Dewoitine D.520 Z
The D.520 Z was a late-war development of the Dewoitine D.520 fighter intended to significantly improve performance through the installation of a more powerful engine and incremental aerodynamic refinement. The project originated during the German occupation of France and later re-emerged briefly in the post-war reconstruction of the French aviation industry.
Development history
Work on the D.520 Z began in 1941, when French engineers sought to modernise the D.520 airframe by fitting the new Hispano-Suiza 12Z engine. This powerplant, projected to deliver roughly 1,500–1,600 hp, promised a substantial increase over the Hispano-Suiza 12Y series engines used in production D.520 fighters (Green, 1972; Pelletier, 2002). The redesigned aircraft required modifications to the forward fuselage, cooling system, and engine mounts to accommodate the larger and more powerful engine.
German authorities initially permitted limited continuation of fighter development within the French aviation industry. As a result, construction of a prototype D.520 Z began in 1942. However, the programme was halted in March 1943 when German occupation policy shifted and further fighter development was prohibited (Green, 1972; Pelletier, 2002). At that point, the prototype had not entered full flight testing in its intended configuration.
Post-war revival
Following the Liberation of France, the French aircraft industry resumed a number of interrupted piston-engine projects. The D.520 Z programme was revived in the later 1940s under the reorganised nationalised aviation sector. Development interest centred largely on evaluating the Hispano-Suiza 12Z engine and exploring the limits of upgrading existing wartime airframes rather than preparing the aircraft for production (Pelletier, 2002).
By this stage, however, jet propulsion had become the dominant direction of fighter design. Even with the more powerful engine, the D.520 airframe represented a pre-war aerodynamic concept approaching the limits of piston-engine fighter evolution. Testing activity associated with the revived D.520 Z project remained limited, and the aircraft did not proceed toward series manufacture. Ground evaluation work continued briefly before the programme was abandoned in the late 1940s (Green, 1972).
References
Green, W. (1972). War Planes of the Second World War: Fighters, Volume 1. London: Macdonald.
Pelletier, A. (2002). French Fighters of World War II in Action. Carrollton, TX: Squadron/Signal Publications.se, Vincennes. Fonds SNCASE, dossiers techniques 1945 1947.