1952 Socema Gregoire turbine concept

The first French car powered by a gas turbine, the Socema-Grégoire had the effect of a bomb at the 1952 Paris Motor Show.

In this post-war period, military aeronautics buried the piston engine, which was living its last years. A subsidiary of CEM (Electro-Mechanical Company) which, in 1945, had produced a turbojet, then a turboprop, Socema (Société de constructions et d’équipements mécaniques pour l’aviation) was looking for new outlets for its technology. At the beginning of the 1950s, it became interested in the automobile, imitating the American Chrysler and the British Rover, the most advanced manufacturer with its Whizzer which reached 138 km/h in 1950. This would be the objective set for Socema’s future car and the record to beat in order to achieve fame.

The engineers designed a lightweight 100 hp turbine (named TGV 1) conventionally composed of three elements: a turbocharger consisting of a high-pressure turbine (45,000 rpm) driving a centrifugal compressor, a two-stage drive turbine (low pressure) rotating at half the speed of the high-pressure turbine, and a reduction gear (ratio of 5 to 1, or 25,000 rpm).

For the production of the automobile part, an area in which it had no expertise, Socema turned to engineer Jean-Albert Grégoire. The car would therefore borrow heavily from the Hotchkiss-Grégoire, in particular its alpax cast body inaugurated in 1937 on the Amilcar Compound, as well as its four-wheel independent suspension with variable flexibility.

Since front-wheel drive was inapplicable to a turbine-powered car, the Socema-Grégoire was a rear-wheel drive. The turbine is arranged in a front overhang and the transmission is entrusted to a Cotal electromagnetic gearbox. In the absence of any engine brake, characteristic of a turbine engine, the drums are assisted by a Telma retarder mounted on the transmission. The latter comes into action when the driver lifts his foot.

Made of aluminum at Hotchkiss, the body takes the form of a magnificent coupé with a tapered line - the aerodynamic study allowed an exceptional Cx of 0.19. As for the front, it is adorned with an air intake reminiscent of fighter jets.

Alas, in June 1952, Rover raised its record to 244 km/h. With its theoretical 200 km/h, the Socema-Grégoire is far from it. And in addition to its insufficient efficiency, the turbine still requires a lot of investment for its development. Produced for advertising purposes, the car only partially fulfilled its mission. It is true that the demonstration of the unrealistic nature of the application of the gas turbine to the automobile had not yet been made at the time.

Source:

• SOCEMA GREGOIRE concept
  https://www.motorlegend.com/salon-auto/retromobile-2005/socema-gregoire-concept/6,10944,10934.html