The arrival of the high-flying, long-range Boeing B-29 "Superfortress" strategic bomber in May of 1944 led United States Army officials to consider a long-range fighter escort to protect their expensive, technology-laden investment. Northrop managed to introduce their impressive P-61 "Black Widow" that same year and this marked the first purpose-built American night fighter. Engineers were convinced of the merits of the large fighter as a long-range bomber escort and the company championed the idea to Army officials. Enough interest was had in the endeavor to result in the "XP-61E", a modified version of the successful night fighter.
A pair of P-61B-10 aircraft were set aside for conversion to the long-range, high-altitude bomber escort role. The dorsal turret was removed and the upper fuselage cut down to produce a slimmer, lighter and more aerodynamically refined form. No longer requiring radar (the fighter would be a daytime operator), the nose assembly was cleared of the radar fit and in its place a battery of 4 x 0.50 caliber Browning heavy machine guns installed (the ventral battery of 4 x 20mm cannons seen in the original P-61 fighter was retained). As no radar was carried, the radar operator crewman was expendable which led to a reduction of total crew to two and these personnel were now seated in tandem under a shared bubble-style canopy. More internal fuel stores were added to help increase the aircraft's range - a requirement for the long-range bomber escort role.
The result was a powerful, reasonably fast and well-ranged performer with sleek contours and a promising future. The aircraft held a wingspan of 66 feet with a length of 49.6 feet and height of 13.4 feet. Empty weight was 21,350lb against a laded weight of 40,181lb. Power was from 2 x Pratt & Whitney R-2800-65 radial piston engines of 2,000 horsepower each propelling the aircraft to speeds of 376 miles per hour. Rate-of-climb was 2,500 feet-per-minute with a service ceiling of 30,000 feet and range out to 2,250 miles.
A first-flight was had on January 3rd, 1945. However, in April of that year, the program suffered a considerable setback when the second prototype was lost after an attempted full-power take-off test which resulted in too much damage to save the airframe (the test crew survived after a belly landing).
The changing face of war also meant that the XP-61E was never furthered beyond the pair of flyable prototypes: the B-29 found few challengers in the Pacific and was never fielded over Europe against Germany. Also the age of the jet fighter had arrived which limited the long-term commitment on the part of the Army to prop-driven types like the XP-61E. The long-range escort role was fulfilled, at least for the interim, by the stellar, prop-driven North American F-82 "Twin Mustang".
The design became the last fighter-minded offshoot of the Black Widow series and never saw the light of day as an operational-level product. One of the XP-61E aircraft was reworked by Northrop to become the XF-15 prototype which, in turn, became the F-15 "Reporter" in USAF service - though only thirty-six of the type were acquired. The P-61 itself was retired as quickly as 1954 though not after some 700 were produced.
- Fighter
- X-Plane / Developmental
49.61 ft (15.12 m)
66.01 ft (20.12 m)
13.39 ft (4.08 m)
21,352 lb (9,685 kg)
40,179 lb (18,225 kg)
376 mph (605 kph; 327 kts)
30,003 feet (9,145 m; 5.68 miles)
2,249 miles (3,620 km; 1,955 nm)
2,500 ft/min (762 m/min)
PROPOSED:
4 x 0.50 caliber heavy machine guns in nose installation
4 x 20mm cannons in ventral gun pack
XP-61E - Base Project Designation; two examples configured from existing P-61B airframes.