USA (1943)
Night Fighter – 706 Built

The Northrop P-61 was a night fighter designed to fulfill a largely overlooked gap in America’s air defenses in the years prior to its entry into the Second World War. Ambitious and groundbreaking, the P-61 would be the first fighter aircraft designed to carry a radar and was to be equipped with a state of the art remotely operated turret. However, the aircraft suffered numerous technical problems which led to many delays in its development. Despite its quirks, the plane proved to be popular with its pilots, effective in service, and far more capable in its mission than preceding American night fighters, while also proving itself effective in roles not envisioned at the time of its design.

Nascent Developments

The US Army’s night air defense services during the interwar years were perhaps their most neglected and least developed. This was in part due to the meager capabilities of the aircraft and detection systems of the time, but also general disinterest from senior leadership and, resultantly, poor funding. Despite advances in night flying instrumentation and training aids, most notably Edward Link’s ground trainer, efforts during the period to detect and intercept aircraft at night were largely futile. Success in testing was almost entirely based on the weather, as the search lights they coordinated with relied on acoustic detection, and their ability to find the enemy was largely based on luck whenever the skies were not clear. Attempts were even made to detect enemy aircraft by the weak electromagnetic waves emitted by their spark plugs, but these were met with predictably poor results. What methods they did develop were subsequently made useless by advancements in bomber design, as the new Martin B-10 was faster than most contemporary fighters, and the B-17, still in development at the time, showed even greater promise (McFarland 3, 4).

Night fighters would prove a largely unworkable concept during the interwar years due to the crude instruments employed to find the bombers, which themselves also stood a good chance of outrunning their pursuers, however, this would soon change. The development of radar and more capable fighters would prove to be the decisive factor that would transform the practice of intercepting aircraft at night from a clumsy mission dependent more on luck than anything else, to an essential service that would grow ever more precise in its ability to detect and bring down enemy aircraft.

 

Lessons Abroad

Virtually all major new developments of the Air Corps’ night fighting capabilities in the years prior to the US entry into the Second World War were a result of two factors, new developments in radar and reports from observers sent to take note of the lessons the RAF were learning during the fall of France and the Blitz.

As the clouds of war drew over Europe during 1938 and 1939, it was clear that airpower would be a decisive component of any potential conflict. It was for this reason that president Franklin Delano Roosevelt massively built-up US military forces for the goal of defending both the mainland United States and its overseas military installations in 1939 and 1940. This build up had broad aims, but perhaps most importantly it saw the vast expansion of the US Army’s air power. This was to prove instrumental for those officers who wished the service to take on a much larger role in the US Armed Forces, and to finally cement their position in it, as the department had been reorganized several times during the interwar period.

They would soon see a massive leap in responsibilities as the Air Corps took up the bulk of air defense duties with the founding of the Air Defense Command in February of 1940. However, despite their eagerness to play such a major role, they also recognized their lack of experience and sought to understand the fundamentals of the modern air war in order to better fulfill this task. With the war waging in Europe, General Henry “Hap” Arnold was able to argue for the presence of US Air Corps observers overseas. In the spring of 1940, four officers were sent to London, Paris, and Berlin (Harrison&Pape 26). While these early postings were important for shaping foreign policy and building ties that would facilitate easier coordination with the RAF later in the war, they would soon become an essential source of information for Air Corps planners following the fall of France and throughout the Blitz.

It was during the Blitz that perhaps the largest gaps in US air cover would become evident, with various solutions being presented to help bridge them. Thankfully for the Air Corps observers, the Blitz would demonstrate exactly what they would need to develop to face any threat from the air. They recognized that they needed a modern air force, which could cooperate with sophisticated detection and communication networks to form a comprehensive air defense system that would leave any attacker badly mauled, day or night.

Brig. General Tooey Spaatz was the primary observer for RAF night fighting operations, and it was no coincidence that he later became Chief of the Air Corps Material Division at Wright Field. While the British night fighter services were still extremely crude at this point in the war, they presented a much better starting point for US planners than the virtually useless interwar experiments. Spaatz’s efforts largely shaped the requirements for the Air Corps’ night fighter, these being relayed to Northrop’s Chief of research, Vladimir Pavlecka, while he was at Wright Field working on another project. Alongside a set of specifications, he was told the plane would need to be a two-engined aircraft with a crew of two, a pilot and a radar operator, though the specifics of radar were not disclosed. At this time, Northrop was a new company and made for an obvious choice, as they had previously worked on an unbuilt night fighter design for the British, and were one of the only firms that were not at capacity at the time.

Soon, this new aircraft, designated the ‘Air Corps Night Interceptor Pursuit Airplane’, began to take shape. It would be powered by a pair of Whitney Double Wasp engines carried in nacelles that would be connected by a twin boom tail, and joined to the fuselage through the wings. It would carry a crew of three, a pilot, a gunner, and a radio operator who also doubled as a rear gunner. It would mount two turrets carrying four .50 caliber guns each and would be a large aircraft with a height of 13 feet and two inches (4.013 m), a length of 45 feet and six inches (13.87 m), a wingspan of 66 feet (20.12 m), it would weigh 22,654 pounds (10276 kg), and feature the new Zaparka flaps.  While this proposal bore many similarities to the later XP-61 prototype, much would change as the design was revised.

While the design was promising, work was slow, and though Northrop had a prototype designed in January of 1941, it would be many months until it was ready to fly, and years before it was ready for service (Harrison&Pape 30). As a result, the aircraft would not be ready for the war to come, leaving most of the night fighting duties to stop gap designs, such as the converted A-20 bomber designated the P-70, and the British supplied Bristol Beaufort.

Clean slate, Dull chisel: A history of early American night fighting

With the attack on Pearl Harbor, the night fighter force found itself entering the war with the lessons learned from the RAF, but without adequate training programs or equipment. Compared to what existed in England, the communications and detection infrastructure was very poor, as it relied on high frequency radio sets which proved troublesome, lacked sufficient identify-friend-or-foe capability, with early warning radar set up in poor positions, and worst of all, they lacked a dedicated night fighter force.

With the help of RAF advisors, they set out to correct these faults, with the Air Defense Operational Training unit being activated March 26th, 1942. The 81st Fighter Squadron (special) was chosen on May 28th, 1942 as the first official night fighter training unit and was staffed with officers who were enthusiastic about the promise of this new mission. This unit was later placed under the new Night Fighter Department, which itself was reorganized as the Night Fighter Division and made subordinate to the Fighter Department . Their curriculum was composed on July 4th, 1942, as pilots were to be trained to a high level of proficiency in instrument flying, blind take offs and landings, night formation flying, night gunnery, pilot-radar operator interception teamwork, Ground Control Intercept (GCI), and general air defense procedures.

While this unit was extremely useful in testing and building confidence in new equipment, like the SCR 540 radar, it was hit by numerous hurdles which prevented it from turning out the number of pilots needed. This was mostly the result of a shortage of aircraft, as the relatively small number of P-70’s, DB-7’s, AT-11’s, T-50’s, and B-80’s would prove a serious bottleneck, as would the delays in getting Airborne Intercept ground trainers. This problem remained late into 1941, as the 81st was deactivated and its personnel used to form the 348th and 349th Night Fighter squadrons in October of 1941. These two squadrons would be used to train new night fighter personnel with the hope that they could build 15 squadrons by 1943. However, this training schedule was overly ambitious and hampered by insufficient supplies of equipment. Sadly, in line with much of the troubled program, night fighter pilots graduated with no fanfare or any formal ceremony. They simply signed on a line and received their wings.

Night Fighter Squadron building would continue slowly until James Doolitle would push for its accelerated development in late 1942. Doolittle, after being so impressed by RAF night fighters over North Africa, called for four new night fighter squadrons to be formed, these being the 414th, 415th, 416th, and 417th. It was not until July of 1943 that real Night Fighter Squadron development began in earnest, as more aircraft and training material became available, and the new 481st Night Fighter Operational Training Group was formed under the command of Lt.Col. Winston Kratz (Harrison&Pape 104).

Trial by Fire: Pacific

The first night fighter deployments were to Panama and Hawaii, with the first P-70s becoming available in January of 1942. These planes were first used in improvised night fighting squadrons, like the 6th Night Fighter Squadron initially based out of Hawaii. They were, however, badly constrained by their inadequate support infrastructure and, as pilots would soon find out, the performance of their aircraft. Problems soon arose over the personnel shortages which required volunteers from signal corps officers and the enlisted maintenance crews to serve as radar operators. Problems improved very little following their move to Guadalcanal in February of 1943, where conditions were brutal.

Their objective was to try and stop the nightly raids by Japanese bombers which came over the islands to conduct nuisance raids. The P-70s were vectored onto these aircraft using the ground-based SCR 270 early warning radar without success, as the radar could provide only the azimuth to the target but not its altitude. Neither the radar crews nor pilots had much experience with GCI procedures and, combined with the meager capabilities of the P-70, the night fighters brought down few Japanese aircraft. While the night fighter crew’s living conditions improved thanks to new prefabricated shelters, their operational success did not. Their challenges were made far more difficult as the Japanese adapted to their tactics and their bombers began to fly above the P-70’s service ceiling, and went so far as to imitate American GCI operators in attempts to give faulty information to pilots (Harrison&Pape 68). P-70 crews did all they could to improve the speed and operational ceiling of the aircraft through serious modification which included installing propellers from B-17F’s and P-38 fuel pumps, though to no success.

Frustration with the P-70 even managed to motivate the squadron to modify some of the P-38s they had been supplied with in an effort to replace the P-70. This would prove difficult, as the aircraft were not equipped with radar as they were to be used in conjunction with searchlights to find their targets. Two P-38Gs were modified by Lt. Melvin Richardson and a squadron radar mechanic by adding a second seat behind the pilot and building an avionics pod for the SCR-540 out of an external fuel tank. These modified planes were much faster than the P-70s and were capable of reaching high flying Japanese bombers, however, they could not convert enough fighters. Both would receive the Legion of Merit for their ingenuity, but apart from this small victory, the 6th would lack the means to conduct their missions.

