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The
Airacobra was never outstanding in combat and was shunned by the
American and British pilots. However, it was excellent for low-level
operations against ground targets and used successfully by the Soviets
who scored an impressive number of air victories.
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It had been a standard practice among
manufacturers to design an airplane around an engine. However, this was
the first time a plane had been designed around a gun.
The Bell P-39
Airacobra |
The P-39 Airacobra was one of the most unusual single-seat fighters ever
ordered by the Army Air Corps. It had been a standard practice among
manufacturers to design an airplane around an engine. However, this was the
first time a plane had been designed around a gun; the American Armament
Corporation's 37-millimeter cannon.
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The P-39 Airacobra had a tricycle landing gear.
It was the first such gear ever used on a production fighter.
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The Bell engineers wanted to mount the cannon so it would fire directly
through the propeller shaft. This meant the engine would have to be located
deep in the fuselage, behind the pilot, so he would have access to the breech
mechanism of the cannon. This, in turn, dictated that the machine should have
a tricycle landing gear--the first such gear ever used on a production
fighter.
The Air Corps ordered one XP-39 on October 7, 1937. The plane was ready for
flight testing in April 1939, and that same month Bell was contracted to build
another 13 for service testing. Meanwhile, various design changes were made in
the XP-39 to improve performance. one of these changes was to eliminate the
supercharger, which lowered the effective operating altitude.
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About 9,560 of the planes were produced,
approximately half of which were sent to Russia under the Lend-Lease
program. |
Eighty production models of the P-39 were ordered by the Air Corps in
August 1939. Before the first of these was delivered, the French ordered the
airplane in quantity. When France was defeated in 1940, the order was taken
over by the British Purchasing Commission.
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Specifications: |
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Bell P-39D Airacobra |
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Dimensions: |
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Wing span: |
34 ft 0 in (10.36 m) |
| Length:
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30 ft 2 in
(9.19 m) |
| Height:
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11 ft 10 in
(3.61 m) |
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Weights: |
| Empty: |
5,462 lb
(2,478 kg) |
| Max Gross:
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8,200 lb
(3,720 kg) |
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Performance: |
| Maximum Speed:
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368 mph (592
km/h) @ 12,000 ft (3,658 m) |
| Service Ceiling:
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32,100 ft
(9,784 m) |
| Range: |
1,545 miles
(2,486 km) |
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Powerplant: |
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Allison
V-1710-35 , 1,150 hp 12-cylinder Inline Vee, Liquid cooled.
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Armament: |
One 37 mm cannon. Two .50 inch machine guns.
Four .30 inch machine guns. Bomb load 500 lb (227 kg). |
Production models of the P-39C started arriving at Air Corps squadrons in
January 1941; six months later the first Airacobras reached England. The
British had planned to order 675 of the planes, but after disappointing combat
experience, the order was canceled. At that time, the Royal Air Force needed
planes for aerial fighting, and while they found the Airacobra fine for
low-level operations, performance fell off sharply at high altitudes.
When Japan attacked the United States, the P-39 and the
Curtiss P-40 were the principal American land based fighters. Airacobras first went into
action against the Japanese in April 1942. Three months later they made their
first sortie in Europe--and six of the 12 planes that took off failed to
return to their base.
The Airacobra was never outstanding in combat. Ironically it was extremely
difficult to service because of the engine placement. However, it was
excellent for low-level operations against ground targets. About 9,560 of the
planes were produced, approximately half of which were sent to Russia under
the Lend-Lease program. The final model, the P-63 Kingcobra, was considerably
improved.
The
Aviation History On-Line Museum
How America's Best Pre-War Single
Engine Fighter
Was Ruined By The Air Corps
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The Bell XP-39 |
The story of the Bell P-39 is one that causes you to stop and
think of what might have been, as opposed to what actually was. Having gone
down in aviation history as the "Iron Dog", the Airacobra had from its
inception, the potential to be the world's finest fighter aircraft at the
beginning of America's involvement in WWII. That it instead became one of
the wars most loathsome fighters, easily conceals the real potential of the
prototype.
Bell's XP-39 prototype
was rolled out for the world to see on April 6, 1939 at Wright Field.
Essentially designed around the new Oldsmobile 37mm cannon (not unlike the
A-10 Warthog), the XP-39 was the second design which incorporated the 37mm
to come from Bell. Their original concept had placed the cannon behind a
front mounted engine, pushing the cockpit too far to the rear of the
fuselage to be practical.
Bell's chief engineer, Robert Woods, went back to work and conceived
an aircraft with a mid engine location, which allowed the plane's nose to be
dedicated to a very heavy ( by late 1930's standards ) battery of weapons.
This rather unusual engine placement was not unique. A mid-engine concept
had been tried by Koolhoven of Holland with limited success due to a poor
choice of powerplant and inadequate technology. Their FK-55 fighter did not
live up to expectations. The general concept, however, was not without
merit.
Woods' design employed the new Allison V1710 engine, rated at 1,150 hp
with the new B-5 turbo-supercharger. Installation of the Turbo-supercharged
Allison promised excellent high altitude performance. This provided for a
critical altitude of 20,000 feet, about the same as the XP-38. Expectations
were fully met and justified when, on April 6, the XP-39 attained a speed of
390 mph. Later flights produced speeds that flirted with 400 mph (398 mph
was reported). Bell's little fighter also displayed a remarkable rate of
climb, reaching 20,000 feet in 5 minutes flat! This odd looking aircraft
created no small stir in the aviation community. Nothing flying in Europe
could match the overall level of performance displayed by the XP-39. At
least nothing having the potential for production. It should be noted that
the prototype was unarmed and was not fitted with armor plate nor
self-sealing fuel tanks (the last two items were not part of the USAAC
specification).
Despite the superlative performance of the new Bell fighter, there
were design flaws. An undersized vertical stabilizer led to problems with
directional stability. Woods' also made a poor choice in airfoil section for
the wing. These problems could have been overcome, and in fact, the vertical
stabilizer was later redesigned to resemble that of the Curtiss P-36/P-40.
Airfoil section design was not addressed until the P-63 Kingcobra, where a
laminar flow wing was employed.
After the initial test flight, the XP-39 was turned over to the
engineers at Wright Field. And here is where the P-39 was generally undone.
At the time the Bell was being evaluated, the AAF was deep into
"streamlining" as a way to improve aircraft performance. This is somewhat
understandable, due to the relatively low powered aircraft engines of the
1930's. By reducing drag, especially parasite drag, the engineering minds at
Wright Field found that significant increases in performance could be
attained. This was all well and good. Unfortunately, they carried it too far
as it related to the XP-39. NACA engineers decided that the Bell's
turbosupercharger inlet created too much drag. Certainly the inlet generated
no greater drag than did the Prestone inlets on the Lockheed XP-38.
Nonetheless, they were insistent, the inlet scoop had to go. They reduced
the height of the canopy, chopped 2 feet off the wing span and lengthened
the fuselage by over a foot. A less powerful Allison with only a single
stage mechanical supercharger replaced the turbo-supercharged engine. This
effectively eliminated decent high altitude performance. Thanks to these
changes, the Airacobra had it's center of gravity shifted further aft,
exacerbating its already marginal stability. All said and done, the people
at Wright Field had reversed the old cliche, and created a sow's ear out of
a silk purse.
Certainly Larry Bell and Bob Woods were outraged at the butchered
result. Unfortunately, there was very little they could afford to do about
it. Bell Aircraft was at the edge of bankruptcy. Having only produced 15
total flyable aircraft, of any type, Bell was deep in debt. Neither Bell nor
Woods were willing to go to the mat for their beautiful fighter. To preserve
the company's financial viability, they would have to take it on the chin.
Their pressing need was to get an order and establish some inward cash flow.
Fortunately, Bell sold the French on the P-39 and received 2 million
dollars in advance on an eleven million dollar order. Later that same year
(1940), Bell received orders for just under 1,000 P-39Cs and Ds from the
USAAF. These were equipped with self-sealing fuel tanks and additional
armor, the weight of which, only further degraded performance. Without the
turbo-supercharger, or even a gear driven two speed, two stage supercharger,
the Airacobra was not capable of taking on modern fighter aircraft at
anything above 10,000 feet. It should also be noted that the early versions
of the Allison V1710 engine never produced anything close to their
advertised power rating without a turbo-supercharger pressurizing the intake
system.
Overall handling had degraded to a point where some claimed (without a
grain of truth) that if the pilot simply sneezed, the plane would spin. Some
Brits flat out refused to fly the plane, one pilot saying it was more
dangerous to RAF pilots than the Luftwaffe. Such extreme examples of
exaggeration followed the P-39 throughout its service life.
Adding to the general unhappiness with the airplane, the 37mm Colt M4
cannon frequently jammed after only firing a few rounds. The balance of the
guns, 2 .50 cal. M2 and 4 .30 cal. Brownings were inadequate by 1942
standards. One of the problems pointed out by the British was the cockpit
being filled with cordite fumes after firing the guns. They also found that
firing the guns would knock the magnetic compass out of whack. The RAF did
admit that at low level they found the Airacobra to be a match for the
Bf-109E. Unfortunately, the RAF needed a high altitude fighter. Besides, the
Luftwaffe was now getting newer and far better performing fighters.
Because the Russians
were seemingly satisfied with the P-39 is not indicative of the aircraft's
performance as much as the Russian's desperate need for combat aircraft.
Moreover, the air war on the eastern front was fought largely below 20,000
feet, and more often than not, well below that. At these heights, the P-39
possessed some marginal level of capability. Credit must be given to those
Soviet pilots who, despite the severe limits of the aircraft, used them very
effectively against the Luftwaffe's superior Bf 109s and Focke Wulf 190s.
Bell P-39s served in North Africa and Italy with the USAAF and several
other Allies including the Free French and Italians. Airacobra service in
the Pacific has been the subject of many books and articles. In a single
sentence; the "Iron Dog" was replaced as quickly as possible.
Taken as a whole, the P-39 was a dismal failure of the AAF's
engineering and procurement establishment to identify and develop the better
attributes of an advanced and promising fighter aircraft. This was the same
establishment that prevented Lockheed from installing Merlin engines in the
P-38 as early as 1941. Had the USAAC (Air Corps) not stripped the
turbo-supercharger from the XP-39, the United States may have entered the
war with a competitive single engine fighter plane already in service.
Indeed, it was not until the advent of the Bell P-63 that the level of
performance finally matched that of the Bell XP-39 of 1939. Of course, by
that time, the P-63 was already outclassed by the P-38, P-47 and P-51.
Indeed, the P-63 was too little too late. In large part, it was the Air
Corps myopic vision of the future of aerial warfare that caused it to be so.
RESOURCES:
Rick Mitchell, The Complete Story of Bell Aircraft Corporation's P-39
Pursuit Fighter Plane.
Ernest R. McDowell, P-39 Airacobra in Action.
