soviet prototype heavily armored ground attack aircraft replace featured number innovative concepts including cockpit mounted engine directly propeller wing mounted adjusted ground fire level depressed allow aircraft ground targets remaining level flight slower immature engine problematic flight tests placed production test pilots called aircraft development concept meet requirement superior aircraft performance firepower heavily armored single engine metal low wing powered newly developed known liquid cooled engine developed horsepower design notable feature pilot cockpit mounted directly engine reminiscent furthermore cockpit situated directly bladed propeller maximize pilot visibility extended propeller hub provided pilot downward field view medium dive view targets directly underneath aircraft traditional ground attack aircraft load bearing armored shell protect pilot gunner engine fuel cooling systems thickness armor varied weighed total pilot canopy armored glass thick main wide variety armament considered involved wing mounted cannon mounted fuselage fixed downwards angle targets level flight version normal bomb load carried condition rockets carried instead version cannon guns wing rockets studies placed rear gunner dorsal turret separated cockpit main fuel tank study armored rear turret required longer fuselage moving wings aft maintain right place mounted fuselage cannon thought difficult aim included prototype weight savings allowed ammunition wing mounted guns increased rounds additional innovation prototype adjusted ground fire downward angle addition normal level position dorsal gunner fired gun mounted separate remotely controlled turret traverse elevated maximum cassette aerial grenades provided deter fighters approaching maximum bomb load bomb bays provided wing center section small bombs alternatively bombs carried wing racks launch rails provided rockets prototype completed november flight shortly december best speed manage mph altitude mph slower altitude possibly consequence increased drag weight penalties inherent greater fuselage cross section area result placement pilot engine new engine proved severe vibration problems problems air_force wasn satisfied armament access engine routine maintenance severely hampered placement cockpit engine concern close placement cockpit propeller believed increase risk pilot bail belly landing case bent propeller blades hit canopy issues coupled emerging jet engine technology led cancellation program specifications data russian aircraft general characteristics crew length wingspan height wing area weight loaded weight powerplant liquid cooled performance maximum speed mph range nmi service ceiling wing loading power mass climb min armament prototype flown cannon mounted turret cannon mounts main legs bombs rockets
Ilyushin Il-20 (1948)