Bell P-63 Kingcobra
The Bell P-63 Kingcobra is an American fighter aircraft that was developed by Bell Aircraft during World War II. Based on the preceding Bell P-39 Airacobra, the P-63's design incorporated suggestions from P-39 pilots and was superior to its predecessor in virtually all respects. The P-63 was not accepted for combat use by the United States Army Air Forces. However, it was used during World War II by the Soviet Air Force, which had also been the most prolific user of the P-39.
Design and development
XP-39E
The P-39 had 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 I-1430 had continued development problems and could not be delivered in time, so it was replaced by an Allison V-1710-47, similar to that powering the P-39. Each prototype tested different wing and tail configurations: 41-19501 had a rounded vertical tail, but squared-off tailplane tips; 41-19502, a squared-off fin and rudder and large wing fillets; and 42-7164 had all its flight surfaces squared off. The XP-39E proved faster than standard Airacobra, reaching a maximum speed of at during tests. However, the XP-39E was considered 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 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. 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, using the Packard V-1650, the US-built version of the Rolls-Royce Merlin engine.The XP-63 was larger in all dimensions than the Airacobra. The wing was redesigned again, this time with new NACA laminar flow airfoils, 66-116 a=0.6 at the root and a NACA 66-216 a=0.6 at the tip. The wing taper ratio was approximately 2:1, span was, and wing area was. The 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 about the Airacobra was that its nose armament was not easily accessible for ground maintenance; 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. The P-63A's armament was to be the same as the current P-39Q, a single M4 cannon firing through the propeler hub, two synchronized.50 BMG| machine guns in the cowl, and two machine guns in underwing gondolas.
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 delivered with another Allison instead, a -93, which 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 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. Most 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 ammunition load from 30 to 58 rounds for the A-9 variant. The P-63 had an impressive roll rate, besting the US P-47, P-40, and P-51—and the Japanese Navy's Kawanishi N1K2 Shiden-Kai fighter—with a rate of 110° per second at.
Swept-wing L-39
After the war, 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 propeler 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 was gathered. L-39-2 also served as a testbed for the Bell X-2 40-degree wing design.Operational service
Soviet Union
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. There has been a common misconception that both the P-39 and P-63 were used mainly as ground attack aircraft. As historian James F. Gebhardt pointed out in a translation of one Soviet memoir, this was likely a result of mistranslations of Soviet military terminology. The role known as prikrytiye sukhoputnykh voysk literally "coverage of ground forces" was not the same as close air support in other air forces.The first version to be supplied in quantity to the Soviet Union was the P-63A-7 with a higher vertical tail, and reinforced wings and fuselage. The fuselage proved to need strengthening; consequently, in October 1944 a reinforcement kit for operational P-63s was developed.
Air Transport Command ferry pilots, including 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 Soviet ferry pilots, many of them also 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. A total of 2,397 aircraft were delivered to the USSR, 72.6% of the overall 3,303 production aircraft.
P-63s were allegedly supplied to the Soviet Union only on the condition that they be reserved for future operations against Japanese forces, under a 1943 agreement with the US. As such, all P-63 units were supposedly based in the Soviet Far East. However, according to anecdotal accounts, from both Soviet and German sources, some P-63s saw service against the Luftwaffe. A Soviet pilot who served under A. I. Pokryshkin, reported that the entire 4th Guards Fighter Aviation Regiment secretly converted to P-63s in 1944. Stuka pilot Hans Rudel stated in his memoirs that, over the Courland pocket, in early 1945, he and other German pilots had often encountered "American types of aircraft, especially Airacobras, Kingcobras and Bostons".. 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, official Soviet records do not record P-63s being used in Europe.
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 theater, 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 IJAAS fighter off the coast of North Korea.
Sufficient aircraft continued in use after World War II for them to be given the western reporting name of "Fred". By 9 May 1945, operational units still had 1,148 Kingcobras on strength. On 8 October 1950, two USAF F-80Cs from the 49th Fighter Group breached the USSR's border and attacked Sukhaya Rechka airfield south-west of Vladivostok and from the Soviet-Korean border, making two strafing runs before returning to their home base. Soviet sources say the attack was intentional, but the pilots claimed it was a result of a navigational error. The airfield belonged to the Air Forces of the Pacific Fleet, but it was occupied by the 821st Fighter Aviation Regiment of the 190th Fighter Aviation Division. 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. There were no human losses.