convertiplane

Vertical takeoff and landing craft (VTOL) with rotors on its wings that spin horizontally for takeoff, but tilt to spin in a vertical plane for forward flight.

At takeoff it looks like a two-rotor helicopter, with both rotors facing skywards. As forward speed is gained, the rotors tilt slowly forward until they are facing directly ahead. There are several different forms of convertiplane. The LTV-Hillier-Ryan XC-142, designed in the USA, had wings, carrying the four engines and propellers, that rotated. The German VC-400 had two rotors on each of its wingtips. Neither of these designs went into production. A Bell/Boeing design, the V-22 Osprey, uses a pair of tilting engines, with propellers 11.5 m/38 ft across, mounted at the end of the wings. It was originally intended to carry about 50 passengers direct to city centres. Crashes of two prototypes led to design changes 1994, but the project continues.