In 1939 Emile Dewoitine had built the D.550 to make an attempt on the air speed record. It had been developed from the D.520 fighter, but with modifications to increase its speed that included a reduced wing span and limited fuel capacity. On 23 October the D.550 reached 420 mph at 19,680 feet, an increase of 90 mph over the D.520. Its military potential was quickly recognised, and work began on the D.551.
The D.551 used the Hispano-Suiza 12Y51 engine, giving 1,300 hp. It was to be armed with five 7.5mm machine guns, one in the engine and four in the wings. It was designed to be easy to produce, and it was hoped that it would only need 4,000 man hours per aircraft. Work advanced quickly at the SNCAM plant at Bagneres-de-Bigorre. Sixteen prototype aircraft were ordered by the French Air Force, and two more built privately by Dewoitine, but none were complete when work was stopped by the armistice (although five were close). The D.551 had an estimated speed of 411 mph at 19,680 feet.
Plans were also in place to produce the D.552, which would have had an additional pair of machine guns in the wings. Two D.551s were converted to unarmed sports planes under the D.560 designation. These aircraft were ready by January 1941, but were then forbidden to fly. All eighteen D.551s were then scrapped.