Francis H. Dean, America's Hundred Thousand.
Warren M. Bodie, The Lockheed P-38 Lightning.
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The History Of The Bell Airacobra |
by Joe Baugher
The Bell P-39 Airacobra was not exactly one of the best
aircraft of the Second World War. Many historians list the P-39 as being a
failure. It was criticized for its low service ceiling, its low service
ceiling, its slow rate of climb, and its generally poor high-altitude
performance vis-a-vis the Japanese Zero fighter. However, along with the
Curtiss P-40, the P-39 was the only fighter available in quantity to fight
against the Japanese advance during the first six months of the war.
Its poor high-altitude performance was a result of a
critical decision made early in the Airacobra's design process, namely, the
decision to remove the turbosupercharger. Nevertheless, the Airacobra did
give a fairly good account of itself, all things considering. It was a
well-built and reliable aircraft capable of absorbing quite a bit of battle
damage and still returning to base. It excelled in the low-altitude ground
support, its heavy armament making it a good tank buster, especially in
service with the Soviet Air Force.
A total of 9589 Airacobras were built. This number is based
on a count of serial numbers. Some other sources list 9558 being built.
The Bell P-39 Airacobra had its origin in June 1936 when the
Buffalo, New York-based Bell Aircraft Corporation's design team, headed by
Robert J. Woods and Harland M. Poyer, began the design of a single- seat
fighter. The Bell corporation was responding to a 1936 Army Air Corps
request for a new single-seat fighter design, one which would be equal to
the new European fighters just then beginning to undergo flight test.
Woods and Poyer conceived the idea of mounting the engine in
mid-fuselage, driving the propeller via a ten-foot extension shaft. Such an
arrangement was not exactly new, having been tried earlier by the
experimental Westland F.7/30 biplane and by the Dutch Koolhoven F.K.55
monoplane. Among the potential advantages offered by such an arrangement was
the possibility of superior maneuverability, since the weight of the plane
would be more nearly concentrated at the center of gravity. In addition, it
would facilitate the installation of a heavy nose armament, since the
armament could be mounted near the centerline, minimizing the effects of
recoil forces. It would also offer good visibility for the pilot, and would
permit the installation of a tricycle undercarriage.
Bell's original proposal was to place the pilot behind the
engine, forcing the cockpit very far to the rear and making the proposed
aircraft look a lot like the Curtiss XP-37. A mockup with this configuration
was built with this configuration and was given the company designation Bell
Model 3. However, the problem of visibility over the engine eventually
forced Bell engineers to move the pilot ahead of the engine, and a revised
mockup, given the company designation Bell Model 4, was used as the basis of
a formal submission to the USAAC on May 18, 1937. The Bell submission
promised a top speed of 400 mph at 20,000 feet and a gross weight of only
5500 pounds.
The USAAC was sufficiently intrigued by the proposal that
they ordered one prototype on October 7, 1937 under the designation XP-39.
The company designation was Model 12. The serial number was 38-326. The
powerplant of the XP-39 was the 1150 hp Allison V-1710-17 (E2) l2-cylinder
liquid-cooled Vee which was fitted with a B-5 two-stage turbosupercharger on
the portside of the central fuselage. A somewhat smaller radiator/oil cooler
scoop was fitted on the other side of the fuselage. Provision was made for
two 0.50-inch machine guns in the forward fuselage and one 25 mm cannon
firing through the propeller shaft. In December 1938, it was decided to
replace the 25-mm cannon by an even heavier 37-mm T9 cannon designed by the
American Armament Corporation, a subsidiary of the Oldsmobile automobile
manufacturer. In the event, no armament was actually fitted to the first
prototype.
The fuselage was of all-metal construction and had an oval
cross section. It was built up in two main sections: the forward section
that included the engine mounts and wing center sections which was built
around two longitudinal strength member and the cockpit deck plate and the
semi-monocoque rear section built up of bulkheads and stringers. The tail
had all-metal fixed surfaces and fabric-covered control surfaces. The wing
panels joined at a point 22 inches out from the centerline. The wing
structure had three spars, and the Frise-type ailerons were fabric covered.
The inboard wing trailing edge carried split flaps.
The cockpit canopy had six transparent panels, and offered
exceptional all- round visibility. An unusual feature of the Airacobra was
the automobile-type door on each side of the cockpit, which allowed easy
access by the pilot to the cockpit from either side. The doors even had
roll-down windows! The cockpit was fairly easy to enter and exit, but the
doors had a tendency to fly open in midair at high speed if improperly
secured.
The engine behind the pilot's seat drove the propeller by
means of a driveshaft mounted under the pilot's seat. Early Airacobra pilots
feared what might happen if the driveshaft were to break loose or were to
start whipping around inside its mount. However, in practice there were no
more problems encountered with this driveshaft than with more conventional
arrangements. However, there were problems with the complex nose-mounted
reduction gear, which caused reliability problems and resulted in fairly low
serviceability rates as compared with other fighters. The exhaust system
lead to six ejector stubs on each side of the fuselage (changed to 12 stubs
on later models).
The Army dictated that a tricycle landing gear be fitted.
The gear incorporated a non-steering, self-castoring nosewheel that
retracted upwards and back. The main wheels retracted inward to wells
underneath the wing. All wheels were constructed of magnesium alloy and used
tubed tires.
The fuel was carried in tanks totaling 60 gallons in
capacity in the wing outer panels. There was a reserve tank of 30 gallons in
the left wing.
The XP-39 was completed at Bell's Buffalo plant and shipped
by truck to Wright Field in Ohio. It was reassembled there and flown for the
first time on April 6, 1939, Bell test pilot James Taylor being at the
controls. The performance was excellent, the prototype reaching a speed of
390 mph at 20,000 feet. An altitude of 20,000 feet could be attained in 5
minutes, quite impressive climbing performance for the time. Service ceiling
was 32,000 feet. Weights were 3995 pounds empty, 5550 pounds gross, and 6304
pounds maximum takeoff. The USAAC was quite impressed with the performance,
perhaps ignoring the fact that the XP-39 carried no military equipment or
armament and was thus much lighter that that which could be anticipated for
production models.
The initial XP-39 tests went quite well, and the only
problem that was encountered being some engine overheating difficulties. At
first, it was thought that the overheating problems might be due to bad
ventilation, and the left-hand supercharger and the right-hand radiator
intakes and exhausts were both enlarged. However, this did not cure the
problem, and it was found later that the problem was easily cured by a
simple change in the structure of the oil system. With this change, the
XP-39 was accepted for production with an initial order for twelve
service-test YP-39s (Bell Model 12) and one YP-39A in April 1939. Serials of
the YP-39s were 40-027/038. The YP-39A (40-039) was to have been powered by
a high-altitude V-1710-31 engine of 1150 hp.
In the meantime, the XP-39 underwent a series of full-scale
wind-tunnel tests in NACA's wind tunnel at Langley Field, Virginia. After
the tests, the XP-39 was returned to Buffalo for revisions. The rebuilt
XP-39 emerged as the XP-39B. Most of the changes were improvements in the
streamlining of the airframe. The cockpit canopy was changed to a longer and
lower shape. Changes were made to the wheel doors. The oil cooler and
radiator intakes were moved from the fuselage right side to the wing roots.
The wing span was decreased from 35 feet 10 inches to 34 feet, and length
was increased from 28 feet 8 inches to 29 feet 9 inches.
The most serious change, however, was the elimination of the
turbosupercharger, and its replacement by a single-stage geared
supercharger. This change was a result of a shift in philosophy on the part
of the USAAC. The USAAC believed that the widths of the Atlantic and Pacific
Oceans made the USA virtually immune from high-altitude attack by enemy
bombers. Therefore, the development of high-altitude interceptors was
curtailed in favor of strike fighters optimized for low-level close support.
The 1150 hp V-1710-17 (E2) of the XP-39 was replaced by a V-1710-37 (E5)
engine rated 1090 hp at an altitude of 13,300 feet. The carburetor air
intake was mounted in a dorsal position just behind the cockpit, where it
was to remain throughout the Airacobra production run.
The XP-39B resumed flight trials on November 25, 1939. Empty
weight had grown from from 3995 lbs to 4530 lbs, and normal gross weight was
up to 5834 pounds from 5550 pounds, and the aircraft STILL didn't have any
armament. The removal of the turbosupercharger was to have fateful
consequences for the future of the Airacobra. Although the Allison engine
was more reliable and more easily service when the turbosupercharger was
eliminated, the engine only performed well at low and medium altitudes and
lost power quite rapidly at altitudes over 15,000 feet. Even in spite of the
improved streamlining, the XP-39B suffered a severe degradation in
high-altitude performance. Maximum speed fell from 390 mph at 20,000 feet to
375 mph at 15,000 feet, and it now took 7.5 minutes to reach 20,000 feet
rather than five minutes. However, there was an increase in low-altitude
maneuverability because of the reduced wing span, and the decrease in
low-altitude performance was only marginal.
The XP-39B was damaged in a belly-landing at Wright Field,
Ohio on January 6, 1940. It was repaired and resumed flying, later to be
demonstrated at Bolling Field in Washington, DC. Unfortunately, the XP-39B
was destroyed in an accident after only 28 flying hours.
The USAAC was satisfied with the low-altitude performance of the
Airacobra, and directed that the twelve YP-39s be completed without
turbosuperchargers. It was decided to embody the changes made in the XP-39B
in the service test machines. effectively transforming them into YP-39B
aircraft, but I don't know if this designation change ever became official.
The YP-39A was originally to have been delivered with the high-altitude
V-1710-31 engine, but the change in USAAC philosophy caused this plan to be
abandoned and this aircraft was delivered as a standard YP-39.
The first YP-39 (40-027) was flown on September 13, 1940 with the 1090 hp
V-1710-37 (E5) engine driving a Curtiss Electric propeller. It differed
externally from the XP-39B primarily in having a wider-chord vertical tail.
The first few YP-39s were initially flown without armament, but subsequent
machines were fitted with a 37 mm cannon with 15 rounds, a pair of 0.5-inch
machine guns with 200 rounds per gun, and two 0.30-inch machine guns with
500 rounds per gun. All of these guns were mounted in the nose. Some armor
protection was provided for the pilot. Empty and normal loaded weights rose
to 5042 pounds and 7000 pounds, respectively. In comparison, the XP-39
prototype had a normal loaded weight of only 5550 pounds. Consequently, the
performance of the YP-39 dropped to a maximum speed of 368 mph at 15,000
feet. An altitude of 20,000 feet could be attained in 7.3 minutes. Service
ceiling was 33,300 feet.
The thirteen YP-39s (40-027/40-039) were delivered between September 6
and December 16, 1940. They were used primarily for evaluation and testing.
Some of them were returned to the Bell factory for use in the development of
improved Airacobra versions. These service-test machines apparently never
reached Army aquadrons. Most of the YP-39s were lost in flight testing
accidents.
