The Northrop P-61 Black Widow was an all-metal, twin-engine, twin-boom, monoplane night fighter and night intruder aircraft flown by the United States Army Air Forces during World War II. It was the first aircraft designed specifically as a radar-equipped night fighter to be used operationally.
In August 1940, a full 16 months before the United States entered the war, the U.S. Air Officer in London, Lt. Gen. Delos C. Emmons, was briefed on British research in RADAR (Radio Detection and Ranging), which had been underway since 1936 and had played an important role in the nation's defense against the Luftwaffe during the Battle of Britain. General Emmons was informed of the new Airborne Intercept radar (AI for short), a self-contained unit that could be installed in an aircraft and allow it to operate independently of ground stations. In September 1940 the Tizard Mission traded British research on many aspects including radar for American production.
Simultaneously, the British Purchasing Commission evaluating US aircraft declared their urgent need for a high-altitude, high-speed aircraft to intercept the Luftwaffe bombers attacking London at night. The aircraft would need to patrol continuously over the city throughout the night, requiring at least an eight-hour loiter capability. The aircraft would carry one of the early (and heavy) AI radar units, and mount its specified armament in "multiple-gun turrets". The British conveyed the requirements for a new fighter to all the aircraft designers and manufacturers they were working with. Jack Northrop was among them, and he realized that the speed, altitude, fuel load and multiple-turret requirements demanded a large aircraft with multiple engines.
Gen. Emmons returned to the U.S. with details of the British night-fighter requirements, and in his report said that US aircraft design bureaus possibly could produce such an aircraft. The Emmons Board developed basic requirements and specifications, handing them over towards the end of 1940 to Air Technical Service Command, Wright Field. After considering the two biggest challenges—the high weight of the AI radar and the very long (by fighter standards) loiter time of eight hours minimum—the board, like Jack Northrop, realized the aircraft would need the considerable power and resulting size of twin engines, and recommended such parameters.
Vladimir H. Pavlecka, Northrop Chief of Research, was present on unrelated business at Wright Field. On 21 October 1940, Col. Laurence Craigie of the ATSC phoned Pavlecka, explaining the USAAC's specifications, but told him to "not take any notes, 'Just try and keep this in your memory!' What Pavlecka did not learn was radar's part in the aircraft; Craigie described the then super-secret radar as a "device which would locate enemy aircraft in the dark" and which had the capability to "see and distinguish other airplanes". The mission, Craigie explained, was "the interception and destruction of hostile aircraft in flight during periods of darkness or under conditions of poor visibility."
Pavlecka met with Jack Northrop the next day, and gave him the USAAC specification. Northrop compared his notes with those of Pavlecka, saw the similarity between the USAAC's requirements and those issued by the RAF, and pulled out the work he had been doing on the British aircraft's requirements. He was already a month along, and a week later, Northrop pounced on the USAAC proposal.
On November 5, Northrop and Pavlecka met at Wright Field with Air Material Command officers and presented them with Northrop’s preliminary design. Douglas’ XA-26A night fighter proposal was the only competition, but Northrop’s design was selected and the Black Widow was conceived.
Following the USAAC acceptance, Northrop began comprehensive design work on the aircraft to become the first to design a dedicated night fighter. The result was the largest and one of the most deadly pursuit-class aircraft flown by the U.S. during the war.
Jack Northrop's first proposal was a long fuselage gondola between two engine nacelles and tail booms. Engines were Pratt & Whitney R2800-10 Double Wasp 18-cylinder radials, producing 2,000 horsepower (1,500 kW) each. The fuselage housed the three-man crew, the radar, and two four-gun turrets. The .50 cal (12.7 mm) M2 Browning machine guns were fitted with 36-inch long "aircraft" barrels with perforated sleeves. The turrets were located in the nose and rear of the fuselage. It stood on tricycle landing gear and featured full-span retractable flaps, or "Zap flaps" (named after Northrop engineer Edward Zap) in the wings.
The aircraft was huge, as Northrop had anticipated. While far heavier and larger multi-engine bombers existed, its length, wingspan and projected full-load weight were unheard of for a fighter, making the P-61 hard for many to accept as a feasible combat aircraft.
Some alternative design features were investigated before finalization. Among them were conversion to a single vertical stabilizer/rudder and the shifting of the nose and tail gun turrets to the top and bottom of the fuselage along with the incorporation of a second gunner.
Late in November 1940, Jack Northrop returned to the crew of three and twin tail/rudder assembly. To meet USAAC's request for more firepower, designers abandoned the ventral turret and mounted four 20 mm Hispano M2 cannons in the wings. As the design evolved, the cannons were subsequently repositioned in the belly of the airplane. The P-61 therefore became one of the few U.S.-designed fighter aircraft to have 20 mm cannons as factory-standard in WWII. Others were the P-38 Lightning, the F4U-1C (a limited-production Corsair sub-variant), and the A-36 Apache dive-bomber (an early form of the P-51 Mustang). While some F6F Hellcats and repossessed British lend-lease P-39 Airacobras (renamed P-400) were also fitted with 20 mm cannons, it was not standard practice.
