russian heavy cannon fighter soviet fighter prototype designed world war development prolonged evacuation design bureau forced german advance moscow fall time second prototype finished soviets fighters equivalent better performance production program cancelled development november proposed heavy cannon armed fighter bomber escort duties ground attack missions new designed engines armament configurations planned consisted millimetre cannon firing propeller hub synchronized millimetre cannon mounted fuselage nose cannon provided rounds rounds second configuration substituted additional rounds cannon racks rockets underneath wings low wing mixed construction wooden fuselage birch metal wing built sections automatic leading edge engine built wing center section wing roots oil cooler located engine curved piece lacked flat panel gave pilot distorted view conventional including fully retractable carried litres imp gal gal fuel tanks wing center section rear fuselage cockpit tail resembled prototype completed october horsepower engine german attacks aircraft evacuated flight february engine proved unreliable changed late gun deleted exchange gun mounted fuselage flight testing completed airframe ground static testing estimated maximum speed metres mph time metres minutes second prototype built fitted engine proved unreliable replaced december flew november manufacturer flight tests completed june aircraft level performance available placed production specifications data gordon soviet world war general characteristics crew length wingspan wing area weight gross weight powerplant liquid cooled propellers bladed performance range nmi service ceiling time altitude minutes metres wing loading armament guns cannons rpg rockets
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