Practice Kit Part 3

Finished fitting the stiffeners to the skins tonight, including dimpling both the stiffeners and the skins. The DRDT-2 is so easy to use, and produces an excellent finish using my Cleveland Aircraft dimple dies. I found out later that I made a mistake in this step. I didn’t test fit the skins together with stiffeners and trailing edge wedge in place. If I had done, I would have found two of the stiffeners to be too long, overlapping with the trailing edge wedge. The stiffeners need to be trimmed, and on one skin they need to be trimmed more than is immediately apparent from the instructions and markings on the material.

I also fitted the spar doublers and ribs to the spar, match drilled everything, then disassembled and deburred all the parts.

With that done, I match drilled the skins to the ribs, and drilled the trailing edge wedge. Doing this without the recommended double-sided tape is a mistake. The tried taping the wedge in position with rivet tape, but it wasn’t strong enough and slipped a few times. At this point I disassembled and deburred everything, thinking I would next prime the parts and then assemble.

Practice Kit Part 2

Started the next practice kit, building a section similar to an elevator. Used my bench grinder with Scotch Brite wheel to debur the stiffeners and remove some excess material. The wheel is great, and quickly eats away at these thin parts. Care is needed not to over-do it, but with some practice the finish is excellent.

Practice Kit Part 1

Started working on the practice kits today. One of the first parts to build is an assembly of aluminum sheet and aluminum angle. Ended up with wavy rivet lines, but the rivets came out nicely. Used my pneumatic squeezer and played around with spacers and squeezer fittings, testing the shop heads to see how they conformed to the spec. All of these were within the tolerance allowed by the mil spec.