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How to Mate Flap to Wing

ArlingtonRV

Well Known Member
I need some help in figuring out how to align the trailing edge of the flap with the trailing edge of the aileron and drill the hinge for the flap. I did it the way the GeoBeck video mentioned. I had the top skins riveted on and the aileron installed and nuetral. With the bottom skins off I alinged everything and drilled the hinge to the flap brace. Worked great, with the exception of one small detail. It didn't work, at least not with the bottom skin on.

At the inboard end where the flap brace has to go over the spar doubler the end of the brace was lower than the rest. When I went to cleco on the lower inboard skin, the flap brace holes were off by a considerable amount. Now, of course, the flap won't fit with the hinge that I drilled in the first place.

It is clear that I will have to replace the wing side of the hinge and drill the holes in the hinge with the lower inboard skin clecoed on so that the flap brace holes are lined up. The only problem is I can't figure out how to get everything lind up and straight and hold it so that I can drill it.

Any insight would be greatly appreciated.

Steve
 
here is what I did

With the wing in the vertical position (in the stand) and the aileron attached, I clampled the aileron so that it was straight and could not move. I made a wood guide consisting of a 6" x 8' piece of plywood with a 2" x 8' piece screwed on. Both long edges were aligned. This effectively gave me an 8' long straight edge with a 4" step in it. I rested 4' this jig on the aileron and allowed it to extend into space over the area where the flap would go. I taped and spring clamped it into position so that it would not move. I then lifted the flap up until it touched this straight edge and spring clamped it into place. Now the flap and aileron were in perfect alignment against the wood edge. The hinge was alread attached to the flap and just hung down. I started at the inboard hole and drilled one hole and clecoed each hole as I went. This allowed enough back pressure on the hinge that it did not bend out of the way as I drilled. The whole procedure took less time than for me to write this description of it. Hope this helps!
 
Andrew,

Thank you for your help. I did it exactly the way you mentioned, except different.

I took a piece of long angle and held it to the aileron with cargo straps. With a helper, I got the angle under the flap and the flap in position held in place with two more cargo straps. A piece of 1/4" ply is between the flap and aileron.

From here the straps can be adjusted to get the flap in just the right position. Just to add a second layer of protection there were two small C-clamps used to hold the inboard and outboard ends.

Once it was all straight plumb and true I started at the outboard end drilling one hole at a time and found that the hinge stayed pretty well in place.

It took a little longer to do than to explain, but was pretty quick and easy.

Thanks again.
 
I just did this the other day but mine is a quick build so things may differ. After studying for a few months it occured to me that the flap brace did not need to be in place to line up the flap. My wings were in the stand verticle.
I marked the centerline of the hinge which should show up in the holes on the lower wing skin for reference. I cut a piece of wood to use for a spacer between the flap and the aileron. I had a helper hold the flap in place while I sighted down the trailing edge and marked a few of the holes. As far as I can tell everything lined up correctly even after I added the flap brace to the equasion. I forgot to mention that the ailerons were held in place to do this.
The key was that the flap brace did not need to be there to line things up.
 
Aileron/Flap Nuetral Alignment

Notably I am tagging onto a very old string. Sorry, but I don't particularly care for how others have done 'it'. What I am really looking for is some sort of positive dimensional key/method for determining and holding
the nominal zero position for the flaps/aileron relative to the rest of the airfoil. There
is nothing in the 7A plans that provides any airfoil datum from which to set zero/neutral aileron/flap deflection.
Tim Cook
 
The tooling holes in the end rib are used to set the aileron trailing edge. The aileron TE then sets the flap TE. It’s in the plans.
 
Aileron/Flap neutral aligment

Thx Mike W.
Upon further study, tooling holes and aileron (then flap) alignment can be found buried on 7A plans, dwg 12A.
Tim Cook
 
Aileron neutral

Hi Tim,

In addition to DWG 12A also check out the Bellcrank Jig P/N: W-730 which is shown on the R/H side of DWG 15A.

This will facilitate setting the neutral position of the ailerons by adjusting the W-818 pushrod to the right length during the initial set up. Plus it will be used later to connect the W-716 Push Rod to the control column (i.e. adjust its length) after you install the wings.

Cheers,
 
I just finished doing this this past weekend. I built my aileron alignment jig from hardware-store aluminum angle. This is used to hold the aileron in-trail (neutral) while you drill the flap and set up the pushrods.

I drilled the flap hinge (wing side) with the wing upside-down on a table and both bottom skins clecoed into place. With the hinge halves connected by the hinge pin, I was able to use cleco clamps on each end of the hinge to hold it in place while I made adjustments for the flap/aileron gap and the alignment of the trailing edges.

There's enough excess piano hinge so that you can drill the outboard 3 holes and test-fit with clecos before committing. This way, if there's a problem, simply cut off the drilled section and do it again.

The bellcrank jig is no help in this task. Its job is to allow you to set the correct length of the small pushrod when the aileron is in-trail.
 
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