In spite of the degradation in performance, the USAAC was generally
pleased with the Airacobra, and an initial order for 80 production examples
(Bell Model 13) was issued on August 10, 1939 under Contract AC13383.
Serials were 40-2971/3050.
For some reason, the USAAC allocated the new designation of P-45 to these
machines, even though they were almost identical to the YP-39 service test
aircraft. However, in the political climate of 1940, it was virtually
impossible for the USAAC to acquire any new aircraft. But it could order
more examples of an already-existing model. Consequently, the designation of
the Airacobra was changed to P-39C prior to the delivery of the first
aircraft.
The first P-39C (Ser No 40-2971) flew in January of 1941. The P-39C was
almost identical to the YP-39, with the exception of the engine, which was a
1150 hp Allison V-1710-35 (E4). The production of the P-39C began in 1940.
The Army discovered almost immediately that the P-39C was not combat
ready, since it lacked armor and self-sealing tanks. In the event, only
twenty Airacobras were actually completed to C-standards--serial numbers
40-2971/2990. On September 14, 1940 the initial order for 80 P-39Cs was
amended to provide for self-sealing fuel tanks. The remaining 60 planes of
the order ( serial numbers 40-2991/3050) were completed to this standard and
were redesignated as P-39Ds.
The P-39C was powered by a 1150 hp Allison V-1710-35 engine. Weights were
5070 pounds empty, 7075 pounds gross (combat weight), and 7300 pounds
maximum takeoff. Maximum speed was 379 mph at 13,000 feet. An altitude of
12,000 feet could be reached in 3.9 minutes. Service ceiling was 33,200
feet. Armament was one 37-mm cannon, two 0.50-inch and two 0.30-inch machine
guns, all in the nose.
Combat reports coming back from Europe led the USAAC to conclude that the
P-39C was inadequately armed and armored for its intended ground-support
role. On September 13, 1940, 394 P-39Ds (Model 15) were ordered. The serials
were 41-6722/7115. It was the first Airacobra which could be considered even
remotely as being combat-ready.
On the day after the P-39D order, the initial contract for the P-39C was
modified, and the 21st and subsequent machines on the P-39C order (serials
40-2991/3050) were ordered completed as P-39Ds.
The P-39D differed from the P-39C primarily in having a heavier armament.
It had four wing-mounted 0.30-inch machine guns with 1000 rpg, two
fuselage-mounted 0.50-inch machine guns with 200 rounds per gun, plus the
37-mm cannon (with increased ammunition capacity of 30 rounds). Bulletproof
windshield panels were added, and some armor protection for the pilot was
provided. Self-sealing fuel tanks were introduced, which reduced internal
fuel capacity from 141.5 Imp. gall. to 100 Imp. gall. This internal fuel
could be supplemented by a 72.4 Imp. gall drop tank carried on a strongpoint
fitted underneath the fuselage. In place of the drop tank, a 300 lb or 600
pound bomb could be carried. A different 10 foot 5-inch Curtiss Electric
propeller was fitted and the fuselage length was increased to 30 feet 2
inches. In addition, a very small dorsal fin was added just ahead of the
rudder. The D model also differed from all other Airacobra variants in
having a slightly smaller wing area of 213 square feet, as compared with
213.22 square feet on all other models.
The bulletproof windshield and armor protection added 245 pounds to the
weight of the aircraft, causing the climb and altitude performance to
suffer. The maximum speed at 15,000 feet dropped to 360 mph.
The first P-39D Airacobras entered service with the USAAC in February
1941, first with the 31th Pursuit Group (39th, 40th, and 41st Pursuit
Squadrons) based at Selfridge Field, Michigan. Between February 12 and March
21, 1941 27 USAAC pilots flew three P-39Ds over 160 accelerated service test
hours at Patterson Field in Osborne, Ohio. In March of 1941, Bell's test
pilot Vance Breese dove an Airacobra 15,000 feet to pass the final Army Air
Corps test. The 39th PS partcipated in the "Carolina Maneuvers" from
September to November of 1941, which was a series of war games during which
five different squadrons flew Airacobras.
The P-39D (along with the P-400) was the first to see combat in US
service. There were a great many weaknesses in the Airacobra, apart from the
general problem of poor high-altitude performance. Among these were the lack
of gun heaters which caused the guns to freeze up and jam at altitudes over
25,000 feet, the lack of hydraulic chargers which made it difficult to
charge the guns in the air, and the forward gear box just behind the
propeller which had a tendency to throw oil.
Specification of Bell P-39D Airacobra:
Engine: One 1150 hp Allison V-1710-35 twelve-cylinder liquid cooled
engine. Performance: Maximum speed 309 mph at sea level, 335 mph at 5000
feet, 355 mph at 10,000 feet, 368 mph at 12,000 feet, and 360 mph at 15,000
feet. An altitude of 5000 feet could be reached in 1.9 minutes. It took 5.7
minutes to reach an altitude of 15,000 feet and 9.1 minutes to reach 20,000
feet. Service ceiling was 32,100 feet. Maximum range (clean) was 600 miles
at 10,000 feet at 231 mph. Range with one 145.7 Imp gal drop tank was 1100
miles at 196 mph. Weights: 5462 pounds empty, 7500 pounds gross, and 8200
pounds maximum takeoff. Dimensions: Wingspan 34 feet 0 inches, length 30
feet 2 inches, height 11 feet 10 inches, and wing area 213 square feet.
Armament: One 37-mm cannon in the nose with 30 rounds. Four wing-mounted
0.30-inch machine guns with 1000 rpg, two fuselage-mounted 0.50-inch machine
guns with 200 rounds per gun. One 250 lb, 325-lb, or 500-lb bomb could be
carried underneath the fuselage.
Serials of P-39D:
40-2991/3050 Bell P-39D Airacobra
60 planes
41-6722/7115 Bell P-39D Airacobra
394 planes
|
The Aircobra I For The RAF, P-400 |
While the YP-39 and the P-39C were being test-flown, Bell Aircraft began
work on an export version of the Airacobra known as the Bell Model 14. It
was to be powered by a 1150 hp Allison V-1710-E4 engine which had twelve
exhaust stacks on each side rather than the usual six. France was
sufficiently interested that they ordered 200 Model 14s on October 8, 1939.
All of the media hype surrounding the spectacular performance of the
XP-39 prototype had caught the attention of the British Direct Purchase
Commission which had visited the USA in 1940 in search of combat aircraft.
Seduced by promises of 400 mph top speed, a tricycle undercarriage, heavy
cannon armament, and high climb rates, the British ordered 675 examples of
the Airacobra. Unfortunately, Bell's glossy advertising brochures did not
distinguish between the performance of a lightly-loaded, unarmed,
highly-polished experimental prototype and a production fighter
heavily-loaded with military equipment and armament, and the British were to
rue the day that they ever looked at an Airacobra.
In 1940, the British were desperate for combat aircraft and were willing
to consider just about anything that had wings, irrespective of how poor its
performance might be. Consequently, when Bell submitted specifications to
the British Direct Purchase Commission for a fighter with a top speed of 400
mph, a ceiling of 36,000 feet, and a range of 1000 miles, the Commission
literally salivated on the spot and ordered 675 Bell Model 14s sight unseen
on April 13, 1940.
The RAF model was at first named Caribou, but the American name of
Airacobra was adopted in July 1941. The British Airacobra was virtually
identical to the American P-39D, but the slower-firing 37-mm cannon was
replaced with the faster-firing and more reliable Hispano 20-mm cannon with
60 rounds. Two 0.50-inch machine guns were mounted in the fuselage, and four
0.30-inch machine guns were mounted in the wings. The engine of the Model 14
was the 1150 hp Allison V-1710-E4 (-35). The British serials of the
Airacobras were AH570/AH739 (170 planes), AP264/AP384 (121 planes),
BW100/BW183 (84 planes), and BX135/BX434 (300 planes).
Bell began test flying the first Model 14 Airacobra I in April 1941. It
carried the British serial number AH570. Tested on the second British
Airacobra (AH571) was a revised rudder of more angular shape and less area.
Although the aircraft was delivered to England in this form, this rudder was
not adopted as standard. A very small dorsal fin just ahead of the rudder
became a standard feature of the RAF Airacobras and was also a
distinguishing feature of the American P-39D and subsequent versions.
President Roosevelt signed the Lend-Lease Act on March 11, 1941,
permitting large quantities of war supplies to be transferred to the Allies.
Among the early requisitions under Lend-Lease were three P-39Cs intended for
"war tests" plus a batch of 150 Airacobra IAs--the A suffix being used to
distinguish between Lend-Lease and Direct Purchase machines, which were
otherwise identical. In the event, only the three P-39Cs were ever delivered
as British machines, and were assigned the serials DS173/DS175 (USAAF
werials 40-2981, -2983, -2984). The P-39Cs could be distinguished from the
British Airacobras by the four machine guns in the nose and the lack of wing
guns.
The first of these P-39Cs actually arrived at RAF Colerne on July 3,
1941, followed by the other two the next day. It made its first test flight
in England on July 6. However, during trials at Duxford, the performance
proved disappointing. Although the test pilots praised the general ease of
handling of the aircraft, the maximum speed was a shocking 33 mph lower than
that anticipated. The fighter proved to be definitely inferior to the
Hurricane and Spitfire in climb rate and ceiling, and the 750-yard takeoff
run of the Airacobra excluded its operation from some smaller fighter
airfields. There was universal shock and dismay among the RAF personnel.
What had gone wrong? Bell Aircraft executives later sheepishly admitted that
their performance figures had been based on the unarmed and unequipped XP-39
prototype, which weighed a ton less than the armed and equipped P-39C.
The first British-purchased Airacobras began arriving at Colerne before
the end of July, joining the three P-39Cs already there. Deliveries of the
Airacobra to Britain had to be made by sea, since the Airacobra lacked the
range to make the Atlantic crossing. By the end of September, eleven
machines had been received. No. 601 "County of London" Squadron was selected
to be the first Fighter Command squadron to equip with the Airacobra.
No. 601 Squadron pilots found numerous flaws and weaknesses during their
initial work-up with the the Airacobra. Some of them were a question of
improving operational efficiency and pilot comfort, but others were
considered essential to make the aircraft operational. Numerous
modifications were made in the field in an attempt to make the aircraft
suitable for combat. A master valve was introduced to allow oxygen to be
turned on from the cockpit. The gunsight was modified to improve forward
visibility. Changes to the ammunition tanks for the wing guns were made.
Modifications were made to the cockpit harness release in order to simplify
the operation. The IFF (Identification, Friend or Foe) set was removed from
behind the pilot, where it obstructed aft view. A throttle control quadrant
friction damper was introduced.
The Air Fighting Development Unit received a British Airacobra I on July
30. They subjected it to tests and completed their report on September 22.
They found the aircraft to be pleasant to fly and easy to takeoff and land.
