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Bell RP-63G KingCobra
United States — single-engine single-seat fighter
Archive Photos
1942 Bell P-63A-7-BE "King Cobra" (Fatal Fang) (AF 42-69080, c/n 33-380, N94501) c.2009 at the Yanks Air Museum, Chino, CA
1942 Bell P-63A-5-BE "King Cobra" (Pretty Polly) (AF 42-68864, NX163BP) c.1999 at the Palm Springs Air Museum, Palm Springs, CA
1942 Bell P-63A-7-BE "King Cobra" (NX52113, G-BTWR, AF 42-69097) c.1994 at the Imperial War Museum Duxford, Cambridgeshire, England.
Note: The below photo was taken in 1994 during the restoration process at Duxford. The aircraft had civil registry as NX52113, then N52113, then based at Duxford, UK, registered as G-BTWR. This aircraft later crashed at Biggin Hill Air Fair, UK, Jun 3, 2001, killing the pilot.
Overview
The Bell P-63 KingCobra, the prototype type of which first flew on December 7, 1942, is a development of the Bell P-39 Airacobra, which it resembles in all of its general features. The Bell P-63 KingCobra was never used operationally by the USAAF, the greater proportion of the output being delivered to Russia under Lend/Lease. A special modification of the Bell P-63 KingCobra was, however, evolved to serve as a target in the U.S. Army’s live ammunition training program. This model which carried the designation RP-63, was covered with more than a ton of special duralumin-alloy armor plate against which 30-cal lead and plastic frangible machine-gun bullets disintegrated harmlessly. Under the armor were special instruments which, when bullets struck the armor, transmitted impulses to a spotlight in the center of the airscrew hub, causing it to flash brightly. The armor was heaviest round the cockpit and varies from 1/8" to 1/4" inch in thickness. The windshield and cockpit side windows were of bulletproof glass, a steel grille covered the air intake and a steel guard the exhaust stacks. A special thick-walled hollow-blade airscrew was used. In spite of the greatly increased weight of the RP-63 target, it had a maximal speed of over 300 mph (480 kph) at 25,000 feet (7,625 m).
Design and Development
Bell 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 and replacing it with a simpler mechanical supercharger. High-altitude performance suffered dramatically as a result, and Bell proposed an experimental series to test out a variety of solutions.
The resulting Bell XP-39E featured two primary changes from the earlier Bell P-39D Airacobra from which it was developed. One change was the addition of a new laminar flow wing planform, which had recently been revealed to the industry through a National Advisory Committee for Aeronautics (NACA) research project. 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 Bell P-39 Airacobra. 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 386 mph (621 km/h) being attained at 21,680 ft (6,610 m) during tests. However, the Bell XP-39E was considered to be inferior to the stock Bell P-39 Airacobra in all other respects, so it was not ordered into production.
Bell XP-63
Although the Bell 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 laminar flow wings increased the overall span by 4.33 feet (1.32 m) to 38.33 feet (11.68 m). The engine was fitted with a second supercharger supplementing the normal single-stage supercharger. At higher altitudes when additional boost was required, a hydraulic clutch would engage the second supercharger, adding 10,000 feet (3,000 m) 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 Bell 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 Bell P-63A (Model 33) KingCobra. The Bell P-63A KingCobra’s armament was to be the same as that of the then-current Bell P-39Q Airacobra, a single 37 mm cannon firing 2 rps through the propeller hub, two .50 caliber machine guns in the upper nose firing 5 rps each through the prop, and two .50 caliber machine guns in underwing gondolas at a rate of around 13 rps each, for a total of 38 rps. The ballistics of the .50s were far more powerful than the cannon in muzzle velocity. When no longer serviceble, the unreliable Olds 37 mm was replaced often with the new B-20 cannon and the twin .50s with UBS 12.7 mm in the nose only, for a rate of fire on the order of 40 rps with more similar ballistics.
