In this article, we will describe the final steps to completing the main part of the wing test piece, the fin. By now, a large part of the work has been done and the goal of a small wing with a moveable flap and actuator-driven flaperon seems to be within reach.
While producing the small parts for the flap, we also produced most of the small parts needed for the fin itself. As for metal parts, apart from the milled aluminum pieces fixed to the flap, we also added welded steel pieces. Most self-made metal parts were made of standardized parts such as rod-end bearings and bolts, which were then united into the flap drive assembly. Each assembly recieved a solid stop, which wouldn’t exist in the real plane. Instead, these stops are only there to prevent damage to the test piece. Other than the flap mechanism, we also installed aluminum milled flap guide rails. These rails are glued to ribs which will then be fixed to the test piece.
Once we’ve prepared all the sub-assemblies, we could finally begin with gluing them to the test piece. We started with the linear bearings for the push rod, which were fixed to the spar. Next came the above mentioned ribs with the guide rails, which were installed together with the flap itself, along with a rib which held a bell crank. To complete the structure, the rear torsional stringer was added in. Easily visible here are the large holes on the spar flange, through which the guide rails and flap mechanism jut through, and a large diversion towards the leading edge, which allows the placement of the actuator, itself fixed to the flap. These discontinuities in the rear stringer seem extreme in the small test piece, and we will face similar issues when designing and building the real wing later.
After all parts have found their places, it was finally time to close the fin. The gluing area on both sides were sanded down and thickened epoxy resin is spread. The next day, the suspense was great as we opened the molds, and we could finally eye the test piece outside its mold for the first time.
Author: Tim Podufal