Developing a True Night Fighter


The United States, comfortable in the knowledge that British airmen would carry the brunt of night combat for the time being, could afford to develop its night fighters slowly, under peacetime priorities. Wartime priorities, on the other hand, forced the British to take a fast, off-the-shelf U.S. attack bomber, the Douglas A-20 Boston, and convert it to a night fighter equipped with the Mark IV airborne radar.

For the long-term, the Air Corps wanted a specially designed night fighter, built according to Muir Fairchild’s guidance from the early 1920s. The original request for proposals called for a “Night Interceptor Pursuit Airplane.” In response to a proposal from Northrop, the Army Air Corps ordered two XP-61 prototypes in January 1941 for $1,367,000. Hungry for its first night fighter, the Air Corps ordered thirteen YP-61s two months later for service testing. The prototype was an all-metal, twin engine, three-place monoplane with twin tail booms and a fully retractable tricycle landing gear. Its revolutionary slotted flaps and perforated spoilers allowed it to close on a target very quickly-up to 362 miles per hour (P-61A version)-and then to decelerate rapidly to only 70 miles per hour so as not to overshoot the target. Nicknamed the Black Widow, the P-61 had many teething problems, which prevented the first prototype from flying until May 1942, a service test model until February 1943, and a production model until October 1943. The Black Widow made its public debut in January 1944 during a mysterious night flyover of the Los Angeles Coliseum, rapidly appearing out of the dark like some gigantic bat, and then just as strangely disappearing, with only the roar of its engines testifying that it had flown over the surprised crowd at a halftime celebration.

The P-61’s long-delayed development forced the AAF to seek an interim solution. Since the British had been converting Douglas Boston attack bombers to night fighters since 1940, it seemed logical to fill the gap left by the “Night Interceptor Pursuit Airplane” project with the night version of the Boston, known as the Havoc. The RAF had also fitted some Havocs with a powerful searchlight to illuminate enemy aircraft and allow accompanying Hurricane day fighters to attack. Renamed the Turbinlite, these aircraft proved ineffective because the searchlight blinded everyone in the area, friend and foe alike.

In October 1941 U.S. airmen installed in Douglas Boston attack bombers their version of the Mark IV airborne radar, initially the handmade AI-10 and later the manufactured SCR-540. Thus modified and redesignated the P-70, sixty of these aircraft became available at Douglas’s Santa Monica plant when supercharged engines needed for the bomber version could not be allocated. Armed with four 20-mm cannons and airborne radar, the P-70 could carry up to two thousand pounds of bombs on night bomber missions. However, the absence of superchargers and therefore a diminished high-altitude capability guaranteed their failure as night fighters. The desperate need for anything that would fly at night nonetheless warranted orders for 65 more combat versions and 105 trainers. By September 1942, 59 P-70s were ready for combat, with about half going to training schools at Orlando, Florida, and the other half to operational units defending the Panama Canal (24th Fighter Squadron) and Hawaii (6th Fighter Squadron).

Meanwhile, the P-61 Black Widow faced mounting technical problems: aerodynamically-induced tail-buffeting, a move of the cannons from the wings to the belly, a requirement for additional fuel capacity, Plexiglas nose cones that melted in the sun, and delays in receiving remotely controlled gun turrets (in demand for the B-29) slowed production even more. Labor problems and material shortages also contributed to delays at Northrop’s Hawthorne, California, plant, which built only 34 in 1943, 449 in 1944, and 199 in 1945. Only 100 Black Widows were overseas by D-Day, June 6, 1944.

But what a technical marvel! Two 2,000 horsepower Pratt & Whitney Double Wasp engines powered the P-61, two-speed General Electric turbosuperchargers boosted performance at altitude, and four 20-mm cannons and four .50-caliber machine guns provided killing power. Though the Black Widow was designed for a crew of three (pilot, radar operator [R/O], and gunner), the gunner sometimes did not fly in combat because the remote-controlled gun turret was either deleted or fired by the pilot. Armor plates protected the crew from machine gun fire. The pilot could use 5.8 power night binoculars mounted in the cockpit and connected to the optical gunsight. Four illuminated dots on the gunsight allowed the pilot to determine the enemy’s range. The R/O sat backwards, unable to see what lay ahead, his eyes trained on the radar scope between his knees.

