Bloch MB.131 French Bomber
Although based on the previous MB.310 design, the Bloch MB.311 was a more modern and aerodynamic design. The first prototype flew on August 12, 1936, followed by the second prototype on May 7, 1937. This second aircraft added a fifth crewman, relocated the dorsal turret, and added a ventral turret.
During 1937 the Société Avions Marcel Bloch became part of the Société Nationale de Constructions Aéronautiques du Sud-Ouest (SNCASO). A total of 141 machines were delivered to the French Air Force (including the reworked MB.131, 132 and 133 prototypes).
The MB.131 fared poorly against the Luftwaffe. Used for unescorted long range reconnaissance missions many were shot down. As a result, starting in October 1939, aside from a few aircraft in the GR I/36 and II/36 units, they were withdrawn from the front line and relegated to training units.
At the Armistice, 53 were inventoried in unoccupied France and in 1942, the Germans captured 21 that were then scrapped. Photos of German captured aircraft can be found here.
The basic airframe was further developed into the MB.133, powered by Hispano-Suiza 14 Aa radial engines and the tail modified to a twin rather than single vertical stabiliser. It proved uncompetitive with more modern designs and was converted to a standard MB.131 and delivered to the Air Force. Photos of the MB.133 are here.
Following the failure of the MB.133, the Bloch design team developed two improved versions, the MB.134 and the four-engined MB.135.
