The P-63 Kingcobra was a further development of the Aircobra. It had the same general arrangement as its predecessor. The Bell Aircraft designers somewhat increased its dimensions, and changed the tail unit and wing. Out of 3,303 Kingcobra fighters constructed from 1943 to 1945, 2,400 went to the Soviet Union.
In December 1943, the Bell Company sent detailed information about the new fighter to Moscow. In February 1944, representatives of NII VVS, engineer-pilots A. G. Kochetkov and F. P. Suprun, were sent to the U.S. to carry out all-round tests of the plane before its mass delivery to the Soviet Union.
Having crashed one Kingcobra during the spin-tests, Kochetkov managed to convince the Americans of the necessity to modify the airframe. The shipment of P-63s was planned to begin in the first half of 1944. Early that summer American ferry-pilots delivered the first Kingcobras to Fairbanks and began to train Soviet pilots on them. In Alaska only the squadron commanders of the ferrying aviation division were trained. All other pilots would master the new plane directly in their regiments at the front. The P-63 ferrying went along the Siberian ALS/B air route. The first plane was handed over in June 1944. Beginning in September 1944, while still in the American aircraft factory, the P-63A began to be painted with the symbol of the Soviet Air Forces—red stars with white edging.
The new fighter did not arrive at the front immediately since there was no Soviet aviation shortage at that time. This permitted careful flight testing of the P-63. From the end of 1944 until March 1945, the planes of the series A-1, A-5, A-7 and A-10 were consecutively tested in NII VVS and LII NKAP ("Letno Ispytael'nyi Institut Narodnogo Kommissariata Aviatsionnoi Promyshlennosti/ Flying-Test Institute of People's Commissariat of Aviation Industry). On the whole, the P-63 performed well. Among its positive attributes were: high speed, good manoeuvrability, powerful weapons, and safe controls.
The P-63A was at a speed disadvantage to the Messerschmitt Me 109G-4 (9 km/h at a height 5,000 meters) and in rate-of-climb (2 m/sec) at the same height. But in horizontal manoeuvre the American fighter outstripped both the Me 109G- 4 and Focke-Wulf FW 190A-4.
Testing revealed other lacks compared with P-39s: the P-63's useful loading and fuel capacity were lower and its defensive armor was not as good. Also, wing covering deformation appeared on the A-1, A-5 and A-6 series aircraft. Consequently, Bell increased the thickness of the covering and strengthened the wings from the A-7 series on. The aerodynamic instability also emerged while pulling-out and during aerobatics. The latter problem was addressed on the P-63N with the installation of a more powerful engine, the V-1710-117, and a ventral fin. Despite all of the designers' efforts, both the Kingcobra and Aircobra suffered from spins. When the cannon and fuselage machine guns ammunition were spent, the trim of the planes was disturbed, requiring immediate correction by trimming the tabs. Otherwise, the P-63 went into a spin. Therefore, Soviet pilots flying the Kingcobra were forbidden to execute a sharp pull-out and input in vertical figures.
Beginning in the spring of 1945, the P-63 began to arrive at frontline PVO aviation units. The P-63 was best suited for search and interception missions. At altitudes above 7,500 meters, the Kingcobra overtook English Spitfire Mk. IX and Soviet Lavochkin La-7. It had good ceiling of 13,105 meters. The standard equipment of all P-63 was radio semi-compass MN-26Y, that essentially facilitated navigation at night and in clouds. Early in 1945 one P-63-A-10 arrived, equipped with radar. The radar was intended to prevent attacks from behind. By May 1, 1945 51 PVO regiments were equipped with P-63s. The initial Kingcobras went to units that had been armed with Aircobras. The first to receive P-63s was the 28th IAP of PVO, based near Moscow. By August 1945, P-63s arrived at the 17th and the 821st IAPs, ten planes in each. In autumn several Kingcobras came to the 39th IAP. All these regiments entered PVO of the Moscow region.
The P-63 began to be delivered in to Soviet Air Forces in the summer of 1945. As preparations were made for the war with Japan, the new fighters were sent to aviation units of the 12th Air Army in the Far East. The 190th aviation division under the command of Major General Fokin was the first to receive P-63A. The division was transferee! to Trans-Baikal in June 1945 and by August 2 finished retraining on the new American fighter. During air operations in Manchuria it flew from two airfields—"Ural" and "Leningrad"—located not far from Choibolsan in Mongolia.
The 245th IAD, which included the 940th and the 781st IAP regiments also flew P-63s. In July and August Kingcobras arrived at the 128th SAD (mixed aviation division), based on Kamchatka peninsula. At the beginning of air operations 97 P-63s arrived at the 9th and the 10th Air Armies.
During the brief military campaign against Japan, Kingcobras were used to provide air cover from air ground troops and ships, to attack and bomb, provide escort, and conduct reconnaissance. For example, on the second day of the offensive 40 IL-4 bombers, escorted by 50 P-63s bombed the fortifications at Suchzhou. Pilots of the 190th and the 245th IADs working as attack planes and light bombers supported the advancing Soviet and Mongolian troops. They also covered transport planes, delivering fuel to the advanced tank and mechanized units. The P-63s carried two Soviet FAB-100 bombs externally. Underwing large-caliber machine guns were not usually mounted. The 888th and the 410th IAPs from the Kamchatka peninsula inflicted considerable damage to Japanese bases on the Kuril Islands, and then covered the landing of Soviet troops on them.
The Japanese aircraft did not offer serious resistance to the advancing Soviet armies; therefore it was impossible to assess the Kingcobra's performance in air fights. One unique air combat in a P-63 was flown by Junior Lieutenant I. F Mirishnichenko of the 17th IAP. On August 17 he and V. F. Sirotin (a Hero of the Soviet Union) attacked two Japanese fighters, who were attacking transport planes coming in for a landing not far from the ship Vanemyao. One Japanese pilot was shot down, another managed to disappear on low-level flight among nearby hills. Miroshnichenko probably shot down the Japanese Ki-43 Hayabusa fighters.
Soviet pilots liked the P-63 for its ease of operation, and spacious, heated cabin with a perfect view, good devices and a shooting sight. However, after 1948 the problem of engine wear appeared. It was forbidden to fly the planes at extreme speeds. This edict was enforced by locking the throttle limiter quadrant. Kingcobras remained in action right up to the introduction of jet fighters. Their replacement began in 1950. In the end they played the important role in training pilots on jet engineering fighters MiG-9, and then MiG-15. Like the P-63, the jet fighters had a similar undercarriage with a nose-wheel. All Soviet fighters had an undercarriage of the old circuit with tailwheel. Here and there the task was sometimes complicated. For example, the landing approach was mastered without releasing the landing flaps at speeds of 400-500 km/h, imitating the MiG—15. When P—63s were removed from the inventory of combat units, they still remained in flying schools, as transitional plane.