Subject: Number Sixty-Three in the Series--Bell P-63 Kingcobra (1 of 8)

From: [email-masked]
Date: 15 Apr 93 16:32:50 GMT

>From [email-masked]

The P-63 Kingcobra was the result of an attempt on the part of the 
Bell Aircraft Corporation to correct some of the deficiencies of the 
earlier P-39 Airacobra.  Although the Kingcobra had a superficial 
resemblance to the P-39, it was, in fact, a completely new design and 
no parts of the two aircraft were interchangeable.  Of the several 
USAAF single-seat fighter designs which reached the preliminary flight 
test stage after Pearl Harbor, only the Bell P-63 Kingcobra succeeding 
in going into large-scale production and operational service before 
the end of the war.  

Although the Kingcobra met the requirements for which it was designed, 
these requirements were already outdated by the time they were framed.  
The P-63 was, in fact, fated never to enter combat wearing the colors 
of the nation which created it.  Those Kingcobras which did 
participate in combat did so while serving with foreign air forces.  
Of the 3303 Kingcobras built, 2421 were supplied to the USSR under 
Lend-Lease and 300 went to the French.  Of the remaining Kingcobras 
which stayed in the USA, 332 were converted as armored target 
aircraft.  

The history of the Kingcobra actually begins back before Pearl Harbor.  
Even before the USA entered World War 2, the USAAC had come to the 
conclusion that the Airacobra had too poor a high-altitude performance 
to make it an effective interceptor.  The deficiencies of the 
Airacobra were not due to any intrinsic flaw in the basic design, but 
were caused primarily by low engine power at high altitudes due to the 
unfortunate initial decision to omit the two-stage turbosupercharger.  
In February of 1941, the Bell Aircraft Corporation proposed to cure 
some of Airacobra's performance problems by mating the basic P-39D 
fuselage to an uprated engine and a laminar flow wing.  Three 
prototypes were ordered in April of 1941 under the designation XP-39E.  
Serials were 41-19501, 41-19502, and 42-7164.  The engine for these 
three planes was originally intended to have been the experimental 
Continental V-1430-1, but this engine ran into protracted development 
problems and a decision was made to switch to the 1350 hp Allison 
V-1710-47 liquid-cooled V-12 engine..  The wingspan and gross wing 
area were increased to 35 feet 10 inches and 236 square feet 
respectively.  

Each of these three aircraft tested different wing and tail 
configurations.  XP-39E Number one had a rounded vertical tail.  The 
tailplane had squared-off tips.  XP-39E number two had a squared-off 
fin and rudder and had large wing fillets.  XP-39E number three had 
all its flight surfaces squared off.  The XP-39E proved to be faster 
than the standard Airacobra--a maximum speed of 386 mph being attained 
at 21,680 feet 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.  

Even before its first flight, the USAAF considered the XP-39E project 
as showing sufficient promise that on June 27, 1941 they placed an 
order for two prototypes of an enlarged version powered by the same 
Allison V-1710-47 engine.  The designation was XP-63 and serials were 
41-19511 and 41-19512.  The XP-63 was larger in all dimensions than 
the Airacobra.  The wings were of a NACA laminar flow design that 
reduced drag by a significant amount and increased the span by 4 feet 
4 inches to 38 feet 4 inches.  The Allison V-1710-47 engine was fitted 
with a second hydraulic turbosupercharger supplementing the normal 
single-stage supercharger, effectively adding 10,000 feet to the 
service ceiling.  A four-bladed propeller was standardized.  A 
persistent complaint against the Airacobra was that its nose armament 
wasn't easily accessible for maintenance, and in order to cure this 
problem the XP-63 was fitted with larger cowling panels.  

In September of 1942, even before the first flight of the prototype, 
the aircraft was ordered into production by the USAAF as the P-63A.  
The P-63A's armament was to be the same as that of the P-39Q--a single 
37-mm cannon firing through the propeller hub, two 0.50-inch machine 
guns in the upper nose, and two 0.50-inch machine guns in underwing 
gondolas.  

The XP-63 Ser No. 41-19511 flew for the first time on December 7, 
1942.  This was the first anniversary of Pearl Harbor, and the 
significance of that date was not lost on anyone.  The XP-63 was 
fitted with a 37-mm hub cannon and two nose 0.50-inch machine guns 
(the underwing guns were not fitted).  Weights were 6054 pounds empty, 
7525 pounds gross, and 10,000 pounds maximum takeoff.  Dimensions were 
wingspan 38 feet 4 inches, length 32 feet 8 inches, height 11 feet 5 
inches, and wing area 248 square feet.  As anticipated, the XP-63 
exhibited a performance that was much better than that of the P-39.  A 
speed of 407 mph was attained at sea level during early testing.  

On January 28, 1943, the XP-63 prototype was lost in an unfortunate 
accident.  Test pilot Jack Woolams was just about to bring the XP-63 
in for a landing after a routine test flight when he found that the 
landing gear wouldn't extend.  He circled the airfield for several 
hours to burn off excess fuel.  By the time he was ready for the belly 
landing, the sun had set.  Woolams mistook the runway side lights for 
end lights and put the XP-63 down in a field of small trees.  Woolams 
walked away from the accident, but the XP-63 was a total loss.  

The second prototype (41-19512) flew for the first time on February 5, 
1943.  It did not have much better luck.  It crashed on May 25, 1943 
after its engine threw a rod at altitude.  

