Dewoitine D . 520 The Dewoitine D . 520 was French fighter aircraft that entered service in early 1940 , shortly after the beginning of World War II . Unlike the Morane - Saulnier M . S . 406 , which was at that time the most numerous fighter in the French Air Force , the Dewoitine D . 520 came close to being a match for the latest German types , such as the Messerschmitt Bf 109 . It was slower than the Bf 109E but superior in manoeuvrability . Because of a delayed production cycle , only a small number were available for combat with the " Luftwaffe " . The D . 520 was designed in response to a 1936 requirement from the French Air Force for a fast , modern fighter with a good climbing speed and an armament centred on a 20 mm cannon . At the time the most powerful V 12 liquid cooled engine available in France was the Hispano - Suiza 12Y , which was less powerful , but lighter , than contemporary engines such as the Rolls - Royce Merlin and Daimler - Benz DB 601 . Other fighters were designed to meet the specifications but none of them entered service , or entered service in small numbers and too late to play a significant role during the Battle of France . Development . In response to a specification for a new fighter promulgated by the French Air Ministry on 15 June 1936 , work on the D . 520 started in September of that year , at the private design firm led by Émile Dewoitine . The specifications called for a maximum speed of at , the ability to climb to in less than fifteen minutes , with take - off and landing runs not exceeding . The armament was to be two 7 . 5 mm ( . 295 in ) machine gun s and one 20 mm Hispano - Suiza HS . 9 cannon , or two HS . 9 cannon . Dewoitine had been disappointed with the performance of his last design , the Dewoitine D . 513 , which was rejected by the French Air Force in favour of the Morane - Saulnier M . S . 406 , and decided to respond to the specifications with a design using the latest construction techniques and the most powerful available engine , the new 660 kW ( 890 hp ) Hispano - Suiza 12Y - 21 liquid - cooled engine . The first design was rejected by the French Air Ministry , which , after being impressed by the British Hawker Hurricane and Supermarine Spitfire , then uprated the specifications to include a maximum speed requirement of . In response , Dewoitine renamed the further development , the " D . 520 " . Similar aircraft . Other aircraft designed to the same specification included the Morane - Saulnier M . S . 450 , the Loire - Nieuport 60 ( later C . A . O 200 , and the Caudron - Renault C . 770 , none of which either left the drawing board or entered service . Two other concurrent French designs , the Bloch MB . 152 . 01 and Bloch MB . 155 . C1 series and the Arsenal VG . 33 entered service in small numbers with the French Air Force during the Battle of France , but too late to play a significant role . Modifications and first prototypes . In March 1937 the firm became part of a number of design - and - manufacturing pools , in this case SNCAM . Because of this and continued changes in the French Air Force ' s manufacturing programmes , work on the design of the D . 520 was suspended throughout much of 1937 , and it was not until January 1938 that a small number of draughtsmen started work on the first detailed drawings for the prototype . This trial model , D . 520 - 01 , powered by a Hispano - Suiza 12Y - 21 temporarily driving a fixed - pitch , two - bladed wooden propeller , first flew on 2 October 1938 , but only managed to reach in flight tests , and suffered from dangerously high engine temperatures . Most of the problem was judged to come from greater than expected drag from the underwing radiators , which exhausted across the upper wing surface , and these were replaced with a single radiator unit housed under the fuselage in a streamlined fairing . After minor damage in a landing accident , further modifications included changing the engine to a newer - 29 model and incorporating exhaust ejectors for added thrust , along with a three - blade variable pitch propeller . These changes were enough to allow the aircraft to reach its design speed , achieving . The maximum diving speed was . Additional prototypes . The prototype was followed in 1939 by two examples : the D . 