Overall, the night fighter squadron’s experiences in the South Pacific proved dismal, having neither the properly trained personnel, support elements, or even aircraft needed to effectively complete their mission. In the end, what success they did have was a result of their ingenuity and perseverance rather than specialized training or the equipment they had been issued. Each victory over the Japanese bombers was a hard-won achievement equally celebrated by the aircrews and the Marines the enemy harassed on a nightly basis.

Trial by Fire: Mediterranean

While the 6th NFS was still deployed to Guadalcanal, the 414th and the 415th left for England in March of 1943, where they would soon be retraining on Bristol Beaufighters. The switch from the P-70 was a difficult one, as between its tendency for ground looping and engine fires resulting from landing gear failure, the Beaufighter proved an intimidating plane for the US pilots. While the Beaufighter proved to be significantly faster and more agile than their old P-70s, many pilots felt uneasy flying it, and even their RAF instructors would readily admit the aircraft was among the most difficult in British service. Unlearning the habits from the P-70 was difficult, but thanks to a comprehensive program from the RAF, the challenge was soon overcome. Now proficient, the 414th and 415th left for North Africa and went into action in July of 1943 (Harrison&Pape 80).

Unlike their counterparts in the Pacific, the Mediterranean squadrons were largely successful thanks to their far superior Bristol Beaufighters, comprehensive training programs, and good technical support. Not only were they directed by far superior ground based radar systems, but these squadrons would later be the first to use the British AI Mk VIII centimetric radar sets, which, unlike the previous SCR-540, could operate at low altitudes. This radar was particularly useful, as it meant German bombers could no longer fly low to reduce the effective range of the aircraft’s radar. In November of 1943, the campaign proceeded and the two NFS’ would cover Allied convoys against the attacks of German bombers during the advance into Italy. The Germans would use a very different set of tactics compared to the Japanese, and made use of far more sophisticated equipment. As opposed to the single Japanese aircraft that often came in at around 30,000 ft (9144 m), the Germans tended to stay roughly between 10,000 and 15,000 ft (3048, 4572 m) in formations of various sizes. As opposed to the nuisance raids designed to keep the Marines from getting any rest, the Germans often sought to hit strategic targets, like harbor facilities and shipping vessels en masse.  The Germans would also later employ chaff, which cluttered up radar scopes, and tail warning radar on their bombers to warn them of the approach of night fighters.

The efforts of early American night fighter squadrons in the Mediterranean would thankfully prove to be the rule rather than the exception for the air crews still to come. In the future, they would expect well trained, specialized personnel, and effective ground control radar support. However, there were still strict limitations imposed by the equipment afforded to the night fighter squadrons, in particular their aircraft which, despite their greater speed, were anything but easy to fly.

XP-61 & YP-61: trouble, frustration, and promise

While American night fighter pilots had their first experiences in combat during 1942 and 1943, work on the new XP-61 continued. The program truly began in early 1942, after several contracts were issued. It was decided in February of 1942 that 410 aircraft would be procured with $7,136,689.56 being charged to the Defense Aide and $55,656,178.67 to Air Corps Appropriations. This contract stipulated the delivery of the first twelve to take place in April of 1943, with the final aircraft being handed over in January of 1944. However, contract negotiations saw the number of aircraft requested rise and fall significantly in the following months. In addition to deliveries to the USAAF, 50 P-61s were to be set aside for Lend Lease, though this was later dropped due to a lack of RAF interest in the aircraft (Harrison&Pape 89).

The XP-61 first flew on May 26th, 1943, but only after a long and troubled process that saw the prototype fly with different propellers than what were originally called for, a dummy turret, and without a radar. Despite these shortcomings, the prototype was initially quite promising, with the aircraft performing satisfactorily during its short preliminary flight, and its test pilot, Vance Breese, telling Jack Northrop “Jack, you’ve got a damn fine airplane!” (Harrison&Pape 89). The succeeding flights would, however, prove more troublesome ,as they soon revealed stability problems and reliability issues with the engines. These issues were tracked to the horizontal stabilizer and elevator assemblies, the short span Zap flaps, and the buildup of oil and gas in the engine crankcase. Engine failures and violent longitudinal instability soon grounded the XP-61. The stability problems were particularly troublesome, as they required redesigning much of the tail assembly of the aircraft and the addition of full span flaps in place of the Zap flaps.

Issues also arose with the use of the spoileron system on the second XP-61, which was designed to be used in conjunction with short ailerons as part of its lateral control system. The spoilers themselves were thin circular arcs that sat in grooves in the wings. These would deploy and allow the pilot remarkably good control at high speed, but their development would prove to be rather difficult. At first, they proved unstable as a result of their hinge movements, which was solved by reducing the size of the scoop. Later, serious vibration issues were found to destroy the spoilers within their wing slots. This, in turn, was found to be the result of high-speed airflow moving through the slot, and was remedied by installing plates to seal it off (Harrison&Pape 94).

In an effort to improve engine reliability, the initial Pratt & Whitney R-2800-25S engines were replaced with R-2800-10s, though this would fail to solve the problem. Despite the swap, engine failures were common in testing and it was found that cutting oil consumption resulted in oil starvation in the master cylinder, resulting in it freezing. With the rest of the articulating rods still going, the engine would work itself apart. After diagnosing the problem, the engineers at Pratt & Whitney soon resolved it with the installation of additional oil jets (Harrison&Pape 95).

These faults would see a major redesign of the XP-61, with the new model being designated the YP-61, which would act as both a prototype and pre-production model. This would incorporate a number of design modifications, including switching the tail boom’s construction from welded magnesium to aluminum alloy, the Zap Flaps being replaced by a full span trailing edge arrangement, and they would go on to incorporate the fix for the spoilerons (Dean 383). However, this would not represent an end to trouble, as the much-needed improvements in stability meant it could now be used for more demanding tests which would, in turn, uncover new faults.

As testing grew more strenuous, new problems began to arise, most notably with the fuselage. It was soon found that there were several structural weaknesses in the fuselage, with the vulnerable sections being subsequently strengthened, particularly around the canopy. The nose gear door also proved to be fairly fragile, which necessitated strengthening and having the aircraft’s 20 mm guns fitted with blast tubes to prevent the muzzle report from damaging it. It was also found that, at high speeds, the dome at the rear of the radar operator’s compartment could implode as a result of pressure difference. While this component was improved in prototyping, the problem would resurface in production models of the aircraft (Harrison&Pape 114).

At the nose of the aircraft, a new problem was found after a stopover in Arizona. In the sweltering 110-degree weather of the desert, it was found that the Plexiglas radome would deform and collapse once the aircraft was in the air, with the resulting shift in air flow causing the Lucite dome at the rear of the aircraft to blow out. While a new fiberglass dome was designed, it would not be ready well into serial production of the P-61A (Harrison&Pape 115).

The remote-controlled turret was also found to have several faults. The most immediate and concerning of these was that, while the guns were forward, the aircraft remained aerodynamically clean, but there would be intense buffeting as the turret traversed beyond 30 degrees in either direction. Following a redesign, the buffeting was mostly gone save for a far lighter effect that occurred when the turret was fully deflected to either side. In firing tests, it was found that use of the turret resulted in severe structural damage, with a similar problem being encountered with the aircraft’s 20 mm armament. In both cases, it was necessary to strengthen nearby structural elements with steel fittings, though owing to the complexity and size of the remote-controlled turret, a major redesign of the aircraft’s upper structure was required (Harrison&Pape 117, 118).

In spite of its many teething issues, the general flying characteristics earned the aircraft good marks from test pilots, exceeding Northrop’s guaranteed performance by one mile during speed tests, and was remarked upon by production project engineer Capt. Fred Jenks as follows: “The P-61 is an honest airplane. It has no mean tricks. In acrobatics such as loops, spins, Immelmanns, and fast turns, it behaves as a pursuit plane should. Its stalling gestures are near perfect.” (Harrison&Pape 121)

Britain and America on the same wavelength: Cooperation in developing the SCR-720

The Tizzard Mission

The P-61’s highly advanced air search radar was a device many years in the making, being a product of the interwar Tizard Mission, which sought to bring together US and British technical expertise for radar and radio development. It would officially become known as the British Technical and Scientific Mission, and it was not long into the war that approval was granted for the scientific material transfer to the US, which the British hoped would be reciprocated in kind by technical assistance and access to America’s electronics industries. The mission arrived in the US in September of 1940 with two gifts, a cavity magnetron, a device which allowed for the development of more advanced centimeter band radars, and an ASV Mark II surface search radar. Their audience was composed mostly of three groups, the Signal Corps, who had been struggling with the practical employment of radars for nearly a decade, microwave researchers, who were well versed on the technology but had yet to produce practical radar examples, and the US Army Air Corps, who were uninformed on technical matters but saw the promise of the technology (Brown 159, 160).

The mission got off to a good start, with the American audience suitably impressed. On the British side, they gained a great deal of information on the use of microwave techniques, and more importantly, access to larger electronics manufacturing industries and procedures. The US, on the other hand, gained access to the existing British radars and the cavity magnetron. While these advancements would have taken place eventually, the collaboration through the Tizard mission allowed rapid advancements in radar development and production in both countries. It was, of course, not without its negative consequences. Some trust in the American service-labs was lost when they gained the undeserved reputation of producing inferior equipment among the Armed Services when their interwar work was judged against the British (Brown 165, 166).

In the US, work on centimetric radar was mostly carried out through the MIT Radiation Lab, with their first goal being to produce an airborne centimeter band set (Brown 168). The benefits of a centimeter band radar over a meter band were considerable, as they would not require the use of drag inducing aerial antennas. The narrower band also meant less reflection from the ground, and while it was not yet known, they were less susceptible to jamming. In short, they represented a massive leap in capabilities over older radar sets (Brown 145).

The Rad Lab’s first centimetric radar was a 10 cm band set operated from a roof in January of 1941, with an intensive development program to follow. It was hoped that, by February, it would be mounted in a B-18 for testing, and a month following that, they hoped to have it aboard an A-20. However, many issues plagued the rooftop experiment and it was not until March that the device was transferred over to the B-18. Work would continue, and after further collaboration with the British, a new series of technology transfers would benefit both programs, with the British gaining access to a better transmitter, and the US a better receiver. Soon, the lab would produce America’s first practical centimetric Aerial intercept radar, the SCR-520. Western Electric built a few of these sets but work soon transitioned to making a lighter version for the P-61, the SCR-720 (Brown 168, 169).

