Low Altitude Stalls

[skyborne 0]

What types of canopy piloting errors can result in a low altitude stall?

What actions should be taken in response to a low altitude stall?

Last year a skydiver with over 300 jumps stalled on a late turn to final approach and apparently raised the toggles too quickly in an attempt to recover, which resulted in a forward surge that was fatal.

Just trying to better understand this...

[phoenixlpr 0]

Your answers are here : http://www.dropzone.com/safety/Canopy_Control/index.shtml

[drewcarp 0]

Read either of these and you will understand better. Hope you get a chance to check them out! Lots of people try to make it an easy answer but it doesn't really make sense until you experienced it a few times. I have only stalled airplanes so i won't get into it here.

http://www.amazon.com/Parachute-Its-Pilot-Ultimate-Ram-Air/dp/0977627721/ref=sr_1_1?ie=UTF8&s=books&qid=1241975425&sr=8-1

Kind of the same book but more about airplane flight...

http://www.amazon.com/Stick-Rudder-Explanation-Art-Flying/dp/0070362408/ref=sr_1_1?ie=UTF8&s=books&qid=1241976450&sr=1-1

Both are GREAT books, they were required reading for me and I'm glad!

Good Luck!

[theonlyski 8]

Quote

Read either of these and you will understand better. Hope you get a chance to check them out! Lots of people try to make it an easy answer but it doesn't really make sense until you experienced it a few times. I have only stalled airplanes so i won't get into it here.

http://www.amazon.com/Parachute-Its-Pilot-Ultimate-Ram-Air/dp/0977627721/ref=sr_1_1?ie=UTF8&s=books&qid=1241975425&sr=8-1

Kind of the same book but more about airplane flight...

http://www.amazon.com/Stick-Rudder-Explanation-Art-Flying/dp/0070362408/ref=sr_1_1?ie=UTF8&s=books&qid=1241976450&sr=1-1

Both are GREAT books, they were required reading for me and I'm glad!

Good Luck!

"I may be a dirty pirate hooker...but I'm not about to go stand on the corner." iluvtofly
DPH -7, TDS 578, Muff 5153, SCR 14890
I'm an asshole, and I approve this message

[billvon 2,995]

>What types of canopy piloting errors can result in a low altitude stall?

Flaring too deeply. When you are turning you are also more likely to stall due to the increased loading on the wing.

>Last year a skydiver with over 300 jumps stalled on a late turn to
>final approach and apparently raised the toggles too quickly in an
>attempt to recover, which resulted in a forward surge that was fatal.

A few comments here:

1) Learning to do low flat turns and flare turns can help avoid this. Once you know what you are doing you can turn a tremendous amount using little altitude. It's a game of trading energy (speed) against altitude (potential energy) using the wing (which can give you lift and drag.)

2) If you do find yourself stalled, there's a position called the recovery position (about halfway) that will let your canopy keep flying without having it dive as much. That position is different for every canopy and it's different when you're turning.

3) Some canopies stall very, very hard. Older Micro Ravens, for example, stall and just stop flying completely. Other canopies "telegraph" the fact that they're about to stall through signs like brake line pressure, shimmying of the canopy etc. Learn to read these signs on your canopy so you can tell a stall is imminent.

[skyborne 0]

Thanks Billvon.

Your reference to a recovery position is what I was seeking. Just a quick what to do once a stall has occurred too close to the ground.

In the unfortunate fatality, would a more appropriate response to the low altitude stall have been to raise the toggles only halfway up and not too quickly, followed by a full flare and a prayer before touchdown?

I learned a hard lesson last summer on cause and effect of forward surge, and wound up with a mild spinal compression fracture that I just barely walked away from. In this instance I was approaching at half brakes and raised my toggles too quickly to close the ground. I was unable to recover from the sudden forward surge before landing. I am trying to close as many gaps in knowlege as possible, and this forum has been very helpful.

As I went through AFF last year I had to grudgingly accept the fact I am far from the invincible (much less fearless), young paratrooper I thought I was 30 years ago.

I do expect to be jumping again this summer.

[Johnny_Cage12 0]

Quote

Thanks Billvon.

...would a more appropriate response to the low altitude stall have been to raise the toggles only halfway up and not too quickly...

Depending on how comfortable you are under canopy will drastically influence your reaction to a stall.
I recently took a canopy class and the instructor gave us the opportunity to do a full dynamic stall (4000 feet in the air) to see what it was like. He said that the first time you stall your hands will be so far above your head so fast you won't know what happened.
I thought I was going to prove him wrong...but he was right. I fully stalled and while thinking about only going half way I couldn't stop my hands from raising the toggles to the non-brake position. I tried it a second time and basically did the same thing.
My advice is to spend time high above the ground practicing stall recoveries because it will be extremely beneficial when you need it. That being said you can cause malfunctions pretty easily by recovering too quickly so be extremely careful when starting out.
Blue skies,
John

[billvon 2,995]

>would a more appropriate response to the low altitude stall have been to
>raise the toggles only halfway up and not too quickly, followed by a full
>flare and a prayer before touchdown?

That's basically what I tell my FJ students, but it's not a complete answer. There's no one proper "recovery" position; that depends on your wing loading, degree of turn, altitude etc. A more accurate response would be to release toggle pressure until the canopy starts flying, and then release it further depending on how much altitude you have to recover. If this happens at 300 feet, then by all means, get the canopy flying again and gradually go back to full flight. The canopy will surge and recover and you'll be able to flare normally. At 100 feet? Get it unstalled then go a little below that to get some extra speed; prepare to flare again before landing. At 40 feet? Get it unstalled and don't go any further; prepare to do a very good PLF. At 40 feet you don't have the altitude to allow any surge at all.

(And in all cases level the wing while you are doing that.)

[pchapman 279]

Quote

response to the low altitude stall have been to raise the toggles only halfway up and not too quickly,

I believe the toggles should move up to a point where the canopy would normally be completely unstalled, flying slow, but not wobbling around on the edge of the stall. That'll allow the canopy to fly again with as little forward surge as possible.

That surge can both be dangerous at low altitudes and, if not perfectly straight, have the canopy dive off to one side with lines that are unloading and result in the jumper falling into line twists.

It has also been argued that the brake position could be as high as the brakes set position -- you'd have to look at that ahead of time and see at what hand position the brake eyes are at the guide rings. The manufacturer has already determined that the canopy opens well at that brake position -- although some amount of forward surge may be accepted. Also, that brake setting is appropriate for a more orderly, slider up deployment, so it isn't tailored to stall recovery.

I'm not sure exactly where those two brake points might be best, but I'd put emphasis on the slightly-above-the-stall-point answer. That also tends to match what is done in the paragliding world with very surge prone canopies.

In any case keeping ones hands right next to one's body and keeping the arm muscles tight will be useful to avoid having the toggles yanked up on one or both sides by the sometimes sharp and unsteady forces during the stall or recovery.

[erdnarob 1]

We shouldn't forget the error of flying a canopy near obstacles when having high winds and/or gusty winds. You can have an instant collapse too low to recover.

Learn from others mistakes, you will never live long enough to make them all.

[mdrejhon 8]

Or hidden dust devils -- I've flown through the top of one at ~1700 feet before I realized it was a dust devil. I just happened to open right above one!

Closest to unexpected canopy collapse I've ever gotten..