Anatomy of a "spinner".

[johnny1488 1]

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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.

It's not that the brake lines are uneven or even causing the turn.

A turn was caused with the brakes set. The brakes and harness can be totally even. From the best that I can find, the inertia of the turn is overcoming the canopies ability to return to straight and level flight because of the lower airspeed and less area of the canopy creating lift. (Perhaps its from a higher angle of attack from the brakes/flaps being pulled down, but I don't know) Releasing the brakes increases the airspeed and allows the canopy overcome the inertia of the turn.

Know that this is not causing a turn, it is keeping the canopy from straight and level flight because some outside factor caused a turn.

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

[Hooknswoop 19]

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I've heard this is common but since you're a rigger I'd like your opinion. Thanks!

I'm in over my head on this one

Derek

[davelepka 4]

I think this thread is getting out of hand. There seems to be several slightly different issues being discussed at the same time.

I'm really not sure if any of them are even worth the time we're putting into them. I'm pretty sure that everyone is right in some way, pretaining to their own topic, of course.

What I will say is this: If anyone out there has some confusion about any of the topics, locate who is supporting your issue, and PM them with specific questions. Then take what they tell you, and run it by some senior jumpers at your DZ, then take it all with a grain of salt.

None of this stuff is life threatening anyway. In the end, pulling the red handle will put all of these arguements to rest (unless you have a reserve mal, in which case, get tough, it's probably going to hurt).

[kevinwhelan 0]

Could the turn be caused by the outside side of the spining canopy generating more lift because it has a higher airspeed?
Just wondering?

"be honest with yourself. Why do I want to go smaller? It is not going to make my penis longer." ~Brian Germain, on downsizing

[velvetjo 0]

Just a couple of thoughts on the idea of releasing the brakes being helpful:

- releasing brakes decreases the AOA of the entire wing

- line twists would initially induce a "turn"; "spin" is generally reserved in aeronautics for a condition where at least part of the wing is stalled

- if the initial turn induced by the line twists evolved into a higher-speed event with increasing load factor, there's a pretty good chance that at some point the "turn" changes into a "spin" because of an accelerated stall of part of the wing

- so, if part of the wing is now in an accelerated stall (see definition below), wouldn't reducing the AOA (releasing brakes) help with recovery? this seems analogous to neutralizing the controls in a light A/C

- remember that we don't have rudder to consider with a parachute wing - releasing brakes is mostly like the elevator, since the ailerons (brakes) are effectively at the same setting (think flaperons)

- if the wing recovered from the accelerated stall in this manner, it seems like it would seek a stable (non-turning) condition because of its design characteristics

Again, just some thoughts about what might be going on here.

Lance

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Definition from Answers.com:

Accelerated Stalls

A type of stall that is related to the ordinary stall is the so-called Accelerated stall. This is a condition where the wing cannot produce enough lift to support the aircraft's weight and centrifugal force, in spite of otherwise flying at a reasonable airspeed and angle of attack. This can occur when an aircraft is in a tight turn, a high-G pullup, or other manoeuvre where directions is changed with a significant amount of acceleration. This additional acceleration results in a high force that must be borne by the wings. In recent years there have been a number of accidents arising from Accelerated stalls in high-performance aircraft (e.g. the Jet Provost) that have been sold into the civilian sector from the military. Turbulence can cause an accelerated stall if the aircraft is flying below Vno (maximum structural cruising speed. If flying above Vno, turbulence can cause structural failure.

Note that all manoeuvres increase g to some extent - a 60° bank level turn will produce 2g, which will raise the stalling speed by 1.4142 times, or 41%. Quoted aircraft stalling speeds must be taken as the 1g stalling speed (i.e. straight and level flight).

[BrianSGermain 1]

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

I was asked to comment on this issue.

Yes, it is true that eliptical parachutes tend to turn on their own when the brakes are stowed. This is due to the increased horizontal component of lift while the canopy is locked in brakes. The lift vector is on an angle to the horizon, and therefore can create a self-sustaining turn. Releasing the brakes will usually stop the turn, although opposite rear riser is often the way to go as it allow the jumper to pull the slider down once the turn is stopped.

Hope this helps.
+

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[Hooknswoop 19]

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Hope this helps.

A lot, thanks Brian.

Derek