The Heinkel Doppeldecker 43 was a prototype German fighter aircraft of the 1930s.
A single-engined, single-seat biplane, the HD 43 was designed to meet a secret German Reichswehr requirement for a single-seat fighter.
It had two-bay wooden wings with a steel-tube fuselage, and was powered by a 750 hp (600 kW) BMW VI engine.
The single prototype flew in 1931.
[1] Data from The Complete Book of Fighters [1]General characteristics Performance Armament