Dewoitine D.500 / D.501 / D.510

The D 500 was designed by Emile Dewoitine to a 1930 requirement for the Aviation Militaire. It was of all-metal monoplane construction, with neat cantilever low wings, a fixed, spatted landing gear, and open cockpit. Intended to meet the demands of the 1930 C1 programme and eventually selected as winning contender, the D 500 was powered by a 12-cylinder Vee Hispano-Suiza 12Xbrs (HS 72) engine rated at 660hp for take-off and 690hp at 4000m. Armament comprised two 7.7mm Vickers guns in the fuselage, these later being supplanted by 7.5mm Darne guns with provision for two similar wing-mounted weapons.
The prototype was first flown on June 18, 1932, and at the end of November 1933, orders were placed for 60 D 500s of which 45 were to be built by Liore-et-Olivier and 15 by SAF-Avions Dewoitine. Of the former, 40 were to be powered by the HS 12Xbrs engine and the remaining five by the HS 12Xcrs (HS 76) with provision for a 20mm Hispano-Suiza S7 (Oerlikon) cannon mounted between the cylinder banks. With this installation and twin wing-mounted machine guns the fighter was designated D 501.
The SAF-Avions Dewoitine order was eventually to comprise eight D 500s, five D 501s and two D 510s. The first production D 500 was flown on 29 November 1934, contracts having meanwhile been placed for a further 50 D 500s and 80 D 501s to be built by Liore-et-Olivier and 60 D 501s by Ateliers et Chantiers de la Loire, deliveries to the Armee de l'Air commencing May-June 1935. Three D 500s were ordered by Venezuela at the beginning of 1934 and delivered in July 1935, and in the following year 14 D 501s were supplied to Lithuania. The Armee de l'Air received 100 D 500s and 133 D 501s, 30 of the latter type also being supplied to shore-based elements of France's Aeronautique Navale. Small numbers of D 500s and D 501s equipped Escadrilles Regionale de Chasse in the early months of World War II, but had been relegated to tuitional tasks by 1940.

A further-improved model, the D 510, first flew on August 14, 1934. It had a larger-area rudder and a revised engine mounting to accommodate the 860-hp HS 12 Ycrs power-plant.
Two of the 15 D 500 series aircraft (the second and tenth) comprising the initial production contract for the new low-wing fighter monoplane placed with SAF-Avions Dewoitine were fitted with the Hispano-Suiza 12Ycrs (HS 77) engine as prototypes for the D 510. Heavier and longer than the HS 12Xcrs (HS 76) of the standard D 501 fighter, the HS 12Ycrs similarly catered for a 20mm cannon between its cylinder banks, and was rated at 775hp at sea level and 860hp at 4000m. The first of the D 510 prototypes flew (without the cannon fitted) on 14 August 1934, the second (with cannon) following on 10 December. Apart from engine, the D 510 was fundamentally similar to the D 501, the cannon being complemented by a pair of 7.5mm wing guns. In May 1935, the Ministere de l'Air placed an initial contract for 35 (later reduced to 25) D 510s, these being delivered from 9 October 1936. Seven more D 510s were then built for the Armee de l'Air as agreed replacements for a similar number of D 501s taken from the service's deliveries as part of the Lithuanian order. Follow-on contracts then called for a total of 80 more aircraft from which a contract for 24 D 510s from the Chinese Central Government was to be fulfilled. Other export D 510s were single examples to the UK and the Soviet Union, and two to Japan for evaluation purposes, and two, unofficially, to Republican Spain. These last had been the first two of a cancelled contract for Turkey and were ostensibly sold to the Hedjaz (Saudi Arabia). When it was revealed that the two D 510s had arrived in Spain, the French government insisted that their engines be returned to France. Eventually, both aircraft were fitted with M-100 (licence-built HS 12Ybrs) engines from a Tupolev SB bomber and allegedly saw some combat. Three Groupes de Chasse were still flying with the D 510 at the beginning of World War II, but re-equipped during the first months of the conflict. Two Escadrilles Regionale de Chasse in North Africa converted to D 510s in September-October 1939, flying them until mid-1940, and two escadrilles of the Aeronautique Navale formed on D 510s in December 1939 and May 1940.

One hundred and twenty were built, 90 going to the Armee de l'Air, for whom the D 510 was the first fighter capable of a level speed exceeding 400 km/h (248 mph).
Before the Second World War, most D 510s served in metropolitan France or Tunisia but on the outbreak of war, Groupes de Chasse GC 1/ 1, 11/ 1 and 118 were equipped with this model, and some D 501s were still in service in France with ERC (Escadrilles Regionales de Chasse) 561 and 562. Some D 501s were also still in service in North Africa when France capitulated in May 1940.
Prior to the outbreak of war, Dewoitine had export orders from China (24 D 510C), the Hejaz (two D 510), Japan (two D 510J), Lithuania (14 D 510L), Britain (one D 510A), the USSR (one D 510R) and Venezuela (three D 500V). There is some doubt whether those destined for Venezuela were ever received, and it is probable that some or all of the Lithuanian batch and the two for the Hejaz went instead to the Republican forces in Spain during the Civil War.

D 501
Take-off weight: 1787 kg / 3940 lb
Empty weight: 1287 kg / 2837 lb
Wingspan: 12.09 m / 39 ft 8 in
Length: 7.56 m / 24 ft 10 in
Height: 2.70 m / 8 ft 10 in
Wing area: 16.50 sq.m / 177.60 sq ft
Max. speed: 367 km/h / 228 mph
Range: 870 km / 541 miles

D.510
Engine: Hispano-Suiza 12Ycrs (HS 77), 775hp at sea level, 860hp at 4000m
Take-off weight: 1929 kg / 4253 lb
Empty weight: 1496 kg / 3298 lb
Span: 12.092 m (39 ft 8 in)
Length: 7.94 m / 26 ft 1 in
Height: 2.42 m / 7 ft 11 in
Wing area: 16.50 sq.m / 177.60 sq ft
Maximum speed: 393 km/h (244 mph)
Range: 700 km / 435 miles
Armament: 1 x 20mm cannon, 2 x 7.5mm wing guns

Dewoitine D 510