SCR 720

The SCR-720 series was an advanced aerial intercept radar built by Western Electric and Bell Telephone Laboratories (Harrison&Pape 113). The radar operated on a wavelength of 9.1 centimeters at 3,300 megacycles, with a peak pulse power of approximately 70 kW. It had a maximum range of about 6 miles (9.65 km), which was later extended beyond 10 miles, at all azimuths between a search angle of 75 degrees to either port or starboard, with a minimum range of 300 feet (91 m). The system used a helical scan method and, in addition to the previously stated horizontal search angle, covered a total elevation of –30 degrees to +50 degrees. The device lacked provisions for IFF gear but could be used in conjunction with the SCR-729 transmitter, which was compatible with Mk III and Mk IIIG IFF sets along with beam approach beacons.

The display set up was composed of two indicator boxes, a two screen display to be used by the operator, and a far simpler one screen display which was for use by the pilot. The pilot’s indicator typically went unused, as it was less precise than the rear set and was generally redundant, as the pilot would be talked onto the target by the RO. The RO’s scope consisted of a range tube on the right, and an azimuth and elevation tube on the left. The display on the azimuth scope was dependent on the settings of the range scope, as only targets within certain set ranges would appear on the scope. This range was indicated by a marker line on the range scope and could be adjusted by the RO (Survey 28). The settings of these scopes were adjusted through the control box and synchronizer in the RO’s compartment.

In service, the SCR 720 offered many benefits over previous Allied centimeter band aerial intercept radars, in particular the slightly older British AI Mk VIII. A post war survey found that, while using the SCR-720, it was harder to lose maneuvering targets on the scopes thanks to the range/azimuth display which allowed the operator to follow the target’s course. The wide coverage meant it was unlikely a rapidly descending target would be lost, the range scope made course adjustment estimates to the target easier, and the range/azimuth display made intercepts across the flight path of the night fighter easier. Overall, the SCR-720 would prove to be the most precise and advanced AI radar set of the war and would see widespread use aboard the P-61 and DeHavilland Mosquito, which carried a British production of the device designated the AI Mk X (Survey 30).

However, while the radar was the best set in its day, it was also the most complex and was said to require the knowledge and experience on the level of a masters of electrical engineering just to make one’s way around the black boxes that made up the system (Harrison&Pape 113). In service, it would prove even harder to maintain where personnel and spare parts for the system would be sparse, and many of its components would prove vulnerable to the elements. This would generally prove an issue with P-61 squadrons, as they typically lacked personnel able to fix the boxes should problems arise, and often would not have enough spares to replace faulty components. Maintenance notwithstanding, the SCR 720 was a generation ahead of the previous SCR-540 and exceeded it in every capacity except ease of repair.

Enter the Black Widow: P-61A&B

The first P-61A rolled off the line in October of 1943 at Northrop’s plant in Hawthorne, California, with a public reveal later occurring at an Army-Navy show in Los Angeles in January of 1944. These aircraft were mostly unchanged from the last P-61 pre production aircraft, though this plane and the next 36 P-61As would be the only examples of the A model to be equipped with the remotely operated turret. The turret would be absent from the remaining 200 As and many of the succeeding B model, only to be reintroduced after a redesign (Pape 120,121).

Despite the revised model which would arrive much later in 1944, the P-61’s performance was roughly the same for its entire wartime service, with no major overall increases in horsepower or any major modifications to the airframe, apart from those to allow it to carry additional fuel and bombs and rockets for intruder and ground attack missions. Both the A and B models were powered by the Pratt and Whitney R-2800, with many early P-61As using the R-2800-10 and all aircraft beyond the P-61A-15 using the R-2800-65. Both engines produced 2000 hp, with the only major differences being their magnetos and ignition systems (Pilot’s training manual 11). Revisions to the design were gradual and often very minor between subtypes. As the P-61A matured, many new additions were made, including a new fuel system, underwing racks for bombs and fuel tanks, a water injection system, and additional oil capacity. The water injection system would boost the engine’s power about 15%, but only for brief periods and unsuitable for a lengthy climb or long-distance pursuit (P-61 training manual 12).

The P-61B would go on to extend the nose, revise the trim and hydraulic systems, alter certain instruments and displays in the cockpit, revise the heating system, alter the landing gear doors, and restore the turret (Dean 383). Much more work was done with regards the P-61C, which made use of significantly more powerful turbo-charged engines, though this aircraft did not see wartime use.

While the aircraft would mostly resemble the early prototypes, there had been more than a few major reworks of the airframe, most notably, the dropping of the ‘Zap Flaps’ for near full span types with an added lateral control system which made use of spoilerons. While these did prove troublesome in testing, the faults had been ironed out and the system worked to the satisfaction of pilots. The final configuration made use of slot covers and seals for the spoileron slots that solved the vibration problems and allowed for great lateral control for such a large aircraft while requiring little force on the part of the pilot. While this system was unconventional, pilots rapidly adapted to its use and were immediately appreciative of it, as it allowed for easily applied control at both very high and low speeds. It was particularly useful during landings, where they allowed for precise control on approach thanks to the automatic adjustment of the lateral control system with the flaps (Ashkenas 13, 14). This system was a major factor in making this fighter among the most maneuverable in the USAAF inventory, in spite of it also being the largest and heaviest.

Tough most of the aircraft’s worst issues were remedied in the prototypes, a few made it into the production models. The most glaring of these would be the plastic radome fitted to the nose of the aircraft, and the lucite tail cone at the rear, both of which would constitute fairly significant structural weaknesses. The plastic nose fitted to many of the early P-61As was weather sensitive and was prone to warping in the hot, tropical weather of the Pacific, or simply if left uncovered during a sunny and particularly hot day. The solution was painting the nose of the aircraft in a bright, reflective white paint, which raised obvious disadvantages when the aircraft was trying to stealthily pursue its targets in the dark. The lucite cone would prove more persistent and more dangerous (Harrison&Pape 115). On several occasions, these cones imploded during dives and high-speed maneuvers. While this presented little danger to the overall aircraft, the sound of rushing air through the radar operator’s position made communication between him and the pilot virtually impossible. This would be resolved later by the addition of metal reinforcement bands, though many older P-61’s would continue to fly without them.

While this was the first purpose built night fighter, in many ways, the aircraft fell short of the high hopes placed upon it, but would prove adequate for the purpose it was given. Responses to the P-61 were mixed though generally favorable, but complaints over speed and the difficulty of maintaining the SCR 720 radar persisted for all wartime models of the aircraft. Perhaps most unfortunate was that the top turret, which vastly complicated the aircraft’s design and added considerably to the aircraft’s frontal area and weight, was found to be completely unnecessary. The most immediate requests for improvement were for more powerful engines with better high-altitude performance, and for units to be supplied with more maintenance and test equipment for the SCR-720 radar, which the inadequately prepared ground crews struggled to keep in working order. While they were trained in basic maintenance and installation of the device, few had the technical skills necessary to actually repair faulty components. Neither of these would be provided in time to be of use during the war.

ETO: The 422nd and 425th Night Fighter Squadrons

The first P-61 to leave the United States was a P-61A to be evaluated by the RAF in March of 1944. This aircraft was later returned in February of 1945, as the RAF were not particularly impressed with its performance and found its maximum range to be far too low. They needed night fighters for deep penetrations into German airspace in support of the ongoing strategic bombing campaign, and the P-61 simply did not fit the requirements. While the aircraft was by all metrics a poor fit for the RAF, the language and tone surrounding the growing competition between the P-61 and DeHavilland Mosquito would become increasingly petty and hostile within certain sectors of the US War Department and the Night Fighter division.

Beyond this evaluation aircraft, three Night Fighter squadrons would be deployed to England in anticipation of Operation Overlord. These were the 422nd, which departed on March 10th, the 423rd on April 1st, and the 425th which departed May 1st. During this period, only the 425th had P-61As slated to be shipped out with them amidst general concerns regarding the availability of the aircraft. The 422nd and 423rd were still equipped with the inadequate P-70 at the time of their departures (Overlord Build Up). Supplies would thankfully become more available, with the 422nd getting their first P-61As in late May and the 423rd becoming a photographic reconnaissance squadron and would not require the aircraft (Dean 285). Both squadrons would possess a small number of aircraft, with the 425th shipping out with only nineteen aircraft, and throughout their service in the European Theater it remained the case that replacement aircraft were in short supply.

None of these P-61As were equipped with the dorsal turret, and with copious time on their hands and the feeling that a second pair of eyes looking forward would be helpful, several crews in the 425th NFS had the bright idea to move the radar operator’s position up into the now vacant gunner’s seat. Along with technical representatives from Northrop, the chief radar and engineering officers, and a Capt. Russell Glasser, who possessed a graduate’s degree in mechanical engineering, they set out to modify the aircraft. The results were spectacular, with the pilot and R/O now able to communicate in the event of intercom failure, and the resulting shift in weight changing the slightly nose up to a nose down at cruise, increasing the cruising speed between 15 and 20 mph. This change was subsequently authorized for 9th Air Force’s P-61s (Harrison&Pape 205, 206).

It was not until July of 1944 that the European P-61s actually flew their first combat sorties, with the several months prior to this being taken up by training, including joint exercises with the RAF, and a race between the P-61A and a DeHavilland Mosquito NF Mk XVII. The latter was precipitated by a rumor that the USAAF was planning to replace the P-61 with the Mosquito.

In June, Lt. Col. Oris B. Johnson arranged for joint training with an RAF Halifax bomber squadron based at Croft, during which the Night Fighters would practice intercepting the bombers, who would in turn practice evasive maneuvers and other defensive tactics. The night fighters would be given an area to defend and would be vectored onto bombers by GCI. When they were in place to claim a ‘kill’, they flashed their navigation lights (Harrison&Pape 206). While this exercise was undoubtedly easier than what they would later be asked to do over France, it was important in building up the crew’s confidence in their abilities and equipment.

