Differences in bailout technique from comp wings to others

[TommyBotten 0]

For the last six months I've been trying out various competition canopies to much enjoyment. One thing that surprised me is the feeling that bailing on rear risers actually gives more response than stabbing out on toggles.

On the hybrid VK and Airwolf it seems to be somewhat more efficient to use rear risers, whereas on the HK/JPX/PI it feels much more efficient. Could this be the case, or am I way off base here?

I kept testing this up high for multiple jumps, and while I am aware of the potential for high speed stalls, my impressions is that it is very hard to trigger on these canopies.

I've also discussed it with various other CP pilots and coaches, but there doesn't seem to be a consensus. Any insight and experiences are very much welcome.

Do note that my tests were conducted up top after an initiated turn.

[jacketsdb23 45]

I can't imagine a true bail situation close to the ground where risers are the answer over toggles.

A true stab out on toggles has got to be more efficient at getting your body under the canopy. I guess I could be proven wrong.

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[timrf79 0]

Can someone explain to me the theory in regard to bailing on rears?

[TommyBotten 0]

Toggles are more efficient in a bail out scenario as the toggle input rapidly slows down the canopy and puts the pilot (thus the suspended weight) in front of the canopy, leading to a sharp increase in angle of attack.

Rear risers are usually more gradual, as it does not swing you in front of the canopy as toggle input does.

[skow 6]

TommyBotten

Toggles are more efficient in a bail out scenario as the toggle input rapidly slows down the canopy and puts the pilot (thus the suspended weight) in front of the canopy, leading to a sharp increase in angle of attack.

Rear risers are usually more gradual, as it does not swing you in front of the canopy as toggle input does.

I cannot really agree with it. Toggles give you much slower change in angle of attack and that's why the canopy doesn't stall when you stab them.

"Stabbing" on rears changes your AoA very dramatically and that's why the canopy may stall even if you fly 100 mph.

[Pobrause 6]

I have to agree, AoA is not the correct term when talking about stabbing out of a turn with toggles. Change in trajectory would be better.

Of course one can expect full sail modern wings to perform better and more stable even when close to a stall on rears. They are build with a much more stable material and aerodynamic shape.
But as skow pointed out, you can only change the AoA with rears so much before even they stall. Of course it takes more force as they fly faster and hold their shape better but eventually they will stall.

The thing with toggles is, when in a turn you can't stall your canopy, no matter how much force you apply. If you feel, the change in trajetory is weaker with toggles than on rears just apply more pressure on the stopping strings.

From an aerodynamik point of view it also makes no sense in trusting your rears vs toggles.
The smoother the airflow on most parts of your wing, the better your inputs will be converted into a reaction.
And close to a stall on rears there is not much airflow left attached to the canopy and thus can't support your inputs.
Brakes (or flaps for that matter) however don't disturb the airflow on the majority of your wings surface area, slowing down the canopy much more efficiently, swinging you forward like a pendulum and changing your trajectory in the process much faster and more reliably/ safer than rears.

Or at least that is how I imagine aerodynamics to work, I've been wrong before...

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[TommyBotten 0]

Pobrause

I have to agree, AoA is not the correct term when talking about stabbing out of a turn with toggles. Change in trajectory would be better.

But does not the change of trajectory come from the change in AoA? As far as I have come to understand, most of the resulting trajectory change comes from your rears being "pulled down" as a result of you (the suspended weight) being put in front of your canopy, not the exposed fabric/brakes.

Pobrause

Of course one can expect full sail modern wings to perform better and more stable even when close to a stall on rears. They are build with a much more stable material and aerodynamic shape.
But as skow pointed out, you can only change the AoA with rears so much before even they stall. Of course it takes more force as they fly faster and hold their shape better but eventually they will stall.

The thing with toggles is, when in a turn you can't stall your canopy, no matter how much force you apply. If you feel, the change in trajetory is weaker with toggles than on rears just apply more pressure on the stopping strings.

I totally agree on the premise that any wing will stall given enough change in AoA. But what my feeling was/is, and what I somewhat hope to be wrong about, is the efficiency of either input on given wings under given circumstances will vary.

The only thing I can offer here is my own experience on these wings that points to two things:
* Toggle input, even when given sharply has a small delay (~ 0.5 seconds) before really kicking in.
* Sharp inputs on rears _seems_ to give more G-forces (i.e. experienced squeeze into the harness)

Pobrause

From an aerodynamik point of view it also makes no sense in trusting your rears vs toggles.
The smoother the airflow on most parts of your wing, the better your inputs will be converted into a reaction.
And close to a stall on rears there is not much airflow left attached to the canopy and thus can't support your inputs.
Brakes (or flaps for that matter) however don't disturb the airflow on the majority of your wings surface area, slowing down the canopy much more efficiently, swinging you forward like a pendulum and changing your trajectory in the process much faster and more reliably/ safer than rears.

Or at least that is how I imagine aerodynamics to work, I've been wrong before...

I don't know enough about aerodynamics to have a meaningful discussion about this, but I would like to restate that the rear riser input I've mentioned above is quite far from the stall point.

Thank you both for your insight into this.

[skow 6]

TommyBotten

But does not the change of trajectory come from the change in AoA?

Yes, but still those are completely different things. E.g with enough speed and good flare you can change your trajectory e.g. from going 45 degrees down to 45 degrees up (in respect to horrizon). So the change in trajectory is 90 degrees, but change in AoA is very little.

In any case, wing stalls if the AoA is too high - i.e. angle between the wing chord (trim) line and relative wind, no matter the speed. And with risers this change is much more dramatic than with toggles - which always makes toggles the safer option

TommyBotten

The only thing I can offer here is my own experience on these wings that points to two things:
* Toggle input, even when given sharply has a small delay (~ 0.5 seconds) before really kicking in.

Well of course. You have to rememeber you are flying in an airmass, not in rollercoaster car on rails. With high speeds (lots of inertia) you'll experience "drift" before the canopy changes its pitch, especially with sharp stab.
Imagine you are skiing fast down the slope. You won't just turn 60 degrees to the side if you aggressively lean, but the skis will slide before turn.
And if you just turn your feet and skis 90 degrees to the side, you won't turn at all, just keep sliding down the hill in uncontrollable matter (so kind of stall) - which is the same as puling the risers - you turn the whole canopy radically against the relative wind increasing AoA very drastically

This is why those wings are not for beginners but experienced jumpers who know what they are capable of

[skow 6]

TommyBotten

* Sharp inputs on rears _seems_ to give more G-forces (i.e. experienced squeeze into the harness)

Next time you're driving in a car on a motorway, put your hand out of the window and position it flat (parallel to the ground). Now AoA is zero. Now quite fast turn your palm so it's 30-35 degrees up. You'll feel pressure on your wrist (and your hand lifting up).

Now go back to flat position and turn it fast so it's 90 degrees up in respect to the ground. The pressure on your wrist is much higher then previously. But how much did it go up?
This is because AoA is much higher and more air is hitting your palm.

[ChrisHoward 8]

jacketsdb23

I can't imagine a true bail situation close to the ground where risers are the answer over toggles.

This is the correct answer. If you are "bailing out" in a true emergency situation then you should be using toggles. Toggles will provide more lift, arrest the dive faster and slow down your forward speed better. All while providing you with more control over a larger range with less chance of stalling.

[raymod2 1]

Have you collected any GPS data to test your observations?

[TommyBotten 0]

I'm currently doing that, and I'll post my findings when I have a big enough dataset.