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Aileron trim tab, where should it be?

Posted: Wed Mar 10, 2010 3:55 pm
by rans6andrew
I know, I know, on the aileron trailing edge.

But, should it be within the prop wash area or further out towards the wing tip. Full span aileron, single engine, tractor configuration, high wing aircraft situation.

Rans6....

Trim tab position

Posted: Thu Mar 11, 2010 6:55 am
by David Hardaker
Andrew
Apart from the problem of finding somewhere rigid to attach a tab, I'd go for half-span, and outside the prop-wash area.
A tab to use the aileron to raise the "heavy" wing will need to be deflected up. But thats in lower pressure air, so the tab would need to be larger, or deflected more than if it were to be on the other wing, but in the downwards direction.
I've often used balsa-wood wedges just taped on, especially when you don't know how large they need to be. You may need several attempts before you find the ideal size. (typically 6"x 1- 1/4"x 5/16 " shaped trailing edge stock) (support your local model shop !)
d

Posted: Sun Mar 14, 2010 7:47 pm
by John Brady
My old and wise inspector advised me to use trim chord - just a length of nylon cord of maybe 1/8 to 3/16 inch diameter. Cut a foot and tape it to the underside of the aileron trailing edge on the light wing and try it. Cut bits off or add a bit until it is just right and at some convenient time in the future, tape and dope it on properly. It worked magically and nobody knows it is there.

John