Subject: Number Sixty-One in the Series--Northrop P-61 Black Widow (3 of 10)

From: [email-masked]
Date: 15 Mar 93 16:43:33 GMT

>From [email-masked]

The P-61B was the next production version of the Black Widow.  It was 
basically similar to the P-61A version, but introduced numerous 
improvements and refinements that were suggested by operational 
experience in the field.  

The P-61B version of the Black Widow introduced the improved SCR-720C 
A/I radar.  The P-61B had an eight-inch longer crew nacelle.  The 
A-model's hydraulically-operated main landing-gear doors which had 
experienced reliability problems in the field were replaced by 
mechanically-operated doors.  The P-61B introduced split main landing 
gear doors.  The split main-gear doors allowed the aft three-quarters 
of the doors to close back down again after the gear had been 
extended, preventing mud, rocks and other debris from being thrown up 
into the wheelwells during takeoffs or landings.  A main landing gear 
down-lock emergency release was introduced, which allowed the pilot to 
release the locks in an emergency even if the entire hydraulic system 
malfunctioned.  A safety latch was added to the main gear hydraulic valve 
handle to eliminate the possibility of the pilot inadvertently 
retracting the gear while the plane was on the ground.  

One way of visually telling the difference between a P-61A and a P-61B 
was by an readily-noticeable access panel which was added behind the 
radome on the P-61B.  

The B-model had a bigger and better heater system for the crew, and it 
had automatically- operated lower engine cowl flops, oil-cooler air 
exit flaps, and intercooler flaps.  The oil tanks were mounted inside 
the engine nacelles instead of inside the outer wings.  A taxi lamp 
was added to the landing gear strut.  The aileron trim tabs were 
deleted, and a built-in fire extinguisher system was added.  

Operational crews in combat theatres as well as training squadrons in 
the USA determined very early on that the Black Widow pilot needed to 
have night-vision binoculars in order to see his target.  These were 
introduced on the B-model.  Night-vision binoculars consisted of a 
combination of 5.8-power night glasses and an optical gunsight.  In 
place of the circle and the dot of light in his regular gunsight, 
there was a horizontal row of four illuminated dots in the gunsight of 
the binoculars.  The pilot lined up these dots with the wing of the 
target aircraft he was sighting on, and if he knew the type of 
aircraft he was looking at, he could easily determine its range and 
quickly calculate a firing solution.  Night binoculars were later 
retrofitted to many P-61A already in the field.  

Starting with the P-51B-5-NO production block, the SCR-718 radio 
altimeter was replaced with an APN-1 low-altitude altimeter.  

Starting with the P-61B-10-NO block, an APS-13 tail-warning system was 
added.  Some P-61As and many early P-61Bs were retrofitted in the 
field with the APN-1 and APS-13 systems.  The B-10 production block 
also introduced underwing pylons for four 258-gallon drop tanks or 
four 1600-pound bombs 

The P-61B-15-NO reintroduced the dorsal turret (General Electric Type 
A-4), the buffeting problem caused by earlier turrets having by now 
been largely corrected.  

The P-61B-20-NO used the General Electric Type A-7 turret with a 
revised fire-control system.  

The Black Widow night fighter used its on-board radar only to plot 
intercept courses when pursuing enemy aircraft.  Once having used 
closed with his target, the pilot of the Black Widow sighted his prey 
by eye and used a conventional optical gunsight to fire his guns at 
the enemy.  Operationally-practical radar-directed airborne fire 
control was still many years in the future.  Nevertheless, there were 
some experiments with the Black Widow in which automatic airborne fire 
control was tried out.  The P-61B-25-NO was a block of seven 
experimental aircraft which were fitted with a Western Electric APG-1 
gun-laying radar which was coupled with a General Electric 
remote-controlled turret system.  The radar fed data into an analogue 
computer, which in turn directed the turret guns onto the target.  One 
P-61B-15-NO was also modified in this fashion, and the first six 
P-61B-20-NO aircraft were also modified to this configuration.  All of 
these aircraft were tested by the Air Proving Command at Elgin Field, 
Florida and at the night fighter training establishment at Hammer 
Field in California.  However, I don't think that this innovation ever 
made it to the field.  

During 1945, 16 P-61Bs were converted to P-61Gs for weather 
reconnaissance.  All armament was deleted.  

Serials of the P-61B were as follows: 

