Did I just do an accelerated Stall?

[AlexDias 0]

Today, A-license in the mail, so I decide to visit a new DZ to celebrate.
I jumped 190 sq feet hornet on my last jump and was doing some fairly aggressive turns above 2'000ft as I usually do with the spectre 190 I usually fly at my home DZ. I started a right toggle 360 turn and started another 360 left toggle turn straight out of it. Then I suddenly felt myself somehow not where I should be compared to the canopy (felt like I was loosing some tension in the lines).I didn't really understood what was going on for half a second then I looked up only to see I had a 180° line twist!(my first line twist and I did it to myself.. YAY!) So i kicked myself out of it in another half a second and finally finished the flight gently.
I then talked to the instructors on the ground who told me this is something that happens if you put too much pressure on one toggle right after the other and it creates a stall... Of course I knew what a stall was... But i didn't know it could happen by doing some turns.. Is that something proper to each canopy? cause it never happened on the other one I usually jump...

Anyway this was a pretty scary experience.. specially when you don't expect it.. but I definitely learned a lot from it and that is a great example of why no one with my experience should be doing this below 1'000ft... and i would say even higher..

So Can anybody explain to me what really happened to my canopy there? I am thinking it just stalled and felt a bit while i was still turning resulting in that line twist?

Blue skies!

[JackC1 0]

As you apply a brake on one side, you swing out and start to turn. If you release that brake and apply the other, the canopy tries to turn left while you're still turning right. The result can be lost line tension, line twists, a collapsed canopy and if you're unlucky a reserve ride. Sometimes known as cock turns because if you do them and have to chop, you're a cock.

Let your canopy recover from one turn before you change direction and keep that line tension, it's the only thing keeping you in control of your canopy.

[GLIDEANGLE 1]

Simple problem, simple solution.

As you come out of an aggressive turn the lines will often become slightly unloaded (you feel light in the harness).... If you start another turn at that moment the canopy turns... But you don't. This is because the lines are not loaded enough to keep you moving with the canopy. (Note that the unloaded lines cause the line twist.... Not the other way around.)

The second turn can be made by simply maintaining line tension during the transition between the turns.

Here is the move you made:
Right toggle down, right toggle up, left toggle down.

Try this move:
Right toggle down, left toggle down, right toggle up.

The latter Sequence will make you feel quite heavy during the transition... Which will keep the lines tight and will keep you and the canopy moving together.

The choices we make have consequences, for us & for others!

[virgin-burner 1]

a buddy of mine did something similar, only at about 1000ft; resulted in a REALLY low cutaway, about a 3 second reserve-ride and a tree-landing. as if that wasnt enough, he climbed out of the harness and down the tree and walked away. he came back to the dz, took off his jumpsuit, got dressed and went home.

next day he returned to retrieve his rig.

i would not recommend such maneuvres if you dont know the fuck what you're doing..



no stall of what-so-ever-sort, but a goat-fuck stupid thing to do.. just sayin'!

“Some may never live, but the crazy never die.”
-Hunter S. Thompson
"No. Try not. Do... or do not. There is no try."
-Yoda

[pchapman 261]

Self-induced line twists:

The risk of line twists from sudden opposing toggle turns doesn't get much mention in the Canadian PIMs, just this on p47 of PIM2a:

Quote

Be smooth and even with your toggles and avoid jerky motions. Rapid toggle inputs can put an open canopy into line twists, with severe consequences at low altitude.

You have to be sensitive to unweighting the lines if doing sudden turns. With tension on the lines, the lines spreading out from both shoulders have a lot of resistance to twisting around each other. As soon as the lines get like limp spaghetti with no tension on them, there's nothing preventing you and the canopy doing different things.

If one twists up, what typically happens is NOT that 'the canopy twists up'. Instead, the canopy does something that your body can't follow, so your body is rotated relative to it. Once there's a half twist, there's very little stopping any twisting even with tension applied, so then one's body might continue to turn and spin up 2 or 3 full revolutions.

