Variable Geometry airfoil

[Greg McFadden]

So I am sitting here thinking that maybe I would like to make something with a variable servo controlled airfoil geometry (not to make it fly better but just to play with and for the cool factor and because it would be something mechanically interesting to design) I was wondering if anyone had any experience doing that sort of thing.

[Sparky Paul]

Quiet Flight International a few years back showed such a thing.
The airfoil included a diapraghm section which was connected to a lightweight aquarium pump which could inflate/deflate the section to change the shape of the profile.
.
It was in their April issue, though.

[Greg McFadden]

interesting approach to the geometry change... I was looking at having servo controlled spars and having a bit of extra covering rolled on a spring loaded rod that could slide in-out of the wing as needed to maintain the geometry

[DaveGherardini]

I built a varible camber wing out of foam just to see if i could make if fly. It was a fairly succesful and i was thinking of roll controll only. It was very sensitive and took some practice to fly.
Basically it was forward ailerons kinda. I split the foam at 25% mac and hooked up servos like you would ailerons. Not exacty like your thinking. more like old time wing warping but the idea of controlling roll with the least amount of induced drag. You could make alot of neat. I had alot of fun building it and still have some pics. Il try to up load one. Rember This was just a fun project. The plane also has forward swept wings and canard

Dave G

[Sparky Paul]

Here's the concept of the vari-foil.
The designer recommended "weather balloon" covering..
Something non-porous but stretchable probably OK.
.
As mentioned, it was in the April 1995 issue..and the editor then, Davy Jones loved a spoof.
But this is close enough to workable....

[Ollie]

Flaps are the tried and true way to control airfoil geometry. Compound flaps will give you control of camber and camber shape. Throw in a droopable nose for extra complication. With camber control, the only excuses for a thick airfoil are torsional rigidity or, to house stiff, strong spars, servos, retracted landing gear or fuel tanks. In other words a variable camber airfoil should be no thicker than necessary for the stuff in the wing.

[DaveGherardini]

Would you guys happen to no why the XB-70 Valkrye..and the other 3 variants, Had the wing tips fold down during flight. Ive tried to reasearch the subject, and havent had any luck. My brother(AE) now salesman thinks its what caused the midair with the F105 or 104, (airflow phenomena)cant rember now. That is probly the most varible geo wing ive ever seen. maybe except for the Rutan bro's swivel wing.

Dave G

http://www.geocities.com/xstratus/index.htm

[HarryC]

They don't so much fold down in flight , as fold up for ground clearance during landing!

I believe it was to do with trapping the high pressure air below the wing to increase the lift. At the very high speeds the XB-70 could do, the compression of air and shock waves can be harnessed to provide lift. As well as having a pressure drop above the wing, you can use the high pressure compression below the wing. Rather like a hovercraft, the sideskirts trap the high pressure for you to ride upon.

H