Help needed sealing lower aileron gap

[Salto]

I've searched both this and the builder's workshop forum and can't find an answer to this, so I'll ask the question here.

I've got a scale 2.3m glider, balsa/spruce ribbed construction, film covered, with film hinges for ailerons and flaps. I want to seal over the 3/8" wide lower gaps. I've tried very thin Sig plastic sheet cut into strips and glued onto the wing in front of the gap, but it won't conform to the bottom front of the upward going control surfaces. This material seals OK at neutral positions, and when the surface goes down, but no longer touches the surfaces when they go up.

What I need is something that has a residual upward curl in it so that it retains upwards pressure on the control surfaces even when they are deflected up.

Any ideas? I'm sure this problem has been solved many times over.

Graham.

[FlyingPig]

Not sure this will work....

http://www.hobby-lobby.com/spoilers.htm#Gap

[emersunn]

I have never seen a gap cover like what you are describing and it may be unnecessary.

If the gap tape is curled, it will follow the control surface. But when it is in the neutral position it will bulge along the entire span of the surface - making the airfoil quite inefficient.

When a gap is created on the control surface when it goes up -gap tape still deflects the air straight over the gap.

Forgive me if i misread you problem.

;)

[Salto]

FlyingPig,

Thanks, that's just what I want, but it's probably not practical to get one roll shipped down here.

I wonder what it's made of, and how they get it to stay against the control surface.

Graham.

[gdjsky01]

Originally posted by Salto
FlyingPig,

Thanks, that's just what I want, but it's probably not practical to get one roll shipped down here.

I wonder what it's made of, and how they get it to stay against the control surface.

Graham.

Think of it this way. Thick clear packing tape. Cut a piece to length. Cover half the tape's width with thin clear sytrene plastic. Attach the tape sticky part just ahead of the aileron so the styrene is hinged right at the gap. Air pressure keeps it flat, and keeps it pressed against the aileron when it deflects down. When it deflects up you don't care that it stays flat as it still covers the gap. No?

[Salto]

gdjsky01,

Thanks for the suggestion. This is basically what I have now (but with the plastic strip glued not taped), but it doesn't move up to touch the control surface when the surface is deflected upwards. The resulting step created at the free end of the plastic strip looks worse for the airflow than the open gap would have been.

Does airflow alone keep such strips attached to the front of control surfaces? I'd think it would be like an open car door which holds itself slightly open due to the Bernouli effect.

I use the flaps for camber control when I want to go fast, and in this flight condition particularly it seems that sealing the gap and not leaving any steps or bumps is very important.

I'll try your idea, but add a silicon fillet where the plastic strip hinges onto the lower wing surface. If I let it set with the control surface deflected up there should be enough residual pressure to keep it tight.

Graham.

[viti]

its just a guess but i bet your just not using the right material


the gap tape that you see online is made from mylar ,it holds its shape very well and in a case where you need it to lay flat [flap down ,gap on top] it WILL seal properly

the only problem i have found will mylar is in the cold but even then it just gets stiffer

most tape measures are made of mylar these days,they may appear to be metal but there not!

viti