520 - 02 and the 03 , they were first flown on 9 January and 5 May 1939 respectively , featuring new sliding canopies , a larger tail unit , and longer Oleo manufactured undercarriage legs ; they also omitted the Handley - Page slats fitted to the outer wings on 01 . These prototypes were armed with the 20 mm Hispano - Suiza HS . 9 cannon in an engine mount in which the barrel was mounted in a sleeve between the cylinder banks and fired through the propeller spinner . and two MAC 1934 7 . 5 mm ( . 295 in ) machine gun s , each initially with 300 rounds per gun , housed in small pods under the wing . The third prototype also introduced a small tailwheel instead of the original skid . The second prototype was later fitted with a Hispano - Suiza 12Y - 31 engine and achieved a maximum speed of and reached in 12 minutes 53 seconds . Flight tests proceeded successfully , resulting in a contract issued in March 1939 for 200 production machines to be powered by the newer - 31 engine ( later replaced by the - 45 ) . A contract for an additional 600 aircraft was issued in June , albeit reduced to 510 in July 1939 . Production . With the outbreak of war , a new contract brought the total of D . 520s on order to 1 , 280 , with the production rate to be 200 aircraft per month from May 1940 . The " Aéronautique Navale " then ordered 120 . Another French Air Force order in April 1940 brought the total to 2 , 250 and increased production quotas to 350 a month . The first production D . 520 flew in October 1939 . On this and the other aircraft , the rear fuselage was extended by , the engine cowling panels were redesigned , the curved , one - piece windscreen was replaced by one containing an optically flat panel and armour plate was fitted behind the pilot ' s seat . Most production examples were powered by the Hispano - Suiza 12Y - 45 with the new Szydlowski - Planiol supercharger , although later production versions used the Hispano - Suiza 12Y - 49 . The production standard armament was a 20 mm HS . 404 cannon firing through the propeller hub and four belt - fed MAC 1934 M39 7 . 5 mm ( . 295 in ) machine guns in the wings . As the first batch of D . 520s rolled off the production line , 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 of these shortcomings , but as early examples had to be retrofitted with these improvements , the type was not declared combat ready until April 1940 . Design . An all - metal structure was used , except for fabric - covered ailerons and tail surfaces . The wing , even if single - spar , was a solid and rigid unit with a secondary spar and many reinforced parts . The inwardly retracting undercarriage had a broad track , and was fitted with wide , low pressure tyres . A self - sealing fuel tank with a capacity of 396 litres ( 87 imp gallons ) was mounted between the engine and cockpit , along with two wing tanks which , combined , carried another 240 litres ( 53 imp gallons ) , for a total of 636 litres ( 131 imp gallons ) ; this was considerably more than the contemporary Bf 109E , Spitfire I and early Italian fighters , each with about 400 litres ( 88 imp gallons ) fuel capacity . The ferry range was from to at which , from June 1940 , allowed D . 520s to escape to North Africa when France fell . The handling changed according to the amount of fuel carried ; using the fuselage tank alone , fuel consumption had no appreciable effect on handling because the tank was at the centre of gravity , but with full wing tanks , directional control was compromised , especially in a dive . The flight controls were well harmonized and the aircraft was easy to control at high speed . The maximum dive speed tested was with no buffeting and excellent stability both in the dive ( depending on fuel load ) and as a gun platform . Engine . The Hispano - Suiza 12Y - 45 engine was an underpowered , older design , with at takeoff at 2 , 400 rpm , or emergency power at 2 , 520 rpm and at a height of . The Hispano engine had some advantages over some later engines ; for example , its weight was only , compared to the of the Rolls - Royce Merlin III . Fuel was fed via six Solex S . V . 56 carburettors mounted on an inlet manifold which directed compressed air from the supercharger to the engine cylinders ; the 12Y - 45 and - 49s fitted to production D . 