In spite of the loss of the two prototypes, the USAAF was sufficiently 
confident that there was no intrinsic flaw in the basic design, and 
the work on the Kingcobra project continued unabated.  Even though the 
XP-63 had exhibited a much better altitude performance than did the 
P-39, the USAAF nevertheless regarded the Kingcobra as being more 
suited for the low-altitude close-support role than for the 
high-altitude interception role.  

The production prototype (42-78015) flew for the first time on April 
26, 1943.  Designated XP-63A, this prototype differed in having a 1325 
hp Allison V-1710-93 engine in place of the -47.  The -93 engine had a 
war emergency rating of 1500 hp at sea level, and this prototype was 
one of the fastest Kingcobras built, attaining 421 mph at 24,100 feet.  
External differences included the fitting of wing racks for underwing 
stores, a redesigned dorsal air scoop, and 12 rather than 6 exhaust 
stubs per side.  

Production of the P-63 had been ordered by the Army in September of 
1942.  The P-63A (Bell Model 33) was the initial production version of 
the Kingcobra, and deliveries began in October of 1943.  

The initial production block was P-63A-1.  It was virtually identical 
to the XP-63A production prototype.  It was fitted with 87.7 pounds of 
pilot armor and had an internal fuel capacity of 100 gallons.  

The P-63A-5 introduced a dorsal radio mast, which became standard on 
all later models.  

The A-1 and A-5 could carry a 75- or 175-gallon drop tank or a 
522-pound bomb under the center section.  The P-63A-6 was fitted with 
wing racks so that either a 75-gallon tank or a 500-pound bomb could 
be carried under each wing.  

The P-63A-7 was fitted with an Aeroproducts propeller of slightly 
reduced diameter.  An increase in wing loading limited this variant to 
a 64-gallon tank under each wing.  

The P-63A-8 featured 188.8 pounds of armor.  An improved version of 
the Aeroproducts propeller increased maximum speed to 417 mph.  

The P-63A-9 had 198.9 pounds of armor.  It introduced the 37-mm M10 
cannon in place of the earlier M4, and an increase in ammunition 
capacity from 30 to 58 37-mm rounds.  

The P-63A-10 had rocket rails fitted underneath the wings.  The weight 
of the armor increased to 236.3 pounds.  

The P-63A-10 was powered by an Allison V-1710-93 twelve-cylinder Vee 
liquid cooled engine with a single-stage supercharger and auxiliary 
hydraulic turbosupercharger.  This engine was rated at 1325 hp at sea 
level and 1150 hp at 22,400 feet.  Maximum speed was 361 mph at 5000 
feet, 392 mph at 15,000 feet, and 410 mph at 25,000 feet.  An altitude 
of 25,000 feet could be reached in 7.3 minutes.  Service ceiling was 
43,000 feet.  Ferry range was 2575 miles.  Weights were 6375 pounds 
empty, 8800 pounds loaded, and 10,500 pounds maximum.  Dimensions were 
wingspan 38 feet 4 inches, length 32 feet 8 inches, height 12 feet 7 
inches, and wing area 248 square feet.  Armament consisted of a 37-mm 
M10 cannon with 58 rounds firing through the propeller hub, two 
0.50-inch machine guns in the nose with 200 rpg, and one 0.50-inch 
machine gun in each of two underwing gondolas with 900 rpg.  

Production deliveries of the P-63A began in October of 1943, and by 
December of 1944 1725 P-63As had been produced.  The USAAF never saw 
fit to use the Kingcobra for operational combat missions, since by 
that time in the war the need for low-altitude close-support fighter 
aircraft was more than adequately filled by such aircraft as the P-47 
Thunderbolt.  Nevertheless, P-63As did serve for a few months with the 
31st, 444th, and 445th Squadrons while they were based Stateside.  

Most of the P-63s that rolled out of the Buffalo plant were 
immediately ferried to the Soviet Union.  The Russians used the 
Kingcobra primarily for close-support and ground strafing.  The 
Kingcobra had a relatively good low-altitude performance and had the 
ability to absorb a lot of battle damage and still remain flying.  

Serials of the P-63A were as follows: 

42-68861/68910 		Bell P-63A-1 Kingcobra 
42-68911/68930 		Bell P-63A-5 Kingcobra 
42-68931/69060 		Bell P-63A-6 Kingcobra 
42-69061/69210 		Bell P-63A-7 Kingcobra 
42-69211/69410 		Bell P-63A-8 Kingcobra 
42-69411/69860 		Bell P-63A-9 Kingcobra 
42-69861/70685 		Bell P-63A-10 Kingcobra 

Many of these P-63As were converted into RP-63A target aircraft, which 
will be the subject of the next installment.  

The Paul Garber restoration facility of the Smithsonian Institution in 
Suitland, Maryland has a P-63A on display.  However, I was not able to 
get close enough to this plane to record its serial number.  

I also seem to remember a P-63A being on display at the Champlin 
Fighter Museum in Mesa, Arizona.  I remember it as being painted in 
Russian insignia.  However, I have no information about its serial 
number.  

Sources:

  The American Fighter, Enzo Angelucci and Peter Bowers, Orion, 1987.  

  War Planes of the Second World War, William Green, Doubleday, 1964.  

  United States Military Aircraft Since 1909, Gordon Swanborough and 
  Peter M. Bowers, Smithsonian, 1989.  

  P-39 Airacobra In Action, Ernie McDowell, Squadron/Signal 
  Publications, 1980.  

Joe Baugher		AT&T Bell Laboratories   	
2000 North Naperville Road      Naperville, Illinois 60566-7033