If one is on a smaller more sensitive canopy, the canopy might continue to turn and spiral, making it harder to untwist. (Also, one might still have one brake line pulled down and that could be trapped in the twists.)

About 15 years back self-induced line twists killed a then well known Canadian jumper with 4000 jumps.

At least you were keeping your playing around with the canopy up high - good - where emergency procedures are still possible.

[NealFitz 0]

something similar to this?

http://www.youtube.com/watch?v=QECtqCRNKxs

Dudeist Skydiver #170
You do not need a parachute to skydive, you only need one to skydive again

[virgin-burner 1]

that's a comfortably LONG reserve-ride..



but comparable!

“Some may never live, but the crazy never die.”
-Hunter S. Thompson
"No. Try not. Do... or do not. There is no try."
-Yoda

[NealFitz 0]

Dudeist Skydiver #170
You do not need a parachute to skydive, you only need one to skydive again

[virgin-burner 1]

it was right in front of the dz in a forest next to it. those trees are HIGH there, like 60ft at least..

twists, bam-bam, reserve out, flare, hugged a tree.
it happened just as fast as you read that.

it's pretty amazing he walked away from that..

“Some may never live, but the crazy never die.”
-Hunter S. Thompson
"No. Try not. Do... or do not. There is no try."
-Yoda

[NealFitz 0]

i ahve to say i had a very comfortably long reserve ride also- a good minute i think :P

Dudeist Skydiver #170
You do not need a parachute to skydive, you only need one to skydive again

[virgin-burner 1]

i still have yet to have a reserve - knock on wood; but since i'm a dirty high puller, i expect it to be a bit longer!

“Some may never live, but the crazy never die.”
-Hunter S. Thompson
"No. Try not. Do... or do not. There is no try."
-Yoda

[captain_stan 0]

Quote

Did I just do an accelerated Stall?

No, but that question begs another one: do you not understand what constitutes a stall? Your student training should have included that subject. If not, time for a review with an instructor.

Congrats on your new license!

[jhh166 0]

Quote

Simple problem, simple solution.

As you come out of an aggressive turn the lines will often become slightly unloaded (you feel light in the harness).... If you start another turn at that moment the canopy turns... But you don't. This is because the lines are not loaded enough to keep you moving with the canopy. (Note that the unloaded lines cause the line twist.... Not the other way around.)

The second turn can be made by simply maintaining line tension during the transition between the turns.

Here is the move you made:
Right toggle down, right toggle up, left toggle down.

Try this move:
Right toggle down, left toggle down, right toggle up.

The latter Sequence will make you feel quite heavy during the transition... Which will keep the lines tight and will keep you and the canopy moving together.

I believe I have heard this referred to as "active toggle" inputs.

[JackC1 0]

Or this http://video.google.com/videoplay?docid=9194881818135049107

[virgin-burner 1]

HOLY FUCK!!!!

yea, that's more like it..



even a stand-up landing, i'm impressed!

“Some may never live, but the crazy never die.”
-Hunter S. Thompson
"No. Try not. Do... or do not. There is no try."
-Yoda

[NealFitz 0]

o yes i seen that one a couple of years ago- even a woohoo at the end the man has balls!!!! lol

Dudeist Skydiver #170
You do not need a parachute to skydive, you only need one to skydive again

[PhoenixPhive 0]

this is why my trust ability is nil when it comes to the aff... i don't understand wind...
and i have been reading physics books, and cloud patterns and gliding and parachuting...

i would much rather pay to have a TI go fly a kite with me and let me ask questions about the wind before i ever took the aff-

if you think its unrelated to this thread please limit the insults to body blows
thanking you

[jhh166 0]

Quote

this is why my trust ability is nil when it comes to the aff... i don't understand wind...
and i have been reading physics books, and cloud patterns and gliding and parachuting...

i would much rather pay to have a TI go fly a kite with me and let me ask questions about the wind before i ever took the aff-

if you think its unrelated to this thread please limit the insults to body blows
thanking you

Im not to sure what you mean or are stating. The AFF program is a good one but it is only what you make out of it. I think the AFF is only a part of the learning experience; the other part is up to you to throw yourself in the culture, spend days at the DZ and absorb all the knowledge you can. I bet if you stuck around after hrs you would get all the answers you wanted about wind, turbulence or as in the OP case self induced line twists, free of charge too.

