swept forward aileron effect?

[hardlock]

I notice lots of 3D planes use a swept forward aileron hinge line. I've used swept back ones on other planes with no effect that I could notice.

I'm curious if there is any reason to use sweep forward instead of just a straight across hinge line. They appear to be to used just to get more area from the surfaces without changing the wing planform or is there something else going on there?

[hardlock]

(bump) anyone?

[Ollie]

http://aero.stanford.edu/WingCalc.html

[hardlock]

Thanks Ollie, but I'm more concerned about the effect on the aileron control with them swept forward, not how they effect the wing.

[Ollie]

No!

[aussie]

I personally think you'll find that it's simply an effect of the wings being dead straight, unswept, measured from their 1/4 chord line. Airfoil sections then have an ideal aileron width (as a percentage of the chord) which causes the hinge line to be swept forward....

Kye McDonald
Wowings

www.wowings.com (http://www.wowings.com)

[raptor22]

Also, the alot of the small 3d planes (electric parkflyers) only use one servo w/out tourque rods. They use the swept hinge line to allow the conrol rods to meet the surface at right angles.

--Alex

[raptor22]

Ollie: how accurate is that applet?

--Alex

[Gene Bond]

You must be reading my (troubled) mind, Hardlock :)

I just finished a drawing to show my question...

OK, the blue line shows a rear swept hinge line. I believe it will cause yaw in the intended (turning) direction, but make rolls less axial...

The black line is a straight hinge line, which should be nuetral, but probably isn't, sinc ethe wing and aileron are not constant chord...

The red line shows a forward swept hinge line which I believe will cause adverse yaw, but tighter more axial rolls...

I was wanting to hear from the experts if my crude thrust line drawings and assumptions are correct. I am not as concerned with the difference between wing and aileron chord, except where it might effect the aileron function. I know the differential in chords will cause a change in airfoil, but that's another issue (I believe).

[hardlock]

Gene,

Maybe none of the above will cause any yaw effect difference since the opposite wing is being effected equally no matter what angle is used?

I know that differencial travel would screw this up. If equal travel and not considering any tip effect or lifting drag vs spoiling drag difference (down going side vs up going side) then yaw might not be an issue.

I've found with a straight hinge line on a low AR slightly tapered flat plate wing that I'm getting slight proverse yaw with equal travel. The percent of chord for the full span ailerons is about 30%

Oh, and the horizontal stab, wing, and thrustline (except offset for torque) are on the same axis.

[raptor22]

When an weleron goes down it always experiences more thrust that the one going up, since the one going down is increasing induced drag more than the other because it is producing lift.

Therefore, you will always have adverse yaw.