The first prototype, 41-19511, flew for the first time on 7 December 1942, the first anniversary of Pearl Harbor. It was destroyed on 28 January 1943 when its landing gear failed to extend. The second prototype, 41-19512, followed 5 February 1943. It too was destroyed, this time due to an engine failure. The Merlin-engine 42-78015 was later delivered with another Allison instead, as the Merlins were primarily needed for the North American P-51 Mustang. Nevertheless the new -93 version of the Allison had a war emergency rating of 1,500 hp (1,100 kW) at sea level, making this prototype one of the fastest KingCobras built, attaining 421 mph (678 km/h) at 24,100 feet (7,300 m).
Deliveries of production Bell P-63A KingCobras began in October 1943. The USAAF concluded the Bell P-63 KingCobra was inferior to the North American P-51 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. The Soviet Government sent a highly experienced test pilot, Andrey G. Kochetkov, and an aviation engineer, Fiodor Suprun, to the Bell factories to participate in the development of the first production variant, the Bell P-63A KingCobra. 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. Amusingly, 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.
A Bell P-63A-8 KingCobra, s/n 42-69261, was extensively tested at TsAGI in the world’s largest wind tunnel at the time. Soviet input in the development was significant. With the USSR 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 Bell P-63A-5 KingCobra, underwing hardpoints and extra fuel tanks on the Bell P-63A-6 KingCobra, etc. The Soviet Union even experimented with ski landing gear for the Bell P-63A-6 KingCobra, 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 shells for the Bell P-63A-9 KingCobra variant. The Bell P-63 KingCobra had an impressive roll rate, besting the Republic P-47 Thunderbolt, Curtiss P-40 Warhawk, Kawanishi N1K2-J Shiden-Kai and North American P-51 Mustang with a rate of 110° per second at 275 mph.
Operational Service
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 Alaska-Siberia Route (ALSIB), through Canada, over 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. A total of 2,397 such aircraft were delivered, out of the overall 3,303 production aircraft (72.6%).
By a 1943 agreement, Bell P-63 KingCobras 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 Bell P-63 KingCobras 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 Bell P-63 KingCobras in 1944, while officially still flying Bell P-39 Airacobras. One account states they were in action at Königsberg, in Poland and in the final assault on Berlin. There are German reports of Bell P-63 KingCobras shot down by both fighters and flak. Nevertheless, all Soviet records show nothing but Bell P-39 Airacobras 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 Bell P-63 KingCobra was a successful ground attack aircraft in Soviet service. The Soviets developed successful group aerial fighting tactics for the Bell fighters and Bell P-39 Airacobras scored a surprising number of aerial victories over German aircraft, mostly Stukas and bombers but including many advanced fighters as well. 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-engine aircraft were unimportant. In the Far East, Bell P-63 KingCobra and Bell P-39 Airacobra aircraft were used in the Soviet invasion of Manchukoku and northern Korea, where a Soviet Bell P-63A KingCobra downed a Japanese fighter aircraft, an Army Nakajima fighter, Ki-43, Ki-44 or Ki-84, 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." Some American pilots also reported seeing Bell P-63 KingCobras in service with North Korea during the Korean War.
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.
"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/graphite combination were developed that would disintegrate upon impact.
Variants
Postwar Air Racers
Numerous surplus Bell P-63 KingCobras ended up on the air racing circuit in the immediate postwar era.
Charles Tucker purchased two Bell P-63 KingCobras 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 25 ft, 9 inches. The second one (44-4126 (XN63231) 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 28 ft 6 in (8.7 m).
Two other significant racers were flown later. Tipsy Miss, John Sandberg’s clipped-wingtip Bell P-63 KingCobra 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 Bell P-63 KingCobra was destroyed in an accident in 1990. "Crazy Horse Campgrounds" was the most radically modified Bell 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.
Operators
Bell P-63A KingCobra Specifications
Type
Fuselage
Tail Unit
Landing Gear
Power Plant
Accommodation
Armament
Dimensions
Weights and Loadings
Performance
References