Airlocks & Turb.

[agitator 0]

Hey, I have a quick query re airlocked canopies:
What is the common wisdom/experience regarding airlocks and turbulence? Is there any credence to the theory that the airlocks make canopies less susceptible to collapse, etc. in bumpy air. I can see how it might, but then it may seem like it wouldn't make diff.
I am contemplating an airlock canopy. I need to figure out if the extra pain in the ass brought on by trying to collapse the thing after landing is offset by any kind of warm and fuzzy while hooking through turbulence.....

thanks!!!!!!!

[PhreeZone 15]

Don't buy a canopy just for the airlock... buy it because you like how it flies. If the turbulence is bad enough any canopy will collapse. Do I think Airlocks work? Yes to a point. In light turbulence they felt great, but so do most canopies. If the conditions are to the point that canopies are collapsing I won't be jumping anyways...

And they are'nt that hard to pack if you look on Big Air Sportz site they give tips that work.

Yesterday is history
And tomorrow is a mystery

Parachutemanuals.com

[freeflyswc 0]

Airlocked canopied do have less of a chance of collapse in turbulent/bumpy winds , but no canopy is invincible . I've flown a few airlocked canopies , and diddn't like them they dont breath at all , so you feel every little bump in the air . It feels kinda like riding in a car w/ no shocks on a bumpy road.

[freeflyswc 0]

also , say your going to be hooking through turbulence where a conventional canopy might breat a little in your dive or in your swoop , an airlock will drop you a couple feet in some cases

[cobaltdan 0]

there is absolutely no evidence of increased stability in turbulence by the addition of airlocks.

airlocks were first devised for use on parachutes more than 30 years ago, and then later paragliders. in the more technically advanced paraglider industry airlocks never made it into commercial production as scientific tests failed to show bennifit. there are many patents worldwide for canopy airlocks in addition to the familiar brian g. design, all basically the same in principal.

this is definately a richly debated topic by jumpers, but fact remains that there have been decades of various studies and no proof at all of increased preformance or decreased tendency to collapse in turbulence. (and i'm sure not one independent jumper advocating the bennifits of airlocks has jumped the same design canopy with and without airlocks, in order to perform even the most basic of studies from which to form their opinion).

a search on this forum will turn up everybody's point of view.

my position: choose to jump an airlock design if you like its flying characteristics, do not fly one because you believe it will save your butt over a non airlocked design in the event of turbulence. do not have a false sence of security.

(btw before anyone points a finger calling me biased because i manufacture non-airlocked canopies. know that i have manufactured and tested airlocked cobalts and that 2 airlock patents are held by one of atair's canopy engineers.)

sincerely,

dan<><>
atair aerodynamics
www.extremefly.com

Daniel Preston <><>
atairaerodynamics.com (sport)
atairaerospace.com (military)

[billvon 2,435]

>What is the common wisdom/experience regarding airlocks and
> turbulence?

I have noticed they make a slight difference. It is not significant enough to choose one canopy over another unless everything else is exactly equal.

>Is there any credence to the theory that the airlocks make canopies
> less susceptible to collapse, etc. in bumpy air.

As I've stated before, I think this has more to do with the effective cross-bracing of the nose from the airlock than any sort of "pressurization" effect.

>I need to figure out if the extra pain in the ass brought on by trying
>to collapse the thing after landing . . .

I don't have much more trouble collapsing airlocked canopies. It's easier to collapse a Samurai 136 than a Sabre 170 in wind.

[agitator 0]

awesome. thanks for the input folks. anyone else got any comment?

[wonko 0]

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thanks for the input folks. anyone else got any comment?

umm... this topic just reminded me how my teammate broke his femur 2 months ago. The canopy (sabre150) did not collapse. It just lost all the lift at 10ft or so and jumper came down like a stone. It was a hot slightly turbulent day and nobody knows exactly was it about a wind-shift, sudden gust (rotor) from above or what.
So there is always a shit waiting to happen, no matter what gear we fly ... be prepared.

villem
life is what you make it to be
http://www.youtube.com/villu357
http://www.flickr.com/photos/skybound

[flipper 0]

Hi

do some jumps on the a/locked chutes and see if you like them ...plain and simple.

i dont think for a minute that they will offer any more protection against turbulence than a normal chute

my exp. of them is about 30 jumps on a Veng. 107 and 5/6 on my new Veng. 120

it opens and flys really well, because there fairly solid compared to my stiletto 120 you can feel little bumps of turb. more

as for colapsing the chute after landing...i havnt had a hassle with it, even in higher winds

flipper

[alan 1]

