The history of Dewoitine D.520 starts in 1934 when the Staff of the Air Force seeks a substitute in D.510, Dewoitine proposes D.513 but the choice is made on Morane-Saulnier MS.405. Not wanting to remain on this failure, Emile Dewoitine forms in June 1936 a engineering and design department directed by Robert Castello who ends to a project of hunter able to reach 500 km/h, at this point in time Technical Services of the Air Force request a flying plane from 520 km/h. A modified project, indicated D.520 in reference at the required speed, is subjected in January 1937 but it is once again refused.
Its factory having been nationalized and renamed National Société of Aeronautical Engineerings of South (SNCAM), Emile Dewoitine was however an administrator general and it is for this reason that it decided to continue the studies of D.520.
The first of the three prototypes flew for the first time on October 2, 1938 to Toulouse Francazal, controlled by Marcel Doret, motorized by Hispano-Suiza 12Y-21 of 890 HP, but it did not manage to exceed 480 km/h. Following an accident it accepted Hispano-Suiza 12Y.29 with which it reached 825 km/h in piqué. Two other prototypes were built.
D.520 is a single-seat hunter, its fuselage of ovoid section covered with duralumin sheet. The cantilever wing realized of only one part comes to be fixed under the fuselage. The windshield is consisted of the ices “Plywood”, the glass slide backwards. The landing gear is retractable.
The armament comprises a gun of 20 mm HS 404 with charger of 60 blows placed on the engine, like four machine-guns MAC 34 M 39 fed with 675 blows, placed in the wings.
An indicated two-seater version D.520DC (Double Order) was also produced.
A first order of 200 apparatuses had placed on April 17, 1939, followed of another of 600 apparatuses on June 5 which was brought back to 510. To the declaration of war, a new contract carried the total order to 1280 apparatuses. Finally in April 1940 one envisaged a total production of 2240 apparatuses for the Air Force plus 120 for naval Aeronautics.
The production started at the beginning of 1939, the first flying standard appliance in November of the same year.
In 1941 the German authorities allowed the prolongation of the production of D.520, the SNCAM having become the National Company of Aeronautical Engineerings of South-east (SNCASE).
Several projects were not born because of the Occupation:
D.520T with Hispano-Suiza 12Z-89 of 1200 HP.
D.520Z with Hispano-Suiza 12Z of 1600 horses.
D.521 with Rolls-Royce Merlin III of 1030 HP.
D.523 new driving Hispano-suiza 12Y.51 of 1000 horses.
D.524 Hispano-suiza 12Z.89 for the third time.
HD-780, float seaplane equipped with Hispano-Suiza 12Y-51.
The total production of D.520 exceeded the 600 machines.
Some were modified after the war in the two-seaters D.520DC.
D.520 was used fights some by the Air Force in 1940 during the Countryside of France within the Groups of I/3 Hunting, II/3, III/3, III/6, II/7 and engaged against Luftwaffe and Regia Aeronautica. Flotilla AC1 of Naval Aeronautics was also equipped with D.520.
After the defeat the GC I/3, II/3, III/6, II/7 and the flotilla 1AC were stationed in North Africa under the colors of Vichy, however that three D.520 joined Great Britain. Thus D.520 were engaged in Syria against the RAF.
At the time of the invasion of the zone nonoccupied by German, D.520 being were captured there then were used as plane of drive for Luftwaffe, others were implemented by Regia Aeronautica for the drive and hunting, being thus opposed to the allies. Romania and Bulgaria also used it for hunting.
At the end of 1944, German leaving the South-west of France, a group of hunting FFI was created in Tarbes and Toulouse, ordered by Marcel Doret. The Doret Group took part in the combat of the pocket of Royan and the Low register Point as a cover for allied bombers.
The Doret group is dissolved on November 30, 1944 and becomes the G.C. 11/18 “Saintonge”, which yields its D.520 to the G.C.B.1/18 “the Vendée” starting from the second fortnight of February 1945 like with the unit of drive of Toulouse-Francazal.
The last flight of Dewoitine 520 took place on July 13, 1986 in Vannes with the accident which cost the life its pilot, the commander Bove.