520s used either 92 or 100 octane fuel . The - 45 drove an electrically operated Ratier Type 1606M three - bladed , diameter , variable pitch propeller , while D . 520s from № 351 were fitted with the 12Y - 49 engine driving a Chauvière type 3918 pneumatically operated propeller , also in diameter . Fire suppression system . The D . 520 had a fire suppression system with a fire extinguisher activated from the cockpit . The engine was started by a simple but effective system , operating with compressed air . A Viet 250 air compressor charged several air bottles ( one with a 12 litres capacity , as well as another 8 litres tank , three smaller 1 litre units were matched to the weapons ) . The 12 litre air bottle was used for the brakes and later , for the Chauvière propeller ' s constant speed adjustment . The small air bottles provided up to 12 seconds at or 20 seconds at low level , before the Viet air compressor re - charged them . The pilot had a complete set of cockpit instruments , and a 10 litre oxygen bottle located in the fuselage just behind his seat , with either a Munerelle or Gourdou oxygen regulator system mounted on the right instrument panel . Equipment included a " Radio Industrie Type Rl 537 " radio - receiver set , an OPL RX 39 reflector sight ( less effective than the Revi system ) , a height adjustable seat , and a sliding canopy with large , clear panels . Except over the long nose , the pilot ' s view was good , since he was seated quite high over the forward fuselage ; however , no rear - facing mirrors were fitted . Armament . Production - standard armament consisted of a 20 mm HS . 404 , with an ammunition capacity of 60 rounds , firing through the propeller hub , and four belt - fed MAC 1934 M39 7 . 5 mm ( . 295 in ) machine guns in the wings , each with 675 rounds per gun . The MAC 1934 machine guns had a high rate of fire of 1 , 200 rounds per minute ( rpm ) , while the effective HS . 404 fired at 600 rpm and was accurate up to ; the ammunition capacity meant that the machine guns could be fired for a total of 30 seconds , while the cannon had 10 seconds worth of ammunition . In combat the MS . 406 had only two 7 . 5 mm and was , therefore , at a disadvantage when the HS . 404 had used up its ammunition , while a D . 520 could continue to fight effectively because it had four fast - firing machine guns ( over 80 rounds / sec ) , with 20 + seconds of ammunition still available . The D . 520 had provisions for two BE33 " illuminating bombs " , useful for nocturnal interception missions , but these were seldom used because French fighters rarely flew night - time missions . Maintenance . The D . 520 was designed to be maintained easily with many inspection panels , a rare feature for its time . Re - charging the D . 520 ammunition was swift and easy ; the machine gun magazines required five minutes each and three minutes for the 20 mm cannon . To fill the machine gun ammunition boxes took 15 minutes , while five minutes were needed to empty the 20 mm box ( the cartridges were not expelled ) . The D . 520 ' s cockpit was set well back in the fuselage , aft of the trailing edge of the wings . This gave the pilot good downward visibility , but the long nose in front of him was a drawback when taxying on the ground . Production time . Production was optimized with a reduced 7 , 000 man / hour each , roughly half the time compared to the previous D . 510 and MS . 406 , and far less than many other fighters of the time , such as the MC . 200 / 202 ( 21 , 000 hours ) , but around 50 % more than a Bf 109E ( 4 , 500 hours ) . The French Air Ministry planned for over 300 aircraft a month to be built and managed to reach this goal , especially in June 1940 , but it was too late to affect the tide of battle . After the armistice with Germany , a further 180 machines were constructed , bringing the production total to 905 . Flight difficulties . Although employing a modern design philosophy for its time , the D . 520 was considered more difficult to fly than the older MS . 406 . Captain Eric Brown , commanding officer of the Royal Aircraft Establishment ' s Captured Enemy Aircraft Flight , tested the D . 