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RepmikeBrown

Well Known Member
Mounted my aileron as per plan using the female airfoil template to set aileron brackets. Moved over to fit my flap according to hinge pin distance from wing skin and the flaps trailing edge is about 1/4" longer than the aileron. Is cutting the bottom wing skin the length of the flap my solution? I built the flaps complete with the hinge riveted. Thanks for any help or advise.
 
Photos

Hi,

If you can refer us to some photos it will be easier to identify where the problem lies.

Dont cut anything at this point...... move on to something else until the solution is found.
 
Take a measurement first.

From rear of flap skin along through the tooling holes to the front of the spar. What is that? My first set of flaps were 3/16 too long because I built them based on a measurement I got from another website that was incorrect, but made sense at the time. For the next set I clamped and taped the top skin to the bottom while I had the bottom skeleton clamped to the wing. The aileron was already mounted and a string line stretched from one side of the wing stand to the other, parallel to the aileron trailing edge. I adjusted the top flap skin until it matched exactly all along the run and match drilled through a few ribs to secure the position.

That was how I did it the 2nd time. I think the RV4 and RV6 flap are the same.
So the question for you is do you have 10.5 inches as the answer to the measurement? My first flaps were built to a different measurement of 11.25 from trailing edge along the bottom to the forward edge of the flap skin. That was 3/16 too much on my setup. By the way, Vans advised me to look the other way and said that's why flaps are down so much on the ground, to hide that mismatch. Ha ha, but I wasn't laughing.
I think you can squeeze 1/8 or so with your situation, but you soon get into edge distance issues with the flap brace riveting, and skin-to hinge eye interference with full deflection. One respected builder here suggested I consider moving the ailerons back 1/8 inch by putting a spacer under the mounts. I didn't do that but it was an interesting option.
 
Wendell,
Your pretty much dead on with what I've encountered. I will take measurements to verify. I've taken some pics but still figuring out how to upload them. If I shave .25 inch off the bottom skin it would buy me the distance needed but I need to know if there is something I've missed or if I've got alternatives
 
Flap brace will be issue.

Notice the natural lay of the flap brace on the wing spar and bottom skin. When you cut 1/4 inch off skin, the brace doesn't want to cooperate. If you force it to match, it pushes out on the wing skin and could affect airflow past that area. Trimming the flap brace quickly gets into edge safety margins. Also 1/4 inch closer to the wing spar may cause you trouble with the curved top interference with the spar/flap brace with flap in retracted position. Remember the flap endures a lot of stress when you lower it into the airstream. Needs to be nice and strong.

You have to post your pictures on a website, like photobucket, and then you insert into here the link to the picture. It's a little more involved but that's the idea.
 
IMG%5D
 
Wendell, I did end up removing the 3/16 of bottom wing skin. Moving the flap brace up that amount did make the curl on the front of the flap fit tight with flap in up position (airfoil template )I did have to tighten the curl a bit. The nose does touch now but the fit is much better. I measured the right flap and notice it's the correct size from trailing edge to flap spar unlike the left which was 3/16 over. I'll be sure to note this when staring the right wing. Thanks for all the advise and help.
 
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