Northrop Specification 8A was formally submitted to Army Air Material Command at Wright Field, on December 5, 1940. Following a few small changes, Northrop's NS-8A fulfilled all USAAC requirements, and the Air Corps issued Northrop a Letter of Authority For Purchase on December 17. A contract for two prototypes and two scale models to be used for wind tunnel testing, (costs not to exceed $1,367,000), was awarded on 10 January 1941. Northrop Specification 8A became, by designation of the Department of Defense, the XP-61.
The Air Corps Mockup Board met at Northrop on 2 April 1941, to inspect the XP-61 mock-up. They recommended several changes following this review. Most prominently, the four 20-millimeter Hispano M2 cannon were relocated from the outer wings to the belly of the aircraft, clustered tightly just behind the rear of the nose gear well. The closely spaced, centered installation, with two cannons stacked vertically, slightly outboard of the aircraft's centerline on each side, and the top cannon in each pair only a few inches farther outboard, eliminated the inherent drawbacks of convergence.
Convergence was a necessity in wing-mounted guns. Convergence is the specific point or points of range and elevation at which arming crews calibrate the weapons' projectile paths to intersect the aircraft's centerline, preventing a "safe zone" in front of the aircraft through which no projectiles would pass if wing guns were set to fire straight ahead. Projectiles fired at a target beyond the point of convergence crisscross before reaching the target and miss wide; projectiles fired at a target closer than the point of convergence either pass on either side or fail to impact at a concentrated point, minimizing the damage inflicted. In practice, both cases limit the cannons' effective ranges to a very small zone on either side of a set distance, and create additional challenges when calculating deflection ("pulling lead") for a moving target.
Without convergence, aiming was considerably easier and faster, and the tightly grouped cannons created a thick stream of 20 mm projectiles. The removal of the guns and ammunition from the wings also cleaned up the wings' airfoil and increased internal fuel capacity from 540 to 646 gallons.
Other changes included the provision for external fuel carriage in drop tanks, flame arrestors/dampeners on engine exhausts, and redistribution of some radio equipment. While all beneficial from a performance standpoint — especially the movement of the cannons—the modifications required over a month of redesign work, and the XP-61 was already behind schedule.
In mid-1941, the dorsal turret mount finally proved too difficult to install in the aircraft, and was changed from the General Electric ring mount to a pedestal mount like that used for the upper turrets in B-17s, B-24s, B-25s, A-20s and other bombers. Following this modification, the turret itself became unavailable, as operational aircraft, in this case, the B-29, were ahead of experimental aircraft in line for the high-demand component. For flight testing, engineers used a dummy turret.
During February 1942, subcontracting manufacturer Curtiss notified Northrop that the C5424-A10 four-bladed, automatic, full-feathering propeller Northrop had planned for use in the XP-61 would not be ready for the prototype rollout or the beginning of flight tests. Hamilton Standard propellers were used in lieu of the Curtiss props until the originally planned component became available.
The XP-61's weight rose during construction of the prototype, to 22,392 lb empty and 29,673 lb at takeoff. Engines were R-2900-25S Double Wasp radials; turning 12-foot, 2-inch diameter Curtiss C5425-A10 four-blade propellers, both rotating clockwise when viewed from the front. Radios included two command radios, SCR-522As, and three other radio sets, the SCR-695A, AN/APG-1, and AN/APG-2. Central fire control for the gun turret was similar to that used on the B-29, the General Electric GE2CFR12A3.
The P-61C was a high-performance variant designed to rectify some of the combat deficiencies encountered with the A and B variants. Work on the P-61C proceeded quite slowly at Northrop because of the higher priority of the XB-35 flying wing project. In fact, much of the work on the P-61C was farmed out to Goodyear, which had been a subcontractor for production of Black Widow components. It was not until early 1945 that the first production P-61C-1-NO rolled off the production lines. As promised, the performance was substantially improved in spite of a 2,000 pound increase in empty weight. Maximum speed was at , service ceiling was , and an altitude of could be attained in 14.6 minutes.
The P-61C was equipped with perforated fighter airbrakes located both below and above the wing surfaces. These were to provide a means of preventing the pilot from overshooting his target during an intercept. For added fuel capacity, the P-61C was equipped with four underwing pylons (two inboard of the nacelles, two outboard) which could carry four 310-gallon drop tanks. The first P-61C aircraft was accepted by the USAAF in July 1945. However, the war in the Pacific ended before any P-61Cs could see combat. The forty-first and last P-61C-1-NO was accepted on January 28 1946. At least 13 more were completed by Northrop but were scrapped before they could be delivered to the USAAF.
The service life of the P-61C was quite brief, since it was being quickly outclassed by jet aircraft. Most were used for test and research purposes. By the end of March 1949, most P-61Cs had been scrapped. Two entered the civilian market and two others went to museums.
