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SRI85

Why are airlocks not popular?

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Ive been looking into airlocked canopies lately. 1 person at my DZ jumps it and swears by it. I rarely see anyone else flying an airlocked canopy though? Why is this? the airlock idea seems like a good idea to me,and i havent been able to find to much to negatives on them.

Thoughts?

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JP I'll argue that with you all day. I've got almost 1000 airlock jumps and I can count about 6-10 bad openings and the worst of them was a massive line twist issue that lead to a cutaway. I've had about 4-5 hard openings but for the most part my canopies open like a Stiletto or Sabre2.
Yesterday is history
And tomorrow is a mystery

Parachutemanuals.com

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Paraglider designs pioneered the airlock many years ago and abandoned it. The performance and safety gains were a two way street and in the end did not do much of anything. except make the canopy harder to pack and deflate after a flight.

downsides are pack volume and glider weight, (in PG and parachute) inability to deflate quickly in windy situations, (much more an issue in PG). With the airlocks taking up space on the ram air intakes, inflation time was increased and in some cases internal pressure was limited even though it was retained from the airlock.

One idea behind the airlock is it reduce the likelihood of collapse by maintaining internal pressure in the event of an airflow anomaly(turbulence, control input, etc) and thus reducing likelihood of altitude loss and more importantly heading change from a collapse. Turns out the airlock does the opposite in a lot of collapse cases. The retained internal pressure "locks" the canopy in a twisted/deformed shape as opposed to folding and re-inflating without airlocks.

-SPACE-

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(former airlock owner)

The main advantage is that they are more difficult to collapse.
That is considered a safety advantage.

If there was a style of canopy that collapsed a lot, they
would not be in business long. So, most canopies are
reasonably safe about this (except if you are flying in 25mph rotors - you can't fix stupid).
The major advantage is not a huge problem among other canopies.

The disadvantage is that in a 10mph wind, you can't easily walk back to the packing mat because they stay
inflated unless you wrestle with them.

Personal experience - I consistently had my softest openings in the approx 700 jumps.

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Why is this?



While an airlocked canopy has advantages... The advantages an airlock offers are also somewhat answered by other designs.

The primary benefit of an airlocked canopy is it is supposed to stay inflated in turbulence. OK, but most modern canopys do not really suffer from this, and the Xbraced designs also offer extra rigidity.

They can be a PITA to get the air out of to pack. But the major issue has been with the marketing side....

At first these were only being built by Tony and while they were a passion of his, the jump suit business was priority.

Brian rightfully held the patent, so other makers were not able to work on the design.

When Brian sold the rights to PD, Xbraced canopys were the rage and offered many of the same benefits. Many feel that PD's release of the Vengeance was timed too late to capture any market and that the release was only halfheartedly done... In fact, I challenge you to find it on the website (They have it... Just try to find it).

Nothing wrong with the canopy.... Heck, I jumped a Jedi 95 that was amazing. But not really any better than Velo 96 (about the same time I had an FX88)

In the end it was a great idea that due to distribution issues and marketing never really took off and other designs offered solutions to the problems it was designed to fix
"No free man shall ever be debarred the use of arms." -- Thomas Jefferson, Thomas Jefferson Papers, 334

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The last half of my jumps (about 800) are on a 150 size air lock canopy. A few hard openings after a new line set were fixed by the addition of a pocket sewn into the slider to catch more air and thus slow the opening.

Chopped it once out of 800 which was the first jump on a new container.

This canopy does it all for me. The positives heavily outweigh any negatives.


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In most conditions, normal canopies don't collapse, and neither do airlocked canopies.

In really extreme conditions, both will collapse.

Airlocked canopies can be better in between. But that's such a narrow range of situations, that skydivers haven't in the end found it worthwhile to buy them. Or to buy them from the particular companies who held or licensed the patent.

So if weather conditions were too nasty to jump in, they were too nasty for everyone. Did airlocks save a few people from a major injury? They may well have, but I guess it was just too hard to tell to create much demand.

Keeping the canopy from breathing as much in normal turbulence will improve efficiency, but again it wasn't enough to make people stick with them.

When it comes to collapses, the big thing is angle of attack. If the angle of attack gets too low, too negative, there's too much pressure on the top of the nose compared to that inflating it from inside, and the nose will fold down.

Airlocks will slow air from getting out, but if the angle of attack is wrong for a normal canopy, it is wrong for an airlocked canopy too, and the nose will fold.

So airlocks don't magically stop collapses as some tended to think, but they should slow them down and so reduce the severity of brief collapses.

If a wingtip folds and stays more pressurized as with airlocks, that creates a worse problem, as you now have a more solid draggy surface pulling you into a spiral dive.

