hi friends, on 14 October 2011 there was an exhibition organized by some 20 UAV manufactruing companies in New Delhi, India. It was wonderful to have something like this in India. The technology dispalyed was amazing. there were fixed wings and rotary winged UAV's. The show was won by this twin cylinder rotary engine designed for UAV's. The manufacturer claims to having nil vibrations in the engine. a very important issue for IMU's in the autopilot. beautiful engine with circular cross section and excellent cooling fins and fuel injected. runs on petrol as well ATF. amazing. Weight? only 2700gms with air intake and muffler. from outside looks like a turbine engine. more details on www.cubewano.com. It's a british company. a dream engine.