Heinkel He 51 in Bulgarian Service
The Heinkel He 51 was one of the earliest modern fighter aircraft operated by the Bulgarian Air Force during the interwar period. Bulgaria acquired 12 from Germany in 1936 as part of a gradual modernization program following the restrictions imposed after the First World War. At the time, the aircraft represented a significant improvement over older biplane fighters then serving in Bulgarian aviation units.
The He 51 was a German-built single-seat biplane fighter designed by the Heinkel company. Powered by a BMW VI engine, it featured good manoeuvrability and rugged construction, characteristics that made it suitable for training and fighter duties during the period. Although already becoming outdated compared to newer monoplane fighters appearing across Europe, the aircraft still provided valuable experience for Bulgarian pilots transitioning to more advanced combat aircraft.
In Bulgarian service, the He 51 was primarily used for fighter training, air defence preparation, and pilot conversion duties. Bulgaria’s air arm was still relatively small during the 1930s, and aircraft such as the He 51 helped establish a more professional and modern aviation force. Bulgarian pilots used the aircraft to develop formation flying, aerial gunnery, and tactical skills that would later prove important during the Second World War.
The aircraft also reflected the growing military relationship between Bulgaria and Germany during the late interwar years. German aviation technology and training increasingly influenced Bulgarian military planning, and the He 51 formed part of this broader cooperation. However, by the beginning of the Second World War, the He 51 had largely been superseded by faster and more capable monoplane fighters.