The ‘race-off’ was an event long in the making, with its roots in the War Department’s desire to purchase DeHavilland Mosquitoes for use as reconnaissance aircraft and night fighters. There were those in the department who wished to equip the Night Fighter Squadrons in the Mediterranean with Mosquitos, with the ensuing politics eventually driving a rumor that the War Department was planning to scrap the production of the P-61 in favor of the Mosquito, which were to be supplied by the UK and Canada. In any case, these proposals were impractical, as the British were extremely protective when it came to these aircraft. However, rumors soon filtered to the squadrons who were upset enough to propose a fly-off between the types. A demonstration was arranged on July 5th, 1944 at RAF station Hurn. The contenders were a P-61A and a Mosquito NF Mk XVII, with the results being that the P-61 out climbed and out turned the Mosquito between 5,000 and 20,000 feet.

The race was anything but clear cut, and it is extremely unlikely that it was just a fair competition that both sides took part in earnestly. Simply put, the RAF did not want to give the USAAF any more Mosquitoes than they absolutely had to, and were extremely motivated to throw the race. They had a great desire to ensure they were better supplied with the only night fighter in Allied service at the time that could fly long range missions into Germany. The results of the race are extremely suspicious given just how clear the P-61A’s win seemed to be in comparison to the years of evaluations which virtually always claimed that the Mosquito NF had the superior climb rate, and the P-61 had superior maneuverability. Members of the 481st NFTG who had flown planes came to the same conclusion, as did the AAF board, and even Col. Winston Kratz, director of night fighter training and a major proponent of the P-61 (Harrison&Pape 153, 156, 203). His words perhaps best sum up the event, “I’m absolutely sure the British were lying like troopers. I honestly believe the P-61 was not as fast as the Mosquito, which the British needed because by that time it was the one airplane that could get into Berlin and back without getting shot down. But come what may, the ‘61 was a good night fighter. In the combat game you’ve got to be pretty realistic about these things. (Harrison&Pape 209)”

The first real test of the P-61 in Europe came in July of 1944, when they were pressed into service against a new threat, the Fiesler 103 flying bomb or ‘buzz bomb’. The fast, unmanned weapon required the P-61 to enter a slight dive to catch them and, while they flew straight and level, they still proved a dangerous and challenging opponent. The bomb presented a small target but its massive warhead was capable of damaging a pursuer, something Capt. Tadas J. Spelis and F/O Eleutherios ‘Lefty’ Eleftherion would learn on the night of July 20th. Drawing in at 450 ft, Spelis detonated the bomb’s payload. which violently shook his plane and caused serious damage to the plane’s control surfaces and left much of the fuselage dented and perforated (Harrison&Pape 205).

Over the Channel: Autumn through Winter

At the end of July, the 422nd and 425th would make the trip across the channel to provide afterhours protection for the US First and Third Armies, respectively. There, both squadrons would defend the Normandy beachhead as the Allies pushed forward into France. This period would largely inform the kind of fighting they would be doing for much of the campaign, intercepting lone German bombers and the occasional night fighter acting as an intruder, while also taking on alternate support missions. Shortly after the 422nd was deployed to the Cherbourg peninsula, they intercepted several Ju 88s, Do 217s, and Ju 188s as they attempted to harass Allied forces in the area, but kills were difficult to confirm owing to the contested areas these aircraft went down in.

This period also saw the P-61’s first encounter with a German night fighter when Lt. Paul Smith and Lt. Robert Tirney intercepted a Bf 110G-4 on August 7th, 1944. While Smith and Tirney approached the enemy, they were soon spotted and found themselves in a turn fight. While the maneuverability of the P-61 allowed them to keep up with the enemy, the two planes would end up colliding. Despite the impact, both planes would end up returning home, each carrying paint from their opponent. Records show elements of the German night fighter squadrons NJG 5 and 4 had been conducting ground attack operations that night without losses (Harrison&Pape 203; Part 4 Boiten 29).

This period also saw the first use of the P-61 in the ground attack role when the 425th NFS was called to assist an attack on German forces that had broken out of Lorient. Despite their early model P-61As lacking hard points for bombs, they were able to carry out the mission thanks to the powerful cannon armament of the P-61A. They conducted strafing runs on gun positions, truck convoys, and an artillery ammunition dump at the cost of one aircraft which struck a telephone pole in a low-level attack (Harrison&Pape 204).

Following the breakout in Normandy, there was a considerable lull in interceptions of enemy aircraft and the trickle of supplies to the unit meant much of the autumn of 1944 was characterized by inactivity. From September to November, GCI directed the 422nd’s P-61s into a total of 461 chases, resulting in 282 airborne radar contacts, 174 sightings, 20 of which were positively identified as enemy aircraft, and only 7 were shot down (McFarland 28). The use of Identify Friend or Foe (IFF) appeared to be limited, resulting in a high number of interceptions of friendly aircraft, and occasional friendly fire. Air crews in the 422nd NFS believed they had been fired on several times by RAF Mosquitos, and one Mosquito of the 305 Squadron, piloted by WO. Reg Everson, had been shot down by a P-61, with his aircraft being claimed as a ‘Ju 88’ (Harrison&Pape 302, peoples war).

As the Night Fighter Squadrons moved away from the beachhead and into airfields previously held by the enemy, their supply lines grew tighter and the enemy began to develop better tactics. A scarcity of fuel even threatened to keep the 442nd on the ground, but the crisis was avoided thanks to a little ingenuity. As fuel laden B-24’s came in for their deliveries in Florennes, Belgium, they would occasionally overrun the airstrip, whereupon the aviation gasoline would be siphoned out, and then stolen by the 422nd (Harrison&Pape 267).

While the Luftwaffe was less active at night during this period, their tactics had largely improved. Their typical after hours raiders became flights of bomb laden Fw 190s in the place of the lone medium bomber. The common types, the Ju 88, Do 217, Ju 87, and Ju 188, were still encountered, but were eclipsed by the more numerous 190s flying low altitude raids against Allied positions near the front line. The 190s would prove more difficult targets, as their small size made them hard to identify in the dark, and their speed and maneuverability meant they had a much better chance of slipping away from the larger night fighters. While they were harder to shoot down, the P-61 was still more than capable of breaking up their attacks and forcing them to return to base (Harrison&Pape 262).

The lull in Luftwaffe nightly activity in the autumn and winter of 1944 meant that both British and American night fighter squadrons could shift to offensive operations, and thanks to newer models of the P-61A and B mounting additional hardpoints for fuel and bombs, they would have an exceptional tool for this task. Both the 422nd and the 425th NFS would provide a vital service to the beleaguered 101st Airborne Division at Bastogne, Belgium, where they were able to provide air cover and ground attack support, day or night, in weather that kept most planes on the ground. The nightly air battles over the Ardennes took a similar, but intensified form as the Luftwaffe mounted a desperate offensive, sortieing aircraft to attack Allied positions, drop supplies, and mounted a score of night fighter intruder missions. These intruder missions had aircraft loiter around enemy airfields and attack any aircraft attempting to take off or land.

It was during this time that one of the greatest drawbacks of the P-61 made itself well known. It was a high maintenance aircraft and replacement parts and planes were scarce. During the Battle of the Bulge, only four of the 422nd NFS’s sixteen P-61s were operational, and keeping these four planes serviceable was a round the clock effort of the highest importance. Apart from the just as limited number of A-20s, the P-61s were the only aircraft capable of flying in the terrible weather conditions of the battle. Supplies had to be found outside of the regular channels, and crews were rotated out of these aircraft that each flew up to four missions per night. Combined, the 422nd and 425th NFS claimed a total of 115 trucks, 3 locomotives, 16 rail cars, sixteen aircraft, and had disrupted Luftwaffe activities in the area (McFarland 32, 33). The actions of the 422nd would go on to earn them another Distinguished Unit citation, and a commendation from the Commanding General of the 101st Airborne at Bastogne (Harrison&Pape 293).

However, this period was also considerably more dangerous as Luftwaffe’s night fighter squadrons were also performing similar missions in the same area. While they used comparatively obsolete radars, they could still present a threat. Of the scarce P-61’s active during the Battle of the Bulge, three were lost to unconfirmed causes (Dean 286).

Spring to VE-Day

The Battle of the Bulge would mark the apex of the NFS’ activity in the European Theater. The remainder of the European campaign would consist almost entirely of ground attack and intruder missions, as fuel shortages left most of the Luftwaffe grounded. Both the 422nd and 425th would commit themselves to ‘ground work’ against the usual targets; truck convoys and rail lines, as Tactical Air Command ordered a cessation of defensive air patrols, instead focusing on general offensive operations. In this role, the P-61 proved exceptional despite the design never being intended for such use, with the initial models not even possessing bomb racks.

Most ground attack missions would be conducted the same way, though some new tactics would be introduced to take advantage of the bomb racks added to the newer models of the P-61. During the beginning of 1945, P-61s would often carry napalm which they would drop in the vicinity of their targets. Using the fires for illumination, they carried out attacks with a combination of bombs, and in the case of the 425th’s modified P-61s, HVAR rockets. Rail yards, locomotives, and truck convoys were favored targets, as their drivers often felt it was safe to keep their lights on. While this may seem a ridiculous use of what were among the most expensive aircraft employed during the war, the 422nd was credited with damaging or destroying 448 trucks, 50 locomotives, and 476 rail cars for the duration of their service. Perhaps more impressive were the astoundingly low loss rates suffered on these intruder missions. From October of 1944 to May of 1945, the 425th NFS flew 1,162 intruder missions with the loss of only six aircraft. Despite the inherent dangers of flying at night, these missions actually proved to be far safer than daylight sorties (McFarland 29).

Luftwaffe Opponents

The typical encounters with the Luftwaffe were with its bomber, night attack, reconnaissance, transport, and occasionally night fighter forces. Their targets ranged from frontline positions, rolling stock, to airfields, and were typically attacked by lone aircraft or small formations of light attack aircraft, such as the Fw 190F&G or obsolescent Ju 87. P-61 crews would encounter virtually all medium bomber types in service with the Luftwaffe, including the dated He 111 and Ju 88A-4. Of all the aircraft encountered, only the Me 410 proved a serious challenge to intercept. They were employed as reconnaissance aircraft and their high speed meant they were only vulnerable to the P-61 when at a disadvantage. On roughly equal footing, the Me 410 could pull away (Harrison & Pape 275).

