Elevator Trim Tab Prep

On to the elevator trim tab. The trim tab is a small and simple movable control surface that is built into the left elevator. It has a bent trailing edge (just like the elevator) and a single spar on the leading edge. The ends are formed from tabs that are bent together.

Bending the trim tab ends requires the fabrication of a hardwood form around which to bend the sheet metal. The following sequence of photos shows the bending of the tabs:

In the photos, you can see that the hardwood block is cut such that the top piece overhangs the bottom wedge. This prevents the top piece from sliding down the slope of the sheet metal when pressure is applied. I know this because this is the second one I made. The first one didn’t overhang and was a real pain to try to keep stable while pounding away at the metal tab.

The first tab to be bent is the bottom tab. We want the top tab to overlap the bottom one so water dripping off the surface is shed away from the airplane, not collected inside the trim tab. Here’s what it looks like fully bent.

The assembly is then flipped over and the top tab is bent down over the bottom one.

The same is done on the other end of the trim tab.

The assembly, including the skin, spar, and the two-piece trim tab horn, are then clecoed together and drilled for eventual riveting.

The next task will be to fit the trim tab to the elevator. I expect this to be tricky and difficult because I want to make sure it fits properly and aesthetically with the proper alignment and edge gaps. Here is what the finished ends look like:

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