Hawker Siddeley Harrier as VTOL and STOL manoeuvres (where the traditional lift and control surfaces are useless) requiring skills and technical knowledge usually associated with helicopters. Most services demand great aptitude and extensive training for Harrier pilots, as well as experience in piloting both types of aircraft. Trainee pilots are often drawn from highly experienced and skilled helicopter pilots. In addition to normal flight controls, the Harrier has a lever for controlling the direction of the four vectoring nozzles. It is viewed by senior RAF officers as a significant design success, that to enable and control the aircraft's vertical flight required only a
Nord CT41 signature. Two types were produced, the CT.41A for high-altitude use, and the CT.41B for low-altitude training. If the drone was not shot down, recovery was via parachute. The CT.41 began test flights during 1959, with production starting later that year; 62 aircraft were constructed for use by the French Air Force. They had only a brief service life before being retired due to being too fast to provide practical training for interceptor pilots. Hawker Siddley acquired a manufacturing license for the type in November 1960. Six were acquired by Bell Aircraft for evaluation by the United States Navy; Bell also