Heinkel HD 37
 The Heinkel HD 37 was a fighter aircraft designed in Germany in the late 1920s but produced in the USSR for Soviet Air Force service. It was a compact single-bay biplane with staggered wings of unequal span braced by N-type interplane struts. The pilot sat in an open cockpit and the main units of the tailskid undercarriage were linked by a cross-axle.