520 at RAE Farnborough , saying that “ It was a nasty little brute . Looked beautiful but didn ' t fly beautifully . Once you get it on the ground , I was told not to leave the controls until it was in the hangar and the engine stopped . You could be taxiing toward the hangar and sit back when suddenly it would go in a right angle . ” Operational history . France . Battle of France . The " Groupe de Chasse " I / 3 was the first unit to get the D . 520 , receiving its first aircraft in January 1940 . These were unarmed and used for pilot training . In April and May 1940 , operational units received 34 production D . 520s ; the type proving to be very popular with the pilots . In comparative trials on 21 April 1940 at CEMA at Orleans - Bricy against a captured Bf 109E - 3 , the German aircraft had a 32 km / h ( 20 mph ) speed advantage owing to its more powerful engine . However , the D . 520 had superior maneuverability , matching its turning circle , although displaying nasty characteristics when departing and spinning out of the turn repeatedly during the tests . The Bf 109 , owing to its slats , could easily sustain the turn on the edge of a stall . By 10 May 1940 , when Germany invaded France and the Low Countries , 228 D . 520s had been manufactured , but the French Air Force had only accepted 75 , as most others had been sent back to the factory to be retrofitted to the new standard . As a result , only GC I / 3 was fully equipped , having 36 aircraft . They met the " Luftwaffe " on 13 May , shooting down three Henschel Hs 126 s and one Heinkel He 111 without loss . Four more " Groupes de Chasse " and three naval " Escadrilles " rearmed with the type before France ' s surrender . GC II / 3 , GC III / 3 , GC III / 6 and GC II / 7 later completed conversion on the D . 520 . A naval unit , the " 1 Flotille de Chasse " , was also equipped with the Dewoitine . But only GC I / 3 , II / 7 , II / 6 and the naval AC 1 saw any action in the Battle of France . GC III / 7 converted to the D . 520 too late to be involved in any action . In air combat , mostly against the Italians , the Dewoitine 520s claimed 114 air victories , plus 39 probables . Eighty five D . 520s were lost . By the armistice at the end of June 1940 , 437 D . 520s had been built with 351 delivered . After the armistice , 165 D . 520s were evacuated to North Africa . GC I / 3 , II / 3 , III / 3 , III / 6 and II / 7 flew their aircraft to Algeria to avoid capture . Three more , from GC III / 7 , escaped to Britain and were delivered to the Free French . A total of 153 D . 520s remained in mainland France . One of the most successful D . 520 pilots was Pierre Le Gloan , who shot 18 aircraft down ( four Germans , seven Italian and seven British ) , scoring all of his kills with the D . 520 , and ranked as the fourth - highest French ace of the war . Under Vichy . In April 1941 , the German armistice commission authorized Vichy authorities to resume production of a batch of 1 , 000 military aircraft for their own use , under the condition that 2 , 000 German - designed aircraft would later be manufactured in France and delivered to Germany . As part of this agreement , 550 examples of the D . 520 were ordered to replace all other single - seat fighters in service . The plan was to have the Dewoitine eventually equip a total of 17 " Groupes " with 442 aircraft , three " escadrilles " of the " Aéronautique navale " with 37 aircraft each , plus three training units with 13 aircraft . The agreement stated that aircraft of this new batch were to be similar to the ones already in service . From serial number 543 on , however , D . 520s used the 12Y - 49 engine that had a slightly higher rated performance than the 12Y - 45 , although the German Armistice Commission explicitly prohibited replacing the original power plants with the more powerful 12Y51 or 12Z engines . In 1941 , D . 520s of GC III / 6 , II / 3 and naval " escadrille " 1AC fought the Allies during the Syria - Lebanon campaign . The Vichy French Air Force was already relatively strong , but several units were sent to reinforce it . D . 