Nosen P-51 flap modification
 

I built a Nosen P-51 but wasn't at all satisfied with the way the ailerons and flaps looked - not scale at all.

I'm trying to do flaps that are rounded so they rotate within a pair of angled balsa pieces, kinda like the package shows BUT, these are tapered from thick at the root to thinner at the aileron end. Right now I have one piece on the top of the wing and can get it to rotate down and it leaves an acceptable gap, but on the bottom the gap disappears as the flap comes down so it looks like I need to rework the surfaces again.

My question is: How far into the flap does the Robart knuckle have to be to get it to rotate around an axis? I'm thinking it needs to be at some sort of center point which should be measureable and equal down the length of the flap, but I'm at a loss. If I push the flap into contact with the trailing edge, rotating it pulls it away from the trailing edge by fulcrum movement until its about 1/2 inch out at the root and 1/4 inch out at the tip. I can close this gap on top with a tapered triangle, but the bottom can't have one or it blocks the rotation.

I'm thinking one option would be to put a rounded piece on the trailing edge and make a mating concave piece for the flap. However, I'd rather do it the way I'm doing it if it'll work. I'll probably have the same problem with the aileron.

Any ideas or success stories on making a rotating scale flap?

RE: Nosen P-51 flap modification
 

if i get what you are asking, check this out and try with some scrape first as i havent tried it this way but am 99% sure it will work for your needs.

the way i figure it this meathod should give you 30 - 45 degrees motion up and down allowing for 60 -90 total degrees i.e much more than what you need so this may be the easiest way with out buying those weird robar fouler flap hinge things.

please PM me if you ahve any other questions.