Anatomy of a "spinner".

[Dolph 0]

Not sure what forum to lace this post, so moderators, feel free to move it if there's a more appropriate one.

Yesterday, I managed to pack a malfunction it seems. A spinning malfunction.

Canopy is a Katana 97, loaded about 1.7. Upon opening, there were line twist even before the jumper had looked up to verify the canopy was looking good. Did the classical "spin you around while you kick out of line twists" thing. After the jumper had kicked out of the line twists (3-4 of them), the canopy was still in a sharp turn. Both brakes still set, slider fully down. She tried to correct it by using back risers for input, but the G-load made it ineffective and she was rapidly running out of altitude.

Jumper checked alti again: 500 meters, hard deck reached, cut away main, open reserve. Uneventful reserve opening and smooth landing.

We found the main in a tree. There was no visual damage anywhere, except on the outermost right C line. Here, some fraying was evident. The fraying was inconsistent with what you'd expect from being hung up in a tree - some needles (pine tree) from the tree could be found stuck to other lines but no fraying apparent there. No needles attached the frayed line.

Now, I'm wondering what usually causes an elliptical to spin up like that. I know the jumper in question very well. She has about 400 jumps on the canopy (1200 something total) and it hasn't misbehaved before. Jumper doesn't have a problem with bad body position either (although certainly that can happen to anyone, so I will not dismiss it).

Which leads me to believe it was my packjob. Packed it like I always have and I usually take my time. Only modest activity at the DZ, so I wasn't in a rush. Lines straight and no slack, cascade points matching. Decently stowed afterwards, with some excess line stowed in S folds at the bottom of the container.

I'm in no way an expert in gear and aerodynamics. It bugs me that I may have packed a malfunction. It bugs me even more that it was for someone else.

So there is a) the delopyment, which the jumper can affect) and b) the packjob, which the packer can affect.

Any thoughts, aside from the normal flaming?

[RogerRamjet 0]

Any broken or worn out stow bands?

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Roger "Ramjet" Clark
FB# 271, SCR 3245, SCS 1519

[Hooknswoop 19]

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Now, I'm wondering what usually causes an elliptical to spin up like that

Short answer:

Uneven risers from the jumper being uneven in the harness, the legstraps being tightened unevely, or the legstraps being on different parts of the thigh during opening.

Long answer:

"Preventing and Curing Line Twists

Line twists have gone from a common nuisance to a common malfunction requiring a cutaway. There are techniques for reducing the chances of incurring line twists and correcting them if you do get them.

The first step to handling line twists is to prevent them in the first place. The looser the chest strap is the wider the 3 rings will be on deployment, which makes it harder for line twists to develop. Of course, be sure that your harness is secure enough to keep you from sliding out of it. Make sure your leg straps are even. For free flyers, a piece of bungee or elastic between your leg straps will help keep the leg straps from creeping to the back of your knees and keep the risers loaded evenly on deployment. Evenly loading the harness on deployment by keeping your hips and shoulders level with the ground will help keep the canopy opening on heading. Take care when setting the brakes of your canopy and take out any twists in the steering lines, which shorten the line. A pre-mature brake release can easily cause line twists and limits your ability to steer away from others immediately after deploying. When stowing the lines on the deployment bag, one side will have less excess in the line from bottom of reserve container to last stow on deployment bag lines than the other. If your last stow was on the left of the bag, the right side would have the least amount of excess lines in the bottom of the pack tray and vice versus. Leave 12 to 18 inches of excess line between the side with the least amount of excess and the corner of the reserve container. This will prevent the lines from hanging up on the reserve container on deployment and twisting the deployment bag as it leaves the container. A worn out pilot chute can spin on deployment, which can spin the deployment bag. Replace a pilot chute that has holes in the fabric or tears in the mesh. Re-line a canopy that is out of trim. If one end cell “A” line (the line that attaches to the nose of the canopy) has shrunk more than the opposite side, the canopy will open turning in the direction of the shorter line. Also, if one steering line has shrunk more than another, the canopy will want to turn in the direction of the shorter line on opening. Pulling the slider down to the 3 rings can prevent self-induced line twists (caused by jerking on a toggle and the canopy turning faster thant he jumper) and most importantly, smooth control inputs.

