The Bell P-39 Airacobra was a distinctive American fighter aircraft developed by Bell Aircraft and introduced in 1941.
Notable for its mid-engine layout and tricycle landing gear, the P-39 was among the first fighters to feature a nose-mounted 37 mm cannon firing through the propeller hub.
Despite its innovative design, the aircraft’s lack of a turbo-supercharger limited its high-altitude performance, shaping its operational deployment.
The Airacobra saw combat throughout the world, particularly in the South-west Pacific, Mediterranean, and Soviet theatres.
Because its engine was equipped with only a single-stage, single-speed supercharger, the P-39 performed poorly above 17,000 feet (5,200 m) altitude.
In both Western Europe and the Pacific, the Airacobra found itself outclassed as an interceptor, and the type was gradually relegated to other duties.
It was often used at lower altitudes for missions such as ground strafing, where its heavy armament and rugged construction proved effective.
United States Army Air Forces (USAAF)
Initially fielded by the USAAF in 1941, the P-39 served in the Pacific, Mediterranean, and Aleutian theatres.
It was used primarily for ground attack and close air support due to its limited altitude capabilities.
American pilots found it underwhelming in air-to-air combat against high-flying Axis fighters, leading to its gradual replacement by more capable aircraft like the P-51 Mustang.
Soviet Air Force
The USSR received over 4,700 P-39s via Lend-Lease, making it the largest foreign operator.
Soviet pilots exploited the P-39’s strengths at low to medium altitudes, particularly on the Eastern Front, where most combat occurred below 15,000 feet.
The aircraft proved highly effective in dogfights and ground attack roles.
Soviet ace Aleksandr Pokryshkin scored 48 of his 59 kills flying the P-39, making it the most successful US-built fighter in Soviet service.
Royal Air Force (RAF)
The RAF received a limited number of P-39s but rejected them for frontline use due to poor high-altitude performance.
Most were relegated to training or secondary roles.
Other Operators
The Free French, Italian Co-Belligerent Air Force, and Australian units operated small numbers of P-39s, mainly in reconnaissance and training roles.
Legacy
Though controversial and often criticised by Western pilots, the P-39 Airacobra was a critical asset for the Soviet war effort.
Its design innovations influenced later aircraft, including the Bell P-63 Kingcobra.
Over 9,500 units were built between 1940 and 1944, marking it as one of the most produced American fighters of the war.
XP-39 (Bell Model 11)
Prototype 38–326, first flight: 6 April 1938.
Powered by a 1,150 hp Allison V-1710-17 engine with a General Electric B-5 turbosupercharger, enabling two-stage supercharging (mechanical + exhaust-driven).
Designed for high-altitude interception; unarmed testbed.
Provided baseline data for future development; later converted to XP-39B.
XP-39B
First flight
25 November 1939.
Aerodynamically refined based on NACA wind tunnel testing.
27 were converted for ground attack/reconnaissance.
P-39J (Bell Model 15B)
25 built;
featured 1,100 hp V-1710-59 engine with automatic boost control.
P-39K Series
K-1
210 built; Aeroproducts propeller, 1,325 hp V-1710-63.
K-2
Six converted for ground attack/recon.
K-5
One was converted with the V-1710-85 as the P-39N prototype.
P-39L Series
L-1
250 built;
Curtiss Electric propeller,
increased gross weight.
L-2
Eleven converted for ground attack/recon.
P-39M Series
M-1
240 built; 1,200 hp V-1710-83.
11 ft 1 in propeller,
improved altitude performance.
M-2
Modified for ground attack.
P-39N Series (Bell Model 26N)
N
500 built; 1,325 hp V-1710-85, 10 ft 4 in propeller (later 11 ft 7 in), reduced fuel capacity.
N-1
900 built; CG adjustments for nose gun firing.
N-2/N-3B/N-6
Recon variants with belly armour and cameras.
N-5
695 built; reduced armour, SCR-695 radio, new oxygen system
P-39Q Series (Bell Model 26E)
Final production variant, last built August 1944.
Q-1
150 built; replaced wing. 30 cal with .50 cal pods and 231 lb armour.
Q-2/Q-6/Q-11
Recon conversions with K-24/K-25 cameras.
Q-5
950 built, reduced armour (193 lb), increased fuel (110 gal), and a bombsight adapter.
TP-39Q-5
Two-seat trainer conversion.
Q-10
705 built; 228 lb armour, 120 gal fuel, coordinated controls, and winterisation.
Q-15
1,000 built; structural reinforcements and oxygen systems reduced.
Q-20
1,000 built; minor equipment changes and optional gun pods.
Q-21
109 fitted with a four-bladed propeller.
RP-39Q-22
12 converted to two-seat trainers.
Q-25
700 built; reinforced aft fuselage and stabilisers.
Q-30
400 built; reverted to three-bladed propeller.
XFL-1 Airabonita 1
The Bell XFL-1 Airabonita was a prototype carrier-based fighter developed for the United States Navy in the late 1930s.
It was derived from the Bell P-39 Airacobra, sharing many design features but adapted for naval operations.
The project represented Bell Aircraft’s attempt to enter the carrier aviation market but ultimately failed to meet the Navy’s requirements.
Origins and Design Intent
In 1938, the U.S. Navy issued a specification for a new carrier-based fighter.
Bell responded with the XFL-1, a navalised version of its land-based XP-39.
The aircraft retained the mid-engine layout of the Airacobra, with the Allison V-1710-6 engine mounted behind the pilot and driving the propeller via a long shaft.
Unlike the tricycle landing gear of the P-39, the XFL-1 was fitted with a conventional tailwheel undercarriage to meet carrier compatibility standards.
The design included arrestor gear and structural reinforcements for carrier landings, though it lacked folding wings—a significant drawback for shipboard storage.
Technical Characteristics
Powerplant
1,150 hp Allison V-1710-6 liquid-cooled V-12 engine.
Armament (planned)
A 1 × 37 mm cannon firing through the propeller hub, supplemented by .30 and .50 calibre machine guns.
Airframe
All-metal construction with flush riveting, low-drag canopy, and mid-mounted wings.
Propeller
Three-bladed, constant-speed unit.
Flight Testing and Evaluation
First flight
13 May 1940 at Bell’s facility in Buffalo, New York.
The XFL-1 demonstrated poor performance during testing, particularly in climb rate and manoeuvrability.
The tailwheel configuration proved problematic for deck handling and visibility during carrier operations.
Cooling issues and reliability concerns with the Allison engine further undermined its suitability for naval service.
Outcome and Legacy
Only one prototype was built (BuNo 15894).
The project was cancelled in 1941, and the sole aircraft was scrapped after limited testing.
XTDL-1 / F2L-1K
Two P-39Qs converted to target drones for the USN.
redesignated F2L-1K.
P-400
Export variant with 20 mm Hispano cannon,
2 × .50 cal nose guns,
4 × .30 cal. wing guns.
Operated by RAF and USAAF
(128 aircraft reassigned).
Airacobra I / IA
Airacobra I
RAF designation for three P-39Cs tested at Boscombe Down.
