Blériot-SPAD S.91

The Blériot-SPAD S.91 was a light-weight fighter aircraft by the French aircraft manufacturer Blériot.

It was developed in response to a French government program for a light fighter aircraft. The S.91 was a single-seat earlier single-bay biplane that resembled pursuit aircraft produced by André Herbermont except for its wing profile. Duralumin and other light metals comprised a substantial amount of the framework; a single girder composed of out of duralumin tube supported the entirety of the fuselage aft of the cockpit. The majority of the covering was fabric. According to Blériot, it was a highly maneuverable aircraft and was also relatively easy to operate.

On 23 August 1927, the first prototype performed its maiden flight; it was lost in an accident during flight testing. The completion of a second prototype permitted the resumption of flight testing. Despite the French government having lost interest in the general concept, the company opted to continue work for a time, promoting the S.91 to various prospective foreign operators. During 1936, at least one of the surviving S.91 prototypes ended up in the Spanish Republican Air Force. While the S.91 would never go into quantity production, it would eventually be developed into the Blériot-SPAD S.510, which would be the last biplane produced by the French aeronautic industries.