Bell P - 63 Kingcobra The Bell P - 63 Kingcobra was a United States fighter aircraft developed by Bell in World War II from the Bell P - 39 Airacobra in an attempt to correct that aircraft ' s deficiencies . Although the aircraft was not accepted for combat use by the United States Army Air Forces , it was successfully adopted by the Soviet Air Force . Design and development . XP - 39E . While the P - 39 had originally been introduced as an interceptor , later in its development it was decided to reduce the cost and complexity of the engine by removing the turbocharger . High - altitude performance suffered dramatically as a result , and Bell proposed an experimental series to test out a variety of solutions . The resulting XP - 39E featured two primary changes from the earlier P - 39D from which it was developed . One was a redesigned wing . The root airfoil , a NACA 0015 on other models of the P - 39 , was changed to a NACA 0018 , to gain internal volume . The other was a switch to the Continental I - 1430 engine , which featured an improved overall design developed from the hyper engine efforts , as well as an improved supercharger . Three prototypes were ordered in April 1941 with serials " 41 - 19501 " , " 41 - 19502 " and " 42 - 7164 " . The V - 1430 was having continued development problems and could not be delivered in time , so it was replaced by the newer - 47 version of the Allison V - 1710 that powered the basic P - 39 . Each of the prototypes tested different wing and tail configurations : " 41 - 19501 " had a rounded vertical tail , but the tailplane had squared - off tips , " 41 - 19502 " had a squared - off fin and rudder and large wing fillets while " 42 - 7164 " had all its flight surfaces squared off . The XP - 39E proved to be faster than the standard Airacobra ; a maximum speed of being attained at during tests . However , the XP - 39E was considered to be inferior to the stock P - 39 Airacobra in all other respects , so it was not ordered into production . XP - 63 . Although the XP - 39E proved to be disappointing , the USAAF was nevertheless interested in an even larger aircraft based on the same basic layout . Even before its first flight , the USAAF placed an order on 27 June 1941 for two prototypes of an enlarged version powered by the same V - 1710 - 47 engine . The new design was given the designation XP - 63 and serials were 41 - 19511 and 41 - 19512 . A third prototype was also ordered , 42 - 78015 , this one featuring the Packard V - 1650 , the U . S . - built version of the Rolls - Royce Merlin engine . The XP - 87897 was larger in all dimensions than the Airacobra . The wing was redesigned again , this time with new NACA laminar flow airfoils . The wing of the P - 63 was designed with a NACA 66 ( 215 ) - 116 a = . 6 at the root and a NACA 66 ( 215 ) - 216 a = . 6 at the tip . The wing taper ratio was approximately 2 : 1 , span was 38 ft , 4 inches and the area was 248 square ft . The V - 1710 - 47 engine was fitted with a second remotely mounted supercharger supplementing the normal single - stage supercharger . At higher altitudes when additional boost was required , a hydraulic clutch would engage the second supercharger , adding to the service ceiling . A larger four - bladed propeller was also standardized . A persistent complaint against the Airacobra was that its nose armament was not easily accessible for ground maintenance , and in order to cure this problem , the XP - 63 airframe was fitted with larger cowling panels . In September 1942 , even before the prototype flew , the USAAF ordered it into production as the P - 63A ( Model 33 ) . The P - 63A ' s armament was to be the same as that of the then - current P - 39Q , a single 37 mm ( 1 . 46 in ) M4 cannon firing through the propeller hub , two synchronized . 50 in ( 12 . 7 mm ) machine guns in the upper nose firing through the prop , and two . 50 in ( 12 . 7 mm ) machine guns in underwing gondolas . The trajectory of the . 50 in guns was far flatter than that of the cannon . The first prototype , " 41 - 19511 " , flew for the first time on 7 December 1942 . It was destroyed on 28 January 1943 when its landing gear failed to extend . The second prototype , " 41 - 19512 " , followed on 5 February 1943 . It too was destroyed , this time due to an engine failure . The Merlin - engined " 42 - 78015 " was later delivered with another Allison instead , as the Merlins were primarily needed for the P - 51 Mustang . Nevertheless the new - 93 version of the Allison had a war emergency rating of at sea level , making this prototype one of the fastest Kingcobras built , attaining at . Deliveries of production P - 63As began in October 1943 . The USAAF concluded the Kingcobra was inferior to the Mustang , and declined to order larger quantities . American allies , particularly the Soviet Union , had a great need for fighter aircraft , however , and the Soviets were already the largest users of the Airacobra . Therefore , the Kingcobra was ordered into production to be delivered under Lend - Lease . In February 1944 , the Soviet government sent a highly experienced test pilot , Andrey G . Kochetkov , and an aviation engineer , Fyodor P . Suprun , to the Bell factories to participate in the development of the first production variant , the P - 63A . Initially ignored by Bell engineers , Kochetkov ' s expert testing of the machine ' s spin characteristics ( which led to airframe buckling ) eventually led to a significant Soviet role in the development . After flat spin recovery proved impossible , and upon