Sud-Ouest M.1


The half-scale model predecessors of the SO 4000 were the SO M.1 glider (F-WFDJ) and the powered SO M.2 (F-WFDK), these featuring a laminar flow wing swept 31 deg at the mainspar, mounted in the high-mid position and combining small ailerons interconnected with spoilers and leading-edge slats. The undercarriage consisted of a retractable central skid with wingtip stabilising skids in the case of the M.1, while that of the M.2 comprised a nosewheel, three main-wheels in train and wingtip outrigger wheels.

After trials attached to a rig mounted above the Heinkel He 274, the M.1 was tested in free flight for the first time on 26 September 1949 after being launched from an SE 161 Languedoc.