sentences:  This configuration was tested in 1947 with a scale-model in a wind tunnel at the Royal Aircraft Establishment at Farnborough, and much useful data on its performance was acquired.This determined that a single rotor at the front and the pair at the back of the fuselage was preferred for optimum stability and control.A Rolls-Royce Merlin piston engine in the fuselage drove three three-blade rotors mounted on outriggers which projected from the fuselage.