Even if you take all possible precautions, line twists still happen. If you find yourself under canopy with line twists and the canopy is flying straight, simply kick out of the twists. Make sure you are kicking in the right direction. You can also twist the risers to bring the twists closer to you and reach above the twists for leverage to get yourself out of the twists.

If the canopy is spinning with line twists, react quickly, look up at your links and make them even by shifting your weight in the harness. Be careful not to overdo it and cause the canopy to spin in the opposite direction. At the same time, make sure your brakes are still set. You can use any reference you want, but I’ve found using the links to make the risers even is easiest. The canopy should stop spinning and fly straight. Now kick out of the line twists. Again, make sure you are kicking in the right direction. A canopy that is spinning in line twists loses altitude rapidly, so watch your altitude. Remember under a highly loaded elliptical, you don’t have much time and you do not want the twists to include the excess cutaway cable in the back of your risers. This can make for an impossible or difficult cutaway."

Derek

[thepollster 0]

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Upon opening, there were line twist even before the jumper had looked up to verify the canopy was looking good

Shit happens. It could be something odd the jumper did, too little excess line between the risers and last line stow, an incorrectly manufactored pilot chute, or canopy starting to go out of trim (400 jumps=about time for line set on HP canopy). Like I said, shit happens, and you probably won't find a solid cause.

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After the jumper had kicked out of the line twists (3-4 of them), the canopy was still in a sharp turn. Both brakes still set, slider fully down. She tried to correct it by using back risers for input

With brakes set, once you start a HP canopy turning, it often wants to continue to turn. With this jumpers experience, she should have known how to deal with it. Since the line twists were gone (as I read it, correct me if I'm wrong), she probably should have popped the toggles.

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There was no visual damage anywhere, except on the outermost right C line.

Again, 400j line set, probably time for a new lineset. I doubt line twists could cause fraying. Burns, maybe, but fraying?

[davelepka 4]

Both brakes were still stowed when you recovered the canopy? If it was still turning after the line twists were out, a fired brake would be my first guess.

If not, are you sure there wasn't an additional malfunction, maybe a line over or tension knot? This could have contributed to the line twists, and provided the un-stopable spin.

Another possibility is that the jumper kicked out of the twists, gave a half-assed attempt to stop the spin, gave up and chopped it.

In the end, the jumper attemted to unfurl a clever fabric wing while falling at a high speed through the air. Shit is bound to go wrong sooner or later.

[davelepka 4]

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Since the line twists were gone (as I read it, correct me if I'm wrong), she probably should have popped the toggles.

I'm not sure how this would produce a different result than correcting with the rear risers.

[Hooknswoop 19]

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With brakes set, once you start a HP canopy turning, it often wants to continue to turn.

A canopy simply reacts to input. It will continue to spin because the risers are uneven. With more weight on one leg strap than the other and the added "G" forces from the spin, it will continue to spin. For example, if the jumper has 90 pounds on one legstrap and 70 on the other and they are pulling 2 "G's", that means there is 180 on one legstrap and 140 on the other. This is more than enough to harness turn the canopy into a spin. Unless the jumper adds enough input (riser or tiggle) to counter this harness input, or shifts in the harness to correct the weight inbalance, the canopy will continue to spin.

Derek

[CSpenceFLY 1]

About 4'10" and 98 pounds.


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[johnny1488 1]

Unstowing the brakes puts the canopy in full flight. The canopy will stop the turn on its own in full flight. It's happened to me and I've seen it happen to others. Mostly highly loaded ellipticals. As was said, once an elliptical is put into a turn with the brakes set, it doesnt want to recover on its own. I have not though, been able to manufacturer a turn that I couldnt stop with the rear risers. They just happen. Usually after line twist. They have for me, all been solved by unstowing the brakes.

