Bell P-63 Kingcobra
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The Bell P-63 Kingcobra closely resembled the P-39 Airacobra, but was actually a new aircraft and not simply a modified P-39. Very few were used by the US, but a large number did serve in the Soviet Union.
Just to cause a little more confusion between the two aircraft, Bell used the same model number for the P-63 and the XP-39E Airacobra, which had a laminar flow wing and a supercharged V-1810 engine. Both versions of the Model 33 were proposed by Bell on 13-14 February 1941. Two prototypes of the XP-39E were ordered on 11 April, and the first prototype made its maiden flight on 21 February 1942, but was lost on 26 March. The second made its maiden flight on 4 April, and a third on 19 September. The P-39E didn't offer any significant improvement in performance over the P-39D, and so a plan to produce 4,000 as the P-76-BE was cancelled. The two surviving prototypes were used to help with the development of the XP-63.
The second version of the Model 33 led to the P-63. This used the same basic layout as the P-39, but was larger and heavier. It was powered by a 1,325hp Allison V-1710-47 engine with a hydraulically driven supercharger, carried behind the cockpit but powering a tractor propeller on the nose. It had a laminar flow wing. The P-63 had tricycle undercarriage with a nose wheel.
Two prototypes of the new XP-63 were ordered on 27 June 1941 (two months after the XP-39E). The first prototype made its maiden flight on 7 December 1942, after all three of the XP-39Es. The initial flight tests suggested that the new aircraft handled well, but the prototype was damaged beyond repair on 28 January 1943 after a problem with the undercarriage.
The second prototype made its maiden flight on 5 February 1943, but this one suffered from an engine failure in flight on 25 May 1943 and was also lost.
A third prototype was ordered in June 1942, as the XP-63B, a test-bed for the Rolls Royce Merlin. However no Merlins were available and it the airframe was thus available to replace the first two prototypes. This time it was given a 1,500hp Allison V-1710-93 engine and became the XP-63A. It also had a new dorsal air scoop and exhaust pipes, and weapon hard points under the wing. This was the fastest version of the Kingcobra, with a top speed of 426mph at 20,000ft. It was armed with a 37mm cannon firing through the propeller hub, two 0.50in machine guns in the forward fuselage and a 500lb bomb or 75 gallon fuel tank under the fuselage. It also carried 77lb of armour.
The P-63 was ordered into production on 29 September 1942 and the first P-63A was delivered in October 1943.
Service Record
The P-63 saw very little service with the USAAF. Some were used by Advanced Training Units but soon withdraw, put into storage and then scrapped. NACA used a handful for experiments.
The biggest user of the P-63 was the Soviet Union, which received 2,397 of the 3,303 that were built. These were delivered via Siberia between 1943 and 1945. Very little is known about their service in the Soviet Unit. A few may have been used against the Germans, but most were meant to have been concentrated in the Far East, where they were used against the Japanese. The Kingcobra was used to provide fighter cover for ground units, and not as a ground attack aircraft.
Another 300 were allocated to France, although only 150-200 appear to have been taken on charge. The first arrived on 26 July 1945, soon after the end of the Second World War, and were used by the GC 1/5 Vendée. A second unit received the type, but both were disbanded on 23 March 1946. The Kingcobra was brought out of retirement to fight in Vietnam, but even here saw limited use. Two units used them from 1949-1950, and two more in 1950-51, before they were replaced by more modern American types.
Variants
P-63A
The P-63A was produced in seven blocks, each slightly different.
The P-63A-1-BE carried 87.7lb of armour and carried 100 gallons of fuel. It was identical to the XP-63A prototype.
The P-63A-5-BE had double that armour, at 178.8lb. The fuselage hard point could now carry a 500lb bomb, 75 gallon drop tank or 175 gallon flush fitting ferry fuel tank.
The P-63A-6-BE had underwing racks that could carry a 75 gallon fuel tank or 5600lb bomb.
The P-63A-7-BE could carry 64 gallon fuel tanks under the wings.
The P-63A-8-BE increased the armour to 188.8lb and had a new propeller.
The P-63A-9-BE increased the armour again, to 198.9lb. The 37mm M-4 cannon was replaced with a M-10 cannon.
The P-63A-10-BE increased the armour to 236,3lb and could carry three rocket launchers under each wing.
A total of 1,725 P-63As were delivered between October 1943 and December 1944.
