© Science Museum/Science and Society Picture Library
The development of the jet engine during the Second World War produced aero engines with a thrust that was greater than their weight, offering the possibility of aircraft that could take off vertically, and which would not need long, expensive and vulnerable runways.
Rolls-Royce developed the Flying Bedstead in 1953 to test the principle. With two Nene jet engines - at that time amongst the most powerful in the world - and an available thrust greater than the weight of the whole assembly, it was clear that the machine could take off vertically.
The main purpose of the tests was to see whether jet-borne flight could be safely controlled by the pilot. The control system, devised in association with the Royal Aircraft Establishment, Farnborough, used jet reaction from 'puffer jets' carried on long outriggers and fed with high pressure air bled from the engine compressors. The cockpit control column operated valves for these jets, allowing the pitch and yaw of the vehicle to be controlled. The tests showed that pilots could achieve stable hovering flight and the control system used today on the successful Harrier aircraft works in exactly the same way.