[3mpire 0]

Talk to your instructors, they can tell you all you want to know about the basics of canopy flight that will give you the building blocks you need to be able to apply your knowledge to your flight. It's up to you to speak up if you don't know something, that's why your instructors are there. Talk to more than one of them asking the same questions. They will all answer them in their own way, so if one explains it and you don't get it, another instructor might frame the same information in a different way that makes more sense to you.

you aren't going to really learn what you're seeking from a book or the internet. It just takes time asking questions and then doing jumps over and over and really studying how your canopy flies. It's one of those things you just have to keep doing before it clicks.

But really, your instructors is where you should seek your answer. That's what you need.

As for that low reserve deployment video... fuck. that. shit.

[PhoenixPhive 0]

i want to find a mentor that can answer questions about the wind from the ground

[ufk22 32]

Since you were trained in Canada, I don't know your program, but if you have or download a SIM from USPA, look at the Cat G lesson plan. It talks about "performance turns", but does a poor job of explaining it.
The line twists were induced, like others have said, because you unloaded your canopy, but going into brakes (pulling down the other toggle prior to raising the first one) to hold line tension is not the best answer. Doing this puts you out in front of the canopy rather than underneath it.
The idea is to keep the canopy over your head (a relative term if the canopy is diving) and yourself centered underneath it.
USPA talks about a 90 turn then a reverse 180 but I think it's easier to figure out doing 180 then reverse 180.
Initiate a 180, but ease into it,taking about a full second to bring the toggle from full up to full turn, hold the toggle down, but about 2/3 through it start to gently ease up on the toggle, being at toggle full up just prior to 180. As you feel yourself swing under the canopy at level flight ease into the opposing turn (not just jab the toggle all the way down), getting the toggle all the way down about 1/4 way into the opposing turn. As you get better, you can transition from raising one toggle to lowering the other with no break in between.
When you get it right, you'll know. The turns will have a smooth but more aggressive feel, especially in the second 180.
The exact points to ease in and out of the turns will vary with the canopy and the wing-load, but this is a place to start.
Remember to do this stuff up high.

This is the paradox of skydiving. We do something very dangerous, expose ourselves to a totally unnecesary risk, and then spend our time trying to make it safer.

[AlexDias 0]

Thanks so much for all the advice! That's some scary video you posted! luckily I was flying a 190 sq feet so it's relatively forgiving!
Will try to be more gentle and ease into it next time though :)

Cheers

[PhoenixPhive 0]

thank you :)

[GroundResonance 0]

This is most likely a result of pendular action.. as you pull the first toggle hard, the airfoil produces a greater horizontal component of lift. Because you are suspended by lines the centrifugal force created pulls your body to the outside of the turn. Now, when you pull that opposing toggle the airfoil will immediately respond with a turn in the opposite direction, which causes slack in the lines as the airfoil turns, until your body can fall enough to re-tension them.. the momentum created in the meantime will cause the line twist.

This is similar to why helicopter pilots in aircraft with semi-rigid rotor systems must always keep positive g-loading on the rotor system.

[captain_stan 0]

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Will try to be more gentle and ease into it next time though :)

Absoultely correct. Understanding causal theory is a wonderful thing. But after a point, complicated explanations just add more fluff to the issue. Avoiding the repetion of your negative experience is exactly as simple. as you have expressed.