The Bell P-39 Airacobra

United States of America
United States of America

side view front view under view

Although rarely seen in the European theatre of operations, the Airacobra was extensively used by the Russians and in the pacific theatre. It was too heavy and it's engine was suitable only for low altitudes, so it failed being an air superiority aircraft. Against the German and Japanese nimbler aircraft it suffered too much losses, but succeeded greatly in the Eastern Front. Because of it's heavy armament the Airacobra turned out to be an effective ground attack aircraft. The Russians loved the plane because of it's armament and sturdy build.

The Russians received over 5000 of these aircraft in a Lend-Lease program set up by the Allies to help Russia.

Versions:

Further pictures:

Bell P-39 Airacobra in full flight
Bell P-39 Airacobra in full flight

 

Technical data on the Bell P-39N Airacobra
Powerplant 1 × Allison V-1710-85, rated at 1200 hp (894.59 kW) Role during war
  • Fighter
  • (Ground) Attack Fighter
Length 30 ft 2 inch Height 12 ft 5 inch
Empty weight 5645 lb Operational weight 8300 lb max
Wing Span 34 ft 0 inch Wing Aspect ratio 5.43
Wing Area 213 sq ft Service ceiling 38270 ft
Maximum speed 376 mph at 15000 ft Cruising speed 330 mph at 5000 ft
Initial climb rate 2600 ft/min at an altitude of 5000 ft,
Climb to 15,000 ft in 6 min 6 sec
Range 300 miles typical,
975 miles max
Fuel capacity internal 72.4 Imp gal (87 US gal) Fuel capacity external 62.45 Imp gal (75 US gal) in one droptank
Machine guns
  • 2 × 0.50 in fixed forward-firing in the upper side of the nose, 200 rounds each
  • 4 × 0.3 in fixed forward-firing in the wings, 1000 rounds each
Cannons 1 × 37 mm M4 fixed forward-firing in a moteur-cannon installation, 30 rounds
Bomb load Up to 500 lb on one hardpoint, generally loaded with 1 × 500 lb bomb, or 1 × 325 lb bomb, or 1 × 250 lb bomb. Torpedoes/rockets -
Crew 1 Naval or ground based Ground
First flight (prototype) April 1938 Operational Service July 1941 - 1950's
Manufacturer Bell Aircraft Corporation Number produced 9594 total, 2095 this version
Metric system
Length 9.19 m Height 3.78 m
Empty weight 2561 kg Operational weight 3765 kg max
Wing Span 10.36 m Wing Aspect ratio 5.43
Wing Area 19.79 m² Service ceiling 11665 m
Maximum speed 605 km/h at 4572 m Cruising speed 531 km/h at 1524 m
Initial climb rate 792 m/min at an altitude of 1525 m,
Climb to 4570 m in 6 min 6 sec
Range 483 km typical,
1569 km max
Fuel capacity internal 329 liters Fuel capacity external 284 liters in one droptank
Machine guns
  • 2 × 12.7 mm fixed forward-firing in the upper side of the nose, 200 rounds each
  • 4 × 7.62 mm fixed forward-firing in the wings, 1000 rounds each
Cannons 1 × 37 mm M4 fixed forward-firing in a moteur-cannon installation, 30 rounds
Bomb load Up to 227 kg on one hardpoint, generally loaded with 1 × 227 kg bomb, or 1 × 147 kg bomb, or 1 × 113 kg bomb. Torpedoes/rockets -

Here is a quick overview of all different versions, without the full technical specifications:

Different versions of the Bell P-39  Airacobra
Bell XP-39 Airacobra First prototypes, flying in July 1939. This plane saw a radical design difference from all other planes of the era, namely a centered engine (right behind the pilot, and a tricycle landinggear (where most other aircraft still featured a tailwheel). Powerplant: 1 × Allison V-1710-17 l2-cylinder V, with a B-5 supercharger, rated at 1150 hp (857 kW). No armament yet, but provisions for it.
Number built: 1
Bell XP-39B Airacobra The powerplant changed to a non-supercharged V-1710-39 engine, because of changed insights of the USAAC. This model was developed later than the YP-39A
Number built: unknown
Bell XP-39E Airacobra Meant to test the Continental V-1430-1 powerplant. Due to delivery problems, the Allison V-1710-47 rated at 1325 hp (987 kW) was tested in stead.
Number built: 3
Bell YP-39A Airacobra Service-test verion of the XP-39. One YP-39A was delivered to the USAAC in April 1939, fitted with a high-altitude V-1710-31 1150 hp (857 kW) powerplant.
Number built: 1
Bell P-39C Airacobra First production version. Powered by 1 × Alison V-1710-35, rated at 1,150 hp (857 kW). These aircraft were used for the serviceability of the P-39, not as front-line aircraft. This version was armed, like the YP-39, with 1 × 37 mm cannon, 15 rounds, 2 × 0.50 in (12,7 mm) guns, 200 rounds each, and 1 × 0.3 in (7.62 mm) gun, 500 rounds, for help with sighting of the cannon.
Number built: 20
Bell P-39D Airacobra The first operational variant differed from it's predecessor in a number of ways:
  • armament was changed to 1 × 37 mm and 2 × 0.50 in (12 mm) guns in the nose, plus 4 × 0.3 in (7.62 mm) in the wings (no "aiming" 0.3 in gun anymore)
  • armor to protect the pilot
  • self-sealing fuel tanks
  • Changes to the vertical tail (dorsal fin fillet added)
  • Hardpoint added to be able to carry a 500 lb (227 kg) bomb or a drop tank
Two different sub variants were built:
  • P-39D-1: Built for the RAF, and fitted with a 20 mm cannon in stead of the 37 mm one. (519 built)
  • P-39D-2: Powered with 1 × Alison V-1710-63 , rated at 1,325 hp (988 kW)
The British aircraft were declared unfit for the Western European theatre, and shipped to Russia to aid them. A couple of the originals were held back by the USAAF, and the were refitted and redesigned to:
  • P-39D-3: Additional armor protection under the fuselage (26 converted)
  • P-39D-4: Adopted for photo-reconnaissance, and fitted with a K24 and K-25 camera (11 converted)

