Sud-Ouest SO.1310 Farfadet

This is the first French convertible. It can take off vertically, hover in the air, land vertically by means of its rotor, and fly forward at a speed greater than that of pure helicopters by means of a fixed wing and an airscrew fully independent of the rotor.

The change from one state to the other is accomplished without any change at all in the external appearance.
The SO.1310 is provided with two independent power units. In the rear is an Arrius II 360hp Turbomeca unit, which supplies the jet rotor with compressed air at take-off. The all-metal three-bladed rotor is identical with the one used in the SO.1120 Ariel III, but with a larger diameter. 

In the forepart there is a Turbomeca Artouste II turbo-prop engine with a take-off power of 360 hp, operating a variable-pitch airscrew. During forward flight, the rotor originally used for take-off continues to auto-rotate, but with low lift, and the greater part of the lift is transferred to the fixed wing. Mounted over the fixed wing is the pilot's cabin, fitted with dual control, and in this cabin there is room for either three passengers, a freight load or two stretchers stacked on top of each other.

The Farfadet single prototype F-WBGD first flew on 8 May 1953. Its maiden flight, lasting about twenty minutes, was made as a true helicopter, the following one, on the same day, with the rotor and the airscrew respectively powered by their individual engines.