Encounters with enemy night fighters were fairly rare, as their squadrons generally only flew ground attack missions in August against the Normandy beachhead, and much later in December, in support of the Ardennes counteroffensive. They flew Bf 110G-4s, a few of the older Ju 88Cs, and the newest German night fighter at the time, the Ju 88G. While these aircraft flew with radar that had a much more limited range than the SCR 720 and were nearly useless at low altitude, their pilots were capable of putting up a much greater fight than those of the bomber and night attack squadrons. The first encounter between a P-61 and a Bf 110G-4 resulted in the latter being able to slip away after a collision, despite holding clear disadvantages in speed and maneuverability. While most of the new pilots the Luftwaffe were supplied with at the time possessed questionable proficiency at their tasks, most green crews remained on the ground as a result of chronic fuel shortages (Part 4,Boiten 33).

On the night of December 17th, several Luftwaffe night fighter squadrons would be committed to large scale ground attack operations in support of Von Rundstedt’s offensive. These missions were conducted by several dozen aircraft at a time that searched highways, rail lines, and known Allied positions for targets. These operations achieved a level of mixed success but at an extremely high cost, as the pilots were insufficiently trained for the mission and typically encountered accurately directed anti-aircraft fire (1944 Part 5, Boiten 68). The P-61s of the 422nd and 425th would find these night fighters significantly more challenging opponents than the medium bombers and transport aircraft they usually encountered. On several occasions, the German fighters slipped away from their pursuers and claimed two, later disproven, victories against P-61s, with the war diarist of Stab NJG6 commenting the “Black Widow inferior to Ju 88 and Bf 110 in dog fighting (Part 5, Boitens 77).” However, this confidence is likely due more to survivor bias than any major technical difference between these aircraft, as several German night fighters would be lost to P-61s. In all likelihood, it was the German night fighter pilot’s confidence in undertaking aggressive maneuvers in the dark that was the most probable reason for this assessment, as the P-61 was superbly maneuverable for its size.

Over the course of this offensive, the 425th would encounter a number of German night fighters and down several of them. Between the 25th and the 29th of December, three confirmed and two probable German night fighter losses can be attributed to this squadron’s P-61s, these being Bf 110 2Z+DH of NJG 6, Ju 88G-1s of NJG4 3C+RK and 3C+ZK, and two very likely Bf 110s, 2Z+DL and 2Z+CV (1944 part 5, Boitens 79, 84, 85). Given the short period and how few P-61s were serviceable, it is safe to say that the P-61 was certainly capable of taking on these opponents. However, it should also be noted that night fighters comprised a relatively small number of kills during this time, with many more being medium bombers and Ju 52 transport aircraft.

CBI: The 426th and 427th

The 426th Night Fighter Squadron was called upon by General Henry H. Arnold for the defense of the B-29s based in Chengdu, China, as per the request of the Maj. Gen. Curtis LeMay (Harrison&Pape 222). They would also be joined by the 427th NFS following the end of Operation FRANTIC and the cancelation of any further deployments of USAAF bombers in the Soviet Union. While they were sent to defend the B-29 bases, they were soon found to be almost totally unnecessary, as there were little to no Japanese aircraft active after dark in the China-Burma-India Theater. Not long after their arrival in October, 1944, they would pivot almost entirely to an offensive role, and were mostly relieved of their defensive task to search for trains and truck convoys across the theater. Several aircraft were later modified to mount 4.5 inch rockets, as was the case for their counterparts in Europe (Harrison&Pape 215). They would be met with success, as the Japanese Army was reliant on a single network of roads that ran north to south, a single major rail line, and the Irrawaddy River to move men and material across the theater. Despite the massive patrol area, they could expect to find targets at these strategic bottlenecks (McFarland 40).

The challenges of operating in this theater largely mirrored those of the squadrons based in the Pacific, as supply lines were tight, the terrain proved difficult to construct airbases in, and the mountainous geography hampered the use of early warning radar. Fuel was particularly scarce and had to be shared with the B-29 squadrons based with them, which typically meant offensive operations were periodically called off when supplies of fuel ran out, as was a case for the 427th NFS’ detachment in China for the month of April 1945 (Harrison&Pape 236). The squadrons operated mostly dispersed across the theater as detachments, with the peak number of P-61s in the CBI being 53 in July of 1945. The number typically sat around 35 aircraft until June (Dean 386).

PTO: the 421st NFS

The P-61 was a godsend to the Pacific night fighter squadrons who had long been forced to rely on the inadequate P-70, and with the exception of a few field modified aircraft, radar-less P-38s. Starting from early 1944, the various night fighter squadrons in the PTO would begin receiving P-61s and phasing out their long obsolete P-70s. Unlike Europe or the Mediterranean, the operations in the Pacific would not proceed at the pace of a gradual frontline that needed to be supported but rather saw the NFS deployed to newly constructed airstrips in support of larger amphibious operations which were targeted by raiders. Conditions were poor and extremely hard on airmen and planes alike, which brought unique challenges unknown to those in the ETO. In the words of S/Sgt. Harold Cobb of the 421st NFS: “Night fighting is not glamorous, but it is specialized in every degree, especially in the seven-league-boots, island-hopping war in the Pacific. Pilots must be able to take off and land without strip lights and on fields which are so new that construction is still in progress and the Seabees are still working (Kolln 51).”

The 421st got its hands on the P-61 in April of 1944, while it was based in Wakde, New Guinea, the planes having originally been shipped to Brisbane, Australia. The impact of receiving the new planes would prove considerable, both boosting the morale of the unit and giving it a long-needed replacement for its P-70s. The overall mission of the 421st was largely the same as it was for the 6th Night Fighter squadron in Guadalcanal two years earlier, to defend against nightly nuisance raids from Japanese bombers. The Japanese had also largely improved from their earlier campaigns, as they began to seek targets of greater strategic importance which they attacked with a far greater frequency. The men of the 421st were among them and their bases at Wakde and Owi were attacked regularly, often causing casualties and destroying aircraft. These airfields being built on lightly colored ancient coral beds made them both extremely visible at night and made it extremely difficult to dig shelters (Kolln 48). The effects of high explosives were also magnified, as they propelled sharp fragments of coral through the air with every bombardment.

The squadron also faced the same challenges posed by tropical environments, often with little improvement over the conditions almost two years ago. The prepared airfields were often built under difficult circumstances and challenging geography. The Seabees often had to work with coral beds, wetlands, and jungles that proved time consuming to develop into usable airstrips, often leaving little time and resources for improving the living conditions at these airfields.

These conditions were also felt by the sensitive radar systems of the aircraft, especially the pressurized canisters which contained many of the system’s vital components. They had a tendency to depressurize, which resulted in electrical arcing at altitude, disabling the entire system. The 419th NFS had developed an improvised system where the electronics tanks were kept pressurized by engine-driven vacuum pumps, but it is unknown if this modification was ever taken up by any other squadrons (Harrison&Pape 149). Early models of the P-61A, which still had the plastic radome, also encountered trouble in the tropical heat and sun, as the nose of the aircraft would often soften and deform, which would impact the movement of the SCR 720’s scanner. In addition to the reflective white paint added to the nose, crews would fasten ‘sun shields’ while grounded to protect the radome in the tropical heat. As was the case with the European squadrons, supplies of replacement parts and aircraft were scarce, and in a unique twist in the Pacific, the improper packing of engines resulted in the loss of 400 R-2800s to corrosion. Combat readiness suffered as a result. The 421st considered it a ‘good day’ should six of their aircraft be operational during their operations from their later airbase at Tacloban (Harrison&Pape 241).

Conditions for the air and ground crews of the 421st were scarcely better. Harsh tropical weather, limited access to drinkable water, and disease were common in the South Pacific, with conditions only improving after redeployment to the Philippines. At Owi and Wakde, personnel had to overcome an outbreak of Typhus which claimed two, heatstroke which claimed one, and even Silicosis of the lungs which resulted in a single fatality. However, the base at Owi became perhaps the most livable thanks to the discovery of an artesian well near the unit’s bivouac area (Kolln 47,48).

Operations over New Guinea largely proceeded the same way as they had earlier, but with far greater success thanks to their new P-61s, which meant interceptions were comparatively easy, though new Japanese tactics would periodically disrupt their success. Perhaps the most surprising of these was the deployment of radar reflecting chaff from bombers as they made their way to and from their targets. The chaff were aluminum strips that reflected radar and presented on radar scopes as a single large ‘cloud’ that could obscure the positions of aircraft. In practice, the SCR 720 did not prove very vulnerable to chaff if the pilot had already been guided toward the target, as the air search radar proved powerful enough to burn through the interference. Far off ground-based radar stations would prove more vulnerable to it, especially older models (Kolln 55). The Japanese air force would also employ new tactics against the defenders. On August 5th, the Japanese sortied several fighters along with the typical high-altitude bombers. These aircraft were picked up on radar later than the bombers to which the night fighters had already been sent against. The Japanese fighters were, however, unable to inflict much damage and their tactics were soon understood by the defenders (Kolln 50). While the 421st NFS’ P-61s were largely part of the waning war in the South Pacific, their subsequent redeployment to the Philippines would place them in one of their most active theaters of the entire war.

Tacloban

The 421st was deployed to the airfield at Tacloban on October 31st, 1944 to provide nightly air cover for the amphibious operations in the Southern Philippines. The conditions were largely a repeat of those of the prior camps at Wakde and Owi, but the raids were far worse. What were once frequent occurrences became a daily fixture of the stay at Tacloban (Kolln 61). The airfield itself would also prove to be an extremely hazardous and ineffectual location to operate from, as would be the positions chosen for the GCI radars. Tacloban was extremely underdeveloped during the height of operations. It was without runway lights for fear they would attract Japanese bombers and the short, muddy airstrip was difficult for the heavy P-61 to operate from, with most landing attempts having to be repeated (Harrison&Pape 240). From their airfield, they were given a number of tasks which would include providing nightly air cover to invasion forces, escorting PT boats, convoy protection, and even conducting daylight patrols.

