Surface area, Physics

[JeffD 0]

Just curious if anyone knows the effects on how many layers there are. For example right now most canopys are basically like boxes, what would happen if another box were put on top, giving you 3 layers of fabric facing the ground instead of 2.

I am not concerned with opening or packing, just if there would be more lift. Thanks.

[PhillyKev 0]

Total speculation, but all other things being equal (shape and dimensions of the overall wing) I don't think it would make a difference at all.

[quade 4]

The only positive effects that I see it could have would be to increase the ridgidity of the canopy -- like in a cross braced canopy.

Aerodynamically, only the shape is being taken into consideration.

With zero-p fabric, just adding another layer would have a minimal effect on the amount that "leaks" through from bottom to top.

So, no extra lift from the fabric itself, but -maybe- some extra lift if you can get the wing into a somewhat more perfect shape.

quade -
The World's Most Boring Skydiver

[AndyMan 7]

I suspect it would have a smiliar effect as adding cross-bracing - make for a more rigid canopy.

I don't see it being any better then cross-bracing, though.

_Am

__

You put the fun in "funnel" - craichead.

[darkwing 5]

As long as the external shape wasn't changed pretty much all that would happen is that it would pack a lot bulkier. If you did make the airfoil thicker it would also fly slower. I don't see any advantages to this idea, although thinking about things is always a good diea.

-- Jeff
My Skydiving History

[nightjumps 1]

Jeff,

I actually postulated this thought to Simon at Icarus a year ago. His reply was that it would provide more rigidity, but the result would be increased drag and more bulk and would actually reduce the canopies ability to fly as well as they do now.

[JeffD 0]

I think I miscommunicated. I dont mean to sew a layer inside the already existing canopy but basically stacking 2 canopys on top of each other. but having the bottom layer of the top canopy be the top layer of the bottom canopy. I tried to edit a photo to show what I mean.

[nightjumps 1]

Hey Jeff,

Exactly what I sent Simon at Icarus, except with the lower skin and the upper skin being one. Kind of a triplane wing. Feel free to send it to him for the detailed explanation.

While Simon's explanation is understandable for skydivers, I "think" its a great idea for other applications (i.e., ultralights, small aircraft, military tandem operations for increased wing-loading, etc.)

[JeffD 0]

Yeah Im looking seeing if I can adapt something for forward flightish (not FreeFall) like a wingsuit but with more surface area to get away from the 17:1 WL ratio. Thanks for the input!! now I just have to get through school.

[quade 4]

Quote

I dont mean to sew a layer inside the already existing canopy but basically stacking 2 canopys on top of each other. but having the bottom layer of the top canopy be the top layer of the bottom canopy.

Yeah, but functionally you'd end up with just a SINGLE airfoil, so, um, it's the same thing as just adding in another layer.

It's not like trying to fly with helium balloons where more is better. That's just not how it works.

Wings are all about efficiency. You could fly a barn door if you really wanted to and had enough horsepower, but a more efficient airfoil for whatever type of flying you're planning on doing is really the only thing that will make it fly "better".

quade -
The World's Most Boring Skydiver

[cobaltdan 0]

we have made and flown a few "bi plane" canopies, just for sh^ts and giggles. Generally aerodynamically speaking the wings have to be seperated by at least 1 times the cord length.

sincerely,

dan<><>
atair aerosynamics

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

[kallend 2,115]

Quote

we have made and flown a few "bi plane" canopies, just for sh^ts and giggles. Generally aerodynamically speaking the wings have to be seperated by at least 1 times the cord length.

sincerely,

dan<><>
atair aerosynamics

One reason you don't see too many new biplanes is that they are less efficient than monoplanes. Even the Pitts Specials, which dominated aerobatics for a number of years, are now outclassed by Zlins, Extras, etc.

...

The only sure way to survive a canopy collision is not to have one.