Author Topic: Built up trailing edges (Read 799 times)

Geoff Goodworth · « **on:** August 28, 2012, 11:52:14 PM »

We are all familiar with trailing edges that consist of two pieces of sheet with a cap at the back and small blocks to carry flap hinges.

Most of the plans that I have show the cap at the back—often 1/8" thick and 1/4" or 3/8" wide—shaped to the airfoil taper and the TE sheeting applied over the top and bottom. It strikes me that trying to taper the TE cap when all the support is the glue holding the cap to the backs of the ribs is fairly risky and fitting the TE sheets first with the cap glued to the TE sheets and the ribs will be stronger and the cap easier to taper.

How do other people do this?

And I am already building on tubes so please don't suggest Millennium Wing built up LE and TE or anything that will not work for a wing that already has all the ribs main spars and LE fully assembled on the tubes.

Cheers

steven yampolsky · « **Reply #1 on:** August 29, 2012, 08:35:39 AM »

for a 1/4" trailing edge:

1) glue bottom sheeting(I assume you're using 1/16 sheeting)
2) cut out wedges(the shape of the back of the rib) with a 1/8 at the tip and glue them in ribs bays where the hinges will go. You will cut out the hinge pockets out of them later.
3) for the rest of the bays, glue in 1/8 x 1/8 strips. this will prevent trailing edge sheeting from collapsing. If you skip this step, you'll have scalloping sheeting(sagging between the ribs).
4) glue the top sheeting on.
5) cut a 1/8 thick and 1/4 wide strip and butt glue it to the trailing edge. I usually cut the strip a little wider than 1/4 and just sand it down but that's just "insurance" against inborn talent to cut things crooked.

White glue is perfect for this since it is very sandable( I also used to use Ambroid but the glue is tough to come by in my area so I only use it for leather fillets).

Jim Thomerson · « **Reply #2 on:** August 29, 2012, 02:52:25 PM »

I have made the trailing edge as a separate piece on a flat building board. Lay down the bottom 1/16 sheet. Put in vertical grain D tubing sheet at the leading edge, (Make a little fixture to put it in at the proper angle) with spaces for the ribs to stick in. Put the top sheet on. This is for a non flapped wing, so I think you could combine my methods with Steven's method above and be really innovative. Then put titebond on the edges of the rib tips and slide the trailing edge on. Get it good and snug and CA the ribs to the vertical sheet in between each one.

Geoff Goodworth · « **Reply #3 on:** August 29, 2012, 05:49:35 PM »

Thanks guys. Steven, this particular design has 1/16" sheet boxing the TE sheets at their forward edge so your method will allow the box pieces to be fitted before the second TE sheet closes the whole thing. Thanks again.

Author Topic: Built up trailing edges (Read 799 times)

Geoff Goodworth

Built up trailing edges

steven yampolsky

Re: Built up trailing edges

Jim Thomerson

Re: Built up trailing edges

Geoff Goodworth

Re: Built up trailing edges