Oct 25, 2004, 9:56 PM
Post #1 of 12
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CReW and airlocks
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Not a CReW dog, or even puppy, yet, but its a discipline I want to get into. I was thinking about equipment and wondered why there aren't any airlocked crew canopies. Are there even any square airlocked canopies out there? Wouldn't their greater ability to stay inflated make them less likely to collapse/wrap? What am I missing here?
I don't think I've put two and two together before any of the thousands of skydivers before me, just that I can learn something from the answer. Thanks.
(This post was edited by ahegeman on Oct 25, 2004, 9:57 PM)
About a year ago I asked somebody this same question. The answer I got was that while the airlocks would help make a collapse less likely, they would also make a canopy less likely to reinflate following a wrap / collapse.
I don't have any personal experience with --and have very little knowledge of-- airlocks, so I can't offer any educated opinion on this, but for what it's worth, that is the answer I received and it came from a very experienced and well known CReWDog.
The answer I got was that while the airlocks would help make a collapse less likely, they would also make a canopy less likely to reinflate following a wrap / collapse.
About a year ago I asked somebody this same question. The answer I got was that while the airlocks would help make a collapse less likely, they would also make a canopy less likely to reinflate following a wrap / collapse.
I don't have any personal experience with --and have very little knowledge of-- airlocks, so I can't offer any educated opinion on this, but for what it's worth, that is the answer I received and it came from a very experienced and well known CReWDog.
Stay safe, Mike
I've heard that also and I always wonder where extensive airlock CRW has been done to support that conclusion
Michael
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Oct 25, 2004, 11:17 PM
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Ask Brian about his Shogun canopy project. If it ever gets finished and released it would be fun to try and do CRW with it. I've taken (and given) hard docks with my Airlocked canopies and they bounced off people like rigid wings.
I don't get the "would'nt reinflate" part, its a canopy, as long as air goes in the nose it wil reopen right?
In my younger days, I used to do a lot of CRW with the Jedei I owned at the time. It was definitely extremely solid in CRW formations - my 92 would be stable as a rock in a dock with a 250 sq ft 7-cell - even more so than a Lightning - and I think that was because of the rigiditity of the airlocks.
I hounded Brian for a lot of years to send me a 7-cell airlocked canopy to play with but he never did. I'm not sure I'm buying the won't reinflate though - they open as consistently as any other parachute. It might take a tad longer perhaps - but unless its 50 feet off of the deck its not an issue.
I was quite impressed with how well the airlocked canopies flew though. What would be interesting to know though - my canopy has come around/collapsed on the wing numerous times. In general I prefer it collapsed because its a lot more likely to reinflate and not wrap. I wonder whether the airlocked canopies would be more likely to come around than regular canopies.
Just thinking.. but don't you want the canopy to have a little give to it? ..absorb bad docks and mismatched flying? I'm thinking that a more rigid wing will be more likely to come around and be less forgiving of poor flying..
Also.. what affects do airlocks have on toggle and riser pressure?
Airlocks have zip to do with riser pressure or toggle pressure. Those are all functions of the airfoil, the planform, the trim, the AOI and the angle of attack.
I've only got about 400 jumps on 5 different Airlocked canopies... but you could cut the airlocks out and it would fly the same. (minus the nice rigid wing over your head )
Airlocks have zip to do with riser pressure or toggle pressure. Those are all functions of the airfoil, the planform, the trim, the AOI and the angle of attack.
True.. true.. but the point I was getting at was that perhaps a rigid parachute will be more resistant to the type of deformation that toggles and risers apply. Perhaps it is not a major factor, but I'm sure it will be some factor.. but perhaps not as much so as the others. Obviously a perfectly rigid wing will respond differently than one that has elastic/plastic behavior.. but I think you still answered my question.
I think, ceteris paribus, that an airlocked wing should have a higher riser and toggle pressure. A rigid wing should be more resistant to deformation.. right? On the other hand, if the wing could deform without causing internal pressure changes (not taking into account the pressure changes due to AOA, etc), then the riser pressure shouldn't be affected by airlocks.
But I will take your word for it ..
(This post was edited by darkvapor on Oct 26, 2004, 1:22 PM)
Several years ago, Brian Germaine told me about an air-locked CReW canopy that he was experimenting with. It had airlocks near the leading edge, like all the production air-locked canopies. The problem Brian encountered was that the air-locked canopy was too rigid. Every time he tried to dock, he just bounced off the other jumper. Brian said that his next CReW canopy would have air-locks back near the B lines, to "soften" the nose.
If it ever gets finished and released it would be fun to try and do CRW with it. I've taken (and given) hard docks with my Airlocked canopies and they bounced off people like rigid wings. 
) 
