 An "Armée de l'Air" specification for a ground-attack aircraft drawn up in 1948 was intended to spur the French aviation industry to produce a jet-powered design.Sud-Est entered the competition with a development of the earlier SE.2400 attack aircraft, after testing a model in the "ONERA" (Chalais-Meudon) wind tunnel.The design featured an unusual 47˚ swept wing design along with two stacked Nene jet engines fed by a single dorsal inlet in a compact, bulbous fuselage.