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Wednesday, July 2, 2014

Trex 600 Tail Mod

I flew the Trex 600e Pro last week and once again stripped the tail torque tube forward umbrella gear,  the torque tube umbrella gear, and the autorotation gear, and cracked the tail blades when the tail fin buried and the blades struck. I did some research and learned that this is a pretty common problem. I saw that many used a Trex 700 tail fin. Its longer than the 600 fin, and I got a 2mm thick one, so its strong (the one I had was 1 mm and literally flapped in vibration). I also saw someone who put a servo wheel on the end, and I decided instead to use a star as a spur. This keeps the pointed end of the vertical fin from cutting into the ground allowing the blades to strike.

When I was flying it last time we heard some loud rubbing suddenly occur in flight, and I saw evidence that the main gear rubbed the carbon fiber frame (carbon powder on the main gear), but I couldn't reproduce anything rubbing when I landed. Today I replaced the stripped autorotation gear and removed the main shaft. I always clean the main shaft bearings when I change gears and on removing the lower bearing I saw that the top of the autorotation bearing had ground into the bearing block and ground it a bit. I pulled the block (should have took pics, sorry), and Dremel ground the damaged edges. The block and the bearing seat are essentially fine albeit damaged, and the bearing sits clean, straight, and snug. I will need to replace the block at some point, but it functions fine. I gave it a blade-less spin up and it was silent, balanced and vibration free. I'm planning on flying it tomorrow, and bringing it home without stripping the tail assembly!

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