It is known that most modern aircraft engines are equipped with a compressor capable of restoring the effective power they have on the ground and the decrease in air density to a certain altitude (typically 4000 m), as one climbs into the atmosphere, one would reduce in considerable proportions.

The test benches used until now in factories only artificially realized these data, neglecting obligatorily a large number of factors (exhaust pressure, temperature, hygrometry, etc.).

The need therefore arose for a high-altitude test rig equipped with all measuring instruments and instruments to continue testing under any weather conditions.

For this purpose, the Adminstrator of the SOCIÉTÉ NATIONALE DE CONSTRUCTION DE MOTEURS, Mr. Claude BONNIER, obtained from the Ministry of Air the authorization and the necessary assistance to build in Mont-Lachat a first altitude test station.

Opening of the Mont Lachat test station (October 1937).	Air-cooled engine test bench on the platform.

Realized in less than a month during the autumn of 1937, the station and its living quarters made it possible as early as 1938 to obtain numerous results of primary interest, in particular on:

• icing;
• Cold start;
• Injection into the engines;
• Compressor tests at altitude;
• The variation of the ignition advance as a function of altitude, etc.

During the summer of 1938 a new effort was made to enlarge the circle of research by adding new benches, new premises, and better protection against snowfall and avalanches and finally by improving the means link from the station with the factory and the outside world.

One floor has been added to the already existing buildings, which makes it possible to shelter very widely the two new test benches, one for a water-cooled engine and the other for an air-cooled engine.

These two benches can be brought on a large concrete platform close to the workshop and the laboratory.

The lower level is reserved for the test beds of the single-cylinder and the mechanical workshop.

Staff quarters were provided with all the comfort that could be achieved under these circumstances, which eased the harsh conditions of the winter season.

But the projects of the SOCIÉTÉ NATIONALE DE CONSTRUCTION DE MOTEURS do not stop there, and a new station at the altitude of 3.800 m. must in the near future be realized. The lessons learned for aviation engines from these upper-air tests are an important contribution to aeronautical progress and its development in the future.

Installation of the test bench of water cooled engines.	The Mont Lachat test station in winter.