C.19 Mk II by a 105 hp (78 kW) Genet Major I. The C.19 Mk IIA, introduced in 1930, had a longer undercarriage and improved rotor head. Landings were often made at high angles of attack, so the rudders of the C.19 Mk III were reshaped to slope sharply upwards to avoid damage; this variant also had a 5 ft (1.52 m) increase in rotor diameter. In the C.19 Mk IV, the rotor was started directly from the engine via a clutch mechanism, as in all future autogyros. This allowed the elaborate biplane empennage to be replaced by a more conventional monoplane tailplane. The single central fin was low and of correspondingly deep chord, to avoid being struck by the rotor. The C.19 Mk IV had a three-bladed, cantilever rotor. The designation C.19 Mk IVP was also used, the "P" standing for production, that started in 1931. The final variant was the solitary C.19 Mk V, G-ABXP. The aircraft-style controls of earlier autogyros depended on airflow past ailerons, rudders and elevators; during the slow forward speed phases of takeoff and landing, these were ineffective, and accidents resulted. The C.19 Mk V lacked the small wing and all-moving control surfaces, relying instead on a tilting rotor head. Using a long control arm that reached to the rear cockpit, the pilot could direct the aircraft by tilting the plane of rotation of the rotor. After a period of experimentation, the C.19 Mk V flew with a small fixed tailplane and a two-bladed rotor. This control system was adopted for the Cierva C.30. Operational history Some thirty examples were built in England, with licences acquired by Focke-Wulf to produce it in Germany (as the C.20) and by Lioré et Olivier in France (as the C.21), although no actual French production took place. Initially, all fifteen C.19 Mk IVPs appeared on the British civil register. One was used in an attempted flight to South Africa, although it only reached Tunis. Later, it flew with Alan Cobham's Circus. Another went to an autogyro flying school at London Air Park, Hanworth. Several machines were reregistered abroad: in Australia, Germany, Japan, New Zealand, Singapore, Spain (one for the Spanish Air Force) and Sweden. During the early 1930s, the Royal Air Force operated two C.19 Mk IIIs for evaluation of the autogyro concept (serials K1696 and K1948). Variants C.19 Mk.I – The original three prototypes, powered by a