The Philippines would present a greater set of challenges to the 421st than New Guinea. For one, the aircraft and tactics used by the Japanese air forces were of a different nature entirely. While they previously worked mostly against occasional, small formations of bombers coming in at high altitudes, they now also fought against large numbers of fighters which flew continuous attacks, typically conducted at low altitudes. Coupled with poor GCI coverage of the area, the Ki-43s and A6Ms employed by the Japanese would prove an extremely difficult enemy to counter. The nightly attacks continued and many of the invasion planners became frustrated with the squadron’s inability to stop them entirely, eventually leading General Kenny to send much of the 421st to Peleliu, while the 541st Marine Air Squadron, equipped with the 565-5N, took their place at Tacloban. In the end, the 421st achieved seven kills during this time at Tacloban, and while this was a fairly significant level of success for the PTO, it was deemed unacceptable by the invasion planners (McFarland 37).

The reasons for this swap have long been debated, with claims ranging from the P-61 having insufficient range and loiter time, to the SCR-720 being unable to track more the more maneuverable Japanese fighters. In the end, however, the greatest problems faced by the squadron were its poor GCI support, its low number of serviceable aircraft which resulted from supply shortages, and the vulnerable, poorly suited airfield they had at Tacloban. The Marine night fighters who replaced them were credited with 23 kills, though most of these were during dawn or dusk missions. It does not appear that any technical failings of the P-61 were responsible for a perceived lack of performance, but rather, exceedingly poor operational conditions and biases held by the higher headquarters that placed the expectations of daylight fighters on the NFS 421st while not understanding how they would best be deployed or utilized (Kolln 72). Though most of the squadron had departed Tacloban, several planes and their associated personnel remained to ensure a smooth transition for the Marine aviators and to carry out their previous duties, though to a lesser degree.

The 421st would return at full strength to Tacloban in early January of 1945, after five weeks, and largely resumed the work they had been doing before they left. Most notably, this included the joint patrols with motor torpedo boats, especially the 7th PT boat squadron, which they had developed a good working relationship with. The P-61s would provide cover for the boats as they patrolled Surigao strait and the Ormac Bay area, with a squadron representative aboard to ensure smooth operation between the boats and their air cover (Kolln 75). Enemy air activity in the area had decreased significantly and once again took the form of periodic raids by bombers flying alone or in small formations.

The squadron would end the war at Ie Shima, Okinawa, in July of 1945. By this point, the Japanese armed forces were in a state of exhaustion but they were still capable of launching nuisance raids against front line positions and airfields, though the frequency of these raids was low and there were two other P-61 squadrons stationed in the area. This would also mark the beginning of the replacement period of the squadron’s P-61s for P-38Ms. The 421st would spend this time performing intruder missions against targets in Kyushu, Japan, with airfields tending to be the primary targets. In this role, they developed a bombing technique with their search radars, which would be used to measure the relative distance to the target, and in conjunction with the airspeed and altitude of the aircraft, a bomb release window could be worked out. Some pilots would even add marks on their windscreens as visual aids for the technique (Kolln 89). They were, however, unable to account for its effectiveness. There was little resistance to these raids as Japan had a comparatively underdeveloped night fighter service and their night fire control for their anti-aircraft artillery was little better.

With Japan facing famine and industrial breakdowns from the blockade, the prospect of a third atom bomb with more to follow, and their last hope for conditional surrender evaporating as the Soviet Union overran their mainland colonies, the war ended and the P-61’s wartime service came to an end.

Japanese Opponents

Despite being significantly less experienced with the use of ground based and airborne radars than the Germans, Japanese aviators and mission planners consistently demonstrated the ability to develop effective countermeasures and tactics to American night fighters. Japanese signals intelligence services would prove extremely effective and were able to determine the presence of enemy night fighters in areas without radar coverage by monitoring radio transmissions, and were even able to track the position of P-61s by their IFFs (Harrison&Pape 220, 319). They would also successfully employ chaff on a number of occasions, though to decreasing effect, as the US Army began to employ more advanced centimetric search radars that were less vulnerable to it. On Iwo Jima, for instance, raiders would typically use chaff roughly thirty miles out from the island and when they departed, which had the effect of blocking the older meter band SCR-270 and reducing the range of the centimetric SCR-527 (McFarland 39). In addition to this, they would also employ seaplanes to get the attention of night fighters, and once they had drawn them away from the raider’s target, they would land on the water’s surface or return home at low altitude (Thompson 71). This tactic appeared to have been used against the P-61s of the 421st while they were at Tacloban and to good effect, as the loiter time of the P-61 was rather low and they were often forced to return home after several of these non-encounters (Harrison&Pape 234).

In the Pacific, P-61s faced mostly medium and light bombers, though would face considerably more fighter aircraft as the war drew to a close. These aircraft employed a wider variety of tactics than those of the Luftwaffe, often to considerable success. However, they would still employ earlier tactics such as lone bomber, high altitude raids which were far less effective, as the P-61 did not have the difficulty the P-70 had in reaching high altitudes.

What they wanted but never got: The P-61C

The P-61C would be developed largely to fulfill the requests of most of the pilots who had flown P-61As and Bs. The design sought to add two major features, more powerful turbocharged engines to provide better high-altitude performance and a higher climb rate, and a set of air brakes. The air brakes would be designed by the AAF’s Wright Field staff in conjunction with Northrop. The design was first incorporated on a P-61A test aircraft, which was nearly lost after a portion of the air brake was sheared off the aircraft and nearly sent it out of control. The final design proved satisfactory and took the form of a two-part slotted panel with halves above and below either wing. These brakes also incorporated a novel system to reduce the asymmetric forces acting on the brakes. This worked by having the deployment of the lower set of brakes assisted by the raising of the top. The brake system exerted a counter force of roughly 1G when the aircraft was at high speed (Harrison&Pape 278, 281).

The engines would go through a considerably longer development period and were to be mounted on a new airframe. Initially, there was some debate on whether the engine should use either a two stage two speed supercharger, as the previous production models of the P-61 used, or a turbo supercharger. It was a new study under John M. Wild at Northrop that made the case for choosing the turbo charger, with his finding being agreed on by Wright Field’s Fighter Project Office. A CH5 turbo-supercharger was subsequently fitted to a P-61A for testing, the aircraft being redesignated the XP-61C. The XP-61C’s conversion was handled by Goodyear Aircraft out of Akron, Ohio, a firm that provided parts for Northrop. The aircraft was initially to be powered by the R-2800-77, though a production run could not be secured and a temporary installation of the R-2800-14’s were used in their place until the R-2800-73 was chosen for the production model. A parallel development that would later be designated the XP-61D made use of the R-2800-77. Cooling issues would bring an end to its development, with the P-61D being canceled as the P-61C entered production. The P-61C proved to be quite promising and a massive step above the previous models, with the aircraft’s service ceiling being raised to 41,000 ft (12497 m) and its maximum speed rising to 430 mph (692 km/h) (Harrison&Pape 279, 280). The P-61C would be the aircraft the test pilots had wanted from the outset, but would fail to make it into service fast enough to see combat.

Project Thunderstorm

While the P-61C arrived too late to take part in the Second World War, it would go on to make major contributions to meteorological research and aeronautical safety in the post-war Thunderstorm Project. The project began with the passing of the H.R. 164 bill in January of 1945, which authorized and directed the Weather Bureau to conduct a study on the causes and characteristics of thunderstorms for aviation safety. The bill would also authorize the appropriations needed for such a study and authorized the cooperation of other departments for assistance.

The finalized research plan called for a vertical stack of five aircraft to make passes through thunderstorms as they drifted over a network of meteorological recording stations in order to document the conditions within the storm. The Army Air Force would provide several P-61Cs and its derivative, the F-15A, for this purpose, as they were designed to withstand strong maneuvering loads and were judged strong enough to quite literally ‘weather the storm’ (Roscoe 26). These aircraft would be modified for the purpose, with wartime equipment being removed and meteorological research equipment installed in its place. The aircraft were prepared at NACA’s Langley Field with the equipment necessary to monitor turbulence and vertical air currents.

For the tests, the planes entered thunderstorms at altitude differences of five thousand feet, with the highest aircraft being at 25,000 ft (7620 m). No storms were avoided, no matter how violent. The project first began around Orlando, Florida in 1946, before later moving to Wilmington, Ohio the following year. These locations were chosen on the basis of the frequency of thunderstorms and the nearby Air Force installations which had the radars needed to support the project. The project would see the P-61s fly through 76 storms for 1362 fly-throughs, during which they collected vital data which would help pave the way for safer air travel during the post war civil aviation boom and were used to build a foundational study for thunderstorm research (Roscoe).

Pilot’s Remarks

Exhaustive tests were performed on the P-61 to determine its flight characteristics, and they were largely found to be in line with the earlier prototypes. Pilots were highly appreciative of its easy handling on takeoff and landing, along with its favorable stall characteristics. Its controls were effective up until stall condition, which itself only occurred after ample warning. Stalls themselves were relatively predictable and virtually always resulted in the nose dropping, with no tendency for either wing to drop, and no corrections being needed to prevent a roll (Dean 391).

In addition to its great stall characteristics, the P-61 would prove to be exceptionally maneuverable for a plane of its size and weight. However, given its size and with two heavy engines on the wings, its roll rate was rather poor. Tests found the aircraft could be put through all hard maneuvers save for outside loops, continuous inverted flight, spins, snap rolls, and vertical reversements. Pilot’s praise was given mostly for its extremely light controls even at high speeds, which was largely thanks to its unorthodox spoileron based lateral control system. Even at speeds of 400 mph IAS, fast aileron and spoileron movement could be affected with one finger on the control wheel, though controls were found to be ‘sloppier’ around 100 mph IAS. One pilot was so confident in the P-61’s maneuverability that he felt he could turn with the best of fighters and, in the case of the F6F, he would “be on his tail so fast it was incredible.” In addition to its maneuverability, its trimming characteristics were also very good, such that it was possible to trim the aircraft out for cruising on a single engine at 130 mph IAS. It should, however, be noted that despite this praise, pilots rated its maneuverability fair to poor, as it was compared to far lighter single engine fighters. Overall, the plane was rated very stable on all axes with good rudder and elevator effectiveness (Dean 388, 390).

