Update to Rear Torque Tube Modification

In my last post, I documented a problem I found when joining the center and rear fuselages. The modifications I made to the rear torque tube didn’t account for the clearance needed for the rudder conduit fittings, which are mounted very near the torque tube, and were butting up against the shaft collars I added to the torque tube. The fix was pretty straight-forward, which involved adjusting the position of the shaft collars . I had to remove a small amount of material from flanges on the floor ribs, to ensure the shaft collars have enough clearance. Nothing rests on top of these flanges, so there is no impact.

I’ll start with a link to a YouTube video I created showing the changes. After the break, there are a few more pictures showing more details of the modified parts.

The circled areas will be cut to provide clearance for the shaft collars, about 1mm on the front side and 4mm on the aft side
Shaft collars fit just fine after cutting the flanges

While I had this torque tube apart, I decided to make some improvements. I recently started experimenting with powder coating, so I decided to bake on a protective finish to the bearing plates. Secondly, I designed boots to fit over the bearings, to prevent any foreign material from getting into the bearing raceways and causing them to degrade or bind. The boots were 3D-printed with TPU material, which is strong, flexible, and tolerant of high temperatures. The boot are attached with rivets, since I don’t expect to have to replace them.

Bearing plate powder-coated
TPU boot to prevent debris from entering the ball bearing
Completed assembly, minus a close-out washer that goes on top of the bearing on this side

After I was happy with the revised design, I re-assembled the torque tube and put everything back together. The torque tube still rotates very smoothly, and the interference has been eliminated. I am now able to continue with joining the center and rear fuselage.

Re-assembled torque tube

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