History
Background
By the late fall of 1944, the war in the Pacific was going very well for the Allies, and it was just a matter of months before the Japanese homeland would be subjected to devastating air raids by the B-29 Superfortresses. However, these bombers needed fighter escorts while they were over Japan, and the US Army Air Forces did not have a fighter with that range.
Design and Development
Northrop successfully introduced the impressive P-61 Black Widow in the same year, which represented the successful purpose-built American night fighter. Since it had exceptional range and maneuverability, the P-61 aircraft was a suitable choice to be converted into a bomber-escort variant, so Northrop began to develop XP-61E in response to USAAF requirements for a long-range, day, and escort fighter for use in the Pacific Theater. The Army and Northrop had first discussed the possibility of the XP-61E as early as May 1944 to Summer 1944. Specifically, the requirements required XP-61E to produce at least 460 mph and probably 370 at 31,500 feet and have a range of at least 1,300 miles.
Initial plans proposed that the XP-61E’s original fuselage be cut off even with the upper surface of the wings, that all radar equipment be removed, and that a bubble canopy cover the tandem pilot seats. Powerplants were to be changed to R-2800 engines with CH-5 turbo-superchargers for operations as high as 31,000 feet. The armament was six nose-mounted .50-cal. machine guns in addition to the four belly-mounted 20mm cannon. Consequently, the Army awarded Northrop a contract to build two XP-61E prototypes, although not all senior officers in the USAAF liked the idea of the XP-61E project.
In October 1944, two P-61B-10 aircraft were reserved for conversion into XP-61Es. Their fuselage would be significantly modified. The cockpit area was redesigned, with the turret, gunner’s cockpit and radar operator’s position deleted. The cockpit of the XP-61E housed the two-man crew in tandem under a large bubble canopy, and the cockpit was narrower and rearranged for improved forward vision, including a second set of instruments and controls for the relief pilot. The four .50-cal. machine guns were moved from the deleted turret into the nose section to replace the SCR-720C AI radar. A total of 518 gallons of fuel tank replaced the turret behind the crew compartment to increase the overall fuel capacity of 1,158 gallons. The four 20-mm cannons were still retained in the ventral underside of the crew nacelle. The aircraft featured a slimmer, lighter, and more aerodynamic profile. However, it was retained with two R-2800-65 radial piston engines with 2,000 hp each.
Flight Testing
Two P-61B-10s (42-39549 and 42-39557) were rebuilt as the XP-61Es, with the aircraft 42-39557 being the first completed in January 1945. The 42-39557 had the canopy sliding aft on tracks and nose guns mounted in line straight across the nose. The 42-39549 followed in March with a canopy hinged to port, lifting upward, with the nose guns mounted in pairs above and below each other.
The first flight occurred on January 3, 1945, out of Los Angeles, California. The XP-61E attained a speed of 376 mph at 17,000 feet, far below what was outlined in the requirements; however, it could cruise at a normal range of 2,250 miles and an extended range of 3,750 miles using the drop tanks. In addition, the XP-61E far surpassed any production P-61. Yet, a second XP-61E was written off in a takeoff accident on April 11, 1945, when the aircraft retracted the gear too early and crashed on a belly landing, sliding off the runway and suffering propeller strikes.
Epilogue
As the war in the Pacific approached its end, the USAAF saw no need to order XP-61Es into production since their P-51 Mustangs were already in range of Japan to conduct escort missions with the B-29 Superfortresses. In addition, the North American P-82 Twin Mustang won the Long Range Escort Fighter contract, in which its prototype attained a maximum speed of 482 mph at 25,100 feet.
There were plans within a contract placed by the middle of 1945 to convert one P-61C to XP-61E standards with two retained turbo-supercharged R-2800-73 engines. A P-61C (43-8338) was reserved for the conversion on September 1, 1945, in Hawthorne, New Jersey, but the development did not occur as the war ended. The program was effectively halted on October 24, 1945.
However, it was not the end of XP-61E. The surviving XP-61E was modified as an unarmed photographic reconnaissance aircraft in the summer of 1945. All the guns were removed, and a new nose was fitted, capable of holding aerial cameras. This modification introduced a photoreconnaissance variant of XF-15. It flew for the first time on July 3, 1945, and was enough to interest the USAAF to order 175 F-15As with the given name Reporter. Only 36 F-15As were built after September 1946 before the remainder of the order was canceled in 1947 because of the emerging jets that could become fast photoreconnaissance aircraft. These F-15A Reporters remained in service longer than the P-61, with the last aircraft retired in 1954.
