How can SR/C aircraft fly so fast and efficiently? Shouldn the rotor slow them down?
SR/C aircraft are a hybrid between an airplane and a rotorcraft. A rotor is a very efficient device for providing lift at low speeds, but its drag increases rapidly as the aircraft goes faster if it must continue to support the aircraft. In SR/C aircraft, as the aircraft speeds up and the wings begin producing more of the lift, the rotor produces less lift and can slow down given the correct control input. The reduction of rotor lift and lower rpm significantly decrease the rotor drag (in fact, a three fold reduction in rpm results in approximately a 27 fold reduction in rotational drag- drag required to just spin the rotor). The rotor drag at very low rpms and low lift basically becomes a function of its area (which is relatively small compared to an airplane wing of similar gross weight) and the forward speed of the aircraft. Wings are very efficient at high speed, but can’t provide enough lift as the aircraft slows down. In most aircraft, the wings are sized significantly larger tha