The first production F-15A-1-NO was accepted in September 1946. However, the contract was abruptly cancelled in 1947, possibly because the performance of the aircraft (known as the "Reporter") was rapidly being overshadowed by jets, with the last of only 36 examples being accepted by the USAAF in April that year. The last F-15 to be produced (serial number 45-59335) was produced as an F-15A-5-NO, which differed from the Block-1 version mainly in having a new internal camera installation in the nose. It seems that this change had been contemplated for the last 20 F-15s as well, since some records indicate that these were all eventually redesignated as F-15A-5-NO.
The pilot was seated in the front, with the reconnaissance operator in the back. The backseat occupant controlled the cameras and navigated the aircraft. However, the rear seat of the F-15A was fitted with a set of rudimentary flying controls, which made it possible for the reconnaissance operator to relieve the pilot if needed. Both crew members were rated pilots and both were trained in the reconnaissance task, so they usually alternated position on each flight.
Of the 36 F-15As produced, nine were allocated to the Air Materiel Command in the Continental U.S., and the remainder were issued to just one squadron, the 8th Photographic Reconnaissance Squadron attached to the 35th Fighter Group in Japan. These aircraft served in the American occupation of Japan, and several of them participated in the Post-Hostilities Mapping Program, in which the beaches, villages, road networks, and cultural centers were extensively photographed. Included in this job was the mapping of the Korean Peninsula, which proved invaluable when the Korean War broke out in 1950. A few also served in the Philippines and Celebes. Included in their mission was the mapping of the route of the Bataan Death March for war crimes prosecutions.
Spare parts became a problem for the F-15s in the late 1940s, and both damaged and flyable Reporters were cannibalized to keep the rest of them flying. In 1948, the separate F-category for reconnaissance aircraft was eliminated, and the P-for-pursuit category was replaced by F-for-fighter. Surviving Black Widows were redesignated F-61, and the surviving Reporters were redesignated RF-61C (since they were basically modified P-61Cs). On 1 April 1949, the only outfit still using RF-61Cs (the 82nd Tactical Reconnaissance Squadron) was deactivated, and all surviving RF-61Cs were reassigned to the 35th Maintenance Squadron at Johnson AFB for disposal. Some were disposed of as surplus on the commercial market, while others were scrapped.
The United States Marine Corps had planned to acquire 75 Black Widows, but these were cancelled in 1944 in favor of the F7F Tigercat. In September 1945, however, the Marines received a dozen surplus P-61B-10 / 15 / 20 to serve as radar trainers until the F7F-3Ns would be available in squadron strength. Designated F2T-1N and given the build numbers 52750–52761, these aircraft were assigned to shore-based Marine units and served briefly – the last 2 F2T-1s being stricken on 30 August 1947.
The P-61 featured a crew of three: pilot, gunner, and radar operator. It was armed with four 20 mm Hispano M2 forward firing cannons mounted in the lower fuselage, and four Browning M2 .50 cal (12.7 mm) machine guns lined up horizontally with the two middle guns slightly offset upwards in a remotely-aimed dorsally mounted turret. The turret was driven by the General Electric GE2CFR12A3 gyroscopic fire control computer, and could be directed by either the gunner or radar operator, who both had the aiming control and gyroscopic collimator sight assembly posts attached to their swiveling seats.
The two Pratt & Whitney R2800-25S Double Wasp radial engines were each mounted approximately one-sixth out on the wing's span. Two-stage, two-speed mechanical superchargers were fitted. In an effort to save space and weight, no turbo-superchargers were fitted, despite the expected top speed and 10,000 ft operational ceiling increases.
Main landing gear bays were located at the bottom of each nacelle, directly behind the engine. The two main gear legs were each offset significantly towards outboard in their nacelles, and retracted towards the tail; oleo scissors faced forwards. Each main wheel was inboard of its gear leg and oleo. Main gear doors were two pieces, split evenly, longitudinally, hinged at inner door's inboard edge and the outer door's outboard edge.
Each engine cowling and nacelle drew back into tail booms that terminated upwards in large vertical stabilizers and their component rudders, each of a shape similar to a rounded right triangle. The leading edge of each vertical stabilizer was faired smoothly from the surface of the tail boom upwards, swept back to 37 degrees. The horizontal stabilizer extended between the inner surfaces of the two vertical stabilizers, and was approximately three-quarters the chord of the wing root, including the elevator. The elevator spanned approximately one third of the horizontal stabilizer's width, and in overhead plan view, angled inwards in the horizontal from both corners of leading edge towards the trailing edge approximately 15 degrees, forming the elevator into a wide, short trapezoid. The horizontal stabilizer and elevator assembly possessed a slight airfoil cross-section.
