Monday, January 05, 2015

Fuselage, tail wheel

I have ordered the 6 inch tail wheel assembly. It came with the engine. At first look it looks really nice, clean design and nice black anodized parts. A closer look, and I was not so sure.

The first thing was the steel horn. It has sharp edges, and when swung to one side the edges cut into the cylinder holding the tail wheel titanium spring.

The first thing I did was to remove the steel horn and trim the edges son no interference was seen. Then I painted the horn with 3 in 1 paint, so it won't rust.

Then I noticed the but holding the bolt working as the axle. Common aerospace rule of thumb say at least one thread must show, but no more than 4.

Removed it and measured the bolt. New and one size larger must be ordered, preferably with a cotter pin, because the bolt could rotate if the bearings seize up.

The titanium spring rod was way too tight fit. Lots of trimming was needed to make it fit into the tail wheel assembly. Used the bench drill to drill the holes for the AN4 bolts as square as possibly (hopefully the holes in the fuselage that I made earlier is also correct)

Then I saw something strange abut the whole design. All the vertical forces and the torsional forces from the wheel is taken up small bronze bearings. These bearing are completely exposed to the environment. If that bearing last even for one single season with normal rainy weather and mud, I would be surprised. The bearings are easy and cheap to change, and the assembly seems both solid and light, but still.

All in all, the tail wheel assembly is OK. Light and strong, but requires some modding and probably yearly maintenance (changing bearings), but time will tell. Looks very nice though.

Made the handles for the wing folding mechanism.

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