The P-61 also boasted excellent dive and recovery characteristics, with the book limits being set around 430 mph IAS depending on the arrangement of the aircraft, or around Mach .70. Beyond these limits, buffeting and tuck-under would occur, but the aircraft also demonstrated the ability to exceed these limits by a fair margin. One pilot would claim that he had no problems at speeds of 450 to 475 mph IAS at around 10,000 to 15,000 ft. In this case, he had achieved a true airspeed of 599 mph at Mach .83 and returned within the specified limit envelope at 512 mph TAS, Mach .70, as he reached 10,000 ft. Typically, if buffeting did occur, it was advised to exit the dive by means of a gradual pullout and with high caution should external loads be carried. Another pilot would claim that buffeting would occur far in excess of the recommended dive speed limits. The P-61 would be rated good in respects to its dive acceleration, control forces, recovery characteristics, and be ranked 8 out of 11 US fighter types in the category best stability and control in a dive (Dean 389, 390). The engine limits within dives were 30 seconds at 3090 rpm.

The P-61 was, however, not without its faults, and the most criticized and frequently voiced issues were concerning its acceleration and climb rate. These sentiments were echoed in many tests, and were most notable in rating the aircraft for takeoff, where pilots soon found themselves climbing at a disappointing rate after reducing power. Even at combat-power, the aircraft could at most manage 2500 ft/m at an altitude of 5000 ft (Dean 381). In the concluding remarks to exhaustive tests, it was the most frequently voiced complaint. While it was true many test pilots judged the aircraft somewhat unfairly against lighter single engine fighters, even its most enthusiastic testimonies were typically accompanied with remarks regarding its acceleration and climb performance (Dean 393).

The cockpit drew mixed reactions, with the general feeling being that the layout was adequate but not ideal. While most felt the layout was fair, eight of twenty-one pilots felt the arrangement was “cluttered”, with another ten remarking that they felt the pilot was seated too far from the instrument panel. This group was so displeased with the arrangement that they ended up rating P-61’s cockpit 3rd in the category “worst cockpit”. While the layout of the cockpit remained divisive, virtually all of them were displeased by the restricted visibility caused by the canopy frame (Dean 392).

In terms of its weaponry and its stability as a firing platform, the P-61 was well rated. Equipped with four 20 mm AN/M2 cannons and up to four .50 cal AN/M2 machine guns, the P-61 was very well armed. Despite the lack of the turret on most P-61s, the aircraft’s armament was more or less equal to its contemporaries, the Mosquito NF and Ju 88G, which both carried an armament of four 20 mm cannons. Firing stability was also good, with only one out of fourteen test pilots finding it objectionable. However, problems with the turret would impact its usefulness, as early aircraft would experience intense buffeting on the tail surfaces when the guns were set to certain positions. This problem would later be solved and the turret reintroduced to the aircraft when it was redesigned and supply bottlenecks with the B-29 were resolved (Dean 393).

Overall, the P-61 would present an aircraft with mixed, but favorable characteristics. The aircraft would be superbly maneuverable and responsive for its size and presented excellent flight characteristics at high and low speeds. In contrast, pilots were not enthused over what they judged was a poor rate of climb and cockpit layout. The 481st Night Fighter Training Group would also go on to lodge complaints about poor cockpit visibility and short combat radius (Harrison&Pape 156). While the cockpit went unchanged, the relatively limited range, of only about 1000 miles, would be later brought above 1,800 miles with the use of external fuel tanks (Dean 382).

Construction of the P-61A and B

The wings of the P-61, except for the tips, used a fully cantilever riveted, stressed skin construction with two main spars. Each wing assembly was composed of an inner panel, an outer panel, and the wingtip. The inner panel contained the engine nacelle, two fuel tanks, and a section of the flaps. This portion was the largest wing section and was fitted to the crew nacelle by means of bathtub and lug type fittings at the end of the main spars. The front section also provided one of the main air intakes for the aircraft and an outboard for the oil tank. It was constructed in two parts, forward and aft sections.

The aft section was also built in two parts and it contained the wing flaps, spoilers, and ailerons. The section also contained an oil cooler and its associated exit shutter. There were six hydraulically actuated slotted flaps with a full deflection of 60 degrees. Relatively small ailerons were installed outboard of the flaps, which extended to the wing tips. To boost lateral control along with the ailerons, a series of spoilers were used and were found in trailing sections, ahead of the outer wing flaps. These were curved metal panels that extended from slots in the wings and were mechanically driven by the pilot’s control column along with the ailerons. Initially, there were also aileron and booster tabs fitted to the inboard end of the left ailerons, but these were removed on later models. The combined fuel capacity of the wing fuel tanks was 646 gallons (2445 liters).

The center fuselage was a semi-monocoque structure composed of transverse bulkheads and channel section frames, longerons at the upper and lower quarters, longitudinal bulb angle stringers, and stressed skin. It was attached to the wings by means of heavy forged fittings on both sides of the fuselage. This section contained the stations for the aircraft’s pilot, gunner, radio operator, the aircraft’s SCR-720 radar, fixed quadruple 20 mm armament, and the mechanically operated turret. The enclosures for the pilot and gunner positions were made from molded Lucite sheets and extruded metal framing, with forward sections protected by bullet resistant glass blocks. The radar nose cone was made of plexiglass on early models, before a switch to a less heat sensitive resin-impregnated fiberglass on later aircraft. The radio operator’s position was enclosed by a framework of Lucite in extruded metal frames, with a rear tail cone that was formed from two sheets of Lucite that had been cemented together and bolted to the rest of the framework. All positions had a seat with a metal pan, padded backs, safety belts, relief tubes, and hand fire extinguishers. The center fuselage was also fitted with armor plates to protect the crew and ammunition boxes. These were located behind the nose, ahead of the gunner, in front of the turret ammo boxes, and behind the radio operator. The standard crew layout on this aircraft was poor compared to contemporary night fighters. A failure of the intercom system left the aircraft combat ineffective, as each crewmember was isolated, the radar operator particularly so.

The tail booms were of a monocoque structure and connected the nacelle group to the tail group. They also housed components for communication, identification equipment, the flight control cables to the rudders, elevators, and tabs. They were connected to the nacelle groups, which were composed of a semi-monocoque structure. These carried the engine mounts, main landing gear, and fuel tanks. The engines were mounted from a built-up welded steel tube frame that was bolted to this nacelle through vibration isolators and the engine cowling panels. The cowling sections were removable in large sections and were attached to the engine by quickly-detachable fasteners to facilitate easier access to the engines. The adjustable flap segments were controlled from the cockpit and were hydro-mechanically actuated.

The tail section consisted of the horizontal stabilizer, the elevator, and two vertical stabilizers and was connected to the tail booms. The two tail sections were supported by two spanwise spars that ran through the horizontal stabilizer and had the vertical stabilizers at either end. The rudder and elevators were fabric skinned and had trim and booster tabs built into their trailing edges.

The aircraft had a tricycle landing gear arrangement, with its nose wheel housed in the center fuselage and the main gear in the nacelle group. Each main gear was supported by two steel castings which were bolted to either side of the inside of the nacelle. Landing gear loads would be handled by a shock strut which was connected to these castings by a pair of trunnions. When the gear was retracted, it was hinged on these trunnions at the castings by lockbolts which would be held in either the extended or retracted position by a mechanical latching mechanism.

Engines

The mid production P-61A and the P-61B were powered by a pair of 2000 hp class of the R-2800 Double Wasp engines. This was an air cooled, two row, eighteen-cylinder radial engine with a 5.57 inch bore and a 6-inch stroke. These engines had a maximum RPM of 2700 and a compression ratio of 6.7:1. The early A models used the R-2800-10, with the remainder of the series and the B models using the R-2800-65, both of which produced a maximum output of 2000 hp. The later R-2800-65W boosted this to 2250 using water injection, and the C used the R-2800-73 which produced 2800 hp. The A and B models were equipped with two-stage, two-speed superchargers, but the C used turbosuperchargers.

The exhaust system was a stainless-steel arrangement with the exhaust stacks distributed around the edges of the nacelle, making use of a flame dampening system used to reduce the visibility of the exhaust at night. The B model and the late A series aircraft were equipped with a water injection system. The first aircraft with this system carried 26 gallons (98 liters), good for 15 minutes, with later aircraft carrying 34 gallons (128 liters), which was enough for 20 minutes of use, though some aircraft would carry as much as 74 gallons (280 liters). Use of this system could boost engine power by up to 250 hp per engine, though only in short increments, with the suggested limit being five minutes at a time (Pilot’s manual 12). Engines with water injection were designated R-2800-65W.

The engines drove a pair of Curtiss Electric four blade constant speed, selective pitch, full-feathering propellers. The hubs were a pair of C642S with a set of 12-foot 2-inch diameter, 714-7C2-12 blades. Engine speeds between 1800 and 2300 RPM were restricted as a result of propeller vibration in that range. The props were capped by large metal spinners which enclosed the hubs and inboard prop sections.

Avionics

In addition to the SCR-720 search radar, the P-61 carried a well-developed electronics suite. This included an SCR 729 radio navigation system, an SCR 695 IFF, and an RC-36 intercom system. The P-61A and early B models were equipped with the SCR 718 radio altimeter, which was later replaced with the AN/AP1. Early models used a pair of SCR-522 radio sets which was simplified in later models by a single AN/ARC 3. In later aircraft, an AN/APS-13 tail warning radar set was also included. The navigation systems were also supplemented by a MN-26C radio compass with a MC-1206A range receiver.

The P-61’s SCR-720 air search radar was composed of six main units which were installed in a number of boxes throughout the aircraft. These were the modulator, the transmitter, the receiver, an indicator unit, the mixer, and the power supply unit. The modulator was a rotary spark gap, pressured type which produced a 4 kV pulse. The transmitter was magnetron regulated and installed in a pressurized unit. The mixer was a crystal mixer type with a soft rhumbatron switch valve. The receiver used a reflector klystron oscillator with automatic frequency control. The indicating unit used a two-tube range and azimuth elevation display set. The entire system was powered by a 1,200 watt, 115 volt, 1,600 cycle engine driven alternator (Survey 27).

