Sud-Ouest SO.1220/SO.1221/YHO-1 Djinn
SO.1220 prototype first flight: January 2, 1953 (70th anniversary)
SO.1221 first flight: December 16, 1953
Sud-Ouest (SNCASO), a French aircraft manufacturing company, designed the Djinn as a two seat utility helicopter using a unique “cold jet” propulsion system. A 240 hp Turbomeca turbogenerator mounted aft of the cabin supplied compressed air through ducted channels inside the rotor shaft and twin rotor blades to rotor tip ejectors. This created nearly a ramjet effect without the bulky combustion chambers necessitated by the latter system at the rotor tips. The compressed air from the gas turbine engine expelled through nozzles at the rotor tips is warm enough to eliminate the need for other means of de-icing the blades.
The design also eliminated the need for a tail rotor. A cantilever monoplane-type tail unit provided directional stability with two fins mounted at the ends of the horizontal stabilizer and a large central rudder positioned in the engine exhaust. The SO.1221 Djinn was the first production French helicopter, as well as being one of the first practical European helicopters. They were primarily flown by the French military and used for liaison, observation, training and medical evacuation; 178 of the aircraft were eventually produced.
Description: Bob Beggs
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2023 History Calendar Index