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AIRCRAFT
 
NORTHROP P-61 BLACK WIDOW
 
 
 
 

The heavily-armed Black Widow was the United States' first aircraft specifically designed as a night fighter-interceptor. The US Army Air Forces initial requirements for this night interceptor made no mention of radar, but stated that the aircraft would carry a device which would locate enemy aircraft in the dark.  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.

 

Northrop was issued 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 January 10, 1941. Northrop Specification 8A became, by designation of the Department of Defense, the XP-61.NS-8A was submitted to Wright Field. On March 10, 1941, a contract was issued for 13 YP-61 service test aircraft, plus one engineless static test airframe.  The mockup was ready for inspection in April of 1941. At that time, it was decided to move the four 20-mm cannon from the outboard portion of the wings to the belly. This was done to improve the ease of maintenance and to make the airflow over the wing smoother. The internal fuel capacity was increased from 540 gallons in two tanks to 646 gallons in four self-sealed tanks built into the wings. In the meantime, development of the A/I radar had proceeded at a rapid pace.

 

Radar development in the United States had been placed under the control of the National Defense Research Committee. The NDRC's Microwave Committee in turn had established the Radiation Laboratory at the Massachusetts Institute of Technology. The Radiation Laboratory was to handle the development of the XP-61's airborne interception (AI) radar. The designation of the radar was AI-10. The AI-10 radar was given the military designation SCR-520, where SCR stood for "Signal Corp Radio" (some references have this as standing for "Searchlight Control Radar"). The Western Electric corporation was assigned the responsibility of refining the design and undertaking the mass production of the radar.  Although the first prototype flew in May of 1942, the Black Widow did not enter front-line service until 1944.

 

The P-61 was the largest and most powerful fighter aircraft of WW II  The Black Widows bite was mean because of its four cannons and four machine guns. With a wingspan of sixty-six feet and a length of nearly fifty feet, this large aircraft was powered by twin 18-cylinder Double Wasp radial engines, capable of 2,000-HP each.  The B model of the P-61 was capable of speeds in the 365-MPH range, and had an incredible range of 3,000 miles. This great range gave the P-61 added benefits in the Pacific theater of operations. The P-61 utilized 4-bladed, variable pitch props, and incorporated a tricycle landing gear configuration. With its distinctive double tail configuration, the Black Widow had a roughly similar appearance to the P-38 Lightning, which was sometimes utilized in the night fighter role prior to the P-61 becoming available. 

 

Black Widows entered front line service with the 6th NFS based on Guadalcanal who 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 June 25. On June 30, 1944, the P-61 scored its first kill when a Japanese G4M Betty bomber was shot down.

 

In England, the 422nd NFS finally received their first P-61s in late June, and began flying operational missions over England in mid-July. 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 350mph 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 July 16, 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.

 

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.  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. 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 20mm cannons proved highly effective in destroying large numbers of German locomotives and trucks.

 

By spring 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 claimed none. Lt. Cletus "Tommy" Ormsby of the 425th NFS was officially credited with three victories. A total of 941 P-61’s were built in three models, the P-61A, P-61B, and the more powerful P-61C. In addition, 35 F-15 photo recon variants were produced. Today, only 3 survive as complete airframes, one is undergoing restoration, and one is known to survive in China.

 

As the Army Air Force organized units, they would reactivated some of its most historical organizations, one of those, the 325th, standing up as the 325th Fighter Group (All Weather) on 21 May 1947 at Mitchell Field, NY. On the same day the 318th was the first squadron reactivated under the Group (with no men or equipment) also located at Mitchell.  On 19 November 1947, the unit moved to Hamilton Field, CA with the 325th Fighter Group. At Hamilton, the 318th began to receive personnel and aircraft, the Northrop P-61 Black Widow.

 

Beginning in early 1946, an Army Air Force team of 15 pilots held secretive trials at McChord Field testing the performance of P-61's ability to intercept invading bombers. The appearance of the Soviet Tupolev Tu-4 'Bull' (copy of the B-29 Superfortress) in 1947 posed a new threat to postwar USAAF planners.

 

During a number of simulated raids on the United States carried out by Strategic Air Command, defending F-51 Mustangs and F-47 Thunderbolts, being used as interceptors, repeatedly failed to find the incoming bombers, or when they knew they were on their way, rarely got themselves into a firing position. If the fighters intercepted the bombers, it was usually too late since the bombers (primarily B-29 Superfortresses) would have already completed their bomb runs over the intended targets of New York City, Los Angeles, Seattle, Chicago and St. Louis.

 

It was found that the radar-equipped P-61's were very effective in locating and attacking the incoming SAC bombers, and had the range to attack the bombers far from their intended targets. In the late 1940s, there was not a jet US interceptor ready to perform the interceptor mission, so the ADC used the Black Widow as an interim measure.

 

In September of 1946, the Air Defense Commands Fourth Air Force formally activated the 425th Night Fighter Squadron at McChord flying the P-61s, the Commands first squadron to be activated with personnel and equipment. On 25 August 1947, the 425th NFS was redesignated as the 317th Fighter Squadron, the next year, the 318th rejoin its former group mate at McChord with their North American F-82 Twin Mustangs on 26 November 1948, rejoining the 325th All Weather Fighter Group Headquartered at Moses Lake AFB, WA.

 

In September of 1946, the Air Defense Commands Fourth Air Force formally activated the 425th Night Fighter Squadron at McChord flying the P-61s, the Commands first squadron to be activated with personnel and equipment. On 25 August 1947, the 425th NFS was redesignated as the 317th Fighter Squadron, the next year, the 318th rejoin its former group mate at McChord with their North American F-82 Twin Mustangs on 26 November 1948, rejoining the 325th All Weather Fighter Group Headquartered at Moses Lake AFB, WA.

 

 
SPECIFICATIONS
 
NORTHROP P-61B BLACK WIDOW
 
  • TYPE:  Long Range Night Fighter-Interceptor

 

  • POWER:  Two Pratt & Whitney R-2800s of 2,100 hp each  

 

  • SPEED: 425 mph; Cruising speed: 275 mph

 

  • RANGE:   1,650 miles with four external tanks  

 

  • SERVICE CEILING: 46,200 ft

 

  • WEIGHT:  Empty: 23,450 lbs; Max T.O.: 36,200 lbs.

 

  • DIMENSIONS: Span: 66 ft. 0 in.,  Length: 49 ft 7 in. Height: 14 ft 8in.

 

  • ARMAMENT:  Guns: 4 × 20 mm (.79 in) Hispano M2 cannon in ventral fuselage, 200 rpg; 4 × .50 in (12.7 mm) M2 Browning machine guns in remotely operated, full-traverse upper turret, 560 rpg  -  Bombs: for ground attack, four bombs of up to 1,600 lb (726 kg) each or six 5 in (127 mm) HVAR unguided rockets could be carried under the wings. Some aircraft could also carry one 1,000 lb (454 kg) bomb under the fuselage.

 

  • CREW:  Three (Pilot, Radar Operator, Optional Gunner)

 

  • PRODUCTION TOTALS: 200 (P-61A); 406 (P-61B)41 (P-61C)

 

  • COST: $190,000

 

318th FIGHTER-INTERCEPTOR SQUADRON SERVICE: 
 19 November 1947 thru 10 May 1948 at Hamilton AFB, California
 
COURTESY OF THE McCHORD AIR MUSEUM