Fighter First flight: 1938 Dewoitine

The D520 was created according to the 1934 technical assignment for a single-seat fighter to replace old machines (such as the D-510), which lost their significance with the advent of modern fighters, like the English Hurricane.

The draft design for D.520 was developed by young engineers Vautier, Rey and Castello under the leadership of Emile Dewoatin. They took the D.514 aircraft as a basis, on which the wing and tail unit were changed in the process. In 1936, the terms of reference were changed - the aircraft had a cantilever low-lying wing with ailerons, a closed cockpit, retractable landing gear and an engine with a capacity of about 1000 hp. with variable pitch screw.

The first flight of the D-520 prototype took place in October 1938.

The first serial D.520s entered the 1/3 fighter group for military trials in January 1940, where pilots of combat units were also retrained for a new type of aircraft. Despite numerous "childhood illnesses" (constant engine overheating, unreliable supercharger operation and frequent weapon failures), Dewoitine fighters quickly gained recognition among pilots due to their excellent maneuverability, comfortable cockpit with good glazing of the canopy and good takeoff and landing characteristics. And for the graceful, beautiful silhouette, D.520 was soon nicknamed "Miss France". In the process of serial production, the engine cooling system was modified, which made it possible to "squeeze" its maximum power out of the engine.

The aircraft's speed increased to 530 km/h. Unfortunately for the French, the pace of production increased slowly, and by May 10, 1940, when the Germans launched a "lightning" war in the West, the Toulouse plant had built 246 D.520s, of which only 76 were delivered to the Air Force. The only combat-ready unit armed with Dewuatin fighters was Group 1/3, which had 34 serviceable aircraft of this type. The pilots of the 1/3 fighter group entered the fighting on May 13, destroying three Hs 126 reconnaissance aircraft and the He 111 bomber in air battles without any losses on their part. The next day, the pilots chalked up six more downed enemy aircraft, including two Bf 109 and two Bf 110 fighters. This time two D.520s did not return from the mission. The results of the first battles in the sky showed that Dewoitine was somewhat inferior to the single-engine Messerschmitt in maximum speed, but surpassed it in maneuverability. At low altitudes, the Bf 109 had a better climb rate, but above 3000 m, the advantage in climb passed to the D.520.

On May 20, another group, equipped with Dewuatins, II/3, began combat missions, and at the end of the month changed its MS.406 to D.520 group II / 7. By this time, there was no more time left for a thorough study of the aircraft, and the pilots were involved in combat missions after two or three training flights in a new aircraft. In June, ten fighters left the assembly lines of the Toulouse plant every day, and this made it possible to re-equip other units with Dewuatins.

When on June 23, 1940, Marshal Pétain declared an armistice, the plant managed to produce 438 D.520 Dewoitins. Production continued during the German offensive, with a total production of 905 aircraft. Most of these aircraft were used by the Vichy France and transferred to other allies of Germany.

Photo	Description
	Drawing D 520 C
	D 520 C

Fighter First flight: 1941 Dewoitine

The next step in improving the Dewoitine D.520 fighter was the experimental D.520Z. The letter "Z" in the name appeared because it was going to be used to test the new 12Z engine with 1200 hp. The serial D.520 selected for modification was equipped with an enlarged oil radiator, a new water radiator, individual (instead of twin) exhaust pipes and an improved chassis. But due to the fact that the 12Z had not yet been brought to a condition suitable for flight, this machine took to the air with the 12Y49. The first flight took place at the end of 1941. They reached a speed of 560 km/h.

The D.520Z was a prototype for a new serial modification, the SE.520Z. In September 1942, the Germans allowed the production of 105 of these aircraft. In the same month, construction of the prototype began. But its production was interrupted by the capture of previously unoccupied part of France by the Germans.

Under German control, the aircraft was completed in February 1943. The nose of the fighter was lengthened, and under the hood was a Hispano-Suiza 12Z01 engine. In the series, they wanted to use the 12Z89ter with 1600 hp. All armament - two 20-mm cannons and two 7.5-mm machine guns, was concentrated in the wings. According to calculations, the speed should have reached 660 km / h. But it was not possible to test this in practice. The Germans forbade the plant to continue design work and flight tests.

