I asked a question about planes with wingtip propellers on facebook and got some answers. Chance Vought V-173 "Flying Pancake See more here . Alice - Electric Airplane. Looks very efficient. The 3rd engine for safety and takeoff but not cruise. The NASA X-50 Maxwell has extra engines along the wing for short takeoff but for efficient cruise the plan it to just use the two on the wingtips. This next one is the only RC airplane I have found so far with propellers at the wingtips. It has "vectored thrust", meaning servos can chance the angle of the motor/propeller. The creator says that ailerons take 2 servos also so the weight is about the same but if you drop fast in hover mode the ailerons can have air going over them backwards so the control becomes backward. Also, when very near the ground in "ground effect" there can be very little air going over ailerons, so very little control. So for landing "vect