Sethhunter

Hi Alan,
Definitely good points. Not an undercarraige to bang around. I'm not too worried about the machine screws because there is a big steel pin set in the fuselage that runs through the fitting into a dowel in the aluminum strut (you can see the pin in the sketch but not the photos). The pin should take much of the shear load at the fuselage/LG joint; the bolts just hold the gear on the pins. Also, the strap that runs under the nose from side to side is functional, as on the full scale, forming kind of a craddle to distribute landing loads more uniformly to the bulkhead inside. That leaves the aluminum itself - I share your concern and did epoxy dowels a couple inches long in each end to prevent buckling at the joints, but not all the way through - I may regret that! In a hard prang, it may buckle. Incidentally, I used fairly heavy walled tubing from McMaster Carr, not thin hobby-fairing tubing. It came round but I squeezed it down slightly to ovalize it a bit. I can't find a scrap to measure it up (it's in my notes somewhere) but I'd guess the wall thickness is at least .030 or .040", probably T6 hardness. Of course I was trying to save the weight of a lot of steel down there, and of course there's major bungy on the bottom. If it buckles, I'm hoping it saves the fuselage. If it buckles too easily, the next gear would be more traditional; steel wire with wood.

More to Vern's question, I'm a bit more worried the cup that's anchoring the drag wire turnbuckle might pull out in a rough wing-down landing - I did not destructively pull test that joint. If it becomes a problem, I'd drill back into the fuselage and pin the turnbuckle end deeper inside.

The comments are great - please keep them coming - I sure don't want to overlook problems or reconsider other design methods.