520s were the only French single - seat fighters capable of making the trip to Syria . The GC III / 6 was sent first . The ferry trip was very difficult for a 1940 interceptor and the pilots pushed their planes as far as their fuel tanks would allow them to . They flew from France to Syria with intermediate stops at Rome , Brindisi or Catania . Another route was available through Germany and Greece ( Athens ) , but it was seldom used . The trip always included a stopover in Rhodes ( which had an Italian base at the time ) , before the final flight to Syria . This meant several thousand kilometers were flown over mountains and sea . The most demanding part was Catania - Rhodes , which entailed no less than 1 , 200 km flown over water . Even the trip from Rhodes to Syria was 800 km . LeO 451s and Martin 167F bombers had few problems , but D . 520s were forced to fly a strenuous and dangerous mission , without any help or external assistance . Of the 168 French aircraft ( of all types ) sent to Syria , 155 accomplished their mission and arrived successfully . The Vichy Air force was numerically strong , but with very few ground crew and spare parts , which meant that the operational flying time for the D . 520s was very limited . D . 520s of GC III / 6 first saw action against British aircraft on 8 June 1941 , when they shot down three Fairey Fulmar s , losing one D . 520 ( its pilot was taken prisoner ) . Over the following days several escort missions were flown to protect Martin , LeO and Bloch 200 ( 3 / 39 Esc ) bombers from British Royal Navy fighters . Two Hurricanes were shot down ( with another D . 520 lost ) on 9 June . During the Syria campaign , a total of 266 missions were conducted by the Vichy French Air Force : 99 of them were carried out by D . 520s , nine by MS . 406s , 46 by Martin 167s and 31 by LeO 451s . The D . 520s were therefore the most active of the French aircraft in the campaign , where they claimed 31 kills over British and Australian units while losing 11 of their own in air combat and a further 24 to anti - aircraft fire , accidents and attacks on their airfields . On 10 July , five D . 520s attacked Bristol Blenheim bombers from No . 45 Squadron RAF that were being escorted by seven Curtiss Tomahawks from No . 3 Squadron RAAF ( 3 Sqn ) . The French pilots claimed three Blenheims , but at least four of the D . 520s were destroyed by the Australian escorts , including two by Flying Officer Peter Turnbull . The following day , a Dewoitine pilot shot a P - 40 down from 3 Sqn , the only Tomahawk lost during the campaign . This Dewoitine was in turn shot down by F / O Bobby Gibbes . The initial advantage that the Vichy French Air Force enjoyed did not last long , and they lost most of their aircraft during the campaign . The majority of them were destroyed on the ground where the flat terrain , absence of infrastructure and absence of modern anti - aircraft ( AA ) artillery made them vulnerable to air attacks . On 26 June , a strafing run by Tomahawks of 3 Sqn , on Homs airfield , destroyed five D . 520s of Fighter Squadron II / 3 ( Groupe de Chasse II / 3 ) and damaged six more . By the end of the campaign , Vichy forces had lost 179 aircraft from the approximately 289 committed to the Levant . The remaining aircraft with the range to do so , evacuated to Rhodes . The known French losses of fighter aircraft were 26 in air combat and 45 in strafing and bombing actions . The Allies lost 41 planes , 27 of those shot down by French fighters . During Operation Torch [ the invasion of North Africa ] , GC III / 3 ( previously known as GC I / 3 ) , was engaged in combat with the Allies over Oran . " Flotille " 1F saw action versus the United States Navy Grumman F4F Wildcat squadron VF - 41 ( from the carrier ) , over Casablanca . One D . 520 was among 14 US victory claims ; the only Allied losses were due to ground and friendly fire . Other Dewoitine - equipped units in North Africa such as GC II / 7 or GC II / 3 did not to take part in the fighting . Overall , the known D . 520 air strength in North Africa was 173 D . 520s ( 143 combat ready ) of GC II / 3 , III / 3 , III / 6 , II / 7 and II / 5 , another 30 were in Senegal with GC II / 6 . The Navy had Esc 1AC and 2AC . Many D . 520s were destroyed on the ground by Allied bombing . The French Air Force lost 56 aircraft , among them 13 D . 520s . The Navy lost 19 D . 520s . Among the 44 kills that the French scored overall , there was an entire squadron of nine Fairey Albacore from , all shot down by D . 520s of GC III / 3 . Free French Dewoitines . A very small number of D . 