Breguet Gyroplane Laboratoire
Towards the end of the 1920s Louis Breguet returned to the study of helicopters and in 1929-30 took out patents for systems for stabilising aircraft of this type while in flight. In 1931 Louis Breguet formed the Syndicat d'Etudes du Gyroplane, with Rene Dorand (who had joined the Breguet company in 1924) as technical director, and began the design and construction of an experimental machine known as the Gyroplane Laboratoire.
In 1935, with the cooperation of René Dorand, Louis Breguet completed the coaxial Gyroplane Laboratoire, which was the first helicopter to meet the aviation industry's control and performance expectations for a practical design. Returning to his lifelong fascination with helicopters, an older Louis Breguet oversaw but did not participate directly in the construction and testing of this compact single-seater.
Intended originally to be powered by a 240hp Breguet-Bugatti engine, it consisted basically of a steel-tube open framework supporting the engine, fuel tank, flight controls and pilot, with rear booms carrying the plywood-covered tail surfaces. An unusually wide track main undercarriage was mounted on outriggers from the central framework, with a small tailwheel and a nosewheel to prevent the machine tipping forward on landing. The transmission from the big radial engine drove a pair of co-axial, counter-rotating, 2-blade metal rotors whose blades had an aerofoil section and an unusually large diameter. One rotor shaft turned inside the other, each rotor thus cancelling out the torque created by the other. Novel features for the time were the use of a cyclic pitch control for lateral and longitudinal movement, and collective pitch for movement in the vertical plane.
The Gyroplane was badly damaged in a ground accident at the end of 1933. Rebuilt with extensive modifications and tested conservatively on the ground, it resumed flight tests in June 1935. Breguet then committed it to maneuvering, speed, altitude, and endurance requirements far in excess of anything so far accomplished by a helicopter.
The Gyroplane Laboratoire set four world records in 1936 when test pilot Maurice Claisse flew the craft at 98 kph (61 mph) (September 11), to a height of 158 m (518 ft), over a distance of 43 km (27 miles), and for a duration of 62 minutes.
In 1937 (after a similar achievement by the Fw 61 in Germany) it made its first 'engine off' landing using autorotation. The Gyroplane was badly damaged in June 1939 during autorotation tests. It was subsequently destroyed by Allied bombing of historic Villacoublay Airfield in 1943.
It is not certain whether the Bugatti engine was ever installed; the aircraft did most or all of its flying with the more powerful Hispano engine.
Engine: Hispano-Suiza, 225kW
Rotor diameter: 15.89m
Max take-off weight: 1950kg
Empty weight: 1430kg
Speed: 98 kph (61 mph)
Ceiling: 158 m (518 ft
Range: 43 km (27 miles)
Endurance: 62 minutes.