Northrop P-61 Black Widow: First American Airplane Designed and Built to Fight at Night, Part II

*This is the second blog in a two part blog series of the Northrop P-61 Black Widow. Read part one.*

High-priority projects, such as the XB-35 all-wing bomber, distracted Northrop’s engineering team and delayed the P-61 Black Widow’s combat debut until 1944. The first P-61A sent overseas arrived in England in March but not for combat. A rivalry had developed between fans of the De Havilland Mosquito and supporters of the Black Widow and Britain’s Royal Air Force wanted to evaluate the P-61. On July 5, 1944, a fly-off happened between a pilot flying a P-61 and another pilot flying a night fighter version of the Mosquito called the NF. XVII. As the story goes, after mechanics in the 422nd Night Fighter Squadron (NFS) tweaked the P-61 for maximum performance, the hot-rodded Black Widow "proved faster at all altitudes, outturned the Mossie at every altitude and by a big margin, and far surpassed the Mossie in rate of climb."  There never seemed to be enough Mosquitos to undertake the many missions the Royal Air Force found for the aircraft, and the British may have lost the competition on purpose to keep more Mosquitos for their own use. Air Chief Marshal Courtney had admitted in January 1944 that production of Mosquito night fighters was already behind schedule.

The 422 NFS conducted its first combat mission on July 6, 1944—not against piloted enemy airplanes but pilotless V-1 Buzz Bombs. On July 16, 1944, the first aerial victory for a P-61 crew in the Europe happened when pilot Herman E. Ernst and radar operator (R/O) Edward H. Kopsel shot down a V-1. Black Widow crews shot down eight more Buzz Bombs before the war ended.

Since 1942, crews flying Mosquitos and other aircraft had met the need for Allied night fighters so when the 425 NFS arrived in France on August 18, 1944, war planners tasked the unit to attack ground targets. U.S. Army Air Forces leadership had early in the design process envisioned the Black Widow interdicting ground targets, with the goal to harass enemy forces at night as well as in daylight. Armed with machine guns, cannons, bombs, and rockets, the P-61 crews could lay down devastating fire. In December 1944, the 425^th began using 5-inch diameter HVAR (High-Velocity Aerial Rocket) rockets to attack trucks, trains, and structures.

As operational squadrons flew more missions in the A-model P-61, they reported back to the factory the lessons learned and Northrop modified Black Widows on the production line. Some accounts say that the gun turret caused turbulence that buffeted the tail, so Northrop engineers began omitted the turret from most A-models. The true cause may have been an inadequate supply—Boeing B-29 Superfortress bombers used the same turret. Northrop engineers restored the turret when newer P-61 B-models began to appear, however several front-line squadrons removed them again and installed fuel tanks in the empty space. The 6th NFS flying in the Pacific Theater of Operations fixed the turret to only fire forward. The 425th NFS in Europe did the same and moved the radar operator into the vacant gun turret operator’s seat behind the pilot.

The detection range of the SCR-720A radar mounted in the nose of the fighter was about 16 miles in “good conditions.” Crews considered this capability barely adequate, so Northrop installed a new upgraded radar set called the SCR-720C on the P-61B. To complement the pilot’s standard N-6 gunsight, Northrop introduced night binoculars. This interesting equipment combined a gunsight with 5.8 power binoculars designed to gather as much light as possible. The Pilot Training Manual for the Black Widow, P-61 (Office of Assistant Chief of Air Staff Training, Headquarters AAF, Washington, D.C.) claimed that pilots could see four times farther using night binoculars than they could unaided. The gunsight component included a row of tiny lights to help the pilot judge target range. When not in use, the binoculars folded up against the canopy. Army technicians also retrofitted night binoculars to A-model P-61s.

In the Pacific, crews in the 6th NFS in Hawaii and the 419 NFS on Guadalcanal were the first to fly Black Widows. Members of the 6th NFS achieved the first victory over an aerial opponent by anyone flying a P-61 when pilot 2nd Lt. Dale F. Haberman and R/O Flt. Officer Raymond P. Mooney shot down a Mitsubishi G4M Betty bomber on the night of June 30, 1944, over Saipan. They were flying a Black Widow named Moon Happy. On July 7, 1944, a P-61 crew in the 421st NFS based in New Guinea shot down a Japanese twin-engine Mitsubishi Ki-46 Dinah reconnaissance airplane. Charles A. Lindbergh was also in New Guinea to show pilots how to get the best performance from the Lockheed P-38 Lightning and took the opportunity to fly the P-61, describing it as an “exceptionally fine airplane.” During five days in December 1944, crews flying Black Widows downed eight Japanese aircraft in five days. As in Europe, when Japanese night intruders became scarce in late 1944, Black Widow crews began to fly more interdiction missions. The P-61s supported the invasion at Balikpapan, Borneo, after mechanics installed HVAR rockets and four 165 gal. external fuel tanks, extending mission endurance to as much as eight hours when pilots throttled the engines to the most economical power setting.