Number built: 923
Bell P-39F Airacobra To be ahead of a possible lack in Curtiss Electric propellers, the P-39F received a Aeroproducts propeller. Some of these aircraft were later refitted:
  • P-39F-2: Additional armor protection under the fuselage for ground attack, and reconnaissance cameras
There were 27 aircraft adapted to this subvariant
Number built: 229
Bell TF-39F Airacobra Conversion of a P-39F, to be a two-seater trainer
Number converted: 1
Bell P-39J Airacobra The last 25 P-39F's were fitted with 1 × Alison V-1710-59 engine, and were redesignated accordingly
Number built: 25
Bell P-39K Airacobra Similar to the P-39J, the P-39K was powered by 1 × Alison V-1710-63, rated at 1,325 hp (988 kW). Also the propeller was an Aeroproducts metal propeller of the constant speed type. About six were converted to:
  • P-39K-2: Additional armor protection under the fuselage for ground attack, and reconnaissance cameras

Number built: 210
Bell P-39L Airacobra Identical to the P-39K, except for the Curtiss Electric propeller. 11 Aircraft were converted to:
  • P-39L-2: Additional armor protection under the fuselage for ground attack, and reconnaissance cameras

Number built: 250
Bell P-39M Airacobra Identical to the P-39L, except for the Aeroproducts propeller and the engine: 1 × Alison V-1710-83, rated at 1,200 hp (895 kW). Because of the changes the P-39M was 10 Mph (16 km/h) faster than the P-39L At a top level speed of 370 Mph (595 km/h). 8 Aircraft were converted to:
  • P-39M-2: Additional armor protection under the fuselage for ground attack, and reconnaissance cameras

Number built: 240
Bell P-39N Airacobra First large-scale production model. For specifications, see above.
Durin the production some improvements were incorporated, like a bigger propeller, more fuel capacity, better radio equipment, a revised oxugen system , lighter armor and bullet proof glas behind the pilot. A number of aircraft were converted to the following gsubvariants:
  • P-39N-2: Modified for ground attack and reconnaissance (128 converted)
  • P-39N-3: Modified for ground attack and reconnaissance (35 converted)
  • P-39N-6: Modified for ground attack and reconnaissance (84 converted)

Number built: 2095
Bell P-39Q Airacobra Final production version. This version differed mainly in it's armament from it's predecessors: 1 × 37 mm cannon, 2 × 0.50 in (12 mm) guns in the nose, and 2 × 0.50 in (12 mm) in underwing fairings under the outer wing. Other changes during the production mainly concerned it's propeller, which switched from an Aeroproducts 3-bladed model to a 4-bladed model, and back to a 3-bladed (but larger) model again.
Number built: 4905
Bell RP-39Q Airacobra Conversion from the P-39Q, to act as a trainer without armament
Number converted: a few
Bell TP-39Q Airacobra Bell RP-39Q Airacobra's, but redesignated later
Redesignated aircraft
Bell P-400 Airacobra A number of aircraft were ordered by France or Britain, but were never delivered due to capitulation or unsatisfactory evaluation (respectively). The remainder that was used by the USAAF was redesignated to P-400, mainly because it had a different armament.
Number built: about 400
Bell Airacobra Mk I Assembled in Britain, some P-39's were evaluated by the RAF and redesignated consequently. It showed that the Spitfire Mk V had a better overall performance, so the Airacobra was thought to be unsatisfactory. Part of the about 400 built aircraft were sent to Russia, another part went back to the USA. Theose aircraft saw service in the Pacific theatre, and had subsequently a number of successes there.
Redesignated aircraft
Bell F2L-1K 2 Bell P-39Q's were transferred to the US Navy to be evaluated.
Number transferred: 2

Remarks:

The Airacobra was most effectively put to use by the Russians in a ground attack role. Since the airial warfare in Russia was fought in low altitudes (due to the atmospheric conditions?) the Airacobra proved to be more then just cannonfodder for the Germans like it did in the Mediterranean and Pacific theatres. Also, the engine was situated behind the pilot in an attempt to give it more agility. As a result the designers could implement a automobile style door in stead of a canopy.

Strengths:

Weaknesses:

 

 

© by Frans Bonné, 2000
Last revision: 9/20/00