Hi Tom, I saw an old article in an old magazine of a Cox .049 engine attached to a small block of wood and two shop rags hanging from it. Bob Stought at our meeting said he had one that he had flown a dozen times and a few days later presented it to me. See picture attached. You get the engine running and give it a twist in the direction of torque and send it straight up. The rags each with a knot in the end swing out with centrifugal force and it goes up like a helicopter. He said it works great. The rags are saturated with oil presumably from the exhaust so I have to believe it. What could be simpler. Not a good glider though.