In modern times, it’s hard, or even impossible, to imagine a fighter without a radar. Powerful modern radars have made possible fighters that can fly in all weather conditions, day or night. But during WWII, the roles of day fighter and night fighter were, for the most part, separate. Smaller, more agile fighters did the fighting by day, while larger aircraft capable of carrying the early heavy radar sets did the fighting by night. British development of radar had been progressing steadily since the early days of the war, and its land-based radar stations had proven vital during the Battle of Britain in detecting incoming German bombers and directing RAF fighters to intercept them. By late summer of 1940, the British finally had an airborne radar unit, called the Airborne Intercept (AI) radar, but they didn’t have an aircraft that could carry it. So they requested aircraft designs from every manufacturer they knew, one of which was Jack Northrop, who realized that any aircraft capable of the speed, altitude, range and firepower that the RAF needed, along with the ability to carry the heavy radar, needed to be big and would require more than one engine. While work on the AI was progressing in England, the British Tizard Missioncame to the US to receive assistance in developing their new technologies away from the danger of German bombing. They brought with them their AI radar and, with the exchange of technologies, the US saw the potential for making their own night fighter, and the Army made a formal request for such an aircraft. With the work Northrop had already done on the British proposal, his new XP-61 beat out the only competitor for the contract, the Douglas XA-26A, a night-fighter based on the Douglas A-26 Invader. Northrop’s design placed a large gondola between two booms housing 18-cylinder Pratt & Whitney R-2800 Double Wasp radial engines.
Following the earlier British request, the gondola housed two turrets, one in the nose and one in the rear, each with four guns. Eventually, the ventral turret was removed, and the rear turret was replaced with a powered turret on the top of the fuselage, which was often fixed in a forward firing position to provide more forward firepower. Northrop also finalized the design by placing four 20mm cannons in the belly of the aircraft, becoming one of the few American aircraft to mount four cannons. Though history notes the Black Widow as America’s first dedicated night fighter, it was difficult, by the standards of contemporary fighter design, to call the Black Widow a fighter. It was a true behemoth, with a wingspan of 60 feet (8 feet longer than the Lockheed P-38 Lightning), a height of nearly 15 feet, and an empty weight of over 23,000 pounds. When Black Widows arrived in Europe in the spring of 1944, Army commanders were convinced that the P-61 was too slow and cumbersome to counter German aircraft. Instead, they wanted to procure the British de Havilland Mosquito, and even went so far as to organize a competition between the two aircraft. However, with a few tweaks to the engine to improve performance, the Black Widow was able to outperform the Mossie in speed and rate of climb and, with its special “Zap Flaps” and retractable spoilers, the P-61 could even outmaneuver the Mosquito. While still unable to outduel German single-engine fighters, the Black Widow proved quite effective against larger German bombers and fighter-bombers. In the Pacific, the Black Widow arrived too late to have a profound impact on the war, but it did play a vital role in the rescue of over 500 Allied prisoners from the Cabanatuan prison camp in the Philippines. Though it never fired a shot, a lone P-61 performed aerobatics over the camp to distract Japanese guards while Army Rangers positioned themselves for the assault. A Black Widow is also unofficially credited with scoring the last aerial victory of WWII. While most WWII designs didn’t last after the war, the Black Widow, as America’s only night fighter, soldiered on until the US could produce a jet-powered alternative. They also played a leading role in research into ejection seat technology, and as part of the Thunderstorm Project, the nation’s first large-scale, scientific study of thunderstorms and weather as it pertains to aviation safety. Northrop also developed a reconnaissance variant called the F-15 Reporter, which removed the top portion of the central gondola and housed of the two-man crew under a single canopy. While the final P-61 flight was made in 1954, the Reporter would serve in various roles until 1968. (US Air Force photos)