The P-61 was perhaps the first “stealth” technology to fly for the United States. Following tests at the National Defense Research Committee, Northrop painted the night fighter glossy black to help it hide in darkened skies by reflecting light away rather than down to the ground. Baptized the Black Widow, certainly one of the most apropos nicknames ever, the P-61 (including the version with water injection) could fly up to 370 miles per hour in level flight at 30,000 feet, reach an altitude of 41,000 feet, and climb to 20,000 feet in 8.5 minutes. Fully loaded, it weighed only as much as an empty B-17 Flying Fortress. The seven hundred Black Widows built were, by any terms, the most sophisticated and advanced piston engine-powered, propeller-driven aircraft of the war.

All this performance came with a high pricetag. With Northrop’s assembly line in full gear, a completely equipped P-61 cost $180,000 in 1943 dollars, three times the cost of a P-38 fighter and twice the price of a C-47 transport. But, unconcerned with cost, the men who flew the Widow loved it. According to one, it was “fun to fly” and especially suited for its role of flying by instruments because of its stability. The P-61 pilot manual said: “When the Black Widow takes to the night sky, sticking her long nose into whatever trouble lies there, she is hard to see, hard to hit, and hard to beat.” Its full-span landing flaps and retractable ailerons afforded great maneuverability. Some pilots believed the plane needed more speed, but what fighter pilot has not asked for greater speed? Others criticized the multiple ribs in its canopy that obstructed vision. Still, any aircraft that could bring down an Me 410 flying 375 miles per hour at 24,000 feet and a Ju 52 flying 90 miles per hour at 1,000 feet in the darkness of midnight was obviously a successful fighter.

The Germans soon learned what the Black Widow could do and endeavored to collect one. Pilot 1st Lt. Paul A. Smith and R/O 1st Lt. Robert E. Tierney followed a bogey (enemy aircraft) to the ground, the German plane playing a game of tag, always staying safely ahead of the P-61, but never attempting to lose it either. After nearly thirty minutes of chase, Smith and Tierney found themselves at low altitude flying through a “killing field” of light German antiaircraft guns supported by searchlights. Having lost their port engine, the 422d Night Fighter Squadron (NFS) crew nursed the damaged Black Widow back to their home base. Though the P-61 bore eighty-seven holes, the Germans were unable to claim their prize.

AAF Col. Phineas K. Morrill laid the groundwork for a major controversy in September 1943, when he requested that all of the night fighter squadrons trained by his 481st Night Fighter Operational Training Group be equipped with twin-engine British Mosquitoes rather than American P-70s or P-61s. The proposal received little attention until June 1944, when Maj. Gen. Hoyt S. Vandenberg, Deputy Commander in Chief of Allied Expeditionary Air Force in Europe, added his weight to Morrill’s request. Considering that “neither the P-61 nor the P-70 type aircraft are suitable night fighters . . . and that little success can be expected,” Vandenberg wanted U.S. night fighter squadrons to switch to British-provided Mosquitoes.

To resolve the controversy, Lt. Gen. Carl A. Spaatz, Commander of United States Strategic Air Forces in Europe, ordered a July 5, 1944, flyoff at Hurn, England, pitting the P-61 directly against Vandenberg’s choice, the British Mosquito. Lt. Col. Winston W. Kratz, director of night fighter training in the United States, bet $500 that the Mosquito could outperform the Widow. According to the 422d NFS historian, the competing P-61, “tweaked” to get maximum performance, 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.” All in all, the historian noted, “a most enjoyable afternoon-Kratz paid off.” The official report concluded that the “P-61 can out-climb the Mosquito due to the ability of the P-61 to operate indefinitely at military power without overheating,” critical to closing on a bogey.

Despite this impressive performance, the Black Widow lacked the speed advantage necessary to intercept some high-flying enemy bombers. At Leyte in the Pacific, chagrined Army pilots had to ask for help from single-engine Marine F6F-3N Hellcats to stop nightly Japanese high altitude intruders. The AAF had tested its own single-engine and single crew night fighters in 1944 over France, sending two P-51s and two P-38s on twenty-one sorties with a RAF night squadron. Their lack of success, at a cost of one P-38, prematurely ended the AAF’s experiment with single-engine or single-crew night fighters. U.S. airmen were convinced that such aircraft should be twin-engined and carry more than a single crewman-the P-61 Black Widow would have to do the job.