Controls were well balanced and although heavier than those of the Spitfire
at normal speeds, did not increase appreciably in weight at high speeds as
they did in the Spitfire. It was difficult to hold the aircraft in a dive at
high speeds unless the aircraft was trimmed nose-heavy. During a turn, the
Airacobra would give ample warning of a high-speed stall by severe vibration
of the whole airframe. Handling in formation and formation attacks was good,
although deceleration was poor because of the plane's aerodynamic
cleanliness. Take-offs and landings in close formation were not considered
safe, since there was considerable difficulty in bringing the aircraft back
to its original path after a swing.
The Airacobra I was powered by an Allison V-1710-E4 twelve-cylinder V
in-line engine rated at 1150 hp for takeoff. Weights were 5462 pounds empty
and 7845 pounds normal gross. Maximum speeds were 326 mph at 6000 feet, 343
mph at 10,000 feet, 355 mph at 13, 000 feet, 341 mph at 20,000 feet. Initial
climb rate was 2040 feet per minute. With an internal fuel capacity of 100
Imp gal the Airacobra had an endurance of 1 hour 20 minutes at maximum
continuous cruising speed at 6000 feet, 1 hour 5 minutes at 12,000 feet, and
1 hour 35 minutes at 20,000 feet. The true airspeeds at these altitudes were
287 mph, 327 mph, and 308 mph, respectively. Under most economical cruise
conditions, the endurance increased to 3 hours 20 minutes, the relevant
speeds being 183 mph at 6000 feet, 217 mph at 12,000 feet, and 215 mph at
20,000 feet. Under maximum continuous climb conditions, it took 15 minutes
to reach 20,000 feet. The operational ceiling was considered to be about
24,000 feet, although there was a marked decrease in performance above
20,000 feet. At the Airacobra's rated altitude of 13,000 feet, it was 18 mph
faster than the Spitfire VB. However, the speed fell off rapidly above that
height, and the two planes were almost exactly matched at 15,000 feet. At
20,000 feet, the Spitfire VB was 35 mph faster and at 24,000 feet it was 55
mph faster. The ground run of the Airacobra during takeoff was 2250 feet, as
compared with 1470 feet for the Hurricane II and 1590 feet for the Spitfire
V.
The AFDU also did some comparative dog-fighting tests with the Airacobra
against a Spitfire VB and a captured Messerschmitt BF 109E. The Airacobra
and the Bf 109E carried out mock dog-fighting at 6000 feet and 15,000 feet.
The Bf 109E had a height advantage of 1000 feet in each case. The Bf 109,
using the normal German fighter tactics of diving and zooming, could usually
only get in a fleeting shot. The Bf 109 could not compete with the Airacobra
in a turn, and if the Bf 109 were behind the Airacobra at the start, the
latter could usually shake him off and get in a burst before two complete
turns were completed. If the Bf 109 were to dive on the Airacobra from above
and continue the dive down to ground level after a short burst of fire, it
was found that the Airacobra could follow and catch up to the Bf 109 after a
dive of over 4000 feet. When fighting the Bf 109E below 20,000 feet, the
Airacobra was superior on the same level and in a dive.
A similar trial was carried out against a Spitfire V. Although the
Airacobra was faster than the Spitfire up to 15,000 feet, it was outclimbed
and out-turned by the Spitfire. Unless it had a height advantage, the
Airacobra could not compete with the Spitfire. If on the same level or
below, at heights up to about 15,000 feet, the Airacobra would have to rely
on its superior level and diving speeds and its ability to take negative "G"
without the engine cutting out. Above 15,000 feet, the Airacobra lost its
advantage in level speed.
The Airacobra was considered to be very suitable for low altitude
operations because of the excellent view and controllability, and it was
fully maneuverable at speeds above 160 mph. It was not difficult to fly at
night, but the exhaust flames could be seen by another aircraft flying three
miles to the rear. The flash from the nose guns was blinding, and could
cause the pilot to lose not only his target but also his night vision.
Firing of the nose guns caused the buildup of carbon monoxide contamination
in the cockpit, and this could reach a lethal level very quickly. The guns
were fairly inaccessible, and maintenance was troublesome.
By the end of September, No. 601 Squadron had received permission to take
its Airacobras into action. On October 9, two Airacobras took off from RAF
Manston and flew across the Channel on a "rhubarb"--a code name for a
small-scale raid by fighters against targets of opportunity. On this raid,
they shot up an enemy trawler near Gravelines. The next day two Airacobras
visited the same area, but found no targets. On October 11, two aircraft
flew to Gravelines and Calais and hit some enemy barges and then three
Airacobras flew to Ostend, but no targets were found.
After these four missions, the RAF Airacobras were taken off operations
because of difficulties encountered with the compass. The compass was too
close to the guns in the nose, and when the guns were fired, the compass got
thrown out of alignment. Deviations of anything from 7 degrees to 165
degrees were recorded. Without a reliable compass, pilots tend to get
themselves lost. In December of 1941, the Airacobra was officially withdrawn
from operational service with the RAF.
In spite of the problems with the compass and the need for flame dampers
for the exhaust and flash suppressors for the nose guns, the RAF concluded
that the Airacobra would make an excellent day fighter at altitudes below
20,000 feet and was well suited for the ground-attack role. However, before
these plans could be implemented, a decision was made to divert the bulk of
the British Airacobra contract to Russia.
By the time this decision was made, production of British-contract
Airacobras had reached four a day at Bell's Buffalo plant. The initial
contract for 170 planes (RAF serials AH570 thru AH739) had been completed
before the end of September, and all but six of these planes had actually
been shipped to Britain. However, many of them remained in their crates and
were shipped directly to the Soviet Union without being opened. Somewhere
between 80 and 100 Airacobras were assembled and flown in Britain by the end
of 1941. They were gathered at maintenance units for final modification
before being re-crated and shipped to the Soviet Union during 1942. In all,
the Soviet Union received 212 of the British Airacobras (some of them
shipped direct from the USA), but 49 more were lost at sea en route.
No 601 Squadron relinquished its 13 Airacobras in March of 1942 in favor
of Spitfires. One Airacobra was fitted with an arrester hook and was used
for deck landing trials at the RAE at Farnborough.
After Pearl Harbor, the USA found itself in desperate need of aircraft to
stem the Japanese onslaught in the Pacific. Consequently, nearly 200 of the
British direct-purchase Airacobras still in the USA were promptly
requisitioned by the USAAC. Although they were similar to the USAAC's
P-39Ds, they were not identical and were known by the USAAC under the
non-standard designation of P-400. The P-400 designation had, in fact, been
associated with the British Airacobras for contractual purposes as early as
August 1941. The USAAC P-400s retained their original British serial numbers
and their three-color camouflage paint. Most of these planes were used for
training stateside, but some of them were rushed to the Southwest Pacific in
an attempt to stem the onrushing Japanese advance.
The P-400s also saw some use closer to Britain. 179 of the Airacobras
sent to Britain were re-acquired by the USAAF and were sent to North Africa
to join the Twelfth Air Force.
Disposition of RAF Airacobras
AH573 crashed Feb 11, 1942 from Boscombe Down. Engine failure just after takeoff. Pilot killed.
AH576 in belly landing Aug 29, 1941
AH581 crashed after engine failure Nov 21, 1941.
AH582 crashed during aerobatics Oct 19, 1941. Pilot killed.
AH596 in forced landing at Colchester Sep 29, 1941.
AH602 crashed during aerobatics Jan 12, 1942.
AH603 crashed on takeoff Dec 12, 1941
AH733 delivered to RAF, but transferred to USSR
Disposition of P-400s
AH728 (c/n 14-159) transferred to USSR. Reports that it was lost at sea, but other reports have it
actually having been delivered. There are reports of this plane being diverted to Austraila
and condemed there Sept 3, 1944.
AH735/738
AH737 not delivered to Britain, To USSR. There are reports of this plane being diverted to
Australia Mar 1942, and condemned there Apr 13, 1943.
AP266/268 to USAAF
AP274 to USAAF
AP278 to USAAF
AP280 to USAAF
AP287 to USAAF
AP290 to USAAF
AP291 to USAAF
AP295 to USAAF
AP297 to USAAF
AP300 to USAAF
AP304 to USAAF
AP305 to USAAF
AP319 to USAAF
AP322 to USAAF
AP326/346 to USAAF
AP335 to USAAF. crashed landed Aug 2, 1943 at Lakekamu River, PNG
AP347 to USAAF. force landed Aug 20, 1943 at emergency strip with 36th FS of 8th FG. Retrieved by RAAF Chinook and
now rests at the Jackson's Airport Pilots Club in a fenced enclosure.
AP348/357 to USAAF
AP359/360 to USAAF
AP361 to USAAF. Pilot bailed out near 14-Mile Drome PNG Jun 18, 1942.
AP362/383 to USAAF
BW100/105 to USAAF
BW107/108 to USAAF
BW110/117 to USAAF.
BW114 was c/n 14-306 and came to Australia Apr 1942 for conversion for RAAF. Damaged
Feb 10, 1943, condemned Apr 1, 1944.
BW118 delivered to RAF and returned to USAAF
BW119/130 to USAAF
BW134/148 to USAAF
BW150/168 to USAAF
BW169 to USAAF. pilot bailed north of Port Moresby PNG Jun 18, 1942.
BW170/183 to USAAF
BX135 to USAAF. condemned Sep 3, 1944
BX136 to USAAF. condemned Nov 25, 1942
BX137 to USAAF. wrecked at Tontouta AB, New Caledonia Jun 7, 1942
BX138 to USAAF. wrecked at Tontouta AB, New Caledonia Jun 9, 1942
BX139 to USAAF. condemned Oct 27, 1943
BX140 to USAAF. condemned Sep 3, 1944
BX141 to USAAF wrecked Jan 28, 1942 at Margualo Station. Pilot bailed out OK.
BX142 to USAAF. condemned Sep 3, 1944
BX143 to USAAF. condemned Apr 27, 1943
BX144 to USAAF. condemned Sep 3, 1944
BX145 to USAAF. to CL-26 Mar 19, 1942
BX146 to USAAF. condemned Sep 3, 1944
BX147 to USAAF. condemned Sep 3, 1944
BX148 to USAAF. condemned Sep 3, 1944
BX149 to USAAF. condemned Mar 23, 1943
BX150 to USAAF. wrecked Jun 8, 1942 at Tontouta AAB, New Caledonia.
BX151 to USAAF. condemned Nov 25, 1942
BX152 to USAAF. wrecked Jun 8, 1942 at New Caledonia.
BX153 to USAAF. condemned Sep 3, 1944
BX154 to USAAF. condemned Nov 25, 1942.
