Heinkel HD 56

The Heinkel HD 56 was a two-seat reconnaissance seaplane designed in Germany by Heinkel for the Imperial Japanese Navy. Aichi Tokei Denki requested a design for a shipboard reconnaissance floatplane from Heinkel to enter in a navy competition, and Heinkel built a single HD 56 prototype, a conventional single-bay biplane with staggered wings braced by N-type interplane struts, the pilot and gunner sitting in tandem open cockpits, and a Wright Whirlwind engine. It was evaluated against the Nakajima E4N and the Kawanishi E5K and was announced the winner in 1931, on the condition that Aichi would address some shortcomings, particularly a lack of range. Aichi then reduced the length and span, replaced the Whirlwind with a locally built Hitachi Tempu and made numerous detail changes, and the result entered Japanese service as the Aichi E3A, the navy Type 90-1 Reconnaissance Seaplane.