 Tiltrotor

A tiltrotor is an aircraft which generates lift and propulsion by way of one or more powered rotors (sometimes called "proprotors") mounted on rotatable engine pods or nacelles usually at the ends of a fixed wing or an engine mounted in the fuselage with drive shafts transferring power to rotor assemblies mounted on the wingtips.Almost all tiltrotors use a bicopter design with two transverse rotors, with the exception of only a few (such as the quadcopter Bell X-22).