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Karl wrote:even awesomer:
http://www.aviafrance.com/aviafrance1.p ... =&MOTCLEF=
Design of the D.520 started in November 1936 at the private design firm led by Émile Dewoitine. Trying to address problems in earlier designs, he created a fighter using only the latest techniques and engines. The new design was to be able to reach 520 km/h (320 mph) and became known as the "520". Only months later, the firm was conglomerated into one of a number of design-and-manufacturing pools, in this case SNCAM. Still known as the D.520, work on the design continued at the new company.
The prototype D.520 flew on 2 October 1938, powered by the new 660 kW (890 hp) Hispano-Suiza 12Y-21 liquid-cooled engine. The aircraft managed to reach only 480 km/h (300 mph) in flight tests, slower than expected. Most of the problem seemed to come from greater than expected drag from the underwing radiators, so these were merged into a single radiator under the fuselage. After minor damage in a landing accident, the engine was changed to a newer -29 and included exhaust ejectors for added thrust, along with a variable pitch propeller. These changes were enough to allow the aircraft to reach its design speed.
The prototype was followed in 1939 with two airframes with a new sliding canopy and a larger tail unit. These were armed with a 20 mm cannon firing through the propeller spinner (a feature also found on many German and Russian designs) and two 7.5 mm (.295 in) machine guns in small pods under the wing. The third also included a small tailwheel instead of the original skid. Flight tests went fairly well and a contract for 200 production machines to be powered by the newer -31 engine (later replaced by the -45) was issued in March 1939. A contract for an additional 600 aircraft was issued in June reduced to 510 in July.
With the outbreak of war, a new contract brought the total to 1,280, with the production rate to be 200 machines per month from May 1940. The Aéronautique navale then ordered 120. Another Armée de l'air order in April 1940 brought the total to 2,250 and increased quotas to 350 a month.
The first production D.520 flew in November, powered by the 620 kW (830 hp) 12Y-31 and armed with two 7.5 mm (.295 in) machine guns in housings underneath the wings. It had a curved, one-piece windshield and a sliding canopy. The rest of the production machines were delivered with the 690 kW (930 hp) 12Y-45 engine with a new supercharger and a Ratier three-blade propeller (a few had the -49 of 680 kW/910 hp). They were armed with a 20 mm cannon firing through the propeller hub and four MAC 1934 7.5 mm (.295 in) machine guns in the wings. The curved, one-piece windshield from the prototypes was replaced with one containing an optically-flat panel.
As the first batch of machines rolled off the production lines, they failed acceptance tests due to insufficient top speed and troublesome cooling. Redesigned compressor intakes, a modified cooling circuit and propulsive exhaust pipes proved to be effective remedies for these shortcomings, but as early examples had to be retrofitted with these improvements, the type was not declared combat-worthy until April.
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