known russian prototype soviet seat fighter designed 1920s sole prototype built crashed ninth flight manufacturing defects program cancelled design development began design seat fighter initially designated seat fighter single engine october moscow soviet indigenous seat fighter single bay wings arranged configuration oval shaped semi fuselage birch wings covered upper wing lower wing internal wires wings built ribs large holes separated wings connected upper wing fuselage steel wires externally enclosed axle fixed small ski served imported engine enclosed metal carried fuel oil armament consisted single fixed synchronized machine gun machine gun mounted ring observer cockpit flight prototype took place january known demonstrated excellent performance flew observer fourth eighth test flights ninth flight march aircraft making speed runs measured kilometer airfield height metres upper surface right upper wing ripped followed lower skin right wings collapsed crashed killing pilot observer examination wreckage revealed large portions wings skin badly number rib caps panel connected structure holes necessary pressure inside wing outside missing entirely crash advanced aircraft shocked entire industry caused month hiatus design work loss built structure number subsequent aircraft stronger heavier needed work project abandoned following crash nominally lack suitable engine specifications data general characteristics crew length wingspan height wing area weight loaded weight powerplant lion cylinder engine performance maximum speed mph range nmi service ceiling wing loading power mass time altitude min horizontal turn time sec armament machine guns
Polikarpov DI-1