Begins his career in 1945 with the Air Ministry. The following year he moved to SIPA where he designed the SIPA 90, of which 130 were built. Based on this success, the company was moved in 1949 to Pau. Next came the Minicab, of which 30 were built by the company, but a further 130 were built by amateur builders.

This two seater achieved many successes with speed and distance records. In 1952 over a closed circuit of 1 080nm, the Minicab completed the distance at an average speed of 99kts, with an engine of only 65hp. The SIPA 200 Minjet came next with Turbomeca Palas engine of 160kg of thrust, a wingspan of 7,2 m, it was an excellent aerobatic aircraft. The SIPA 300 two-seat tandem never made it past the prototype stage. A return to roots came next with the Supercab, 90hp engine, retractable undercarriage, cruise of 142kts. The idea of the SIPA 3000 followed but only 3 were built, the SIPA1100 remained as a prototype.

Between 1958 and 1962 in Pau, Yves Gardan designed a four place all-metal aircraft with retractable undercarriage and conjugated flaps. Two engines would be possible, 150hp and 160hp, two propeller configurations, fixed pitch and variable pitch. This design would be the eventual GARDAN HORIZON.

First flight was in 1960. The plane attracts the attention of Sud Aviation - enough attention for the company to buy the licence. The GY 80 was certified in 1962, a total of 270 were built. The public life of the GY80 really started on the 6th May 1963.

The Gardan GY80 of the Musée.

Jean Caillard, test pilot and long time friend of Hirsh ( also a friend of Yves Gardan ) donated the aircraft to the Musée Aéronautique - under strange circumstances !

The aircraft was used extensively for experiments into flight in turbulence. Hirsh continued his thesis into the absorption of turbulence that he had started in 1938. He died in 1995, leaving the aircraft in his will to Jean Caillard. Jean for his part, decided to pass the aircraft on to the Musée to maintain it in flying condition as a tribute to Hirsh. In the last months of his life, Hirsh moved on to a TB20H ( H for Hirsh ) to continue his experiments with his lifelong friend Jean Caillard at the controls.