The engines and nacelles were outboard of the wing root and a short "shoulder" section of the wing that possessed a four-degree dihedral, and were followed by the remainder of the wing which had a dihedral of two degrees. The leading edge of the wing was straight and perpendicular to the aircraft's centerline. The trailing edge was straight and parallel to the leading edge in the shoulder, and tapered forward 15 degrees outboard of the nacelle. Leading edge updraft carburetor intakes were present on the wing shoulder and the root of the outer wing, with a few inches of separation from the engine nacelle itself. They were very similar in appearance to those on the F4U Corsair — thin horizontal rectangles with the ends rounded out to nearly a half-circle, with multiple vertical vanes inside to direct the airstream properly.
The P-61 did not have ailerons. Aside from the full-span retractable "Zap flaps", all control of the aircraft about the roll axis was maintained through the use of curved, tapered spoilerons, of approximately 10 feet in length and 6 inches in width (in overhead plan view) each. They were located outboard of the outer edge of each nacelle in overhead plan view, approximately one-quarter the length of the outer wing (the section of wing outboard of the edge of each nacelle furthest from the aircraft's centerline) and offset towards the wing leading edge approximately one third the wing's chord from the trailing edge, running towards the wing-tip approximately half the length of the outer wing. Operation was as follows: the spoileron in the inside wing rotated out of the wing's upper surface into the airstream, disrupting the effect of Bernoulli's principle and reducing lift over that wing, causing it to drop.
The main fuselage, or gondola, was centered on the aircraft's centerline. It was, from the tip of the nose to the end of the Plexiglas tail-cone, approximately five-sixths the length of one wing (root to tip). The nose housed an evolved form of the SCR-268 Signal Corps Radar, the Western Electric Company's SCR-720A. Immediately behind the radar was the forward crew compartment, seating the pilot and behind him the gunner, the latter elevated approximately six inches. The multi-framed "greenhouse" canopy featured two distinct levels, one for the pilot and a second for the gunner above and behind him. Combined with the nearly flat upper surface of the aircraft's nose, the two-tiered canopy gave the aircraft's nose a distinct appearance of three wide, shallow steps. The forward canopy in the XP-61 featured contiguous, smooth-curved, blown-Plexiglas canopy sections facing forward, in front of the pilot and the gunner. The tops and sides were framed.
Beneath the forward crew compartment was the nose gear wheel well, through which the pilot and gunner entered and exited the aircraft. The forward gear leg retracted to the rear, up against a contoured cover that when closed for flight formed part of the cockpit floor; the gear would not have space to retract with it open. The oleo scissor faced forwards. The nosewheel was centered, with the strut forking to the aircraft's left. The nosewheel was approximately three-fourths the diameter of the main wheels. Nose gear doors were two pieces, split evenly longitudinally, and hinged at each outboard edge.
The center of the gondola housed the main wing spar, fuel storage, fuel piping and control mechanisms, control surface cable sections, propeller and engine controls, and radio/IFF (Identification Friend or Foe) /communications equipment, but was predominantly occupied by the top turret mounting ring, rotation and elevation mechanisms, ammunition storage for the turret's four Browning M2 machine guns, the GE2CFR12A3 gyroscopic fire control computer, and linkages to the gunner and radar operator's turret control columns, forward and aft, respectively.
The radar operator's station was at the aft of the gondola. The radar operator controlled the SRC-720 radar set and viewed its display scopes from the isolated rear compartment, which he entered by way of a small hatch with a built-in ladder on the underside of the aircraft. In addition to the radar systems themselves, the radar operator had intercom and radio controls, as well as the controls and sight for the remote turret. The compartment's canopy followed the curvature of the gondola's rear section, with only a single rounded step to the forwards canopy's double step. The rear of the gondola was enclosed by a blown Plexiglas cap that tapered quickly in overhead plan view to a barely-rounded point; the shape was somewhat taller in side profile than it was in overhead plan view, giving the end of the "cone", a rounded "blade" appearance when viewed in perspective.
The cross-section of the gondola, front to back, was generally rectangular, vertically oriented. The tip of the nose was very rounded, merging quickly to a rectangular cross-section that tapered slightly towards the bottom. This cross-section lost its taper but became clearly rounded at the bottom moving back through the forward crew compartment and nose gear well. Height increased at both steps in the forward canopy, with the second step being flush with the top of the aircraft (not counting the spinal gun turret). At the rear of the forward crew compartment, the cross-section's bottom bulged downwards considerably and continued to do so until just past the midpoint between the rear of the forward crew compartment and the front of the rear crew compartment, where the lower curvature began to recede. Beginning at the front of the rear crew compartment, the top of the cross-section began to taper increasingly inwards above the aircraft's center of gravity when progressing towards the rear of the gondola. The cross-section rounded out considerably by the downward step in the rear canopy, and rapidly became a straight-sided oval, shrinking and terminating in the tip of the blown-Plexiglas "cone" described above.
