I am at the point of attaching flaps to my 40 size GP RV-4.
The flaps have a flat LE and are hinged near the lower edge. The problem I see is that when deployed there will be a big honkin crevace in the top
surface of the wing.
This would totally disrupt the airflow over the top surface of the wing and flap, thus defeating the flaps purpose.
I am thinking of modifying the LE to a round shape with corrosponding
cup shape mate surface on the wings TE.
Anyone else have experiance here?
Dan

O.K, have figured out a solution.
I have repositioned the hinges from the bottom of the flap to 1/8in from the top of the flap LE, and angled the LE from the hinge to the bottom of the flap to 3/8in back.
Now the flap will rotate from the top edge thus keeping the top surface of the wing smoother for the airflow. There is a gap on the bottom of the wing when the flap is in the up position, but that is much less critical than having a gap on the top.
I suppose I could even rig up a flexible gap seal for the wing bottom, but we will see.

Dan

[rmcdicken]

Scale freak;

I'm building a GP RV-4 as well and like you, thought the idea of a huge gap at the top of the flap a bit unsightly as well as being aerodynamically unclean. Like you I milled over the idea of creating a scale leading edge for the flaps, but decided not to go through the hastle for a stand off scale aircraft.

I ended up putting the hingline for the flaps just below the midpoint of the flap leading edge and beveling the bottom. I also used robart hinge points instead of the ca hinges included in the kit. I'm quite pleased with the result. A nice clean line when the flaps are retracted and only a small gap when extended. The robart hinge keeps everything nice and tight to the back of the wing with no rubbing or binding.

Cheers,