The fighter was completed after the war, in 1947, using the machine as a flying test bed for debugging the engine. In October 1948, the SE.520Z began taxiing around the airfield, but never took off. The following year, it was scrapped.

Photo	Description
	Drawing Dewoitine D520Z

Fighter Firdt flight: 1939 Dewoitine

Continuing work on improving the D.520 fighter, engineers from the Dewoitine company, under the general supervision of E. Dewoitine, developed a record version of it, designed to break the speed record. In general, the design of the D.520 did not undergo significant changes. Improvements were carried out mainly in the direction of improving the aerodynamic qualities of the aircraft, which would allow, with the installation of a standard Hispano-Suiza 12Ycrs engine (900 hp), to reach a speed of about 650 km / h. Accordingly, weapons and other military equipment were not installed. Work on the first prototype of the aircraft, designated D.550, began in the winter of 1939, and by the summer the prototype was ready for flights. From its prototype, the D.520C1 fighter, the record aircraft differed in smoother shapes and an almost complete absence of protruding parts, with the exception of the exhaust pipes and radiator.

The first flight of the D.550-01 took place on June 23, 1939, after which they immediately began preparing for the record flight. Four months later, on October 23, a new French record was set: the D.550-01 reached a maximum speed of 677 km/h at an altitude of 7,000 meters. Although this achievement was not officially registered according to FAI rules, the success of the French engineers was obvious. Not stopping there, the company modernized the aircraft, once again improving the aerodynamics and installing a forced Hispano-Suiza 12Y-51 engine with a capacity of 1,300 hp.

In November 1939, test pilot Marcel Doré reached a speed of 700 km/h on the improved D.550, and the aircraft climbed to an altitude of 6,000 meters in 4 minutes 25 seconds. The maximum speed that was achieved on this aircraft was 703 km/h at an altitude of 6,600 meters - this figure was reached on February 2, 1940. Towards the end of the program, two underwing radiators were installed on the D.550-01 instead of one under-fuselage radiator. It made its last flight on May 27, 1940. The fate of this machine then turned out to be quite tragic.

Fighter Dewoitine

The high speed characteristics of the D.550 made it possible to develop a Fighter variant on its basis, designated as the D.551. The Dewoitine company began working in this direction simultaneously with the issuance of the specifications for the new Fighter by the French Ministry of Aviation. The technical specification A23 called for the creation of an aircraft that had a speed of 650 km/h at an altitude of 7,000 meters, a flight range of 1,500 km, and it was supposed to gain an altitude of 7,000 meters in 11 minutes.

The fighter's armament, as stipulated in the specification, was quite powerful: one 20-mm cannon and six 7.5-mm machine guns or two 20-mm cannons and four 7.5-mm machine guns. The design of the record-breaking D.550 remained the same, except for the wingspan increased to 9.33 m. The aircraft was also equipped with a sight, oxygen device and other equipment necessary for a combat vehicle. The capacity of the fuel tanks was increased from 300 to 410 cubic meters. However, the weapons turned out to be not so powerful.

As calculations showed, if the specifications were followed, the weight of the D.551 would exceed the permissible norm and the speed would be below 650 km/h. Then they decided to reduce the number of barrels by installing four 7.5 mm machine guns in the wing and one such machine gun was installed instead of a cannon in the collapse of the Hispano-Suiza 12Y-51 engine cylinders. By June 25, 1940, when France left the war, they had managed to build both prototypes and almost complete 18 serial fighters, 3 of which were in the final stage of assembly. While the German administration was deciding what to do with the French programs for the construction of promising combat aircraft, the tests of the D.551 were postponed indefinitely and ultimately all unfinished aircraft were dismantled, and both prototypes were converted into sports aircraft. These aircraft, called D.560 (the second with the same name), were ready in January 1941, but they never made a single flight. The D.551\D.552 construction program was finally closed, since it was then considered that for the modernized "Armistice Air Force" a more acceptable solution would be to continue building the D.520C1.

Bibliography

• Encyclopedia of military engineering /Aerospace Publising/
• Un siecle d'aviation francaise. Dewoitine D-520 /Aviafrance./