Ivan's RV-7

The reinforcement anglesTimer icon3h

March 25, 2023

In the last two days, I worked on the reinforcement angles.

These are the angles where the fuel tank attachment bracket bolts to the fuselage. They need to nest between the longerons and have two spacers behind them.

They are not particularly hard to make but require some finesse as the edge distances are already too short on them. The better they fit, the more edge distance you get. Also, the middle three holes through them go through the 5 layers (the skin, the F-902 bulkhead, two spacers, and the angle itself), which requires some careful match-drilling.

I tried to use a technique I saw on the [url=https://www.youtube.com/@KaretakerAero]Karetaker Aero[/url] (great source of information, by the way): use a drill bit to mark the location of the hole, then drill it separately. This reduces the risk of accidentally enlarging the holes and avoids parts movement. To mark the location, it is enough to hold the parts by hand, then slightly twist the drill bit.

After drilling the holes, I used the drill bits to locate the parts so I can mark the next hole.

Using the drill bits to align.

In the end, everything turned out fine. I got the angles for both sides.

The right angle. The left angle.

This completes the preparation of the fuselage. Almost -- the remaining work is the hinges that attach the cowling. I thought, I have the correct material, but turns out these hinges come with the finishing kit which I don't have. I can skip that part, but that would mean one of two things:

  • I can dimple the skin and the firewall flanges now, but that will make it harder to match-drill the hinges later.
  • I can skip the dimpling, but then I will either need to countersink the skin or dimple two layers at once.

So instead I decided to order a short piece of the hinge. I only need 14-1/2", so a 3' long hinge should be enough. Unfortunately, that means I will have to wait for a week or two. Will see if I can progress on other parts.

This is what the project looks like now.

The fuselage.]