So since the last post a lot of things have made some progress. I didn’t blog about them at the time, but here are some things that happened, including what got done today.
I got the oil cooler duct fitting better and also drilled to the aft baffle to finish securing it in place.
Today we also worked a bit on the aileron trim. We put together a relay pack to be able to drive the trim motor. We now need to run the wires from the stick to the relay pack, then mount and wire the actual motor.
I made a pushrod for the autopilot roll servo to connect to the roll torque tube. It the short pushrod you see here. It was a simple job of chucking up some aluminum bar in the lathe, drilling and tapping it. Here it is in place.
It took a bit of fussing to get the servo rigged properly. I don’t think the manufacturer intended for the pushrod to go on the side of the servo bellcrank that I planned for. In the photo above you can see minimal clearance between the servo mounting bracket and the pushrod. The clearance is tight and requires specific hardware and pushrod length. But it does actuate without rubbing or binding. I lucked out on that one. I also painted the steel bellcrank that attaches to the aileron torque tube.
Lastly, baffles. They are the bane of my existence. I am more or less copying the Berkut baffling setup that James Redmon uses since my cooling is most similar to his. So I made templates and started bending up some cylinder head baffles. It was a miserable failure. There is just no way to get aluminum to follow the complex curves of the cylinder cooling fins without gaps and air leaks. Doing it this way seems to work well for James, but I am not happy with my attempts. This is my best attempt and there are all kinds of problems with it.
I know James has had success with this method and says he can bend one up in minutes. But I can’t. In talking with other friends I came to the conclusion that I have to be able to do better in fiber glass. So I set to work on that method.
It starts with putting tape down in the cylinder to protect the engine and provide for a mold release.
Then just layup the glass with west systems epoxy. In this photo you can see that I decided to make this baffle go around the nose of the crank case. There were some gaps here that were larger than I would like. This would spill my precious cooling air. Instead of using an ugly mess of RTV caulk, I figured that my glass baffle could serve this purpose too. It may require RTV as well. But much less and it will be less likely to deteriorate or break loose.
It was actually fairly difficult to do this layup. Mostly because of poor planning on my part. I was trying to use too big of pieces of cloth and do it all at once. It would have been easier to do multiple small pieces. It is 3 plies of glass, with a total of 5 plies where the fiberglass baffle will be fastened with screws to the aluminum baffle. We will see how this turns out when I release it in the morning. I think the idea will work, I’m just not sure this attempt will turn out as I want it to. More on this tomorrow.