Dewoitine D.520

The Dewoitine D.520 was the best fighter available to the French Armee de l'Air during the Battle of France in May-June 1940, and the only French fighter that could meet the Messerschmitt Bf 109E on roughly equal terms. Designed by Emile Dewoitine and his team at the Societe Nationale de Constructions Aeronautiques du Midi (SNCAM), the D.520 combined a clean, modern airframe with a reliable Hispano-Suiza engine and the hard-hitting 20mm HS.404 cannon that was the finest aircraft weapon in its class.

With a top speed of 332 mph and crisp, responsive handling, the D.520 was competitive with the best fighters in the world when it entered service in early 1940. French pilots who had previously flown the sluggish Morane-Saulnier MS.406 were delighted with the D.520's superior performance, and the aircraft quickly proved itself in combat during the desperate six weeks of the Battle of France, claiming 147 confirmed aerial victories against Luftwaffe aircraft.

The D.520's tragedy was one of timing. Only 36 had reached frontline squadrons when Germany attacked on May 10, 1940, and despite a frantic acceleration of deliveries, with factory workers laboring around the clock, fewer than 350 were operational by the armistice on June 25. Had the D.520 been available in the numbers originally planned, the air battle over France might have taken a very different course.

The D.520 originated from a 1936 Armee de l'Air specification calling for a modern single-seat fighter capable of 520 km/h (hence the designation). Emile Dewoitine's design team produced a sleek, low-wing monoplane with an enclosed cockpit, retractable landing gear, and a monocoque fuselage that represented a quantum leap over the parasol-winged and open-cockpit fighters that still equipped most French squadrons.

The prototype first flew on October 2, 1938, initially powered by a Hispano-Suiza 12Y-21 engine. Early flights were disappointing, the aircraft failed to reach its design speed due to excessive cooling drag and a host of aerodynamic imperfections. Over the following months, Dewoitine's team undertook an intensive program of refinement, redesigning the cowling, sealing gaps, adjusting the radiator intake, and fitting the more powerful 12Y-45 engine. By April 1939, the D.520 was exceeding 332 mph and demonstrating excellent handling.

Production orders were placed in June 1939, but French aircraft manufacturing was in a state of near-chaos following the nationalization of the aviation industry in 1937. The factories of SNCAM at Toulouse struggled with labor shortages, supply chain disruptions, and the need to set up entirely new production lines. The original plan called for 600 D.520s by April 1940, but by that date only 76 had been completed, and many of those lacked guns, radios, or propellers.

A crash production program in the spring of 1940 dramatically accelerated deliveries, with the factories eventually producing 10 aircraft per day by June. But this heroic effort came too late, the Battle of France was already lost by the time production reached its stride. After the armistice, production continued under Vichy France, eventually reaching a total of 905 aircraft, many of which were seized by Germany and Italy for use as trainers and second-line fighters.