On Wheels

With everything attached for the front and main landing gear, and all of the fuselage riveted together, I decided it was time to drop the fuselage onto its wheels, and free up my workbench. I’ve been working on the fuselage for a little over a year now, so I suppose this is something of a milestone. But there’s still a lot of work to do!

It’s a tricycle!
Nose wheel

The last thing I did before dropping it on the wheels was to install some shims on the bushing for the nose wheel. Despite the improvement I saw from sanding the bushings, I was still observing a gap between the split bushing halves, and this seems to cause some friction as the bushings get compressed by the retaining plates. So, I 3D-printed some shims that are 1.1mm thick. It seems to help.

This is the gap that I think is causing the bushings to come out of round when they are compressed by the retaining plates
Shims for the split bushings
Shims installed with the split bushings
Last photo I took just before dropping the fuselage onto the ground

Despite all my efforts, I still see about 7 pounds of break-out force on the nose gear. That’s not much to have to push with my feet, but since the nose wheel is mechanically linked with the rudder, I want to be sure that the rudder will return to neutral when I let off the rudder pedals. I’ve been unable to find a spec for break-out force, so I don’t know if 7 pounds is too much or two little. From what I understand, you want some resistance to avoid having the nose wheel wobble while taxiing on the ground. Here’s a little video showing how I measured the break-out force:

Measuring break-out force

Fellow Sling builder Evan B. has strongly recommended that I grease the contact surface between the leg and bushing; apparently they do this even at the factory. I tried using some LPS-2 spray lubricant, but that didn’t work at all, in fact it made things worse! Instead, I think I’ll need to use some of the grease that’s supplied with the kit for the wheel bearings. For now I’ll leave the bushings dry until I can attach the rudder and see how well the rudder springs work. I will also consult with TAF.

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