Building a Sling TSi

This week I visited TAF with my friend Anatoli to work on the flaps and ailerons. We assembled the right flap, but could not proceed with the left flap because our kit had been shipped with two right-side skins.  So we proceeded with the assembly of the ailerons. This time there was a missing spar of the right aileron, so we only assembled the left one. We could not perform the alignment because you need both flaps and ailerons for each side for that.  Then we tried to install the heat exchanger behind the firewall. We could not finish that because a part had been borrowed for another plane. So we did some interior work and called it a day. Lesson learned, make sure all the parts you need are present before you show up for work!

Today we used this ingenious gadget to pressure test the fuel tanks. You simply block all the ports to the fuel tank and pressurize the tank to 1 psi and wait. You then apply soapy water to all the seams. If you don't see any bubbles, and the the tank holds pressure for an hour or so, it passes. We immediately founds a small leak, but it turned out to be a bad seal in the pressure tester. After that was fixed both tanks passed the test, and are ready to be installed on the wings.

  Keeping the cabin cozy and quiet is an interesting challenge. Key vectors are in fierce competition: weight, strength, workability cost, just to name a few. We want to try our best to insulate the cabin, to keep the noise out with reasonably thermal protection while keeping weight under control ( a quick reminder, the TSI offers one of the best useful load numbers in this class of airplane, and we don’t want to screw such record!). This weekend we had fun removing some skins, adding extra insulation when possible and covering every place we thought would contribute to our goals. Arthur did have fun reaching to incredible places, and he did a terrific job!

I built my first RC when I was 13 years old. It looked great. It flew like a brick, from my hand (the launch pad) to the ground, in what now I would call a deadly spin. It took me several years until I went back to building models. Our first son was my assistant. One of the things I knew, was there was a need to “misalign” the engine in the longitudinal axis to compensate for turning tendencies. Then I earned my PPL certificate, and I could say I had a better understanding of adverse yaw, and left turning tendencies (no, I am not talking about politics). And that was when the lightbulb went off: sometimes, airplane designers, tweak engine mounts to offset the left turning tendencies. This weekend, we work in N333ST, our TSI. Arthur and I were in awe when we noticed how the offset looks like. You can easily see the engine mount itself (view from the top), and once the engine is mounted, it clearly points to the right.