The cross-section of the nacelles was essentially circular throughout, growing then diminishing in size when moving from the engine cowlings past the wing and gear bay, towards the tail booms and the vertical stabilizers. A bulge on the top of the wing maintained the circular cross-section as the nacelles intersected the wing. The cross-section became slightly egg-shaped around the main gear bays, larger at the bottom but still round. An oblong bulge on the bottom of the main gear doors, oriented longitudinally, accommodated the main wheels when the gear was retracted.
Wing tips, wing-to-nacelle joints, tips and edge of stabilizers and control surfaces (excluding the horizontal stabilizer and elevator) were all smoothly rounded, blended or filleted. The overall design was exceptionally clean and fluid as the aircraft possessed very few sharp corners or edges.
The production model of the SCR-720A mounted a scanning radio transmitter in the aircraft nose; in Airborne Intercept mode, it had a range of nearly five miles. The unit could also function as an airborne beacon / homing device, navigational aid, or in concert with interrogator-responder IFF units. The XP-61's radar operator located targets on his scope and steered the unit to track them, vectoring and steering the pilot to the radar target via oral instruction and correction. Once within range, the pilot used a smaller scope integrated into the main instrument panel to track and close on the target.
The first unit to receive production aircraft was the 348th Night Fighter Squadron in Florida which was responsible for training night fighter crews.
P-61 crews trained in a variety of ways. Several existing night fighter squadrons operating in the Mediterranean and Pacific theatres were to transition directly into the P-61 from Bristol Beaufighters and Douglas P-70s, though most P-61 crews were to be made up of new recruits operating in newly commissioned squadrons. After receiving flight, gunnery or radar training in bases around the U.S., the crews were finally assembled and received their P-61 operational training in Florida for transfer to the European Theatre, or California for operations in the Pacific Theatre.
The 422nd Night Fighter Squadron was the first to complete their training in Florida and, in February 1944, the squadron was shipped to England aboard the Mauritania. The 425th NFS was soon to follow aboard the Queen Elizabeth.
The situation deteriorated in May 1944 when the squadrons learned that several USAAF Generals believed the P-61 was too slow to effectively engage in combat with German fighters and medium bombers. The RAF shared this view, based on the performance of a single P-61 they had received in early May, and championed switching to their de Havilland Mosquito Mk XVI. Several pilots in the 422nd NFS threatened to turn in their wings if they weren't permitted to fly the "Black Widow". At the end of May, the USAAF insisted on a competition between the Mosquito and the P-61 for operation in the European Theatre. RAF crews flew the Mosquito Mk XVI while crews from the 422nd NFS flew the P-61. In the end the USAAF determined that the P-61 had a slightly better rate of climb, and could turn tighter than the Mosquito. The RAF disputed these claims and continued to push for the use of the Mosquito, but to no avail. In later tests conducted by the manufacturers, the two aircraft were actually found to be very similar in performance with no clear advantage for either aircraft.
The 6th NFS based on Guadalcanal received their first P-61s in early June, 1944. The aircraft were quickly assembled and underwent flight testing as the pilots transitioned from the squadron's aging P-70s. The first operational P-61 mission occurred on 25 June, and the type scored its first kill on 30 June 1944 when a Japanese Mitsubishi G4M "Betty" bomber was shot down.
Throughout the summer of 1944, P-61s operating in the Pacific Theatre would see sporadic action against Japanese aircraft. Most missions ended with no enemy aircraft sighted, but when the enemy was detected they were often in groups, with the attack resulting in multiple kills for that pilot and radar operator, who would jointly receive credit for the kill. Since pilots and radar operators did not always fly as a team, the kills of the pilot and radar operator were often different. On some occasions a pilot with only one or two kills would fly with a radar operator who was already an "ace".
In England, the 422nd NFS finally received their first P-61s in late June, and began flying operational missions over England in mid-July. These aircraft arrived without the dorsal turrets so the squadron's gunners were reassigned to another NFS that was to continue flying the P-70. The first P-61 engagement in the European Theatre occurred on July 15 when a P-61 piloted by Lt. Herman Ernst was directed to intercept a V-1 "Buzz Bomb". Diving from above and behind to match the V-1's speed, the P-61's plastic rear cone imploded under the pressure and the attack was aborted. The tail cones would fail on several early P-61A models before this problem was corrected. On 16 July, Lt. Ernst was again directed to attack a V-1 and, this time, was successful, giving the 422nd NFS and the European Theatre its first P-61 kill.
In early August 1944, the 422nd NFS transferred to Maupertus, France, and began meeting piloted German aircraft for the first time. A Bf 110 was shot down, and shortly afterwards, the squadron's commanding officer Lt. Colonel O. B. Johnson, his P-61 already damaged by flak, shot down a Fw 190. The 425th NFS scored its first kill shortly afterwards.
