The Gyrodyne was a compact, streamlined rotorcraft weighing just over 4,410 lb (2,000 kg) and powered by a 520–540 hp (390–400 kW) Alvis Leonides 522/2 radial engine, the power from which could be transmitted in variable ratios to the fixedshaft/swashplateactuated tilting hubcontrolled rotor and the wing tip mounted propeller. The Gyrodyne possessed the hovering capability of a helicopter, while its propeller provided the necessary thrust for forward flight to enable its rotor, driven at low torque in cruise flight, to operate at low collective pitch with the tippath plane parallel to the flight path to minimise vibration at high airspeed. Collective pitch was an automatic function of throttle setting and profile drag of the propeller, which to maintain rpm diverted torque away from the rotor as airspeed increased.


This promising helicopter gained a speed record of 200.03km/h not long after the first flight. Unfortunately the success was overshadowed when a fatal accident occurred ten months later and the project was discontinued.