How did the propellers attach on a Lazair attach if the shafts had a woodruff key instead of opposite thread?
I believe that while the original engine shafts had a slot for a woodruff key, no key was actually used in attaching the props to the crankshaft. Instead, a nominal arrangement of multiple (6, I believe) bolts attached the props to the crankshaft for mutual transmisal of both engine torque and prop thrust. Presumably the bolts were secured with safety wire, but I have no data on this.