Kochetkov ' s making a final recommendation that pilots should bail out upon entering such a spin , he received a commendation from the Irving Parachute Company . The Kingcobra ’ s maximum aft CG was moved forward to facilitate recovery from spins . P - 63A - 8 , SN " 269261 " , was extensively tested at TsAGI in what was then the world ' s largest wind tunnel . Soviet input was significant . With the Soviet Union being the largest buyer of the aircraft , Bell was quick to implement their suggestions . The vast majority of the changes in the A sub - variants were a direct result of Soviet input , e . g . increased pilot armor and fuselage hardpoint on the A - 5 , underwing hardpoints and extra fuel tanks on the A - 6 , etc . The Soviet Union even experimented with ski landing gear for the P - 63A - 6 , but this never reached production . Most significantly , Soviet input resulted in moving the main cannon forward , favorably changing the center of gravity , and increasing its ammo load from 30 to 58 rounds for the A - 9 variant . The P - 63 had an impressive roll rate , besting the Americans ' P - 47 , P - 40 , and P - 51 — and the Japanese Navy ' s Kawanishi N1K 2 " Shiden - Kai " fighter — with a rate of 110° per second at 275 mph ( 443 km / h ) . Swept - wing L - 39 . Two war surplus P - 63Cs were modified by Bell under Navy contract for flight testing of low - speed and stall characteristics of high - speed wing designs . The aircraft received new wings with adjustable leading edge slats , trailing edge flaps and a pronounced sweep of 35 degrees . The wings had no wheel wells ; only the nose gear was retractable . L - 39 - 1 first flew 23 April 1946 , demonstrating a need for extra tail surface and rear fuselage length to balance the aircraft in flight - the wing repositioning reduced empennage effectiveness and moved the center of lift aft . A lighter three - bladed propeller from a P - 39Q - 10 was mounted and the necessary changes to the empennage were made . L - 39 - 2 incorporated these adjustments from the start . L - 39 - 1 later went to NACA at Langley for wind tunnel testing , where much valuable data were gathered . L - 39 - 2 also served as a testbed for the Bell X - 2 40 - degree wing design . Operational service . Soviet Union . The first version to be supplied in quantity to the USSR was the P - 63A - 7 with a higher vertical tail , and reinforced wings and fuselage . The fuselage proved to require strengthening , consequently in October 1944 , a reinforcement kit for operational P - 63s was developed . ) Air Transport Command ferry pilots , including U . S . women pilots of the WASP program , picked up the planes at the Bell factory at Niagara Falls , New York , and flew them to Great Falls , Montana and then onward via the Northwest Staging Route through Canada to Alaska , where Russian ferry pilots , many of them women , would take delivery of the aircraft at Nome and fly them to the Soviet Union over the Bering Strait via the Alaska - Siberia route ( ALSIB ) . A total of 2 , 397 ( 2 , 672 , according to other sources ) such aircraft were delivered to USSR , out of the overall 3 , 303 production aircraft ( 72 . 6 % ) . By a 1943 agreement , P - 63s were disallowed for Soviet use against Germany and were supposed to be concentrated in the Soviet Far East for an eventual attack on Japan . However , there are many unconfirmed reports from both the Soviet and German side that P - 63s did indeed see service against the " Luftwaffe " . Most notably , one of Pokryshkin ' s pilots reports in his memoirs published in the 1990s that the entire 4th GvIAP was secretly converted to P - 63s in 1944 , while officially still flying P - 39s . One account states they were in action at Königsberg , in Poland and in the final assault on Berlin . There are German reports of P - 63s shot down by both fighters and flak . Nevertheless , all Soviet records show nothing but P - 39s used against Germany . In general , official Soviet histories played down the role of Lend - Lease supplied aircraft in favor of local designs , but it is known that the P - 63 was a successful fighter aircraft in Soviet service . A common Western misconception is that the Bell fighters were used as ground attack aircraft . The Soviets developed successful group aerial fighting tactics for the Bell fighters and scored a surprising number of aerial victories over a variety of German aircraft . Low ceilings , short missions , good radios , a sealed and warm cockpit and ruggedness contributed to their effectiveness . To pilots who had once flown the tricky Polikarpov I - 16 , the aerodynamic quirks of the mid - engined aircraft were unimportant . In the Far East , P - 63 and P - 39 aircraft were used in the Soviet invasion of Manchukuo and northern Korea . In the Pacific theatre , the Kingcobras flew escort , close air support and ground attack missions . The Soviet P - 63s achieved their first air victory on 15 August 1945 , when " Lejtenant " I . F . Miroshnichenko from 17th IAP / 190 IAD , shot down a Nakajima Ki - 43 Hayabusa Army fighter off the coast of North Korea . Sufficient aircraft continued in use after the war for them to be given the NATO reporting name of Fred . By 9 May 1945 , operational units had still 1 , 148 Kingcobras on strength . On 8 October 1950 , two USAF F - 80C s from 49 FG breached the USSR ' s border and attacked Sukhaya Rechka airfield ( 31 km / 25 miles SW of Vladivostok and 100 km / 66 miles from the Soviet - Korean border ) , making two strafing runs before returning to their