Machining the Trunnion

the first operation

The first stage, after surfacing a block of aluminum flat and parallel on both sides and adding some hold down slots, was to clamp it down on a scrap piece and machine the first side profile, using standard carbide endmills for roughing and ball endmills for finishing. The picture shows after this first operation is complete. We’ve added four bosses outside the actual part profile for hold down capscrews and dowels. They will be cut off in a later operation.

Nosegear Trunnion

Nosegear assembly for Sunseeker Duo

This is a recently finished part that we did for Eric Raymond, who is currently building a 2-place solar powered airplane in Europe at www.solar-flight.com. The mechanical design of the nosegear was done by Rick McWilliams at Tangent Instruments, with assistance on the shock absorbing portion from Gil Vallaincourt of Works Performance Shocks. Eric is building an extremely light and efficient airframe from carbon fiber, and weight is a huge factor. So this unit has to incorporate oleo-pneumatic shock absorbing and damping, steering, and retraction- all in a very compact unit. Total weight with hydraulic fluid is about 4 pounds, and the design has been optimized with finite element analysis to meet the anticipated landing loads. The trunnion (main piece) is 6061T6 aluminum, machined from the solid, Type I anodized, and the stanchion (moving cylindrical piece) is 7075T6, because it sees the highest stresses. It is hard anodized and polished for wear resistance.  Most of the fasteners are titanium. It has some fairly fancy internal bearings and seals. I will publish additional bits as I go along showing how some of the components were made. We can’t wait for his first flight.