BX155 to USAAF. condemned Sep 3, 1944
BX156 to USAAF. condemned Nov 25, 1942
BX157 to USAAF. condemned Nov 25, 1942
BX158 to USAAF. condemned Mar 23, 1942
BX159 to USAAF. condemned Nov 25, 1942
BX160 to USAAF. condemned Nov 1, 1942
BX161 to USAAF. condemned Nov 25, 1942
BX162 to USAAF. condemned Mar 23, 1943
BX163 to USAAF. condemned Dec 28, 1942
BX164 to USAAF. surveyed Jan 24, 1944
BX165 to USAAF. condemned May 27, 1943
BX166 to USAAF. condemned Sep 3, 1944
BX167 (c/n 14-359) to USAAF. surveyed Jul 14, 1944
BX168 to USAAF. condemned Oct 27, 1943
BX169 to USAAF. condemned Sep 3, 1944
BX170 to USAAF. condemned Aug 30, 1942
BX171 to USAAF. surveyed in USA Jul 15, 1945
BX172 to USAAF. to RFC in Cincinatti Feb 10, 1945
BX173 to USAAF. condemned Sep 3, 1944
BX174 (c/n 14-415) to USAAF. condemned Nov 23, 1942
BX187 ended up with USAAF in UK in 1942
BX192 to USAAF. to RFC at Rome, NY Aug 8, 1945
BX204 to USAAF. off inventory Feb 29, 1944
BX206 to USAAF. to RFC at Yuma AAF, AZ Mar 20, 1945
BX209 to USAAF. salvaged Aug 17, 1944
BX210 to USAAF. to RFC at Yuma AAF, AZ Feb 29, 1945
BX216 to USAAF. to RFC at Yuma AAF, AZ Apr 4, 1945
BX227 to USAAF. to RFC at Yuma AAF, Mar 16, 1945
BX245 to USAAF. to RFC at Rome, NY May 8, 1945
BX247 to USAAF. off inventory Aug 26, 1944
BX270 to USAAF. to RFC at Yuma AAF, AZ Feb 29, 1945
BX279 to USAAF. to RFC at Yuma AAF, AZ Mar 24, 1945
BX290 to USAAF. condemned Jul 8, 1944
BX302 to USAAF. Shipped overseas after Oct 1943. Returned to USA Jul 30, 1944.
To RFC at Rome, NY May 8, 1945. There is a photo of this aircraft in Soviet AF colors.
BX310 to USAAF. to Italy Feb 11, 1946
BX320 to USAAF. crashed May 27, 1944
BX323 to USAAF. surveyed in USA Mar 2, 1944
BX326 to USAAF. to RFC at Yuma AAF, AZ Mar 20, 195
BX327 to USAAF. to RFC at Yuma AAF, AZ
BX345 to USAAF. salvaged Jun 12, 1944
BX348 to USAAF. to RFC at Yuma AAF, AZ Mar 16, 1945
BX409 to USAAF. to reclamation at Luke AAF, AZ Mar 13, 1946
BX424 to USAAF. salvaged Nov 9, 1944
Further P-39D versions were ordered specifically for delivery under
Lend-Lease. They were produced in two batches--P-39D-1-BE and P-39D-2-BE.
150 P-39D-1-BEs were ordered on June 11, 1941 under contract AC 32. 185
more were ordered on September 17, 1941 under Contract AC 156. An additional
P-39D-1 was provided under a separate contract.
The P-39D-1-BE (Bell Model 14A) was powered by an Allison V-1710-35
engine. Like the P-400, the P-39D-1 was armed with a 20-mm M1 cannon rather
than the 37 mm Oldsmobile cannon, but the four 0.303-inch wing guns of the
P-400 were replaced by 0.30-in guns. The two fuselage-mounted 0.50-inch
machine guns were retained. A small dorsal fillet gave the tail a new shape,
which became standard on all later P-39s and was retrofitted to most earlier
P-39Ds. A total of 336 P-39D-1s were built.
The remaining 158 machines on the Lend-Lease order were produced as
P-39D-2-BE (Model 14A-1). These were assembled under contract AC 156 placed
on June 1, 1941. The P-39D-2 introduced the uprated 1325 hp V-1710-63 (E6)
engine and had a 2:1 reduction gear. It brought back the 37-mm nose cannon.
It was otherwise identical to the P-39D-1. The P-39D-2-BE could carry the
145 US gallon drop tank underneath the fuselage.
Most of these planes were originally intended for the United Kingdom.
However, the Royal Air Force had rejected the Airacobra as a combat type,
and most of these planes were delivered to the Soviet Union instead.
Not all of the P-39D-1 and D-2 aircraft were delivered to the Soviet
Union. Several dozen were taken on charge by USAAC squadrons and were flown
in combat. Some of these P-39D-1s (along with the P-400) were flown by the
347th Fighter Group at Guadalcanal in August of 1942. Some flew with the
31st Fighter Group in North Africa in 1943.
26 P-39D aircraft were modified to P-39D-3 reconnaissance configuration.
These aircraft had K-24 and K-25 cameras mounted in the rear fuselage, plus
extra armor added to protect oil and glycol coolers from ground fire. . They
retained the V-1710-35 engine. The P-39D-4-BE was the designation given to
11 similar modifications of the P-39-1-BE. The D-3 and D-4 saw action
exclusively in Italy.
Serials for the P-39D-1s and D-2s were:
41-28257-28406 Bell P-39D-1-BE Airacobra
41-38220/38404 Bell P-39D-1-BE Airacobra
41-38405/38562 Bell P-39D-2-BE Airacobra
41-38563 Bell P-39D-1-BE Airacobra
P-39D-3 modifications: 40-3025, 41-6767, 6773, 6780, 6791, 6818,
6965, 6985, 6990, 7002, 7011, 7012, 7025, 7027, 7031, 7035, 7040, 7061,
7062, 7065, 7068, 7073, 7075, 7094,7 097
P-39D-4 modifications: 41-28288, 38340, 28367, 28370, 28375, 28400,
28402, 38296, 38301, 38315.
On April 10, 1941, two P-39Ds were ordered modified and flight tested
under contract AC18373 as flying testbeds for the experimental Continental
V-1430-1 supercharged inverted-Vee engine that was expected to deliver 2100
hp. These aircraft were assigned the designation XP-39E. The company
designation was Model 23. A third machine was later added to the order as a
nonflying static test example. Serials were 41-19501, 41-19502, and
41-71464. I am not sure whether these were newly-built aircraft, or modified
P-39Ds that were assigned new serials.
However, the Continental engine was not yet ready when the XP-39E
airframes were completed, and the 1325 hp Allison V-1710-47 engine was
installed in its place. In pursuit of better high-altitude performance, the
-47 engine was equipped with a two-stage supercharger and drove an
Aeroproducts propeller.
The XP-39E bore the same armament as the P-39D but featured a new wing
with square-cut tips. Wing span and gross area were increased to 35 feet 10
inches and 236 square feet. Contrary to some other sources, the wing was not
a laminar flow wing. Each of the three examples tested different vertical
tail surfaces--the first being conical, the second being cut-off square and
rather short, and the third being rather similar to that of the P-51. The
carburetor air intake was relocated and the wing-root radiator intakes were
enlarged. The fuselage was lengthened by 1.75 feet to accommodate the longer
-47 engine.
Empty and loaded weights were 6936 lbs and 8918 lbs respectively, making
the XP-39E the heaviest of all Airacobra variants. During tests, a maximum
speed of 386 mph at 21,680 feet was attained, which was much better
high-altitude performance than other Airacobra variants. An altitude of
20,000 feet could be reached in 9.3 minutes.
About two weeks after its maiden flight, the first XP-39E crashed during
spin tests on March 26, 1942. Test pilot Bob Stanley parachuted to safety.
The second aircraft flew on April 4, 1942. Following the loss of the
first example, the static test example was brought up to flying condition.
The XP-39E had a much better high-altitude performance than other
Airacobra variants. It was redesignated XP-76 and no less than 4000 were
ordered by the USAAF. However, the new design was considered to be inferior
to the basic Airacobra in many respects, and the order for the XP-76 was
later cancelled in its entirety. Nevertheless, the XP-39E was to provide
some valuable basic data for the later P-63 Kingcobra.
Serials of Bell XP-39E Airacobra
41-19501/19502 Bell XP-39E Airacobra
41-71464 Bell XP-39E Airacobra
The next production version of the Airacobra was the P-39F (Bell Model
15B). It was almost identical to the P-39D, but had an Aeroproducts
constant-speed propeller in place of the original Curtiss-Electric, because
the Curtiss-Electric propellers could not be delivered in sufficient
quantities. The F also differed externally from the D in having twelve
exhaust stacks on each side of the fuselage rather than six.
Initial orders, placed on September 13, 1940 under contract AC 15675,
called for 229 aircraft. Serials were 41-7116/7344. 27 Fs were modified in
the field to become P-39F-2s with the addition of belly armor and the
fitting of cameras to the rear fuselage to suit the aircraft for ground
support duties.
There are reports that a single P-39F was experimentally modified as an
advanced trainer with a second cockpit ahead of the original one. All
armament was removed, and dual controls were fitted. The designation given
to this odd-looking aircraft was TP-39F.
The last 25 P-39Fs were fitted with the 1100 hp V-1710-59 engine with
automatic boost control and were redesignated P-39J. Serials were
41-7043/7056 and 41-7059/7079. At this stage of the war, the production
block system of subdividing model changes was not yet in effect, and
relatively minor changes brought about letter changes in the series.
Serials of P-39F-1 Airacobra
41-7116/7344 Bell P-39F-1 Airacobra
7123,7177,7182,7183,7226,7230,7248,7266,7270/7272,7278,
7294,7295,7299,7302,7303,7305,7309,7310,7312,7318,7325,
7326,7332,7334,7339 modified as P-39F-2.
The remaining 25 aircraft on the initial P-39F order were delivered as
P-39Js. They differed from the F in having a different engine, the 1100 hp
V-1710-59 (E12) with an automatic manifold pressure regulator. Serials were
41-7053/7056 and 42-7059/7079. These serials were from the original P-39D
batch. At this stage of the war, the production block system of subdividing
model changes was not yet in effect, and relatively minor changes often
brought about letter changes in the series.
|
The Bell P-39G/H Airacobra |
1800 examples of the P-39G (Bell Model 26) were ordered on August 21,
1941. Serials were 42-4244/5043 and 42-8727/9726. These aircraft were
originally intended to be identical to the P-39D-2 except for the new
Aeroproducts propeller. However, the P-39G underwent several modifications
during the contract stage, leading to different suffix letters being applied
as production progressed, and none were actually being delivered with the
"G" suffix letter. At this time, the production-block suffix had not yet
been introduced into the USAAF designation system, and these aircraft were,
instead, delivered as P-39K, P-39L, P-39M, and P-39N.
For some reason, the suffix letter "H" was never assigned. The suffix
letter "I" was never used in any case, since it could be confused with the
number one.