In October 1944, a P-61 of the 422nd NFS, now operating out of an abandoned Luftwaffe airfield in Florennes, Belgium, encountered a Messerschmitt Me 163 attempting to land. The P-61 tried to intercept it but the rocket plane was traveling too fast. A week later, another P-61 spotted a Me 262, but was also unable to intercept the jet. On yet another occasion, a 422nd P-61 spotted a Me 410 Hornisse flying at tree top level but, as they dove on it, the "Hornet" sped away and the P-61 was unable to catch it. Contrary to popular stories, no P-61 ever engaged in combat with a German jet or any of the late war advanced Luftwaffe aircraft. The most commonly encountered and destroyed Luftwaffe aircraft types were Junkers Ju 188s, Bf 110s, Fw 190s, Dornier Do 217s and Heinkel He 111s, while P-61 losses were limited to numerous landing accidents, bad weather, friendly fire and flak. Apart from an attack on a Bf 110 that turned against them, there were no reports of a P-61 being damaged by a German aircraft; and apart from one accidentally shot down by an RAF Mosquito, none were confirmed to be destroyed in aerial combat.
The absence of turrets and gunners in most European theater P-61s presented several unique challenges. The 422nd NFS kept its radar operator in the rear compartment, meaning the pilot had no visual contact with the R/O. As a result, several courageous pilots continued flying their critically damaged P-61s under the mistaken belief that their R/O was injured and unconscious, when in fact the R/O had already bailed out. The 425th NFS had a more novel solution: they moved the R/O to the former gunner's position behind the pilot. This gave the pilot an extra set of eyes up front, and moved the aircraft's center of gravity about 15 inches forward, changing the flight characteristics from slightly nose up to slightly nose down which also improved the P-61's overall performance.
By December 1944, P-61s of the 422nd and 425th NFS were helping to repel the German offensive know as the "Battle of the Bulge," with two flying cover over the town of Bastogne. Pilots of the 422nd and 425th NFS switched their tactics from night fighting to daylight ground attack, strafing German supply lines and railroads. The P-61's four 20 mm cannons proved highly effective in destroying large numbers of German locomotives and trucks.
By early 1945, German aircraft were rarely seen and most P-61 night kills were Ju 52s attempting to evacuate Nazi officers under the cover of darkness.
The 422nd NFS produced three ace pilots, while the 425th NFS officially claimed none. Lt. Cletus "Tommy" Ormsby of the 425th NFS was officially credited with three victories. Unfortunately Lt. Ormsby was killed by friendly fire moments after attacking two Ju 87s on the night of 24 March 1945. His radar operator escaped with serious injuries and was saved only by the quick actions of German surgeons. He later reported that they had successfully engaged and shot down both Ju 87s before being shot down themselves. This claim was corroborated by other 425th aircrew who were operating in the area at the time. To this day many members of the 425th question why Lt. Ormsby was never credited with his final two kills, and "ace" status.
In the Pacific Theater in 1945, P-61 squadrons struggled to find targets. One squadron succeeded in destroying a large number of Kawasaki Ki-48 Lily Japanese Army Air Force twin-engined bombers, another shot down several G4M Bettys, while another pilot destroyed two Japanese Navy Nakajima J1N1 Irving twin-engined fighters in one engagement; but most missions ended with no enemy aircraft sighted. Several Pacific Theater squadrons finished the war with no confirmed kills at all. The 550th could only claim a crippled B-29 Superfortress, shot down after the crew had bailed out having left the plane on autopilot.
It is widely believed that the last two enemy aircraft destroyed before the Japanese surrender were both downed by a P-61 of the 548th NFS. This aircraft, known as "Lady in the Dark" was piloted by Lt. Lee Kendall, gaining its victories over a Nakajima Ki-43 on the night of 14 August/15 August 1945, and a Ki-44 on the next night.
On 30 January 1945, a lone P-61 performed a vital mission that was instrumental in the successful effort of the U.S. Rangers to free over 500 Allied POWs held by the Japanese at the Cabanatuan prison camp in the Philippines. As the Rangers crept up on the camp, a P-61 swooped low and performed aerobatic maneuvers for several minutes. The distraction of the guards allowed the Rangers to position themselves, undetected, within striking range of the camp. The story of the rescue and the role of the P-61 is told in the book Ghost Soldiers (by Hampton Sides) and in The Great Raid, a movie based upon the book.
In the Mediterranean Theater, most night fighter squadrons transitioned from their aging Bristol Beaufighters into P-61s too late to achieve any kills in the "Black Widow".
Though the P-61 proved itself very capable against the majority of German aircraft it encountered, it was clearly outclassed by the new aircraft arriving in the last months of World War II. It also lacked external fuel tanks that would have extended its range and saved many doomed crews looking for a landing site in darkness and bad weather. External bomb loads would also have made the type more adaptable to the ground attack role it soon took on in Europe. These problems were all addressed eventually, but too late to have the impact they might have had earlier in the war. The P-61 proved very capable against all Japanese aircraft it encountered, but saw too few of them to make a significant difference in the Pacific war effort.
