The history of the Bloch MD 800s is probably the most complicated of any Bloch aircraft. It appears that three aircraft were given this designation.
The first was a tandem three-seat trainer (category P3: advanced trainer) with twin tails, of wooden construction. It was designed by Pierre Le Bihan. Equipped with 180hp Bloch 6B-1 engines, this MB 800 took off for the first time, with Daniel Rastel at the controls, on 18 December 1940, at Mérignac in the occupied zone.
A second MB 800 T3 (three-seat aerial work plane) was in the process of construction in 1939.
The third MB 800 was a mail plane, designated MB 800P. Also designed by Pierre Le Bihan and built in Châteauroux, it made its first flight in Cannes on 23 December 1941, with Daniel Rastel at the controls, accompanied by a test engineer, Lucien Servanty, and a mechanic, Armand Raimbeau. It was a twin-engine monoplane with a single tail, for five passengers, powered by two 350hp Béarn 6D engines, baptized “Biarritz” in April 1943. Under German “Aryanisation” rules, the Jewish name “Bloch” could not be part of the aircraft designation, so it became the SO-800P. There were two series of designations for the same aircraft: the SO-80 of the design bureau and the SO-800, which performed the flight tests. The aircraft was abandoned in favor of the larger SO-90, which was scrapped between 1945 and 1947.