The first of the redesignated P-39Gs were the P-39K-1-BE production lot
(Model 26A). They differed from the P-39D-2 in being powered by a 1325 hp
V-1710-63 (E6) engine driving an Aeroproducts propeller. 210 examples were
ordered on August 25, 1941. The armament was the same as that of the P-39D,
but the aircraft weighed 800 pounds more and had a slightly reduced range.
Some P-39Ks were flown in New Guinea in 1943.
Six P-39Ks were converted to ground attack/photo reconnaissance
configuration under the designation P-39K-2-BE. Serials were 42-4244, 47273,
4352, 4387, 4433, 4437.
One P-39K was converted to P-39K-5-BE with a V-1710-85 (E19) engine and
acted as the prototype for the P-39N.
Serials of P-39K Airacobra:
42-4244/4453 Bell P-39K Airacobra
The second set of the redesignated P-39Gs were the 250 P-39Ls. Serials
were 42-4454/4703. They were powered by the 1325 hp Allison V-1710-63
engine, the same engine which powered the P-39K. It differed from the K in
reverting to the Curtiss Electric propeller. Gross weight was up to 9100
pounds, but the more powerful engine gave better low-altitude performance
than the P-39D. A new nosewheel of somewhat different design was fitted,
which offered less drag at takeoff. Provision was made for the fitting of
rocket rails under the wings. It was otherwise identical to the P-39D-2.
P-39Ls flew in New Guinea and North African in 1943.
Eleven were modified for photoreconnaissance under the designation
P-39L-2-BE. The serials of these planes were 42-4457, 4461, 4462, 4465,
4466, 4470, 4471, 4476, 4489, 4553, and 4630.
The third series of redesignated P-39Gs were the 240 P-39Ms (Model 26D),
which were ordered on August 25, 1941. They began to come off the production
line in November of 1942.
These P-39Ms were equipped with an 11 foot 1 inch diameter Aeroproducts
propeller. They also had a new engine, the V-1710-67 (E8) which was an
attempt to provide improved high-altitude performance at the expense of
poorer low-altitude performance. This powerplant developed 1200 hp for
takeoff and 1125 hp at 15,500 feet. This variant could fly at 370 mph at
15,000 feet as compared to 360 mph at the same altitude for the P-39L. This
was still considered too low for aerial combat, and the P-39M remained
primarily a low-altitude ground attack aircraft.
A total of 240 P-39Ms were built. Serials were 42-4704/4943.
Some M-1s were fitted with the V-1710-83 (E18) engine, either as a
retrofit or a change midway along the production line.
Some P-39Ms flew in North Africa in 1944.
Eight of these P-39Ms were converted for the photographic reconnaissance
role as the P-39M-2-BE. Serials were 42-4704/4706, 4710, 4712, 4751, 4795,
and 4824.
Serials of P-39M:
42-4704/4943 Bell P-39M-1-BE Airacobra
Up to this time, the Airacobra had been manufactured in relatively small
numbers. The first Airacobra model to be produced in really large numbers
was the P-39N (Bell Model 26C and F), 2095 examples being built. The first
1100 P-39Ns were part of that order for P-39Gs which had been distributed
among P-39Ks, Ls, and Ms, but the remaining 995 Ns were new orders.
All P-39Ns were powered by the V-1710-85 (E19) engine rated at 1200 hp
for takeoff and 1115 hp at 15,500 feet. The power rating was similar to that
of the M- model's V-1710-83, but with a different propeller reduction gear
ratio and an Aeroproducts propeller in place of the Curtiss Electric.
After completion of the first 166 P-39Ns, the USAAF requested that four
fuel cells be removed in order to reduce the internal fuel capacity from 120
to 87 US gallons, and so to reduce the maximum permissible gross weight from
9100 lbs to 8750 lbs. This kept weight down, but unfortunately it also
restricted range. Therefore, kits were provided that allowed the four fuel
cells to be refitted in the field.
The first 166 P-39Ns were fitted with an Aeroproducts propeller having a
dimaeter of 10 feet 4 inches. Beginning with the 167th P-39N, the
Aeroproducts propeller was enlarged to 11 feet 7 inches in diameter, an
increase of six inches.
The 500 P-39Ns were followed by 900 P-39N-1s (Model 26C). These differed
only in some minor internal changes which altered the location of the center
of gravity.
The last Ns were the 695 P-39N-5s (Model 26C-5). They differed from
earlier Ns in having the total weight of armor reduced from 231 to 193
pounds. A curved armor head plate supplanted the bulletproof glass behind
the pilot. An SCR-695 radio was fitted, and a new oxygen system was fitted.
There were numerous conversions to ground support, including 35 P-39Ns
converted to P-39N-3-BE, 128 P-39N-1-BEs converted to P-39N-2-BE, and 84
P-39N-5-BEs to P-39N-6-BE.
An order for 205 additional P-39Ns was cancelled.
The "O" letter was never used, lest it be confused with the number zero.
For some reason, the designation P-39P was never assigned.
The serials of the P-39s were as follows:
42-4944/5043 Bell P-39N-BE Airacobra
originally part of P-39G order. 100 planes
42-8727/9126 Bell P-39N-BE Airacobra
originally part of P-39G order. 400 planes
8808/8842 as P-39N-3-BE
42-9127/9726 Bell P-39N-1-BE Airacobra
originally part of P-39G order. 600 planes
9141,9145, 9148,9150,9152,9211,9255,9416,9615,9677,9697/9712,
9714/9724,9726 to P-39N-2.
42-18246/18545 Bell P-39N-1-BE Airacobra
300 planes
18276/18285,18287/18296,18298/18300,18302/18305,18310,
18327,18466,18485/18546 to P-39N-2
42-18546/19240 Bell P-39N-5-BE Airacobra
695 planes
18676/18681,18712/18725,18768,18818,18829,18831,18841,
18857,18870,18876/18879,18881,18882,18884,18887,
18889/18896,18899/18907,18909/18921,18923/18925,
18927/18933,18935/18941,18947,19043 to P-39N-6.
42-19241/19445 cancelled contract for Bell P-39N Airacobra
The P-39Q was the last version of the Airacobra to roll off the
production lines at Bell. It was also the version which was built in the
largest numbers, 4905 P-39Qs being built before production finally ended.
The principal difference between the P-39Q and earlier version was in the
fighter's armament--the four wing-mounted 0.30-inch machine guns were
replaced by a single 0.50-inch machine gun mounted in a fairing underneath
each wing. The ammunition capacity of the underwing guns was 300 rounds per
gun. The two fuselage-mounted 0.50-inch machine guns with 200 rpg, plus the
hub-mounted 37-mm cannon with 30 rounds, were retained. The replacement of
the four wing guns was generally applauded by American pilots, most of whom
thought that the 0-30-inch guns of the earlier versions were too light to be
effective and it wasn't worth the extra fuel needed to carry the 4000 rounds
of 0.30-inch ammunition. However, the Russians, who got most of the P-39Qs
built, usually had the underwing gun pods removed.
The engine was the Allison V-1710-85 (E19) of 1200 hp, the same
powerplant that was used in the P-39N.
There were several production blocks of the P-39Q:
P-39Q-1-BE: Retained the 72.4 Imp gallon fuel capacity of the P-39N-5 but
returned to the original 231 pounds of armor of the P-39N-1.
P-39Q-2-BE: Five Q-1s were modified to carry cameras for photographic
reconnaissance by adding K-24 and K-25 cameras in the aft fuselage.
P-39Q-5-BE (Model 26Q-5): Reverted to the lighter armor fit of the P-39N-5
(193.4 pounds), as well as the use of the full wing fuel capacity (92.6 Imp
gall) characteristic of the P-39M. Type A-1 bombsight adapters were added to
the P-39Q-5-BEs at the Modification Center before delivery to operational
units.
P-39Q-6-BE: 148 Q-5s were modified to carry cameras for photographic
reconnaissance by adding K-24 and K-25 cameras in the aft fuselage.
P-39Q-10-BE (Model 26Q-10): Internal fuel capacity rose to 100 Imp
gallons and armor weight went to 227.1 pounds. The throttle was linked to
the propeller settings to provide automatic adjustments. There was
additional winterization of the oil system, and there were rubber engine
mounts installed. The first P-39Q-10-BEs were delivered to the USAAF by the
end of July 1943. A total of 705 examples were built, but 995 more that were
assigned serial numbers 42-21251/22245 were actually completed as P-63E-1
Kingcobras.
P-39Q-11-BE: Eight Q-10s were modified to carry cameras for photographic
reconnaissance by adding K-24 and K-25 cameras in the aft fuselage.
P-39Q-15-BE (Model 26Q-15): Differed from the Q-10 in minor equipment
variations. Among these was a reinforced inclined deck to prevent 0.50-inch
machine gun tripod mounting cracking, bulkhead reinforcements to prevent
rudder pedal wall cracking, a reinforced reduction gearbox bulkhead to
prevent cowling former cracking, and repositioning of the battery solenoid.
This example was delivered beginning in August of 1943. 1000 examples were
built.
P-39Q-20-BE (Model 26Q-20): The underwing 0.50-inch machine gun pods were
sometimes omitted in this version.
P-39Q-21-BE: Similar to P-39Q-20, but a four-bladed Aeroproducts
propeller was fitted.
P-39Q-25-BE (Model 26Q-25): Similar to the Q-21 but with a reinforced
aft-fuselage and horizontal stabilizer structure and a four-bladed
Aeroproducts propeller. The wing guns were deleted from these aircraft,
which were exported to the Soviet Union. 700 were built.
P-39Q-30-BE: Tests indicated that directional stability was materially
worsened by the four-bladed propeller, and this version reverted to the
three-bladed unit. This was the last production version of the P-39Q.
On July 25, 1944, all P-39 production ceased, with 9558 examples being
produced.
A few P-39Qs were modified into two seaters with dual controls for use as
advanced trainers under the designation RP-39Q (redesignated TP-39Q after
1944). All armament was removed. The second cockpit was sort of "grafted" in
front of the original cockpit, and the pilot in this extra cockpit sat under
a hinged canopy. The extra cockpit was fitted with only rudimentary
controls. The original cockpit retained the same controls and instruments as
the standard P-39Q. The instructor sat in front in the extra cockpit, the
student in the original cockpit, and the two communicated via an intercom
telephone. The tail fillet was enlarged and an additional shallow ventral
fin was fitted under the rear fuselage. These modifications produced one of
the most grotesque aircraft I have ever seen. :-). The first example,
converted from P-39Q-5 42-20024, was rolled out for the first time on
September 16, 1943. It was designated TP-39Q-5. 12 two-seater fighter
trainers were converted from P-39Q-20s, and were designated RP-39Q-22. The
ventral strake was somewhat different in shape from that of the ventral fin
of the original TP-39Q-5. Serials were 44-3879, 3885/3887, 3889, 3895, 3897,
3905, 3906, 3908, 3917, and 3918.