The useful life of the Black Widow was extended for a few years into the immediate postwar period due to the USAAF's problems in developing a useful jet-powered night/all-weather fighter. The Curtiss P-87 had initially been scheduled as the jet-powered replacement for the Black Widow, but the failure of the XP-87 project meant the Black Widow had to soldier on for another few years.
Replacement of the Black Widow by F-82F/G Twin Mustang night fighters began in early 1948, and by early 1950, most Black Widows were out of operational service. The last operational Black Widow left Japan in May 1950, missing the Korean War by only a month, while the last operational F-61 was retired in 1952.
A Black Widow participated in early American ejection seat experiments performed shortly after the war. The Germans had pioneered the development of ejection seats early in the war, the first-ever emergency use of an ejection seat having been made on 14 January 1942 by a Luftwaffe test pilot when he escaped from a disabled Heinkel He 280 V1. American interest in ejection seats during the war was largely a side-issue of the developmental work done on pusher aircraft such as the Vultee XP-54, the goal being to give the pilot at least some slim chance of clearing the tail assembly and the propeller of the aircraft in the case of an emergency escape, but little progress had been made since pusher aircraft development had never really gotten past the drawing board or the initial prototype stage. However, the development of high-speed jet-powered aircraft made the development of practical ejection seats mandatory.
Initially, an ejection seat was "borrowed" from a captured German Heinkel He 162 and was installed in a Lockheed P-80 Shooting Star in August 1945. However, it was decided that the single-seat P-80 would not be suitable for these tests, and it was decided to switch to a three-seat Black Widow. A P-61B-5-NO (serial number 42-39489) was modified for the tests, the ejection seat being fitted in the forward gunner's compartment. The aircraft was redesignated XP-61B for these tests (there having been no XP-61B prototype for the initial P-61B series). A dummy was used in the initial ejection tests, but on 17 April 1946, a volunteer, Sgt. Lawrence Lambert was successfully ejected from the P-61B at a speed of at . With the concept having been proven feasible, newer jet-powered aircraft were brought into the program, and the XP-61B was reconverted to standard P-61B configuration.
The P-61 was heavily involved in the Thunderstorm Project (1946–1949) that was a landmark program dedicated to gathering data on thunderstorm activity. The project was a cooperative undertaking on the part of four U.S. government agencies: the U.S. Weather Bureau and NACA (National Advisory Committee for Aeronautics, later to become NASA), assisted by the U.S. Army Air Force and Navy. Scientists from several universities also participated in the initiation, design and conduct of the project. The project's goal was to learn more about thunderstorms and to use this knowledge to better protect civil and military airplanes that operated in their vicinity. The P-61's radar and particular flight characteristics enabled it to find and penetrate the most turbulent regions of a storm, and return crew and instruments intact for detailed study.
The Florida phase of the project in 1946 continued into a second phase carried out in Ohio during the summer of 1947. Results derived from this pioneering field study formed the basis of the scientific understanding of thunderstorms, and much of what was learned has been changed little by subsequent observations and theories. Data was collected for the first time from systematic radar and aircraft penetration of thunderstorms, forming the basis of many published studies that are still frequently referenced by mesoscale and thunderstorm researchers.
P-61B-1NO serial number 42-39458 was operated by the Navy at the Patuxent River test facility in Maryland in a number of tests. P-61A-10NO serial number 42-39395 was subjected by the Navy to a series of test catapult launches to qualify the aircraft for shipboard launches, but the Black Widow was never flown from an aircraft carrier. These aircraft did not receive the naval designation F2T-1 but continued on as P-61.
Shortly after the war, the Navy borrowed two P-61Cs (43-8336 and 43-8347) from the USAAF and used them for air-launches of the experimental Martin PTV-N-2U Gorgon IV ramjet-powered missile, the first launch taking place on 14 November 1947. While carrying a Gorgon under each wing, the P-61C would go into a slight dive during launch to reach the speed necessary for ramjet operation to be initiated. These two naval Black Widows were returned to the USAF in 1948, and transferred to the boneyard shortly afterwards.
Surviving aircraft were offered to civilian governmental agencies, or declared surplus and offered for sale on the commercial market.
An RF-61C (ex-F-15A, serial number 45-59300) was used by NACA at Moffett Field in California to test some early swept-wing designs by dropping recoverable aerodynamic test bodies from high altitude. This program was later joined by F-61C serial number 43-8330, borrowed from the Smithsonian Institution for the duration of the tests. These drops were carried out over Edwards Air Force Base in the Mojave Desert in California. F-61B-15NO serial number 42-39754 was used by NACA's Lewis Flight Propulsion Laboratory in Cleveland, Ohio for tests of airfoil-type ramjets. F-61C-1NO 43-8357 was used at Ames as a source for spare parts for other F/RF-61 aircraft.