520s were briefly operated by Free French Forces for training purposes . Along with the three examples that had flown to Britain in June 1940 , two other Dewoitines were recovered from retreating Vichy forces in Rayak , Lebanon . These D . 520s were flown by pilots of the " Normandie - Niemen " unit before it was sent to the USSR , where they flew the Yakovlev Yak - 1 that had many similarities with the French aircraft . With the Allies . In December 1942 , as French forces formerly under Vichy sided with the Allies , there were 153 D . 520s left in French hands in North Africa . They flew a few patrols during the Tunisia Campaign , but were considered obsolete , and their radio sets were incompatible with Allied equipment . From early 1943 on , they were relegated to training duties at the fighter school in Meknes , and progressively replaced by Supermarine Spitfire s and Bell P - 39 Airacobra s in combat units . During the liberation of France , a few D . 520s abandoned by the Germans , were used by " ad hoc " units in ground attack s against the isolated German pockets of resistance on the Western coast . Foreign users . German forces invading Vichy ' s so - called " free zone " in November 1942 , captured 246 D . 520s ; additionally , a batch of 62 was completed under German occupation . The captured Dewoitines were to be delivered to the Axis Balkan Front , although some were used by the " Luftwaffe " for training purposes while 60 were transferred to Italy and 96 , or 120 , to the Bulgarian Air Force for use in combat . But D . 520s reached Bulgaria only in August 1943 , as the fighter pilots of that country were still training on the type at Nancy with JG 107 . The following month , the first 48 Dewoitines were taken over in a ceremony on Karlovo airfield . Two months later , on 24 November , the D . 520s were used in combat , when 17 out of the 60 B - 24 Liberator s of the 15th USAAF arrived over the capital , Sofia , to bomb it . Twenty four Dewoitines took off from Vrashdebna base ( along with 16 Bf 109G - 2s from Bojourishte ) and attacked the bombers and their 35 escorting P - 38 Lightning s . The Bulgarian pilots claimed four American aircraft for the loss of one fighter , three more had to force land . American bombers attacked Sofia again , on 10 December 1943 . That day , 31 B - 24s escorted by P - 38s , were intercepted by six Dewoitines of the II / 6th Fighter Regiment from Vrashdebna and 16 D . 520s of the I / 6th Fighter Regiment from Karlov ( along with 17 Bf 109G - 2s ) . The Americans claimed 11 D . 520s for the loss of only one P - 38 . The later examination of records showed that only one Dewoitine was lost during that air battle . The Bulgarian Air Force D . 520s were again up in force , to face the massive Allied air raid of 30 March 1944 . To intercept the 450 bombers ( B - 17 Flying Fortress es , B - 24s and Handley Page Halifax es ) escorted by 150 P - 38s , the Bulgarians scrambled 28 Dewoitines from I . / 6th at Karlovo , six D . 520s from II / 6th at Vrashdebna ( together with 39 Bf 109G - 6s and even Avia 135s ) . At least ten Allied aircraft ( eight bombers and two P - 38s ) where shot down , while the Bulgarian Air Force lost five fighters and three pilots . Two more Bulgarian aircraft had to force land . During the last Allied raid on Sofia , on 17 April , the II . / 6th fighter scrambled seven Dewoitines ( plus 16 Bf 109s ) , against 350 B - 17s and B - 24s escorted by 100 P - 51 Mustangs . Bulgarian pilots , that up to that time had encountered only P - 38s , mistook the P - 51s for their own Bf 109s and before they realized their mistake , seven Bf 109G - 6s had been shot down . That day the Bulgarian Air Force suffered the heaviest losses since the beginning of the war : nine fighters shot down and three that had to crash land . Six pilots lost their lives . By 28 September 1944 , twenty days after Bulgaria joined the Allies , Dewoitines still equipped an " Orlyak " ( Group ) of the 6th Fighter regiment : I Group had a total of 17 D . 520s , five under repair and 12 operational , for its three " Jato " ( Squadrons ) . Numerous sources have mentioned use of the D . 520 by the Romanian Air Force , but no evidence has ever been provided . One source claims the so - called Romanian Dewoitines were , in fact , in transit to Bulgaria and only flew over Romania in order to get to their final destination . This seems the most reliable explanation , viewed against the numbers of Dewoitines actually available . About 60 D . 