The first P-39Qs were delivered to Eglin Field, Florida and Wright Field,
Ohio for testing. The first P-39Qs were delivered to the Army Air force by
the end of July of 1943.
Production of the P-39Q finally terminated in August of 1944. Most of the
P-39Qs were delivered to the Soviet Union. Only a few ended up serving with
American units. One of these was the 332nd Fighter Group which took on 75
P-39Qs in Italy in February 1944. After only two months, these Airacobras
were replaced by P-47s, finally retiring the type from US service.
A P-39Q (serial number uncertain -- anyone know? I wrote down a tail
number of 298667 when I was there, but this can't be correct) is on display
at the WPAFB Museum. It is, however, marked as a P-39J serial number
41-7073.
P-39Q-15 serial number 44-2433 Galloping Gertie is currently in storage
at the Paul Garber Storage and Restoration Facility in Suitland, Maryland.
Specifications of the P-39Q-5-BE:
One Allison V-1710-85 engine rated at 1200 hp at sea level and 1125 hp at
15,500 feet. Maximum speed 330 mph at 5000 feet, 357 mph at 10,000 feet, 376
mph at 15,000 feet. Climb to 5000 feet in 2.0 minutes. Climb to 20,000 feet
in 8.5 minutes. Maximum range (clean) was 525 miles at 20,000 feet at 250
mph. With one 145.7 Imp gal drop tank, range was 1075 miles at 196 mph.
Service ceiling was 35,000 feet. Weights were 5645 pounds empty, 7600 pounds
normal loaded, 8300 pounds maximum loaded. Dimensions: Wingspan 34 feet 0
inches, length 30 feet 2 inches, height 12 feet 5 inches, wing area 213
square feet.
Serials of P-39Q Airacobra
42-19446/19595 Bell P-39Q-1 Airacobra
150 planes
19479/19483 to P-39Q-2-BE.
42-19596/20545 Bell P-39Q-5 Airacobra
950 planes
19608,19610,19612,19614,19616,19624,19626,19628,19636,
19640,19642,19644/19646, all even numbers 19648/19719,
all odd numbers 19697/19719,19723,19725, odd numbers
19927/19975,19977/19979, 19981,19983,19985,19987,
all odd numbers19989/20011,20013/20015,20017/20019,
odd numbers 20021/20065,20067/20069,odd numbers
20071/10092,20095/20097,20099,20101,20103,20105
converted to P-39Q-6-BE
42-20546/21250 Bell P-39Q-10 Airacobra
705 planes
44-2001/3000 Bell P-39Q-15 Airacobra
1000 planes
44-3001/3850 Bell P-39Q-20 Airacobra
850 planes
44-3851/3858 Bell P-39Q-21 Airacobra
8 planes
44-3859/3860 Bell P-39Q-20 Airacobra
2 planes
44-3861/3864 Bell P-39Q-21 Airacobra
4 planes
44-3865/3870 Bell P-39Q-20 Airacobra
6 planes
44-3871/3874 Bell P-39Q-21 Airacobra
4 planes
44-3875/3880 Bell P-39Q-20 Airacobra
6 planes
44-3881/3884 Bell P-39Q-21 Airacobra
4 planes
44-3885/3890 Bell P-39Q-20 Airacobra
6 planes
44-3891/3894 Bell P-39Q-21 Airacobra
4 planes
44-3895/3900 Bell P-39Q-20 Airacobra
6 planes
44-3901/3904 Bell P-39Q-21 Airacobra
4 planes
44-3905/3910 Bell P-39Q-20 Airacobra
6 planes
44-3911/3914 Bell P-39Q-21 Airacobra
4 planes
44-3915/3919 Bell P-39Q-20 Airacobra
5 planes
44-3920/3936 Bell P-39Q-21 Airacobra
17 planes
44-3937/3940 Bell P-39Q-20 Airacobra
4 planes
44-3941/4000 Bell P-39Q-21 Airacobra
60 planes
44/32167/32666 Bell P-39Q-25 Airacobra
500 planes
44/70905/71104 Bell P-39Q-25 Airacobra
200 planes
44/71105/71504 Bell P-39Q-30 Airacobra
400 planes
|
The Bell XFL-1 Airabonita, XF2L-1 |
The XFL-1 Airabonita was an experimental shipboard version of the
land-based P-39 Airacobra which was developed in parallel with the Army
version. However, the Airabonita had the misfortune to be in direct
competition with the Vought Corsair for Navy orders, and only one example
was built.
In February 1938, the US Navy had issued a specification for a
high-speed, high-altitude fighter. Bell submitted a navalized version of the
Airacobra in response to this request. At the same time, Chance Vought
submitted a design which was eventually to emerge as the superlative F4U
Corsair. A US Navy contract for one XFL-1 prototype was placed on November
8, 1938. The BuAer Number was 1588.
The XFL-1 was powered by a 1150 hp Allison XV-1710-6 (E1), the first
in-line engine to be fitted to an American naval fighter since 1928. The use
of a liquid-cooled engine in itself was quite a gamble for Bell, since in
1927 the Navy had explicitly excluded liquid-cooled engines from aircraft
carriers, fearful of storing the flammable glycol coolant aboard ship.
The XFL-1 differed from its land-based counterpart primarily in having
underwing radiators and a tailwheel undercarriage. The main undercarriage
members were transferred to the front wing spar, and an arrester hook was
fitted. The relocation of the main undercarriage members to the forward part
of the wing necessitated the relocation of the wing-root radiators to
exterior points under the rear of the central section of the wing. The
fuselage was shorter than that of the P-39, the vertical tail surfaces were
redesigned, and the airframe was stressed for carrier operations. The canopy
was of a higher profile than that of the P-39, and the pilot sat higher in
the cockpit. The wing was of larger span with greater chord. The dorsal
intake was smaller and shallower than that on the YP-39. Armament was to
have been two 0.30-inch machine guns in the fuselage nose, plus a 0.50-inch
machine gun or a 37-mm cannon firing through the propeller hub, although no
armament was actually ever fitted to the XFL-1 prototype.
The XFL-1 flew for the first time on May 13, 1940, with test pilot Brian
Sparks at the controls. The aircraft was painted overall Navy grey, except
for the upper wing surfaces which were chrome yellow. It was transferred to
NAS Anacostia in Washington, DC for further testing in July of 1940. During
tests, the XFL-1 achieved a maximum speed of 307 mph at sea level, 336 mph
at 10,000 feet, and 322 mph at at 20,000 feet. Initial climb rate was 2630
feet per minute, and an altitude of 20,000 feet could be attained in 9.2
minutes. Service ceiling was 30,900 feet. Weights were 5161 pounds empty,
6651 pounds loaded, 7212 pounds maximum. Dimensions were span 35 feet 0
inches, length 29 feet 9 1/8 inches, height 12 feet 9 2/3 inches, wing area
232 square feet.
Since the use of an in-line, liquid-cooled engine as a powerplant for
carrier-based aircraft had for many years run counter to Navy thinking, the
project was regarded with disfavor by many. Longitudinal stability proved to
be marginal, and the vertical tail surfaces were enlarged after a series of
wind-tunnel tests. Difficulties with the Allison engine delayed delivery of
the XFL-1 to the Navy until February of 1941. The XFL-1 failed its carrier
qualification trials due to problems with the undercarriage. The aircraft
was returned to the manufacturer for modifications. Shortly thereafter, the
superior performance of the F4U Corsair against which the Airabonita was
competing led the Navy to decide on May 12, 1941 that the XFL-1 was
unsuitable for further development and the project was abandoned with only
one example ever being built.
The Navy later did operate a couple of Airacobras, but they acquired them
directly from the Army and never used them from carriers. Towards the end of
the war, the US Navy acquired a pair of P-39Qs from the Army (Ser No
42-20807 and 19976) for use as target drones. They were delivered to NAS
Cape May, New Jersey in February of 1946 and used for test work fitted with
smoke generators. They were initially designated XTDL-1, but their
designations were later changed to F2L-1K. Their BuAer numbers were 91102
and 91103.
|
The Wartime Service Of The P-39 With The
USAAF |
The first P-39D Airacobras entered service with the USAAC in February
1941, first with the 31th Pursuit Group (39th, 40th, and 41st Pursuit
Squadrons) based at Selfridge Field, Michigan.
At the time of Pearl Harbor, the USAAAF had five pursuit groups flying
the P-39 Airacobra. These were the 8th Pursuit Group based at Mitchell Field
near New York City, 31st and 52nd Pursuit group at Selfridge Field,
Michigan, the 36th Pursuit Group based in Puerto Rico, and the 53rd based at
MacDill Field in Florida. I also have a reference which lists the 16th
Pursuit Group based in the Canal Zone,and the 31st Pursuit Group based at
Baer Field, Indiana. The 15th Pursuit Group's 47th Pursuit Squadron became
active at Wheeler Field in Hawaii on December 21, 1941.
At the time of Pearl Harbor, the P-39 (along with the P-40 and a few
P-38s) was virtually the only modern fighter available to the USAAC. Those
P-39s already in service with the USAAF at the time of Pearl Harbor were
deployed at home bases, but were quickly moved forward to overseas bases in
Australia, Alaska, Hawaii, Panama, and New Guinea to try and stem the
Japanese advance.
On April 30, 1942, thirteen P-39s from the 35th and 36th Pursuit Squadron
flew their first combat mission under Lt Col Boyd D. Wagner. For the next 18
months, the P-39 and the P-40 were the principal front line equipment of
USAAF fighter units in the Pacific. They carried much of the load in the
initial Allied efforts to stem the rapid Japanese advance. Many Allied
pilots lacked adequate training, and equipment and maintenance were below
average. The Airacobras operating in the Southwest Pacific were sometimes
called upon to serve as interceptors, a role for which they were totally
unsuited. They proved to be no match for the Japanese Zero in air-to-air
combat. In fact, because of difficulties with the oxygen supply, the
Airacobra was not even able to reach the Mitsubishi G4M (code name *Betty*)
bombers raiding from altitudes above 25,000 feet. In the laconic words of
the official AAF history: "The Airacobra, even in a good state of repair,
was unable to meet the Japanese fighters on equal terms." Experienced
Japanese pilots such as Saburo Sakai regarded the Airacobra as a relatively
easy "kill". The P-39s were not as manauverable as the lighter and more
nimble Japanese fighters, and enemy fighters could often avoid combat with
the P-39s by outclimbing them. Nevertheless, the Airacobra was quite tough
and was able to absorbing a great deal of battle damage and still keep on
flying, and its armament was able to deliver lethal blows to many a
lightly-armored Zero.
Some interesting hybrids were produced during those days. The 67th
Fighter Squadron was responsible for fitting a P-39D wing to a P-400, and a
little later the 68th Fighter Squadron produced a P-400 fuselage with one
P-39D wing, one P-39K wing, and an Allison V-1710-63.