42-39398/39401 	Northrop P-61B-1-NO Black Widow 
42-39402 	Northrop P-61B-2-NO Black Widow 
42-39403/39405 	Northrop P-61B-1-NO Black Widow 
42-39406 	Northrop P-61B-2-NO Black Widow 
42-39407 	Northrop P-61B-1-NO Black Widow 
42-39408 	Northrop P-61B-2-NO Black Widow 
42-39409/39411 	Northrop P-61B-1-NO Black Widow 
42-39412/39414 	Northrop P-61B-2-NO Black Widow 
42-39415/39417 	Northrop P-61B-1-NO Black Widow 
42-39418 	Northrop P-61B-2-NO Black Widow 
42-39419/39423 	Northrop P-61B-1-NO Black Widow 
42-39424 	Northrop P-61B-2-NO Black Widow 
42-39425 	Northrop P-61B-1-NO Black Widow 
42-39426 	Northrop P-61B-2-NO Black Widow 
42-39427 	Northrop P-61B-1-NO Black Widow 
42-39428 	Northrop P-61B-2-NO Black Widow 
42-39429 	Northrop P-61B-1-NO Black Widow 
42-39430 	Northrop P-61B-2-NO Black Widow 
42-39431 	Northrop P-61B-1-NO Black Widow 
42-39432 	Northrop P-61B-2-NO Black Widow 
42-39433/39451 	Northrop P-61B-1-NO Black Widow 
42-39452/39456 	Northrop P-61B-2-NO Black Widow 
42-39457/39460 	Northrop P-61B-1-NO Black Widow 
42-39461/39462 	Northrop P-61B-2-NO Black Widow 
42-39463/39465 	Northrop P-61B-1-NO Black Widow 
42-39466 	Northrop P-61B-2-NO Black Widow 
42-39467/39470 	Northrop P-61B-1-NO Black Widow 
42-39471/39473 	Northrop P-61B-2-NO Black Widow 
42-39474 	Northrop P-61B-1-NO Black Widow 
42-39475 	Northrop P-61B-2-NO Black Widow 
42-39476/39477 	Northrop P-61B-1-NO Black Widow 
42-39478/39480 	Northrop P-61B-2-NO Black Widow 
42-39481/39482 	Northrop P-61B-1-NO Black Widow 
42-39483/39490 	Northrop P-61B-2-NO Black Widow 
42-39491 	Northrop P-61B-1-NO Black Widow 
42-39492/39493 	Northrop P-61B-2-NO Black Widow 
42-39494 	Northrop P-61B-1-NO Black Widow 
42-39495 	Northrop P-61B-2-NO Black Widow 
42-39496/39497 	Northrop P-61B-1-NO Black Widow 
42-39498/39500 	Northrop P-61B-5-NO Black Widow 
42-39501/39547 	Northrop P-61B-6-NO Black Widow 
42-39548/39572 	Northrop P-61B-10-NO Black Widow 
			39549 and 39557 converted to XP-61E 
42-39573/39611 	Northrop P-61B-15-NO Black Widow 
42-39612 	Northrop P-61B-10-NO Black Widow 
42-39613 	Northrop P-61B-15-NO Black Widow 
42-39614 	Northrop P-61B-15-NO Black Widow 
42-39615 	Northrop P-61B-10-NO Black Widow 
42-39616 	Northrop P-61B-15-NO Black Widow 
42-39617 	Northrop P-61B-10-NO Black Widow 
42-39618 	Northrop P-61B-15-NO Black Widow 
42-39619 	Northrop P-61B-10-NO Black Widow 
42-39620 	Northrop P-61B-16-NO Black Widow 
42-39621 	Northrop P-61B-11-NO Black Widow 
42-39622 	Northrop P-61B-16-NO Black Widow 
42-39623 	Northrop P-61B-11-NO Black Widow 
42-39624 	Northrop P-61B-16-NO Black Widow 
42-39625 	Northrop P-61B-11-NO Black Widow 
42-39626 	Northrop P-61B-16-NO Black Widow 
42-39627 	Northrop P-61B-11-NO Black Widow 
42-39628 	Northrop P-61B-16-NO Black Widow 
42-39629 	Northrop P-61B-11-NO Black Widow 
42-39630 	Northrop P-61B-16-NO Black Widow 
42-39631/39633 	Northrop P-61B-15-NO Black Widow 
42-39634/39636 	Northrop P-61B-10-NO Black Widow 
42-39637/39639 	Northrop P-61B-15-NO Black Widow 
42-39640/39641 	Northrop P-61B-10-NO Black Widow 
42-39642 	Northrop P-61B-15-NO Black Widow 
42-39643 	Northrop P-61B-10-NO Black Widow 
42-39644 	Northrop P-61B-15-NO Black Widow 
42-39645 	Northrop P-61B-10-NO Black Widow 
42-39646 	Northrop P-61B-15-NO Black Widow 
42-39647 	Northrop P-61B-10-NO Black Widow 
42-39648/39649 	Northrop P-61B-15-NO Black Widow 
42-39650 	Northrop P-61B-10-NO Black Widow 
42-39651	Northrop P-61B-15-NO Black Widow 
42-39652 	Northrop P-61B-10-NO Black Widow 
42-39653 	Northrop P-61B-15-NO Black Widow 
42-39654 	Northrop P-61B-10-NO Black Widow 
42-39655 	Northrop P-61B-15-NO Black Widow 
42-39656 	Northrop P-61B-10-NO Black Widow 
42-39657 	Northrop P-61B-15-NO Black Widow 
42-39658 	Northrop P-61B-10-NO Black Widow 
42-39659/39661 	Northrop P-61B-15-NO Black Widow 
42-39662 	Northrop P-61B-10-NO Black Widow 
42-39663/39665 	Northrop P-61B-15-NO Black Widow 
42-39666/39667 	Northrop P-61B-10-NO Black Widow 
42-39668/39757 	Northrop P-61B-15-NO Black Widow 
43-8231/8236 	Northrop P-61B-25-NO Black Widow 
43-8237/8320 	Northrop P-61B-20-NO Black Widow 

Sources:

  Northrop P-61 Black Widow--The Complete History and Combat Record, 
  Garry R. Pape, John M. Campbell and Donna Campbell, Motorbooks 
  International, 1991.  

  The American Fighter, Enzo Angelucci and Peter Bowers, Orion, 1987.  

  Warplanes of the Second World War, Fighters, Volume 4, William Green, 
  1964.  

  American Combat Planes, Ray Wagner, Third Enlarged Edition, Doubleday, 
  1982.  

  United States Military Aircraft since 1909, Gordon Swanborough and 
  Peter M. Bowers, Smithsonian, 1989.  

Joe Baugher       AT&T Bell Laboratories    2000 North Naperville Road 
		  Naperville, Illinois 60566-7033.   (708) 713-4548