Northrop P-61A
Black Widow
of
422nd Night Fighter Squadron
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The Northrop P-61A was the first production version of the Black Widow night-fighter, and the first version to enter combat. The P-61A was very similar to the YP-61 service-test aircraft. The only significant changes were the use of aluminium instead of welded magnesium alloy in the tail boom and a modified cockpit canopy. On the XP-61 and YP-61 the pilot and gunner had unframed curved windscreens, but on the P-61A these were replaced by stepped windscreens. These slightly reduced visibility, but at the same time allowed for the use of armoured glass panels.
The first 37 aircraft were produced with the upper gun turret, but flight tests revealed that the turret caused dangerous tail buffeting whenever it was moved. Northrop also had trouble getting access to the turrets, which were also used on the B-29 Superfortress, and so starting with the 38th aircraft the P-61A was built without the turret. Not only did this solve the buffeting problem, it also saved weight, increasing the aircraft's top speed. A number of turretless aircraft were modified in the field to bring the radar operator forward into the gunner's position, improving the efficiency of interceptions. The loss of the turret still left the P-61 with four fixed closely grouped 20mm cannon, more than enough guns to deal with any German or Japanese target.
Three major modifications were given block numbers. The P-61A-5 (starting with the 46th aircraft) was given 2,250hp R-2800-65 engines. The P-61A-10 had water-injection, which could provide short bursts of extra power. The P-61A-11 was given underwing pylons each of which could carry a 165 gallon fuel tank or 1,000 bomb.
The first unit to receive the P-61A was the 481st Night-Fighter Operation Training Group, which was activated at Orlando Field, Florida, on 20 July 1943. All but two of the wartime night-fighter squadrons were trained by 481st, the exceptions being two squadrons (6th and 414th Night-Fighter Squadrons) which were already operational.
During 1944 the P-61A was twice tested against the de Havilland Mosquito. On 5 July the USAAF arranged a fly-off against an Mk XVII in which the Black Widow was the winner, but earlier in the year the RAF had conducted its own tests, with a view to taking the P-61 on lend-lease, and had rejected it because of a lack of speed. This suggests that the RAF's own test had been between the P-61A and the Mosquito Mk 30, which made its maiden flight in March 1944, and had a top speed of just over 400mph. The P-61A did have two clear advantages over the Mosquito – its Pratt & Whitney engines could be run at close to maximum power for much longer periods, and it could loose speed much more efficiently than the Mosquito, having been designed with that in mind. This was essential for a radar-equipped night fighter, as many first-hand accounts of night fighting make clear – a fighter that couldn't slow down quickly and without loosing position tended to overrun its target, forcing the crew to begin their hunt again.
The P-61A made its combat debut in Europe and the Pacific during the summer of 1944. The first confirmed victory came in the Pacific, where on 30 June 1944 a crew from the 6th Night Fighter Squadron shot down a G4M Betty. Two weeks late, on the night of 15/16 July, the 422nd NFS scored the aircraft's first victory in Europe, shooting down a V-1 flying bomb over the English Channel.
Engine: Two Pratt & Whitney R-2800-10 or 65 radial engines
Power: 2,000hp each (early), 2,250hp (late)
Crew: 3 (with turret), 2 (without turret)
Wing span: 66 ft
Length: 45ft 10in
Height: 14ft 2in
Empty Weight: 20,965lb
Maximum Weight: 32,400lb
Max Speed: 372mph
Service Ceiling: 34,000ft
Range: 1,210 miles
Armament: Four 20mm cannon plus four .50in machine guns in turret if present
Bomb-load: Two underwing pylons capable of carrying 1,000lb bombs on later aircraft