The 31st Fighter Group was provided with Airacobras in Southern England
in August of 1942. Between August and October of 1942, the Group
participated in missions against enemy targets in France. The Group suffered
heavy losses in air-to-air combat against the Luftwaffe, and the 31st FG
re-equipped with Spitfire Mk Vs.
With the formation of the US Twelfth Air Force in the Middle East in the
Autumn of 1942, Airacobras saw service in the Mediterranean area with the
81st and 350th Fighter Groups and two squadrons of the 68th Observation
Group. These aircraft were diverted from a Soviet consignment, being a
mixture of P-400s and P-39D-1s. In the Middle East, the Airacobras were used
primarily for very low-altitude strafing missions, escorted by Warhawks or
Spitfires. They took part in the Allied landings in Tunisia, at Anzio, in
Sicily, and operated throughout the entire Italian campaign. In spite of the
Airacobra's obvious deficiencies, units using the P-39 achieved the lowest
loss rate per sortie of any USAAF fighter used in the European theatre.
Airacobras based in Alaska took part in the battles for the Aleutians. On
September 14, 1942, Airacobras of the 54th Fightr Group took part in the
first counter-strike actions against Japanese forces in the area. Airacobras
were also deployed to the Canal Zone to defend the Panama Canal, but no
action ever took place there.
The Airacobra reached its peak usage in the USAAF in early 1944, with
over 2100 in service. However, the drawdown was fairly rapid after this, as
they were quickly replaced by P-38s, P-47s and P-51s. By April of 1944, the
last P-39 squadrons in New Guinea (the 82nd and 110th Tactical
Reconnaissance Squadrons) had turned in their Airacobras for other aircraft.
The 347th Fighter Group was the last to fly the Airacobra in the Southwest
Pacific in August of 1944 before re-equipping with P-38s. Thereafter, P-39Qs
were flown at training bases in the United States until the end of the war.
The following Fighter Groups operated the P-39 between 1941 and 1945, but
in some cases only relatively briefly:
- 8th Fighter Group (35th 36th and 80th Squadrons
- 15th Fighter Group (12th 15th and 36th Squadrons)
- 18th Fighter Group (78th and 333rd Squadrons)
- 20th Fighter Group (55th, 77th, and 79th Squadrons)
- 21st Fighter Group (531st Squadron)
- 31st Fighter Group (39th, 40th, and 41st Squadrons)
- 33rd Fighter Group (58th, 59th, and 60th Squadrons)
- 52nd Fighter Group (2nd and 4th Squadrons)
- 53rd Fighter Group (13th, 14th, and 15th Squadrons)
- 54th Fighter Group (42nd, 56th, and 57th Squadrons)
- 56th Fighter Group (61st, 62nd, and 63rd Squadrons)
- 58th Fighter Group (67th, 68th, and 69th Squadrons)
- 318th Fighter Group (72nd Squadron)
- 332nd Fighter Group (99th, 100th, 301st, and 302nd Squadrons)
- 338th Fighter Group (305th, 306th, and 312th Squadrons)
- 343rd Fighter Group (18th Squadron)
- 347th Fighter Group (67th, 68th, and 70th Squadrons)
- 350th Fighter Group (345th, 346th, and 347th Squadrons)
- 354th Fighter Group (353rd, 355th, and 356th Squadrons)
- 357th Fighter Group (362nd, 363rd, and 364th Squadrons)
- 367th Fighter Group (392nd, 393rd, and 394th Squadrons)
- 372nd Fighter Group (407th, 408th, and 409th Squadrons)
- 473rd Fighter Group (451st and 452nd Squadrons)
P-39s were also used by the 342nd Composite Group (33rd Squadron) and the
59th Observation Group (488th, 489th and 490th Squadrons). The P-39 was also
used by the 48th, 84th, 85th, 339th, 494th, 405th, 496th, and 478th
Bombardment Groups in the training role.
|
The Airacobras In The Soviet Union |
Over half of all the Airacobras produced went to the Soviet Union, and
they were the most numerous of the foreign fighters in the Soviet air force
inventory. A total of 4924 P-39s were delivered to the Soviet Union between
December 1941 and February 1945, of which 4758 actually reached their
destinations.
Soviet pilots had first seen the Airacobra in Great Britain, when a group
of pilots was sent to No. 601 Squadron at RAF Duxford for training. The
British had found the Airacobra unsuitable for their own use and were more
than happy to turn over their Airacobras to the Soviets, and some 212 of the
675 Airacobra Is ordered by the RAF were diverted to the USSR. The
Airacobras first entered service with the Soviet Air Force in May of 1942.
It is in Soviet service that the Airacobra was used to its best effect.
Soviet Air Force military doctrine was that its primary mission was to
support the ground operations of the Soviet Army, and the P-39 was a natural
for this role since it had an excellent low altitude performance and was
heavily armed. Contrary to many published reports, the Soviet Airacobra was
not primarily used as a ground-attack aircraft and tank buster, although it
is certainly true that it often strafed targets of opportunity. It was
actually primarily used as a low-altitude escort fighter for ground attack
aircraft such as the Il-2 and later the Il-10.
The Airacobra was quite popular with its Russian pilots, who appreciated
its heavy armament, its excellent low-altitude performance, and its ability
to absorb an incredible amount of battle damage. When operating at low
altitudes, the Airacobra was often able to hold its own against
top-of-the-line German fighters. Some Soviet pilots felt that the P-39
outclassed even the Messerschmitt Bf 109 and Focke Wulf FW 190 at altitudes
below 10,000 feet. Some of the users of the type were Guard (ie. elite)
Fighter Regiments 16 GIAP, 19 GIAP, 21 GIAP, 72 GIAP, 100 GIAP, 213 GIAP
(previously 508 IAP) and Fighter Regiments 196 IAP, 255 IAP, 508 IAP (later
213 GIAP).
Several Soviet Airacobra aces are known. Lieutenant Colonel of the Guards
Alexander I. Pokryshin, a Soviet ace with 59 kills to his credit, scored 48
of these in a P-39. He was awarded the Distinguished Flying Cross by
President Roosevelt. There are eight other P-39 pilots with at least 20
kills. Among top Airacobra aces were Grigorii A Rechkalov (44 kills) ,
Nikolai D Gulayev (36 kills), Ivan I Babak, Aleksandr F Klubov, Andrei I
Trud, and the brothers Boris B Glinka and Dmitrii B Glinka
The Soviets preferred the 20-mm Hispano cannon of the P-400 over the 37mm
of other Airacobra variants because of its greater reliability. In addition,
the trajectory of the shells from the 20-mm cannon more closely matched that
of the 0.50-inch guns, making for a greater concentration of fire. In the
P-39Q, the Soviets usually removed the underwing guns or had them removed at
the factory, preferring a better performance over the enhanced firepower.
The Airacobra remained in Soviet service well after the war was over.
When the original US-built armament became unserviceable, it was replaced by
the Soviet 20-mm B-20 cannon and the 12.7mm Berezin UBS machine guns. How
long the Soviets operated their P-39s after the war was over is not known.
However, it does appear that some P-39s ended up with the air force of North
Korea. They saw some combat with the North Korean Air Force during the early
months of the Korean War in the summer of 1950.
|
The P-39 And Postwar Air Racing |
After the war was over, the USAAF rapidly disposed of most of its
Airacobras, with most being scrapped during 1946. However, a few were sold
as surplus on the commercial market.
Some surplus P-39s ended up on the postwar unlimited racing circuit.
Perhaps the best known of these were a pair of surplus P-39Qs named Cobra I
and Cobra II. They were originally P-39Q-10s 42-20733 and 42-20869
respectively. Bell test pilots Chalmers "Slick" Goodlin, Alvin M. "Tex"
Johnston, and Jack Woolams prepared these planes for entry into the Thompson
Trophy race which was to be held over the Labor Day weekend in Cleveland,
Ohio in 1946. They were lightened by the removal of all military equipment,
and they received uprated Allison V-1710-135 (G4) engines taken from P-63s
and were fitted with four-bladed propellers. When so equipped, they were
capable of achieving speeds as high as 420 mph at low altitude.
On August 29, both planes qualified for the race. Untortunately, before
the race was run, Cobra I was lost on August 30, 1946 over Lake Ontario,
killing the pilot, Jack Woolams.
Cobra II (flying under the civilian registration of NX92848) went on to
win the 1946 Thompson Trophy air race, with Tex Johnston at the controls, at
an average speed of 373 mph over the 300-mile course. Cobra II raced again
in the 1947 Thompson Trophy race, finishing 3rd. It raced yet again in the
1948 Thompson trophy race, but was unable to finish owing to engine
difficulties.
Cobra II did not race any more. It sat derelict for many years and was
sold to Ed Maloney in 1960. He restored it to wartime colors and displayed
it in his museum in Claremont, California. It was purchased in 1967 by Mike
Carroll for use in an attempt to break the world piston-engine speed record,
held at that type by the Messerschmitt Me 209. He installed a
highly-modified V-1710-CG engine rated at 2850 hp, driving a four-bladed
propeller. Four feet of outer wing were removed from each tip.
Unfortunately, Cobra II crashed on August 10, 1968 during a test flight,
killing pilot Mike Carroll.
P-39Q-15 (44-2433/NX57521) was flown in the 1946 National Air Races by
Earl Ortman. This plane is now in storage at the NASM facility at Silver
Hill, Maryland painted with the name Galloping Gertie.
Joe Baugher
Sources:
- War Planes of the Second World War, Fighters, Volume Four, William
Green, Doubleday, 1964.
- The American Fighter, Enzo Anguluci and Peter Bowers, Orion Books,
1987.
- United States Military Aircraft since 1909, Gordon Swanborough and
Peter M. Bowers, Smithsonian Institution Press, 1989.
- P-39 Airacobra in Action, Ernie MCDowell, Squadron/Signal
Publications, 1980
- The Calamitous 'Cobra, Air Enthusiast, August 1971.
- Airacobra Advantage: The Flying Cannon, Rick Mitchell, Pictorial
Histories Publishing Company, Missoula, Montana
- Airacobra Advantage--The Flying Cannon, Rick Mitchell, Pictorial
Histories Publishing Company, 1992
- Bell Cobra Variants, Robert F. Dorr, Wings of Fame, Vol 10,
AirTime Publishing , Inc., 1998.
- E-mail from Gordon Birkett on disposition of AP347, BW169, AP361,
plus serial numbers on USAAF P-400s.
- E-mail from Terence Geary on P-400 dispositions.
- Andrew Thomas, Bell Airacobra In RAF Service, International Air
Power Review, Vol 6, 2002
- E-mail from Franek Grabowski on AH728, AH733, AH737, BW118, BX302.
- E-mail from Nick Jenkins on crash of AH573.
