canopy collapse

[happythoughts 0]

How does it happen ?

What are the forces? Actions? Turns?
...that cause it?

[Witelli 0]

Good question. I've been wondering this myself. If you open up under a perfectly good canopy, what could make it turn bad? I'm very curious as well.

[MB38 0]

As far as I can tell... just stalling it. At least that's all I can think of.

Come to think of it, I hit some strong turbulence on a .9 loaded canopy at 3,000 which caused it to collapse temporarily. The center cells dropped down and the canopy went into a big "U" shape. I lost probably 50 feet before I was under a fully inflated [and panic flared] canopy.

I really don't know what I'm talking about.

[sirenoremac 0]

A canopy collapse occurs when the airspeed of the canopy becomes too low to support inflation. A deep stall, turbulence, lazy eights (turning fast one way and very quickly reversing direction) can all cause this condition but for different reasons. A deep stall will stop the parachute from flying, and directly cause airspeed loss and therefore pressurization loss. Turbulence may effect a canopy many different ways, but a collpase can occur when different portions of the canopy are flying through distinctly different types of air masses, i.e. the sides of the canopy get caught in a solid up-draft, but the center does not. This will cause part of the canopy to lose inflation. Lazy eights can induce slack in your lines, causing a brief loss of your gravitational force on the canopy, and possibly leading to some type of collapse, although this would be difficult to induce. Basically anything that you can picture to make the air flowing into the front of your canopy or part of your canopy can cause some type of collapse. Turbulence is the most likely to cause an accidental collapse, while holding a deep stall is the easiest way to induce a collapse.

[darkwing 5]

Usually related to turbulence. The standard prevention (not perfect) is stay at full flight, and avoid turbulence generators (ie, don't be downwind of obstacles).

-- Jeff
My Skydiving History

[happythoughts 0]

Thanks.

Probably the definiton of a canopy collapse is the lack of internal pressurization.

According to what I've been reading, low "G" loading is what causes this. Lack of weight on the steering lines. I've been trying to collect some causes of low "G" loading.

Usually, it seems it is when the angle of attack reaches zero (pilot control).

Quote

a collpase can occur when different portions of the canopy are flying through distinctly different types of air masses, i.e. the sides of the canopy get caught in a solid up-draft, but the center does not.

With a little bit of caution, people can stay away from fixed objects and reduce their exposure to down-rotors.

Turbulent up-drafts would be a little more difficult to avoid.

[Samurai136 0]

Read Brian Germain's Book.

He explains it all.

Ken

"Buttons aren't toys." - Trillian
Ken

[bigorangemd 0]

Agreed. He does a very good job of explaining the dangers of diconnecting the engine (jumper) form the canopy. Any sudden loss of gravitational pull on the lines risks collapse as well as tubulent conditions (due to wind or poor angle of attack) causing loss of internal pressurization.

[happythoughts 0]

I fly an airlock now, but I used to have a square. When things got bumpy, I would go to 1/4 brakes. It slowed me down a bit, but it kept the wing from waffling up and down. That "accordion" look is very unsettling.

[jsaxton 0]

Flying through a dust devil can do it.