I watched a 200lb russian pull a rear riser to his chest trying to stop a turn and it did not. He chopped.

As far as how a twist gets there, aside from all the normal stuff, I think a bag can just spin now and then. I (try to) deploy in the same position everytime, but have had a handfull of occasions that I feel something is wrong when the bag leaves my back. Most of these have been sorted before the slider is down.

Sometimes shit happens.

Johnny
--"This ain't no book club, we're all gonna die!"
Mike Rome

[Hooknswoop 19]

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Unstowing the brakes puts the canopy in full flight. The canopy will stop the turn on its own in full flight. It's happened to me and I've seen it happen to others. Mostly highly loaded ellipticals. As was said, once an elliptical is put into a turn with the brakes set, it doesnt want to recover on its own.

If it is spinning with the brakes set, it will spin with the brakes released, all other things being equal. Think about it. Something is causing the canopy to turn, an unequal input, otherwise it would fly straight. The only way releasing the brakes will stop a spin is if one brake line is shorter than the other between the brake setting and the tail.

Derek

[johnny1488 1]

Something caused the canopy to start turning. Or it could be something causing the canopy to turn. If you start a turn with the brakes set and then stop the input, the canopy will continue to turn with no additional input. And in some cases opposite input might not be enough to stop the turn with the brakes still set. I have new elliptical jumpers try this up high because many have approached me about wild spins that do not stop with nothing visibly wrong with the canopy.

Start a turn up high the rear risers with the brakes set and then let go of the rears. Then after a few revolutions unstow the brakes and let them go. The turn will stop.

But this is not the answer if there is input ie un even harness or other factor.

Johnny
--"This ain't no book club, we're all gonna die!"
Mike Rome

[bob.dino 1]

Question: on a small, highly-loaded elliptical with the brakes set, is it possible that you don't have enough control range with your rear risers to stop a turn?

[Hooknswoop 19]

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Question: on a small, highly-loaded elliptical with the brakes set, is it possible that you don't have enough control range with your rear risers to stop a turn?

With my VX-60, I could make it fly straight with harness input with only one brake stowed. There is plenty of input from a rear riser to sto a spin.

Derek

[Hooknswoop 19]

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Something caused the canopy to start turning. Or it could be something causing the canopy to turn. If you start a turn with the brakes set and then stop the input, the canopy will continue to turn with no additional input. And in some cases opposite input might not be enough to stop the turn with the brakes still set. I have new elliptical jumpers try this up high because many have approached me about wild spins that do not stop with nothing visibly wrong with the canopy.

It is turning because of harness input. No input = no turn.

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Start a turn up high the rear risers with the brakes set and then let go of the rears. Then after a few revolutions unstow the brakes and let them go. The turn will stop.

Releasing the brakes alone doesn't stop a turn unless the brake lines are uneven.

Derek

[johnny1488 1]

It could have started turning because of harness input or uneven inflation or any number of things. Even if this things are neutralized (neutral or no input) an elliptical canopy in brakes will continue to turn. Putting the canopy in full flight (releasing the brakes) returns the canopy to straight and level flight as long as there are no inputs.

The long and short of what I am saying is the input that started the turn no longer has to be present for the turn to persist if the brakes are set.

As I also said this is only one in a long list of causes of spinning malfunctions.

Johnny
--"This ain't no book club, we're all gonna die!"
Mike Rome

[Hooknswoop 19]

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Even if this things are neutralized (neutral or no input) an elliptical canopy in brakes will continue to turn.

Why?

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Putting the canopy in full flight (releasing the brakes) returns the canopy to straight and level flight as long as there are no inputs.

How does releasing the brakes stop the turn?

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The long and short of what I am saying is the input that started the turn no longer has to be present for the turn to persist if the brakes are set.

What is causing the canopy to turn that releasing the brakes removes?

Derek

[johnny1488 1]

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Even if this things are neutralized (neutral or no input) an elliptical canopy in brakes will continue to turn.

