The gyroplane is not a helicopter because its rotor is not connected to the engine. The rotor is activated by the air flow which forms during the take off run and maintains its rotation when out of gear. Unlike a helicopter the gyroplane has a tail unit instead of a tail rotor. Moreover — just like an aeroplane — it needs a take off strip because it can not lift vertically. The radial engine and rotor work just as they do in an aeroplane. This Cierva C-30 was the first and most common gyroplane before WWII. The British Avro, already financially and industrially connected to the de La Cierva, started its production in 1934. This model was an evolution of the 1931 C-19 type, fitted with a more powerful engine: the Armstrong Siddeley Genet Major IA, 140 HP.