Dan, you also used to claim (and still do) that your non-cross braced canopy (Cobalt) was (is) the superior choice to over the popular cross braced canopies. Yet, cross bracing seems to found its way into your line of canopies, such as the competition cobalt with the cross braced nose....where it really counts. Your Onyx also utilizes cross bracing.

alan

[alan 1]

Quote

say your going to be hooking through turbulence where a conventional canopy might breat a little in your dive or in your swoop , an airlock will drop you a couple feet in some cases

When the conventional canopy breaths, that implies that it "exhales". During the exhale, the canopy is less pressurized and therefore more distorted and less efficient, providing less lift. In addition to that, during the exhale the canopy "accordians" in, giving it less wing span (effectively giving you less wing area) and also adding more curveature to the top skins between the ribs, which increases the vectored lift component and decreases the vertical lift component. What this means is that you have it backwards. The conventional canopy will be less efficient in turbulence and be more likely to drop you a few feet more than the airlocked canopy.

alan

[Samurai136 0]

I've jumped my Samurai in winds of 25mph, not gusting.
There is significant turbulence at SD Iowa in these wind conditions about 40'agl from a tree line. The airlocks will keep air in the canopy and maintain some form of wing over your head as opposed to total depressurization. At altitude I've pulled rear risers to my shoulders and still had a pressurized canopy over head. The canopy loses forward drive and begins to gently sink. non-airlocked canopies will go back to a snivel.

Once I hit a small rotor in the middle of my flare, which dropped me 5' to the ground and put a grass stain on my jump suit.

Based on observation of other non airlocked parachutes in these conditions, I believe I'm safer w/ airlocks than w/out. Airlocks do not make it SAFE to jump in windy turbulent conditions.

Demo an airlocked canopy and judge for your self.

Ken

"Buttons aren't toys." - Trillian
Ken

[ramon 0]

I have a vengeance 135, FX 109 and VX 97.

This is probably contrary to common thinking but I have been dropped on my ass by the fX and the vX in bumpy wind but never the vengeance. maybe it has the ability to flare better if I am below full flight (due to braked turns or 1/4 brake flight) because it has more material. I really don't know. Could be just coincidence and I am due to get dropped on the vengeance one of these days

I do like all 3 canopies, but I don't want to jump any non-cross braced in gusty wind other than my vengeance or a competition cobalt (jumped Eric Butz's 120 it wa really neat).
s
ramon

"Revolution is an abrupt change in the form of misgovernment.", Ambrose Bierce.

[SkyMissy 0]

I really dig my Vengeance for the way it flies. Just my .02, never noticed a difference in turbulence, but never been dropped either.

Peace!

________________________________________________
Mike

[bobsoutar 0]

Haven't jumped an airlock canopy. I switched from a Stilletto to an Icarus FX (tri-braced) and hardly notice turbulence any more.
Profile says you are a D licence but I wouldn't recommend you go tri-braced (or X-braced) unless you are prepared to be agressive under canopy (you have to fly them in pretty hard for landing) and have a load of experience under heavily loaded elipticals.

[alan 1]

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Profile says you are a D licence but I wouldn't recommend you go tri-braced (or X-braced) unless you are prepared to be agressive under canopy (you have to fly them in pretty hard for landing) and have a load of experience under heavily loaded elipticals

I've flown an FX, VX, Modified VX, Velocity and Xaos -27 all at wing loadings from about 2.0 to 2.5 in variety of conditions, including hot days with light and variable winds. I've been able to land them all nicely doing a simple straight in approach. I'm curious as to what you mean by "fly them in pretty hard for landing". I agree, you should have a load of experience under heavily loaded ellipticals before attempting to fly one. I think a pilot with enough experience to fly one should be able to land it on an easy straight in approach. If you can do that, then move on to high performance approaches. All the aggressive approach does is lengthen the surf, the landing is the same.

alan

[ramon 0]

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I've flown an FX, VX, Modified VX, Velocity and Xaos -27

What is a modified VX? hmmm....

"Revolution is an abrupt change in the form of misgovernment.", Ambrose Bierce.

[PhreeZone 15]

VX with the Xaos trim, hma lines and I think even the staliribs.

Yesterday is history
And tomorrow is a mystery

Parachutemanuals.com

[ramon 0]

ohh just one of those?

I was hoping it was something radical or new from Icarus not an 'x-VX'.

"Revolution is an abrupt change in the form of misgovernment.", Ambrose Bierce.

[bobsoutar 0]

Fully agree. I meant that you can't afford to be timid. If brakes are applied too close to the ground you lose air speed and in turbulence with a high wing loading the canopy may drop you.

[alan 1]

Quote

ohh just one of those?