Why?

I dont know

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How does releasing the brakes stop the turn?

All I can say about that is a canopy that is in trim flies straight with no input. Most elliptical canopies I have jumped have some degree of oversteer but always return to straight and level flight if you remove the input of a turn ( while in full flight .)

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What is causing the canopy to turn that releasing the brakes removes?

Again I am not sure. Its an eerie feeling having a canopy turn when you think you should be going straight. But I have only been able to do it when the brakes are set. Why it does it is beyond my realm of understanding for now.

Johnny
--"This ain't no book club, we're all gonna die!"
Mike Rome

[Hooknswoop 19]

Exactly, there is no reason it should. It is doing it because of harnes input. Releasing the brakes while countering the harness input with the toggles (doesn't take a lot) stops the turn and takes the "G" forces off the harness. It takes more harness input to start a turn than it doea to sustain it.

Derek

[johnny1488 1]

Saying there is no reason it should doesnt make it true, Derek.

I am pretty sure I know how to sit square in the harness. And I know I am not countering with the toggles when I release them. I pop them and let them go (for the tests I have done).

I will have a better answer for you tomorrow when I consult some people who might have an answer, but for now I ask that you trust me when I say I was giving no input and the canopy was not recovering. And I gave no input when I released the brakes and the canopy recovered.

I would like to take some belly mount footage of me doing this to look at the canopy. The 3 rings will be in the shot for reference of harness input.

But that is a few days away.

Johnny
--"This ain't no book club, we're all gonna die!"
Mike Rome

[Hooknswoop 19]

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I would like to take some belly mount footage of me doing this to look at the canopy. The 3 rings will be in the shot for reference of harness input.

Even with the 3-rings even, you can still have more weight on one side than the other. If everything was even, it would fly straight.

Derek

[jumperconway 0]

Again I am not sure. Its an eerie feeling having a canopy turn when you think you should be going straight. But I have only been able to do it when the brakes are set. Why it does it is beyond my realm of understanding for now.

The only reason a canopy will turn is because of uneven input period if the canopy is in trim or a brake fire short of a line over or tension knots! The turn can be harness via uneven leg straps(harness turn) with a good canopy overhead Been spun up on my back on a highly loaded eliptical(2.4+) watched the lines and kicked out successfully.

[bob.dino 1]

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If everything was even, it would fly straight.

Given that many hp canopies exhibit oversteer to some degree, is it possible that those characteristics are exaggerated when the canopy is flying with brakes set?

In other words, is it possible that some asymmetry causes the turn to start, but once everything is symmetrical, the canopy could continue turning?

[Hooknswoop 19]

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Given that many hp canopies exhibit oversteer to some degree, is it possible that those characteristics are exaggerated when the canopy is flying with brakes set?

Even if it did, the canopy would still recover. Without some aerodynamic force making it turn, a canopy will fly straight. Oversteer is just how long after everything is equalized it takes for the canopy to come out of the turn.

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In other words, is it possible that some asymmetry causes the turn to start, but once everything is symmetrical, the canopy could continue turning?

If everything was even, weight, lines, risers, etc, then the canopy would recover to straight and level. Without something causing a turn, it doesn't turn. Even if the pilot isn't aware of more weight going though one set of risers than the other doesn't mean that it isn't happening.

Derek

[bob.dino 1]

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If everything was even, weight, lines, risers, etc, then the canopy would recover to straight and level.

So all parachutes are positively stable in the roll axis when flown in deployment brakes?

All your points make sense. I'm just attempting to tease all this out in my head, as I've no intention of borrowing a Velo or VX to test this stuff out for real...

[Hooknswoop 19]

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So all parachutes are positively stable in the roll axis when flown in deployment brakes?

Yes.

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All your points make sense. I'm just attempting to tease all this out in my head, as I've no intention of borrowing a Velo or VX to test this stuff out for real...

Stilettos are a good canopy for this type of testing.

Derek