520s were acquired by the " Regia Aeronautica " ( the Italian Air Force or RA ) . Italian pilots appreciated the aircraft ' s capabilities and Hispano - Suiza HS . 404 cannon , at least by 1940 – 1941 standards . The first three D . 520s were assigned to 2° " Stormo " based at the Torino - Caselle airfield , where they were used for the defence of Torino ' s industrial area . Other D . 520s were captured in Montélimar , Orange , Istres and Aix - en - Provence . At the beginning of 1943 , the Italian ace Luigi Gorrini ferried D . 520s taken as prizes of war to Italy to be used for defence . " I have collected several dozen Dewoitines from various French airfields and the Toulouse factory " , he recalled later . " At the time , when we were still flying the Macchi C . 200 , it was a good , if not very good , machine . Compared to the Macchi 200 , it was superior only in one point : its armament of the Hispano - Suiza HS 404 20 mm cannon . " . Italian pilots liked the 20 mm gun , the modern cockpit , the excellent radio set and the easy recovery from a spin but they also complained about the weak undercarriage and the small [ cannon ] ammunition drum capability ; the ammunition was not available in quantities ( the HS . 404 was not compatible with Breda and Scotti 20 mm guns , so everything depended on France ' s depots ) . Some D . 520s were delivered to 22rd " Gruppo " ( 359a " Squadriglia " ) , led by Major Vittorio Minguzzi . At that time , American B - 24s frequently bombed Naples , so an effective interceptor was badly needed , and D . 520s were all that were available in early 1943 . The 359a pilots used Dewoitines with some success . On 21 May 1943 , the " Regia Aereonautica " and the " Luftwaffe " agreed to exchange 39 Lioré et Olivier LeO 451 s , captured by the Italians at the SNCASE factory in Ambérieu - en - Bugey ( Lyon ) , with a stock of 30 D . 520s . Subsequently , in the spring and summer of 1943 , the Dewoitines were used by 161° " Gruppo Autonomo " , based in southern Italy with 163a " Squadriglia " in Grottaglie , 162a " Squadriglia " in Crotone and 164a " Squadriglia " in Reggio Calabria . On 31 July 1943 , the " Regia Aeronautica " still had 47 Dewoitines in service . After the armistice of 8 September 1943 , three D . 520s , previously in service with 24° " Gruppo " , were used by the Aeronautica Nazionale Repubblicana of the Italian Social Republic for training . Postwar service . After the war , the D . 520s that remained in France were used as trainers . One example was field - modified as a two - seater in late 1945 . In March 1946 , after further experiments , the French Air Force ordered a further batch of 20 D . 520s to be converted ; however , only 13 of these D . 520 DC conversions were completed . The last flight of an operational D . 520 was made on 3 September 1953 with EPAA ( " Esquadrille de Presentation de l ' Armée de l ' Air " ) . Initially , this unit had flown Yak - 3s , formally of the Normandie - Niemen fighter squadron ; these were later replaced with seven D . 520s , three of them being two - seaters . Variants . Direct derivatives . In 1940 , SNCAM had several projects to fit the D . 520 airframe with more powerful engines . These developments were halted by the June armistice . Post - armistice developments . Several projects were initiated after the June 1940 armistice . They were all terminated with the German occupation of Southern France in November 1942 . Markings . Apart from the first prototype and postwar examples , D . 520s sported the usual French camouflage of dark blue - grey , khaki , and dark brown with light blue - grey undersurfaces . The camouflage pattern was not standardized . National markings were the standard light blue - white - red roundels on the wingtips , as well as on the rear fuselage , and the rudder flag . Specific markings were applied during the Vichy era , consisting of white outlined fuselage roundels with a white fuselage stripe , and from mid - 1941 on , the infamous " slave ' s pajamas " with red and yellow stripes on the engine cowling and tail surfaces . Operators . Main operators Intended operators Royal Romanian Air Force