On 7 April 1934, general Denain inaugurated the L1 wind tunnel in the presence of the first director of the I.M.F.L., Professor J. Kampé de Fériet. This wind tunnel is of the Eiffel type, with a streamlined return hall.
The wind tunnel occupies a 27 m long hall, covered by a 14 m wide and 30 m high circular roof; the concrete experimental chamber, which has a length of 16 m and which is divided into three stages, rises in this hall. The air enters this chamber through a 3.30 m diameter collector, taken in by a fan with 6 vanes of length 1.90 m. The air leaves through a conical diffuser, which spreads out into a wide toric diffuser of 8.40 m diameter. Between the collector and the diffuser, the part of the air stream where the models under test are placed has a diameter of 2.40 m.
So as not to leave anything to chance, extensive research was carried out on a 1/6 scale wind tunnel model by Mr Martinot-Lagarde. The aim of the study was to minimize the losses of the original installation designed by G. Eiffel. A number of innovations were hence added to the circuit in order to optimize its efficiency. These include:
Elimination of sharp edges in the return corridors
Detailed study of the profile of the collector and the filter which is attached to it
Profiling of the wall at the end of the hall on the collector side
The design of the fan and the vast toric diffuser are due to the design services of the Neu establishments. All this careful preparation has made it possible to achieve a motor fan unit efficiency of 89%.
This specific installation, validated by the initial tests, showed that the ratio of the kinetic power to the motor power could achieve 4.40 as against 2 (2 m diameter St-Cyr) to 1.33 (3 x 16 m at Chalais-Meudon) for existing wind tunnels of the Eiffel type.
In its first years of activity, the wind tunnel progressively became the installation of choice for the Potez house located at Meaulte. In 1938, the threats of war took predominance. Aircraft manufacturers were using the wind tunnel almost constantly: Potez of course, but also Latécoère, Dewoittine, Liore-Olivier and so on, and the tests were carried out at the rate of 52 hours per week. In 1940, faced with the German advance, forced relocation to Toulouse was announced. In 1945, the return of the staff and the recommissioning of the wind tunnel, which had suffered little, allowed a rapid return to activity. Mr Martinot-Lagarde succeeded Professor J. Kampé de Fériet as head of the I.M.F.L. in July 1945. During the 1950s, the wind tunnel served Nord-aviation, Dassault, Morane Saulnier, Hurel-Dubois and the like.
Since then, the wind tunnel has undergone numerous improvements or conversions. In 1981, the entire installation was refurbished. A module room was set aside for storing various setups on standby. Two large communicating doors were fitted so as to allow access for these setups in the experimental stream. Four hoists and a rolling gantry were installed in order to handle heavy or bulky elements. The worn-out floors were replaced by tiled surfaces. A room set aside for measurement was created. The wind tunnel motors were overhauled: 80 m/s can now be achieved. In 1988, the installation of the P.Q.R., a new dynamic setup, required new refurbishment. Open stream operation was restored. A glass fiber take-up collar was produced.
In 1995, the I.M.F.L. extension work allowed direct axis between the wind tunnel and the outside. An unloading bay was constructed behind the motor room.
