Category: Flaps

October 22, 2011 – The flaps themselves are complete. All that’s left on them is to drill the wing half of the hinges to mount the flaps. That will come after the ailerons are fitted and rigged.

I located roughly the halfway point for the hinges where I cut out the eyelets to allow for the two-hinge pin method of securing the flaps. The hinges are 56″ long, so I measured and marked at 28″

I removed that one eye in the flap-side hinge, and the two surrounding it on the wing-side half of the hinge. Then I marked where that would fall on the flap brace mounted on the wing.

Hopefully, the hinge cutouts and the flap brace will be situated so I can secure the pins cleanly. If not, I’ll just run a plate across a lightening hole in the brace.

I primed the flat surfaces of the hinges, especially because I wanted the mating surface to be primed.

Then I riveted the hinges to the flaps. No big deal; I was able to use the squeezer on all of them.

I set the flaps up in the wing trailing edges just for storage.

Time: 1:30

October 18, 2011 – I have finished with the assembly of both flaps, except for installing the hinges.

I riveted the upper skins to the ribs, then I installed the inboard and outboard end ribs. With the “aft spar” as part of the lower skins, you don’t have access to put in solid rivets at the trailing edges, so you have to install blind fasteners.

The nutplate for the flap control rod also made things a little interesting as far as installing that skin rivet right there, but with a little patience, it can get done.

You also have to remember to install the shims where the upper and lower skins overlap.

That got me down to the aft two fasteners in the outboard ribs, where you can’t fit a bucking bar. I used my normal indirect back-riveting method here.

I’m ready now to attach the hinges, after I cut the slots for the hinge pin installation.

Time: 4:55

October 7, 2011 – Not a bad way to start a long weekend. I started riveting on the flaps.

I began by installing the doublers for the flap control rods on the inboard ribs. I also installed the nutplate for the rod end. The plans call for a flush rivet for the side that does not go through the doubler. I didn’t see the sense in removing material there, so I just used a regular rivet.

I also installed the corresponding angles onto the inboard ends of the spars.

I then placed the ribs (except for the end ribs) in place on the lower skins. I installed the rivets in the aft ends of the ribs attaching them to the faux spar of the lower skin. On the first flap I installed the rivets from the aft end. Didn’t really like the result, so on the next flap I installed the rivets from the rib side. Much better result. I used a squeezer in both cases.

I then riveted the ribs to the lower skin.

Once both lower skins were done, I started on the right flap by sliding the lower skin into place in the upper skin, then I riveted the two skins together along the row on the bottom where they overlap. The first picture below shows the two skins “exploded” to show their relative positions. The second picture shows them nested in place.

Here’s a shot of the rivets from the inside:

After that row of rivets was done, I clecoed the upper skin to the ribs. I’m ready to do those rivets next.

Time: 2:05

October 2, 2011 – Over the last week or so I have deburred, dimpled, cleaned, alodined and painted the skins, ribs and other parts for the flaps. Not much to tell other than that.

Time: 6:35

September 19, 2011 – Now that the main structure of the flaps (ribs, skins and hinges) are drilled, it’s time to move on to other parts of the flaps. The spar where the hinge attaches gets countersunk. I removed the bottom skins and left the hinges in place to add as a guide for the pilot of the countersink.

I’m debating whether I want to countersink the top side of the spar. The plans call for dimpling, but I think the spar is too thick for that. I’ll have to do a little more research on that, plus I, like many other people before me, dimpled the flap brace that’s attached to the wing. It is NOT supposed to be, so I may add a doubler to that when I attach the hinge to the wing. That comes later on, though.

There is an angle and a bent doubler attached to the inboard rib of each flap. This is where the flap control rod attaches. I cut the angles to size and laid out the fastener pattern per the plans.

When I had one drilled to #40 holes, I clamped the two together, since they are identical left and right, and drilled the other one.

I clamped the angle in place on the spar, using a drawn center line as a guide, piloted the holes in the spar to #40, then took the holes up to the required #30 (1/8″).

I bent the control rod doublers to the approximate 6.3 degrees that Van’s calls for, then clamped it in place and back-drilled to the rib and the angle.

The aft-most hole in the apex of the doubler aligns with a hole in the rib. That hole gets taken up to 1/4″. This is where the control rod rod end attaches. I used 2 core drills to take the hole up from 1/8″ to 1/4″. I prefer core drills and reamers for larger holes because they make a much cleaner hole than a regular drill bit.

After all this was done, I took everything apart for dimpling and prepping for paint. Part of this process is the usual labeling of parts using wire and aluminum tape, and removing the blue film from the rivet holes on the skins.

Time: 5:20

September 12, 2011 – I started the flaps by sorting and clecoing the ribs to the spars. It was a little mind-bending putting the left- and right-handed ribs in the correct locations.

The bottom skins for the flaps are interesting in that they have the aft spar bent into them. The short inner ribs get riveted to that “spar”. The instructions allow for spacers to be installed as required. I don’t think any of mine require spacers at this location except for one. This is what the typical gap looks like for me:

The flaps hinge at the lower skin, and the hinge must be drilled at this point. I started by drawing a line along the length of the hinges on both sides at 1/4″. This will ensure that the hinge is straight and that I will have good edge distance for the rivets.

With these lines drawn, I clamped the hinge in place, and made sure I could see the line through the lower skin rivet holes.

I drilled all of the holes in the hinges.

After the hinges and the bottom skins were all drilled, I slid the top skins in place and clecoed them.

The top skins require shims at the trailing edges of the inboard and outboard ribs. I made these per the plans. They are 1 7/8″ by 5/8″. You drill a rivet hole in a specified position, then put the shim where it belongs to drill the other holes. I drew a center line from the first placement hole so I would know the hinge was in the perfect spot.

When I put the shims in place, and clecoed them, I could see the center line that I’d drawn. I knew I could drill the second hole.

I then drilled all the remaining holes for the top skin.

This is the left flap. I still need to drill the top skin for the right.

Time: 3:10