Gear Legs

Last updated November 8th, 2022!?  Time sure gets away from you sometimes, doesn't it. Woof..

 A lot of time was spend figuring out main landing gear legs. The first step was taking the info from the Piper drawings and laying out the gear v's full size on my table, then jigging the parts in place.

 This is what we're building. The left side of the picture would be facing the front of the aircraft.

 

And here's the jig laid out on my table. The nearer jig sets the relationship between the forward tube and the axle. The farther jig aligns the forward and rear tube as well as the bushings on which the gear leg will pivot.

With the jigs laid out it's time to manufacture parts. First came the pivot bushings, and they were a bit of a process. First the little U-shaped piece of metal that holds the bushing needs to get bent to shape. I made a little die the right size to bend the material in my vice. After the U is bent it then gets a notch ground out to fit around the bushing and the bushing is welded in. The jig has bolts pushed through the table where the bushings go to register them properly. 

 

Tubing is then slid up against the bushing assemblies, marked, and cut to fit. Paper patterns from an online tube-notching calculator help get everything cut to the right shape. The next problem is one of fitting the tubing to the bushing assembly. The tubing is round (obviously) but the base of the assembly is square. Leaving it like this would make welding them together and adding the subsequent reinforcement strap very difficult. I took some scrap tubing and tried a couple different techniques to make them fit together. Ultimately I was able to heat the end of the tube 1/4 at a time and hammer it flat until I got a pretty even square shape. 

A similar technique was used on the rear tube, but because this meets the bushing assembly at an angle only two sides were flattened. The assembly was then tacked on, the overhanging tube notched, heated, and bent back onto itself.

 

 

 That sets most of the actual V to rest. Next I had to move onto the axle. Well, actually, the axle is also a two piece assembly. There is the thinner outer sleeve which welds to the V and the thick inner axle. Both the outer sleeve and axle need ears cut on one end then drilled and flattened. I cut the ears into the first one then heated it to flatten out the ears. I had cut the notch too square and the tube was now scrap. I ordered some more tubing. In the meantime I lopped the ears off, marked them out again, and tried cutting a rounder notch. I was much happier with how this one turned out and duplicated it when the new tubing came in.

With that part done, the axle then needed to be threaded for the axle nut. I managed to find a die the right size to cut the threads, but couldn't find a reasonably priced die-wrench. So I made up a tool to keep the die aligned with the axle so I could turn it with a wrench for the actual threading operation. More scrap tubing for the win!

 

And the axle nut threads on perfectly.

 

With those parts all made and the weather warm enough I could finally start welding the gear V's. The front and rear tubes were tacked together then fully welded. The inner and outer axle were welded together as one assembly and then jigged up and tack welded to the V. That's what's happening in the following pictures. There's more, but that will have to be saved for the next post.