Heinkel HD 55

The Heinkel HD 55 was a biplane flying boat produced in Germany in the early 1930s for use as a reconnaissance aircraft aboard Soviet warships. The design was based on the HD 15 mail plane of 1927: a conventional layout with equal-span unstaggered wings, an engine mounted on struts above the pilot open cockpit, and a second open cockpit at the rear for a gunner. It came from a meeting between Heinkel and Soviet officials in May 1929 and a contract for 15 aircraft and two pneumatic catapults, an order that later grew. In Soviet service it was the KR-1. The first catapult went on the battleship Parizhskaya Kommuna in October 1930, trials revealed problems that were never fully resolved, and the type was plagued by structural defects. The final operational use was around 1938, and by 1941 all had been scrapped or placed in storage.