Dewoitine D.520
The Dewoitine D.520 was a French single-seat fighter aircraft that entered operational service in early 1940, just ahead of France’s involvement in the Second World War.
It was developed in response to a 1936 French Air Force requirement for a modern fighter featuring high speed, an effective climb rate, and a powerful armament centered on a 20 mm cannon.
Powered by the Hispano-Suiza 12Y liquid-cooled V-12 engine—the most advanced of its type available domestically at the time—the D.520 was lighter but less powerful than its British and German contemporaries, such as the Rolls-Royce Merlin and the Daimler-Benz DB 601.
Despite this, the aircraft achieved a balanced performance envelope and was considered a significant improvement over earlier French fighters.
Although several aircraft were designed to meet the 1936 specification, the D.520 was the only one to enter meaningful service before the Fall of France.
It arrived too late and in too few numbers to influence the Battle of France significantly but showed promising performance in combat.
Compared to the widely deployed Morane-Saulnier M.S.406, the D.520 was far more competitive with Germany’s Messerschmitt Bf 109.
While it lagged slightly behind in speed, it offered superior manoeuvrability, giving it a fighting chance in dogfights.
After the 1940 armistice, the D.520 remained in service with both the Free French and Vichy French air forces.
Production resumed in 1942, though at a reduced pace.
The type was also operated by other Axis and Allied-aligned forces, including the Luftwaffe, Italy’s Regia Aeronautica, and the Bulgarian Air Force.
It saw action in diverse theatres, including North Africa, the Balkans, and the Eastern Front, and was also employed in France and Germany for training and local defence roles.
In its final years, the D.520 served primarily as a trainer.
The aircraft was officially retired on 3 September 1953, marking the end of its long and varied service life.
Variants
D.520
The main production version, sometimes designated the D.520 S (for série – production) or the D.520 C1 (for chasseur – fighter, single-seat).
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.
D.521
engine replaced by a Rolls-Royce Merlin III, one example was built, but the project was cancelled.
D.523
engine replaced by slightly different sub-variants of the 820 kW (1,100 hp) Hispano-Suiza 12Y-51, with
Szydlowski-Planiol supercharger.
D.523 Prototype was completing pre-production trials in June 1940.
D.524
Version powered by Hispano-Suiza 12Y-89ter engine.
One prototype built, but it never flew.
D.525
development version of the D.523
D.530
planned version with a 1,044 kW (1,400 hp) Rolls-Royce Merlin
or
a 1,342 kW (1,800 hp) Hispano-Suiza 12Y.
Related pre-war projects
HD.780
Floatplane derivative of the D.520, one prototype built, but it never flew, the development was cancelled with the armistice.
D.790
Carrier-borne derivative project, none built.
D.550
Unarmed aircraft built for speed record attempt, with an airframe loosely based on the D.520, but using weight-saving construction techniques.
One example was built.
D.551 & D.552
Military developments of the D.550.
12 examples were built, but none flew.
The development was resumed in 1941, but was quickly terminated by the Germans.
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.
D.520 Amélioré
Single production D.520 experimentally fitted with minor improvements to improve top speed with an unchanged engine.
D.520 Z
D.520 airframe with 12Z engine and minor improvements.
One example was built.
The development resumed after the war (as SE.520Z), but was eventually cancelled in 1949.
Post-war derivative
D.520 DC (double commande – dual control)
Two-seat trainer conversion, at least 13 built.
