Arguably the best French fighter at the outbreak of World War 2. After a number of prototypes and proposals (including the D.520) were rejected Dewoitine decided that it's fighter would gain official aproval once the military saw their performance. The first prototype D.520.01 flew in October 1938, and featured a Hispano-Suiza 12Y-21 Vee engine cooled with ethylene glycol. It's maximum speed was only a dissapointing 301 Mph (485 km/h), partly because of the two underwing radiators and the fixed-pitch type wooden two-blade propeller. When these were changed to a metal 3-blade propeller, 1 central radiator and a Hispano Suiza 12Y-29 engine, the prototype reached its designed top level speed, and possessed a high diving speed. Two further prototypes followed, the D.520.02 and D.520.03, which differed in armament (a moteur-canon 20mm cannon firing through the propeller, and 4 x 0.295 inch/7,5 mm machineguns in the leading edge of the wings), and the .03 version had a Szydlowski supercharger in stead of the standard Hispano Suiza one.
At the outbreak of the War only these three prototypes had flown, and too much emphasis on development and evaluation as well as a rigorous reorganisation of the French air industries delayed deliveries of much needed aircraft. The first order for 200 D.520C.1 aircraft was placed in april 1939, quickly followed by further orders. The production of the aircraft went woefully slow, and only 36 were delivered to the French Army when Germany invaded them. Initial production figures were 50 aircraft per month, later stepped op to 350 per month, but this was only reached when the War already had begun: 10 aircraft per day were delivered during the months before France had to capitulate. At that time 437 had been completed (of the 2.200 ordered), of which 351 had reached operational status. The rest was still to be finalized, concerning the supercharger and ejector exhaust stubs. | 
