

Under a larger canopy you have a wider range of inputs. For example a few inches of rear riser on a larger lightly loaded canopy will flatten out the glide and the pilot won't be near the stall point. The same amount of rear riser on a Xaos (or any small highly loaded canopy) will plane it out and just a bit more will stall it.

I imagine most of these canopy collapses have to do with a combination of pilot error encountering some turbulence while flying the canopy near the stall point.

Ken

"Buttons aren't toys." - Trillian
Ken