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
Hawker Hoopoe fitted during the short trial period, two variants of the Bristol Mercury were later replaced by an Armstrong Siddeley Jaguar and Panther with an increase in performance. Trials at Felixstowe in 1929 with floats fitted showed that the aircraft was severely underpowered with the Mercury powerplant, requiring the change to the Jaguar engine. Service interest in the type had waned by autumn 1930 although the single prototype continued in development flying with Armstrong Siddeley and the Royal Aircraft Establishment until 1932 when the Hoopoe was scrapped. Hawker Hoopoe The Hawker Hoopoe was a British prototype naval fighter aircraft designed and