Trim Tab Advice Request

[David Paule]

How did y'all bend the long flange on the trim tab? I'm having trouble with that.

It needs to be bent slightly past the 90 degree point to fit the trim tab spar that's supplied in my kit. So far I've been trying to do it with the side flanges already bent.

The side flanges aren't hard at all. Just use a flange bender and bend them.

Right now I've got replacement trim tabs number three and four on order and I'd really be annoyed if I had to order replacement number five.

Anyway, thanks for any help!

Dave

[danbenua]

I recall bending this flange with the hand seamer. Just work your
way back and forth along the bend line and don't increase the
bend angle more than 15 deg. on each pass.

Another way to do it is with a wooden form block that clamps
the trim tab down to the table with the flange hanging over
the edge. The flange can be bent up with gentle tapping
from below. If you use this method, be sure to radius the
edge of the form block. If the corner on the block is sharp,
the skin will crack.

- Dan Benua
RV-3B

[David Paule]

Thanks, Dan. Guess I'll have to build up some more skill - I tried the first approach and the flange stretched and then buckled. I'll try the second one next time.

Dave

[JonJay]

David - part of the problem is trying to bend the flange after you bend the end tabs. Bend the flange first. Take a simple piece of plywood or scrap of wood 2" or 3" wide and long enough to span the length of the part with extra on the end allowing you to clamp both ends of the board on the edge of a table. You can then gently hammer the flange into shape similar to how you would make a rib over a form. As Dan mentioned, sand a radius in the edge of the board appropriate for the thickness of the sheet. You may need to use your hand seamer to complete the bend after you unclamp it.
For the end pieces, take a similar board shortened so it will fit inside the tab. Carefully clamp the tab and board that is inside the tab so the boards end is located just inside the bend line and insure the same radius. Hammer those flanges up.
I am going off of memory here but this method is roughly how I did mine.

[hcccs]

Originally Posted by David Paule

How did y'all bend the long flange on the trim tab? I'm having trouble with that.

Dave

I realized that this was going to be tricky so I made two small ribs for the trim tab and riveted them on. I thought this was easier.

[David Paule]

Thanks everyone for the help.

Hans, the RV-3 trim tab is a bit different. The bottom lip gets bent up to mate with the spar, which is simply a tapered angle. It's this bend which has been troublesome for me. The side flanges, which you made as ribs, turned out to be easy.

Dave

[pekuba1610]

Was there an extra .016 in your empennage kit for the trim tab?
In my kit there is a so called trim tab bundle of various sheets, but the maximum width is 4 1/2", which is not enough. Or should one use the piece, cutted from the elevator?
Thanks for advice.
Peter

First time builder since. 02/2014

[steve lenne]

you need to use the piece you cut from the elevator skin .

[David Paule]

Steve said it.

Van's also sells trim tab blanks separately.

Dave

[pekuba1610]

Thanks a lot for the advice. I'll try to cut it carefully from the elevator skin.
Peter