Max Effective Wing Loading on a Non-Crossbraced

[jeiber 0]

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Airlocks - the fat mans crossbrace.

Could you (or someone) elaborate on this? I've heard people comparing airlocks to primitive crossbraces.

I'm not fat, I'm big boned!

Jeff

Shhh... you hear that sound? That's the sound of nobody caring!

[AndyMan 7]

Airlocks add rigidity to the nose of the canopy. By closing the nose off, airlocks ensure the canopy stays pressurised even in low speed flight.

Crossbraces are different. The key design goal of crossbraced canopies is to have the design characteristics of a 21 cell with the line drag of a 7 cell. This design choice affects the aerodynamics in a very specific way. Airlocks do not approximate this.

One popular side effect of crossbraces is they add to the rigidity of the canopy in slow flight. Crossbraces help keep the canopy stay well formed through the flare, which keeps the wing flying efficiently. This means that you can safely load a crossbraced canopy to a higher level knowing that you'll still be able to reasonably shut it down on landing. This is the aspect that airlocks mimic.

I should mention that I'm hardly a crossbracing expert. I've not yet found one big enough to play with.

_Am

__

You put the fun in "funnel" - craichead.

[Widgeon 0]

Several canopy designs touch on this issue. The crossfires and the cobalt competition come to mind. I think one of the Parachutes de France canopies (the Ninja or Electra or some shit) incorporates this design aspect as well. While not being airlocked, or crossbraced, the leading edge of the nose is partially formed in between the cells so it gives the nose a cleaner more efficient profile. The Katana and Mamba get in on this as well, but not in the same design method of the crossfire 1/2 and cobalt comp. I don't know whats going on with them. They both appear to be pretty normal ellipticle canopies but the results speak for themselves. I've heard several people who owned both a katana and the vengeance said the katana was more rigid than any airlocked canopy they've flown.

Jeff..........you take up the whole back of the cessna, stop it.

[bob.dino 0]

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While not being airlocked, or crossbraced, the leading edge of the nose is partially formed in between the cells so it gives the nose a cleaner more efficient profile.

To the best of my knowledge, closing up the nose was to slow down the openings to a tolerable speed.

[Widgeon 0]

That was the concept with the Howard modification, but it yielded other benefits as well. Improved aerodynamics once the wing was deployed was one. The H modded canopies fly distinctly different, IMHO to canopies without them...but you're right, they open alot softer too.

[VectorBoy 0]

My H-mod will dive faster than before and it flairs a little stronger. I got the mod for the dives not for the openings which were perfect before. Now the openings are unbeliveable.

[Widgeon 0]

You're not the first person that I've heard say that. Not everyone got as lucky as you, but the formed nose advantage is hard to argue with. Glad to hear it worked out for you. I'd be curious to do some jumps on an old, cheap baffed out sabre, and then get the mod and compare.