In the China-Burma-India Theater, Maj. Gen. Curtis Lemay asked the army for Black Widows to protect the Chinese bases that launched the first B-29 Superfortress missions against Japan. Maj. Gen. Claire Chennault, commanding the 14th Air Force, initially resisted, arguing that he could not support the logistical needs of a P-61 unit, but he eventually agreed. Black Widow crews patrolled at night over Lemay’s B-29 base at Chengtu and aided crews flying lost and damaged Superfortresses to find their way to safe landings. The U.S. Navy asked for 200 P-61s, perhaps to patrol at night above their ships, but the service never actually accepted any Black Widows. Beginning in March 1944, the U.S. Marines began training to fly the Black Widow on night fighter missions until the service cancelled the program a few months later. By the time World War II ended, the U. S. Army Air Forces had formed a total of 14 Black Widow squadrons. Two operated in the European Theater of Operations (ETO), eight in the Pacific Theater (PTO), two in the China-Burma-India (CBI) Theater, and two in the Mediterranean (MTO). The crews in these units tallied the following aerial victories:

The 422nd NFS operating in Europe produced more aces flying Black Widows than any other unit during the war. A crew reached ace level after downing five enemy aircraft.

To meet the Army’s need for more speed, faster climb, greater range and endurance, and the capability to operate at higher altitudes, Northrop developed the P-61 C-model. Engineers added: exhaust-driven turbosuperchargers instead of the mechanical units fitted to the A- and B-models; hardware in the wings to attach four pylons for mounting fuel tanks or bombs; air brakes mounted in the wings; and propellers with thick-chord blades. The improvements came too late for C-model Black Widows to see combat. Northrop stopped building the P-61 after the war ended.

Northrop had built the P-61 for combat. The airframe was strong, stable, and easy to control in the air, and the C-model could climb well to altitudes exceeding 40,000 feet. These attributes led the U.S. National Weather Service to select P-61Cs to investigate the inner workings of thunderstorms. Black Widow crews could fly into the storms carrying an array of sensors to measure turbulence, temperature, wind speeds, and the amount and types of precipitation. The Weather Service started Project Thunderstorm in 1945 using federal grant money. Phase I of the project was based at Pinecastle Army Airfield, Florida and the flight program took place from late June to mid-September 1946. A typical mission used five Black Widows flying into a storm at altitudes varying from five to twenty-five thousand feet. In February 1947, Phase II of the project moved to Clinton County Army Air Base, Ohio, and pilots flew storm missions from May to September 1947. Three years later, the National Air Museum (NAM)—forerunner of the Smithsonian’s National Air and Space Museum—accepted one of the Project Thunderstorm P-61s, a P-61C-1-NO (serial number 43-8330), for its collection.

Northrop had delivered this Black Widow to the U.S. Army Air Forces on July 28, 1945. By October, it was flying at Ladd Field, Alaska, in cold weather tests and remained there until March 30, 1946. The Army then moved the P-61 to Pinecastle Air Force Base, Florida, for the Thunderstorm Project. Early in 1948, the air force assigned the airplane to the Flight Test Division at Wright-Patterson Air Force Base, Ohio. Two years later, the service declared the P-61 surplus in 1950 and moved it to Park Ridge, Illinois, where it joined many other World War II aircraft set aside for the National Air Museum. But 43-8330 was not done flying.

On November 30, 1950, the National Advisory Committee for Aeronautics (NACA) asked to borrow the NAM Black Widow. The request was approved, and the aircraft was delivered to the NACA Ames Aeronautical Laboratory at Naval Air Station Moffett Field, California, on February 14, 1951. To confirm legal ownership, NAM staff accessioned the aircraft on February 15, 1951.

Because wind tunnels that could test models and aerodynamic shapes at transonic speeds had not yet been built, the NACA used three airplanes including the NAM P-61 to carry aloft and drop large unpowered model aircraft and aerodynamic shapes weighing up to 1,500 pounds from altitudes as high as 43,000 ft. Crews had to endure extreme cold but the height was needed to allow the models and shapes to accelerate to transonic and even supersonic speeds as they fell. Engineers maneuvered the models to descend at different angles of attack and then deployed air brakes and parachutes to slow the models for landing. Tests were conducted at the Edwards Air Force Base bombing range in the Mojave Desert in California. NACA engineers Alun Jones, James Selna, Bonne Look and Loren G. Bright helped develop the drop-test program at Ames. Among the pilots who flew the tests were George Cooper, Rudolph Van Dyke, Don Heinle, Fred Drinkwater, Robert Whemper, and Joseph Walker.

The NACA completed its research program by summer 1954 and NACA pilot Donovan R. Heinle flew the airplane from Moffatt Field to Andrews Air Force Base, Maryland, arriving on August 10, 1954. When the engines shut down for the last time, the Museum P-61 had accumulated 530 flight hours. In May 2006, a team of museum artifact treatment specialists completed their work on the Black Widow and reassembled it on display at the National Air and Space Museum’s Steven F. Udvar-Hazy Center.