The SIPA S.90 was designed by Yves Gardan for the Société Industrielle Pour l’Aéronautique (SIPA). The prototype first flew on 15 May 1947, winning a French government competition for a new light two-seat aircraft for operation by the French aero clubs. The initial production S.90 was a low-wing aircraft with fixed tailwheel undercarriage and side-by-side seating for two. It was powered by a 75 hp (56 kW) Mathis G4F engine. Four examples were built. 100 aircraft were ordered by the French government, on behalf of the aeroclubs, and these were powered by the 75 hp (56 kW) Minie 4DC engine as the SIPA S.901. The first made its initial flight on 25 June 1948. Deliveries were completed in the early 1950s. Various engines were later installed in the S.901, giving rise to new model numbers. In later years, the S.90 series readily found buyers in the secondhand market and examples have flown with private owners in Belgium, Germany, Switzerland and the United Kingdom. Nine further aircraft were built later with plywood covering in lieu of fabric, receiving new designations. In 2001, 15 examples remained airworthy in France, Switzerland and the UK. Total production of all models was 113 aircraft. Variants S.90 4 aircraft with 75 hp (56 kW) Mathis G4F engine S.901 100 aircraft with 75 hp (56 kW) Minié 4.DC.32 engine. Most were re-engined as follows. S.902 S.901 with 85 hp (63 kW) Continental C85-12F engine. (Specifications below). S.903 S.901 with 90 hp (67 kW) Continental C90-14F engine S.904 S.901 with 75 hp (56 kW) Salmson 5AQ-01 engine S.91 2 new aircraft as S.902 but with plywood-covered fuselage and wings S.92 1 new aircraft as S.91 with 85 hp (63 kW) Mathis 4GB-62 engine S.93 1 new aircraft as S.91 with 75 hp (56 kW) Salmson 5AQ-01 engine S.94 5 new aircraft as S.91 with 90 hp (67 kW) Continental C90-8F engine