A few other Black Widows also ended up in the civilian market. P-61B-1NO serial number 42-39419 had been bailed to Northrop during most of its military career, who then bought the aircraft from the government at the end of the war. Having the civilian registration number NX30020 assigned to it, it was used as an executive transport, as a flight-test chase plane, and for tests with advanced navigational equipment. Later it was purchased by the Jack Ammann Photogrammetric Engineers, a photo-mapping company based in Texas; then in 1963, it was sold to an aerial tanker company and used for fighting forest fires. However, it crashed while fighting a fire on 23 August 1963, killing its pilot.
The last flying examples of the P-61 line were an F-15A Reporter (RF-61C) 45-59300 and the "spare parts" F-61C 43-8357. The latter was rebuilt as a high-altitude mapping airplane, assigned the civilian number N5094V, and offered on the commercial market; however, it attracted no buyers and was finally scrapped in 1957. The RF-61C, originally given the civilian registration N5093V, was sold to Compania Mexicana Aerofoto S. A. of Mexico and assigned the Mexican registration XB-FUJ. It was then bought by Aero Enterprises Inc. of California and returned to the USA in 1964 carrying the civilian registration number N9768Z. The fuselage tank and turbosupercharger intercoolers were removed; and fitted with a 1,600-gallon chemical tank for fire-fighting it was purchased by Cal-Nat at the end of 1964, and in turn in March 1968 by TBM, Inc., an aerial firefighting company located in California (the name of the company standing for the TBM Avenger, the company's primary equipment). It was destroyed in a takeoff accident on 16 September 1968.
|Designation||Changes from previous model|
|XP-61||The first two prototypes.|
|YP-61||Pre-production series; 13 built.|
|P-61A-1||First production version, R-2800-10 engines producing 2,000 hp (1,490 kW); 45 built, the last seven without the turret.|
|P-61A-5||No turret, R-2800-65 engines producing 2,250 hp (1,680 kW); 35 built.|
|P-61A-10||Water injection to increase duration of maximum power output; 100 built.|
|P-61A-11||One hardpoint under each wing for bombs or fuel tanks; 20 built.|
|P-61B-1||Nose stretched 8 inches (20.3 cm), SCR-695 tail warning radar; 62 built.|
|P-61B-2||Reinstated underwing hardpoints as on P-61A-11; 38 built.|
|P-61B-10||Four underwing hardpoints; 46 built.|
|P-61B-11||Reinstated turret with two 0.50 cal (12.7 mm) machine guns; five built.|
|P-61B-15||Turret with four 0.50 cal (12.7 mm) machine guns; 153 built.|
|P-61B-16||Turret armament reduced to two machine guns; six built.|
|P-61B-20||New General Electric turret with four machine guns; 84 built.|
|P-61B-25||Turret automatically aimed and fired by the APG-1 gun-laying radar connected to an analogue computer; six built.|
|P-61C||Turbosupercharged R-2800-73 engines producing 2,800 hp (2,090 kW), top speed increased to 374 knots (430 mph, 692 km/h) at 30,000 feet (9,145 m). However, the aircraft suffered from longitudinal instability at weights above 35,000 pounds (15,875 kg) and from excessive takeoff runs — up to three miles (4,830 m) at a 40,000 pound (18,143 kg) takeoff weight; 41 built, 476 more cancelled after the end of the war.|
|TP-61C||P-61Cs converted to dual-control training aircraft.|
|XP-61D||One P-61A-5 (number 42-5559) and one P-61A-10 (number 42-5587) fitted with turbosupercharged R-2800-14 engines; cancelled when P-61C entered production.|
|XP-61E||Two P-61B-10s (numbers 42-39549 and 42-39557) converted to daytime long-range escort fighters. Tandem crew sat under a blown canopy which replaced the turret, additional fuel tanks were installed in place of the radar operator's cockpit in the rear of the fuselage pod, and four 0.50 cal machine guns took place of the radar in the nose (the 20 mm ventral cannon were retained as well). First flight 20 November 1944, cancelled after the war ended. The first prototype was converted to an XF-15, the second lost in an accident in 1945.|
|XP-61F||Abandoned conversion of one P-61C to XP-61E standard.|
|P-61G||Sixteen P-61B converted for meteorological research.|
|F-15A Reporter||Photoreconnaissance variant with a new center pod with pilot and camera operator seated in tandem under a single bubble canopy, and six cameras taking place of radar in the nose. Powered by the same turbosupercharged R-2800-73 engines as the P-61C. The first prototype XF-15 was converted from the first XP-61E prototype, the second XF-15A was converted from a P-61C (number 43-8335). The aircraft had a takeoff weight of 32,145 pounds (14,580 kg) and a top speed of 382 knots (440 mph, 708 km/h). Only 36 of the 175 ordered F-15As were built before the end of the war. After formation of the United States Air Force in 1947, F-15A was redesignated RF-61C. F-15As were responsible for most of the aerial maps of North Korea used at the start of the Korean War.|
|F2T-1N||Twelve USAAF P-61B's transferred to the United States Marine Corps.|