Heaters

In addition to navigation, communication, and detection equipment, there were also considerable heating, cooling, and ventilation systems. On the P-61A, a series of fuel-air mixture heaters were used to provide heating for the cannons and to the crew through three ventilators. The B model decreased the number of heaters from four to just two heaters that were placed fore and aft.

Armament

The standard armament of most P-61s was a set of four fixed 20 mm Hispano AN/M2 cannons that were set in a compartment at the bottom of the central fuselage. 200 rounds of ammunition could be carried for each gun. Sighting for the gun consisted of the L-1 type gunsight on the P-61A and the LY-3N on the P-61B, with both being a reflector type lit by a sight lamp. From the B model onward, the aircraft would also carry a set of night binoculars which were a specialized gunsight for use in low light conditions.

While this aircraft is often known for its remotely controlled, quadruple .50 caliber turret, only about half of P-61s actually carried one. The turret’s machine guns were each supplied with 560 rounds, were fired simultaneously at a rate of about 800 rounds per minute, had a 360-degree traverse, and a maximum elevation of 90 degree upward from the horizontal. While the guns could be fired from any of the aircraft’s three positions, only the gunner and radio operator could direct the turret. For the pilot’s use, the guns would be locked forward by latching the turret and flipping the switch labeled “pilot” from either of the other two positions, though in the B model, the turret would automatically return to the guns forward position when not in use. The .50 caliber guns were typically fitted with flash concealing tubes in the field after pilots found it could interfere with their vision adjusted for low visibility flight. In service, the turret was almost always used by the pilot and very sparingly by the gunner against targets ahead of the aircraft. Pilots often found it unnerving to see the turret firing forward without warning from the gunner, as it could both ruin their low light vision and sometimes they misidentified the gunfire as coming from an enemy behind their aircraft. As a defensive armament, it was of little practical use, as the radar operator’s illuminated instruments screens degraded his low light vision. The turret was directed by a sighting arm which sat atop a rotating column with firing controls in the grips and fitted with an N-6 reflector sight.

Several models included wing racks which were capable of carrying additional fuel tanks or bombs with a maximum weight of 1600 pounds (725.75 kg). Field modifications on some aircraft allowed for the use of rockets. (Dean 393-404)

Conclusion 

The P-61 was a somewhat troublesome, yet effective night fighter that proved to be a capable replacement for the useless P-70 and obsolescent Bristol Beaufighter. Most of its faults, apart from the poor layout of crew, were to be expected for such a sophisticated plane still in its ‘teething period’ and supported by a modest supply chain. In the space of roughly a year, which constituted its entire combat service, most of its faults were corrected or lessened.

The aircraft served admirably across the European, Mediterranean, China-Burma-India, and Pacific theaters. P-61 pilots would encounter a variety of opponents among the Japanese and German air forces, utilizing a variety of tactics and equipment. They would prove effective against all but a handful of these combinations. Surprisingly, despite never being designed with such a use in mind, the P-61 would prove exceptional in the ground attack role. It was among the few aircraft at the time capable of carrying out attacks at night, or in poor weather. In service its greatest danger was its limited material support. This scarcity of replacement aircraft and parts would hobble operations, but the resourcefulness of ground crews often kept their squadrons from being entirely grounded. In the end, the aircraft provided effective service during their somewhat short combat tour across much of the world, in the face of inadequate material support and, at times, extremely poor conditions.

While the P-61C would never see combat, it would perform a vital role in a foundational meteorological study. Despite never being used for its intended purpose, this variant’s legacy proved to be no less important.

Specifications and Production Numbers

Type	Number Built	First Delivery	Description
XP-61	2	May-42	First prototype series
YP-61/P-61	13	Aug-43	Second prototype series, pre production
P-61A-1	45	Oct-43	Power turrets installed in first 37 planes, first production model
P-61A-5	35	–	Turret removed, R-2800-10 engine changed to R-2800-65
P-61A-10	100	–	Water injection system added
P-61A-11	20	–	Two underwing racks
P-61B-1,2,5,6,11	155	Jul-44	Extended nose, wing racks on 2,6, and 11
P-61B-10	45	–	Four underwing racks
P-61B-15,16,20,25	250	–	Turret revised and reintroduced with two and four gun versions, wing racks (two on the -16), radar gun laying on -25 with seven built
P-61C-1,5,10	41	Jul-45	Turbosupercharged R-2800-73 engines, air brakes
XP-61D	2 converted airframes	Nov-44	Prototype, turbosupercharged R-2800-77’s, wing racks
XP-61E	2 converted airframes	Apr-45	Prototype daylight fighter, 2 crew, bubble canopy, turret removed, increased fuel capacity, no radar, four nose mounted .50 caliber guns, developed from P-61B.
XP-61G	16 converted airframes	1945	P-61B-20 modified for weather recon, unarmed

All airframes were built at Northrop’s plant in Hawthorne, California

Specifications	P-61A	P-61B	P-61C
Engine	R-2800-10, R-2800-65, R-2800-65W	R-2800-65W	R-2800-73
Maximum Engine Output [boosted]	2000 hp [2250 hp]	2000 hp [2250 hp]	2800 hp
Maximum Weight	29249 lbs	39056 lbs	41138 lbs
Standard Fighter Weight	28202 lbs	29876 lbs	30068 lbs
Empty Weight	23158 lbs	24413 lbs	26418 lbs
Range [maximum external fuel]	~1000 miles [+1800 miles]	~1000 miles [+1800 miles]	–
Maximum Speed	366 mph at 20,000 ft	366 mph at 20,000 ft	430 mph at 30,000ft
Armament [turret]	4×20 mm AN/M2 [4x .50 cal AN/M2]	4×20 mm AN/M2 [4x or 2x .50 cal AN/M2]	4×20 mm AN/M2 [4x .50 cal AN/M2]
Crew	Pilot, gunner, radar operator	Pilot, gunner, radar operator	Pilot, gunner, radar operator
Length	48′ 11″	49’7″	49’7″
Wingspan	66′	66′	66′
Wing Area	664ft²	664ft²	664ft²

 

Specification	P-61A	P-61B	P-61C
Engine {P-61}	R-2800-10, R-2800-65, R-2800-65W	R-2800-65W	R-2800-73
Maximum Engine Output [boosted]	2000hp [2250 hp]	2000hp [2250 hp]	2800 hp
Maximum weight	13267 kg	17715 kg	18660 kg
Standard fighter weight	12792 kg	13552 kg	13639 kg
Empty Weight	10504 kg	11074 kg	11983 kg
Range [maximum external fuel]	~1609 km [~2897 km]	~1609 km [~2897 km]	–
Maximum speed	590 km/h at 6 km	590 km/h at 6 km	692 km/h at 9144 m
Armament [turret]	4x20mm AN/M2 [4x or 2x 12.7mm AN/M2]	4x20mm AN/M2 [4x or 2x 12.7mm AN/M2]	4x20mm AN/M2 [4x 12.7mm AN/M2]
Crew	Pilot, gunner, radar operator	Pilot, gunner, radar operator	Pilot, gunner, radar operator
Length	14.91 m	15.11 m	15.11 m
Wingspan	20.12 m	20.12 m	20.12 m
Wing Area	61.69 m²	61.69 m²	61.69 m²

Cruising Speeds for the P-61A&B at 28,500lbs (12927 kg)

Altitude	Speed
9000ft : 2743m	253mph : 408 kph
16000ft : 4876m	256 mph : 412 kph

Video

Gallery

Illustrations by Ed Jackson

Credits

• Written by Henry H.
• Edited by Stan L. and Ed J.
• Illustrations by Ed Jackson

Primary Sources:

• Ashkenas, I L. The Development of a Lateral Control System for Use with Large Span Flaps. No. 1015. NACA, 1946.
• Pilot’s Flight Operating Instructions Army Model P-61A Airplane. (T. O. NO. 01-15FB-1). Commanding General, Army Air forces. January 15, 1944.
• Pilot Training Manual for the Black Widow P-61. Office of Assistant Chief of Air Staff Training. 1944
• Handbook of Operating Instructions for Radio Set SCR-720-A and Radio Set SCR-720-B. AN 08-10-181. Joint authority of the Commanding General, Army Air Forces, and the Commanding General, Army Service Force. (1943).
• Northrop P61 Black Widow Pilot’s Flight Operating instructions. T.O No. AN 02-35VC-3. USAF, July 1945
• Introduction Survey of Radar Part II. Air Publication 1093D Volume 1 First Edition. Air Ministry, June 1946.

Secondary Sources:

• Boiten, Theo. Nachtjagd Combat Archive 1944 Part Four. Surrey: Red Kite, 2021.
• Boiten, Theo. Nachtjagd Combat Archive 1944 Part Five. Surrey: Red Kite, 2021.
• Braham, Roscoe R. “Thunderstorms and the Thunderstorm Project”
• Brown, Louis. Technical and Military Imperatives: a Radar History of World War II. Taylor & Francis, 1999.
• Dean, Francis H. America’s Hundred Thousand: the US Production Fighter Aircraft of World War II. Schiffer Publ., 1997.
• Kolln, Jeff. The 421st Night Fighter Squadron in World War II. Schiffer Pub., 2001.
• McFarland, Stephen Lee. The U.S. Army Air Forces in World War II: Conquering the Night: Army Air Forces Night Fighters at War. Air Force History and Museums Program, 1998.
• Pape, Garry R., and Ronald C. Harrison. Queen of the Midnight Skies: the Story of America’s Air Force Night Fighters. Schiffer Publishing Ltd., 1992.
• Price, Alfred. Instruments of Darkness: the History of Electronic Warfare. Greenhill, 2005.
• Thompson, Warren E. P-61 Black Widow Units of World War 2. Osprey, 1998.
• “WW2 People’s War – Reg EVERSON’S STORY.” BBC. BBC. Accessed August 1, 2021. https://www.bbc.co.uk/history/ww2peopleswar/stories/26/a3130426.shtml.