Matt's RV-7 Project

I got up this morning and primed the flap braces (only on the side that won't eventually be painted) and then riveted the flap hinges to the wing bottom skin and the flap braces. Notice how the temporary rivet holes are now filled with small-head rivets that have their flush surfaces facing out. Also visible here is the section where I removed three hinge eyes to allow insertion of the flap hinge pins, per the plans.

Here's the backside of the same area. During final assembly I'll capture the bent ends of the hinge pins with some safety wire through the little holes I put in the flap brace.

The flap brace itself is riveted to the rear spar with monel rivets along the entire length, with the exception of the three inboard-most rivets – those are Cherry flush structural blind rivets. Big, solid-looking suckers. Cool.

Here's the finished product. The alignment is correct and the motion of the flaps is smooth throughout the entire range of motion. The outermost foot or so of the hinge isn't riveted yet, since the outboard bottom skin doesn't get riveted on until everything inside the wing is finished.

Once I got the flaps on for good, I started messing around with the pitot tube. I'm planning to mount it just outboard of the rib bay where the aileron bellcrank lives. The Gretz bracket is match-drilled to the spar flange, and a piece of angle stock I cut ties it to the rib. Here's some random photos of the setup so far:

I'm not totally happy with the way the backing plate is a little bit recessed from where the skin will be. I'll probably have to make a shim from 0.020" Alclad or thereabouts.

Lots of progress today. First I primed and attached the aileron gap seals:

All these rivets can be reached with the squeezer and the longeron yoke, which made it a piece of cake. The gap seals themselves are made of pretty thin material (0.020" I think) but when they're riveted in place they add a ton of stiffness to the overhanging edge of the upper skin.

Then it was on to the flaps. I used Dan Checkoway's temporary rivet method of securing the flap brace while drilling the flap hinge. You can read it on pages 8 through 10 of this pdf file.

First I drilled eight additional 3/32" holes through the bottom wing skin and the mating flange of the flap brace, along the pre-drilled rivet line. These holes I countersunk for NAS1097 rivets (used because they have smaller heads than normal AN426 rivets) on the inward side of the flap brace flange, and the preexisting holes on that flange of the flap brace were countersunk on the outward side to accept the dimples in the bottom skin.

The idea is that you put temporary rivets in the additional holes, to hold the flap brace in alignment with the skin while you clamp and drill the hinge. The flush heads of these temporary rivets are on the inward side so the hinge can lay flat against the flap brace:

When the hinge is completely drilled, the temporary rivets are drilled out and the skin is countersunk to accept another NAS1097 oriented with the flush head outward. For now though, the shop heads protrude outside the wing.

The forward half of the flap hinge is the clamped to the wing, with one cleco clamp on either end. Although it's tight, you actually can get the clamp onto the outboard end if you insert it into position before you bring in the flap. The two halves of the flap hinge are pinned together so as to eliminate any possibility for the hinge line to come out crooked (which would prevent smooth operation of the flap). The gap between the aileron and flap is set at 1/4" per the plans – I just juggled things around until a drill bit of the appropriate size fit snugly between the two control surfaces.

Once everything is lined up, you match drill through the prepunched holes in the skin into the hinge. It helps to have a compact and patient building partner. Mary stood between the wings and pressed on the hinge with a piece of wood to keep it from bowing outward from the pressure of the drill:

Five or six dozen holes later, the first flap is hung:

I used a straightedge to ensure that the alignment between the trailing edges of the flap and aileron would come out even for both wings:

Plenty of edge distance on both hinges. Some people wind up having to use a wider -P4 hinge instead of the supplied -P3 hinge stock in order to end up with enough material between the edge and the rivet holes, but mine came out okay.

Both flaps are hung:

Tomorrow I'll cut the hinges to length, drill out the temporary rivets, prime the flap braces, and permanently attach the braces and hinges to the wing.