So if it wasn't a small collapse that was lessened by airlocks (=good), but it went so far as a big collapse, then airlocks can make things worse.

On heading openings might tend to suffer a little from airlocks. Maybe some designs were fine, but the couple local guys with Vengeance's are the ones who are seen to snap into 360 degree spirals right on opening... [Edit: ...and someone asks, "Did that guy pop a toggle?" "No, don't worry, it's just a Vengeance."]

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The positives heavily outweigh any negatives.



What do you see as the positives?

Do you not feel those are solved by other designs?
"No free man shall ever be debarred the use of arms." -- Thomas Jefferson, Thomas Jefferson Papers, 334

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They open like poop.



Hogwash. Samurais open better than Crossfires, Specters, Stilettos, Safires, Omegas, FXes, and the myriad of square canopies which preceded them.

They stay on heading, open uniformly, open soft, and don't take so long to open that you want to pull at student altitudes so you have enough time to fly back to the dropzone and setup for a swoop.

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And that's just not a big enough trade off for the expense, complexity, and limited designs available.



I paid about the same $1600 I would have for a new Crossfire (or another Stiletto, PD didn't have the Katana yet) and there are just nine more pieces of fabric that might increase pack volume 5%.

Availability is a problem, the both Samurai and Lotus are discontinued.

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Which type of canopy gets chopped more often? Air lock or a cross brace?



Personally, I think other design factors play a bigger role than airlocked or not when it comes to chops. Aspect ratio, airfoil, line trim... etc.
"No free man shall ever be debarred the use of arms." -- Thomas Jefferson, Thomas Jefferson Papers, 334

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I've been saved by a small wind sheer situation. I always make it back to the dz when other don't. I can get thermal lift when others can't. It flies slow or fast and has amazing flare power.

Oh and it's cool when you land and deflate it. The air inside is so cold. Maybe the dense air inflation helps some too.:P

But serious question: Do air locks get cut away more often than cross braced canopies? I'm just wondering what you guys think about which type opens better on average.

I'm a weekend fun jumper. I don't claim to know much.


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They can be a PITA to get the air out of to pack.



In low wind situations, you land them on their side and they fold up like an accordion just like any other canopy.

In high wind situations, you land them on their nose, float them on the top skin, and run the slider up.

A few yanks on the tail get enough air out that it's not appreciably different from any other ZP canopy when you're packing. It takes me the same 6-7 minutes to pack my Samurai, Stiletto, Monarch....

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In the end it was a great idea that due to distribution issues and marketing never really took off and other designs offered solutions to the problems it was designed to fix



Right.

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I've been saved by a small wind sheer situation.



Do you think that you were saved only by airlocks? It is the reason they were designed. But do you not think that a Xbraced might also have been fine?

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I always make it back to the dz when other don't



I found the same sized Vengeance to not float as well as the same sized Stiletto. But glide angle is often a factor of line trim, not just airlocked or not.

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I can get thermal lift when others can't. It flies slow or fast and has amazing flare power.



Again, you think that an xbraced would not have the same ability?

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But serious question: Do air locks get cut away more often than cross braced canopies? I'm just wondering what you guys think about which type opens better on average



I think other factors play a bigger role than airlocked or not.

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I'm a weekend fun jumper. I don't claim to know much.



In this case, you know more than me (I have maybe 100 airlocked jumps)... thats why I am asking you questions.
"No free man shall ever be debarred the use of arms." -- Thomas Jefferson, Thomas Jefferson Papers, 334

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But serious question: Do air locks get cut away more often than cross braced canopies? I'm just wondering what you guys think about which type opens better on average.
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In addition to the responses already given I'd guess that the average x-brace is flown at a higher wingload than the average airlock. I'd also guess that the chop numbers increase with wingloading.

I can't imagine airlocks improving x-brace performance in any way. Since such an animal doesn't exist the implication is that manufacturers don't see a reason to build one. I think you may be looking for a solution to a nonexistant problem.

Sometimes you eat the bear..............

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I had my first cut away with an airlock canopy it was my jump number 10 with the canopy, I'm guessing was a line twist that keep my chin to my chest so i could not even see the canopy, mind the aggressive turns I was in. After I cut away I saw the canopy flying towards the sebastian Inlet still inflated Never saw that canopy again needless to say I lost the canopy or any desire to fly another airlock canopy, I do know people who loves their airlock canopy tho! They say bad things about the velo but I'm still yet to see a bad opening or a cut away with mine knock on wood
http://web.mac.com/ac057a/iWeb/AC057A/H0M3.html

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