Have you flown one yet? I noticed what I consider to be a significant improvement in performance on my VX after the mod, most notably better openings, stronger flare and better glide. Don't use the factory toggle settings though, I had to add about 5". I have no idea where they come up with the facory marks, but no experienced high performance canopy pilot who uses front riser turns would use them. The initial price of the mod seems high, but when you take into account the increased life span of the HMA lines over vectran, it is actually economical. The added performance is a real bonus......of course performance is pretty subjective.

alan

[alan 1]

Yes, years ago brakes in turbulence was generally the accepted advice. May have even had some degree of validity on the canopy designs that were prevalent at the time, but with todays canopies, brakes is bad advice. When there is mechanical turbulence on my DZ, I usually choose a crosswind approach and fly though it with as much speed as possible. You may still have to deal with it at the end, but with a little planning, I am usually in a relatively calm area at this point. seems to work for me.

alan

[franck102 0]

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Yes, years ago brakes in turbulence was generally the accepted advice. May have even had some degree of validity on the canopy designs that were prevalent at the time, but with todays canopies, brakes is bad advice. When there is mechanical turbulence on my DZ, I usually choose a crosswind approach and fly though it with as much speed as possible. You may still have to deal with it at the end, but with a little planning, I am usually in a relatively calm area at this point. seems to work for me.

The benefit of using a bit of brake in turbulence is to put your angle of attack in the middle of the range that is acceptable for your canopy.
With a canopy designed to keep flying when you pull hard on both front risers you may not need any brakes, but if the leading edge tends to tuck under when you do this you should really consider applying some brakes in strong turbulence.
Turbulence is really good at creating large shifts in the angle of attack and if you happen to already be at one of the extremes things will get interesting real fast...
Franck

[billvon 2,435]

>but with todays canopies, brakes is bad advice.

Flying in 1/4 to 1/2 brakes does three things. It reduces the forward speed of the canopy, which reduces pressurization. It puts the canopy in a better position to recover if it does collapse. It reduces your speed so that if you do have a collapse near the ground, your impact speed is less.

Larger canopies can be more prone to turbulence than smaller canopies, yet people tend to get injured far more often under small canopies in turbulence. This is because, when you're landing a 2:1 canopy, everything has to work perfectly. A 2 foot dip at 30mph and you have two broken legs, whereas the same dip on a Triathalon 190 will just get you a bit dusty. Another way to look at this is that, if you can fly your approach a little more slowly (i.e. in slight brakes) the odds of bad turbulence causing you serious injury may be reduced.

Nothing can keep turbulence from collapsing your canopy if it's strong enough. Flying at full speed through turbulence may help keep it inflated if the turbulence is weak enough; flying in 1/4 to 1/2 brakes may help you survive a bad incidence of turbulence.

[franck102 0]

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Nothing can keep turbulence from collapsing your canopy if it's strong enough. Flying at full speed through turbulence may help keep it inflated if the turbulence is weak enough; flying in 1/4 to 1/2 brakes may help you survive a bad incidence of turbulence.

All good points, although you do control how easy it will be for a given turbulence to collapse your canopy.
The pressure in the cells isn't the issue here, the angle of attack is. At one end of the spectrum your canopy will collapse if the angle of attack becomes too shallow to keep the cells inflated, but a perfectly airlocked canopy in the same situation would simply stop generating lift, surge forward and probably slam you into the ground even harder than the collapsed canopy.
There is most definitely a best strategy to fly through turbulence with a given canopy, just spend some time watching different pilots flying the same paragliders in severe turbulence.
By applying some brakes, you indeed slow down which makes you angle of attack more sensitive to a given variation in the relative wind, but you also increase you angle of attack (on a typical canopy that is), taking it farther away from the extreme at which you canopy will stop flying, and this is I think by far the overriding factor on most canopies.
As a practical hint if you can apply a bit of brake and you don't feel you significantly slowed down, but you fell your glide ratio increased significantly, your angle of attack probably just increased as well. At some point the slowing down becomes obvious and the glide ratio starts degrading, this is when you are getting closer to the other end of the spectrum, your angle of attack is high and any turbulence may suddenly increase it enough to stall the canopy.
You can get hints at what your angle of attack is doing by watching the top front of you canopy's leading edge, but this is subtle and varies from canopy to canopy.
Disclaimer: I used to fly paragliders, not canopies designed to keep flying even if you hang your whole weight on both front risers. Those canopies may fly at a safely high angle of attack even without brakes; but be sure of one thing, if turbulence collapses it, that is because the change in relative wind moved the angle the attack out of the flying range, and you may have prevented it by flying differently to start with.
Franck