P-63B
The P-63B would have been a version of the aircraft powered by a 1,400hp Packard Merlin V-1650-5 engine, but none were built.
P-63C
The P-63C was the second production version of the aircraft. 1,227 were built. It used a 1,325hp Allison V-1710-117 engine, which offered more power at war emergency settings. The P-63C also had an anti-roll fin under the rear fuselage. The internal fuel tank could carry 107 gallons and the armour weighed 201lb. It carried the same armament as later P-63As and was build in two very similar blocks.
P-63D
The P-63D had a 1,425hp V-1710-109 engine, a bubble canopy and a larger wing. One was produced by modifying a P-63C. Speed increased to 437mph at 30,000ft, but this only put it on a par with the existing P-51D Mustang, so it didn’t enter production. The P-63D was destroyed during dive tests.
P-63E
The P-63E was the same as the P-63D, other than the use of the normal P-63 cockpit canopy. Contracts were placed for 2,930 aircraft, but only thirteen had been completed by VJ-Day, when the contract was cancelled.
P-63F
Two aircraft from the P-63E order were completed as the P-63F, with a 1,425 hp V-1710-135 engine with an enlarged fin and rudder to improve longitudinal stability.
XP-63H-BE
The XP-63H was a single P-63E that was given a 1,425hp V-1710-127 engine for use in comparative trials against the standard type.
XP-63N
Two aircraft were given a V-tail unit for tests.
TP-63A and TP-63C
This designation was given to around 24 aircraft that were given a second cockpit and used for instrument and equipment tests.
RP-63A
The RP-63A was the first in a series of gunnery targets produced by giving the P-63 thicker armour. They were designed to be used as part of bomber crew training. The bombers wound fire frangible bullets, made of a mix of lead and plastic, that would break up when they hit the armour. Five P-63As were converted in August 1944. All internal armour and weapons were removed to save weight and the normal skinning was replaced with thicker metal. An armoured canopy was installed. 110 microphones were buried below the skin to detect hits and a light was installed in the propeller hub that flashed when the aircraft was hit. The first flew on 1 September 1944. Early tests showed that further changes were needed to compensate for the change in weight distribution, and more lights were added around the rear fuselage. A batch of 95 RP-63A-12-BE production aircraft was then ordered.
RP-63C
This was followed by a batch of 200 RP-63-C-2-BEs, with a V-1710-117 engine and with 1,487.7lb of armour.
RP-63G
The final batch consisted of 32 RP-63G-1-Bes, powered by the V-1710--135 engine and with 2,164.9lb of armour. Another 420 were cancelled.
P-63A
Engine: Allison V-1710-93
Power: 1,325hp
Crew: 1
Span: 38ft 4in
Length: 32ft 8 3/8in
Height: 12ft 6 7/8in
Empty Weight: 6,375lb
Loaded Weight: 8,800lb
Maximum gross weight: 10,500lb
Maximum Speed: 361mph at 5,000ft; 392mph at 15,000ft; 410mph at 25,000ft
Cruising Speed: 378mph
Climb rate: 7.3min to 25,000ft
Ceiling: 43,000ft
Range: 390-450 miles
Guns: One 37mm cannon and two 0.5in machine guns
Bomb load: Up to three 500lb bombs
P-63C
Engine: Allison V-1710-117
Power: 1,325hp
Crew: 1
Span: 348ft 4in
Length: 32ft 8 3/8in
Height: 12ft 6/8in
Empty Weight: 6,795lb
Loaded Weight: 8,800lb
Maximum loaded weight: 10,715lb
Maximum Speed: 410mph at 25,000ft
Cruising Speed: 355mph
Climb rate: 8.5min to 25,000ft
Ceiling: 38,600ft
Range: 320 miles
Guns: One 37mm cannon and two 0.5in machine guns
Bomb load: Up to three 500lb bombs
Bell P-39 Airacobra, Robert F. Dorr with Jerry C. Scutts (Crowood Aviation). A detailed looked at the development and service history of this controversial American fighter aircraft. The P-39 had a poor reputation amongst British and American pilots, and Dorr examines the reasons why, as well as looking at why the same aircraft was so much more popular in Soviet Service. Scutts provides a chapter on the P-63 Kingcobra, and the book also covers the numerous Bell fighter projects that failed to enter production.