home base . Although Soviet sources claim the attack was intentional , the pilots claimed it was a result of a navigational error . The airfield belonged to the VVS TOF , but it was occupied by the 821 IAP / 190 IAD . Mostly aircraft of the 1st Squadron of 821 IAP were hit with 12 P - 63s damaged , one P - 63 burned to the ground while the other damaged aircraft were able to be repaired . No human losses were suffered . France . In 1945 , 114 later models were delivered to the French " Armée de l ' Air " , but they arrived too late to see service in World War II . They however saw service during the First Indochina War before being replaced in 1951 . Initially the French Kingcobras were deployed to Algeria . Fighter squadron ( Groupe de Chasse ) 2 / 6 " Travail " , previously equipped with P - 39 Airacobras , received their Kingcobras on 18 July at Casablanca ; the pilots were surprised by the higher landing speed of their new aircraft . The Kingcobra were scrambled to Indochina when the insurgency broke . Only 60 Kingcobras were operational in Indochina in January 1950 , mainly because the Americans refused to supply spare parts . Starting in February 1951 , the squadrons equipped with Kingcobra started to received F8F as replacements . Most Kingcobras were mothballed by July . The last flight of a Kingcobra in Indochina took place on September 6 , 1951 . " Pinball " operations . Its main use in American service was the unusual one of a manned flying target for gunnery practice . The aircraft was generally painted bright orange to increase its visibility . All armament and the regular armor was removed from these RP - 63 aircraft , and over a ton of armored sheet metal was applied to the aircraft . This was fitted with sensors that would detect hits , and these hits were signaled by illuminating a light in the propeller hub where the cannon would have been . This earned the aircraft the unofficial nickname of " Pinball " . Special frangible rounds made of a lead / bakelite combination were developed that would disintegrate upon impact . These were known as the " Cartridge , Caliber . 30 , Frangible , Ball , M22 . " Ivan L . Hickman , a veteran Pinball pilot , eventually authored " Operation Pinball " in 1990 . RAE Testing . British engineers , like the Americans , had a growing interest during World War II in the application of laminar flow airfoils . In an effort to learn more about the practical application of laminar flow airfoils , in 1945 the Royal Aircraft Establishment ( RAE ) undertook a flight test program with one of the two P - 63As that Great Britain had received . The aircraft was equipped with a wake rake array mounted outboard , behind the wing , to allow the momentum deficit , and thus section drag , to be measured . The RAE first tested it in an “ as delivered ” configuration . The wing airfoil was designed to be capable of supporting laminar flow to 60 % of chord . In the “ as delivered ” configuration , a profile drag was measured which was representative of the wing section with boundary layer transition at the leading edge ( 0 % laminar flow ) . Reducing the surface roughness reduced the drag at low lift coefficients to a level representative of laminar flow to 35 % of chord . Measurements were made of the surface waviness . This showed peak wave amplitudes , above the mean , of approximately . 011 inches over a two inch span . The standard waviness criteria shows the critical wave height to be . 0053 inches for this application . To reduce the waviness , RAE personnel stripped the wing to bare metal . The wing was then sprayed with two coats of primer paint and a coat of paint type filler . After the paint was dry , it was sanded in a chordwise direction , using sanding blocks , whose curvature matched the local surface curvature . This was repeated several times . Surface waviness was then measured and found to be no more than . 005 inches . In flight , this configuration was found to have a profile drag representative of boundary layer transition at 60 % of chord . This gave researchers an idea of what level of wing surface quality was required to actually get the benefits of laminar flow airfoils . Postwar air racers . Numerous surplus P - 63s ended up on the air racing circuit in the immediate postwar era . Charles Tucker purchased two P - 63s from the disposal facility at Kingman , Arizona just after the war . He entered one of them , the " Tucker Special " as Race 28 with the name " Flying Red Horse " emblazoned on the nose ( civilian register " N62995 " ) in the 1946 Thompson Trophy race . He had clipped the wing in an attempt to improve its speed , reducing the span to . The second one ( " 44 - 4126 " ( " XN63231 " Race 30 ) was intended for the 1946 Bendix cross country race . It was initially fitted with two wingtip drop tanks . In 1947 , the drop tanks were removed and the wings were clipped to Two other significant racers were flown later . " Tipsy Miss " , John Sandberg ' s clipped - wingtip P - 63 unlimited racer , was identified as " Race 28 , " and painted in bright orange , white and black race numbers with a chrome spinner . Later sold to a European pilot , this P - 63 was destroyed in an accident in 1990 " Crazy Horse Campgrounds " was the most radically modified P - 63 Kingcobra ever . Larry Haven ' s " Race 90 " clipped - wing unlimited racer had a tiny bubble canopy installed ; it appeared in all silver ( unpolished aluminum ) finish with a white rudder and black trim . The aircraft later crashed into the ocean on a test flight in 1972 .