Subject: Number Eighty-Nine in the Series--Northrop F-89 Scorpion (5 of 10)

From: [email-masked]
Date: 24 Sep 93 16:34:34 GMT

>From [email-masked]

The major production version of the Scorpion was the F-89D (Model 
N-68).  A total of 682 F-89D versions of the Scorpion were 
constructed.  

The F-89D differed from the F-89C in having the armament of six 20-mm 
cannon replaced by an all-rocket armament.  The rocket launching pods 
were housed in the forward edges of the wingtip fuel tanks.  These 
tanks were longer and had a larger diameter than the 300-gallon tanks 
carred by the F-89C.  The forward third of each tank contained a 
series of launch tubes for 52 2.75-inch Folding Fin Aircraft Rockets 
(FFAR).  These rockets were known as *Mighty Mouse*, after a 
well-known cartoon character ("Here I come to save the day").  These 
rockets were unguided and had an effective range of about 2000 yards 
and were equipped with high-explosive warheads.  The rear two thirds 
of the tank was taken up by 308 gallons of fuel.  

With the addition of the rocket armament, the six 20-mm cannon were 
deleted.  The entire nose section of the fuselage was redesigned to 
house a Hughes E-6 fire control system with a straight tapered nose 
cone and a larger and flatter radome.  The E-6 fire control system 
consisted of a Hughes APG-40 radar and an AN/APA-84 computer.  The 
space formerly occupied by the cannon was used to carry an additional 
262 gallon fuselage fuel tank.  The F-89D could also carry extra fuel 
in underwing drop tanks, each containing 200 gallons, bringing total 
fuel capacity to 2834 gallons.  

The first F-89D was obtained by modifying F-89B serial number 49-2463, 
the aircraft being redesignated YF-89D.  The first flight of the 
YF-89D took place on October 23, 1951.  The first two production 
F-89Ds were delivered to the USAF on June 30, 1952.  Some 125 F-89Ds 
had been built by the time that the problems with the Scorpion's wings 
resulted in the grounding of the entire fleet.  These F-89Ds remained 
at the factory until the wing modifications could be made that would 
make the aircraft safe to operate in the field.  

The first F-89Ds became operational with the 18th Fighter Interceptor 
Squadron based at Minneapolis/St.Paul, Minnesota on January 7, 1954.  

The pilot could select several options when firing the rocket 
armament.  The 104 rockets could all be fired at once, all the rockets 
leaving the tubes in only four-tenths of a second.  When fired at 
once, the rockets could blanket an area the size of a football field, 
enveloping the target in a pattern reminiscent of a shotgun blast.  
One hit was deemed sufficient to bring down a bomber.  The rockets 
could also be ripple fired, the pilot being able to select two ripples 
(82 and 42 rockets) or three ripples (42,32, and 30 rockets).  

Once in service, there were some problems encountered with the F-89D 
which were corrected as they came up.  During flights at high 
altitude, there were mysterious drops in engine power above 30,000 
feet, which were eventually traced to a temperature sensor element in 
the power control unit.  The problem was cured by shielding the unit.  
In service, the rocket tubes in the wingtip pods were often subject to 
corrosion which, if allowed to proceed unchecked, could result in an 
explosion in the tube during rocket firing.  A new thick-walled tube 
was designed which corrected this problem.  

The F-89D was flown from 1954 onward by the 18th, 61st, 64th, 318th, 
337th and 449th Fighter Interceptor Squadrons based in Alaska, as well 
as by the 497th Squadron.  They were also flown from 1955 onward by 
the 11th, 58th, and 59th Fighter Interceptor Squadrons based in 
Labrador.  The 68th, 75th, 76th , 83rd, 321st, 432nd, 437th, 445th, 
460th and 465th Fighter Interceptor Squadrons received Scorpions in 
1955.  In 1956, Scorpions were issued to the 98th Fighter Interceptor 
Squadron.  In 1957, the 29th, 54th, and 319th Fighter Interceptor 
Squadrons received Scorpions.  In 1959, the 15th and 49th FIS received 
Scorpions.  

During the peak years, 30 of the 39 Scorpion-equipped squadrons were 
based in the northern US or in Canada.  The F-89D served in the Air 
Defense Command, Alaskan Air Command, and the Northeast Air command 
until late 1958, when they began to be replaced by supersonic types 
such as the F-101B Voodoo and the F-102A Delta Dagger.  Ex-USAF F-89Ds 
were then transferred over to the ANG.  The first ANG squadron to 
receive the F-89D was the 178th FIS of the North Dakota ANG, based at 
Fargo.  The last Scorpions were finally withdrawn from active service 
with the USAF in 1961.  The Air National Guard continued to fly 
Scorpions for several more years.  The last Scorpion (an F-89J) left 
ANG service in 1969.  

Specification of the F-89D: 

Two Allison J33-A-33A/41/35, 5440 lb.st. dry, 7200 lb.st. with 
afterburner.  Maximum speed: 636 mph at 10,600 feet, 523 mph at 46,500 
feet.  Initial climb rate 8360 feet per minute.  Altitude of 46,500 
feet could be attained in 18.1 minutes.  Service ceiling 49,200 feet.  
Maximum range 1367 miles.  Dimensions: wingspan 60 feet 5 inches, 
length 53 feet 10 inches, height 17 feet 6 inches, wing area 606 
square feet.  Weights 25,194 pounds empty, 37,190 pounds combat, 
42,241 pounds gross, 46,789 pounds maximum takeoff.  Armed with 104 
2.75-inch folding fin unguided rockets in wingtip pods.  Underwing 
racks could carry 16 five-inch rockets or 3200 pounds of bombs.  

Serials of the F-89D:

51-400/406 	Northrop F-89D-1-NO Scorpion 
51-407/426 	Northrop F-89D-5-NO Scorpion 
51-427/446 	Northrop F-89D-10-NO Scorpion 
51-11298/11317 	Northrop F-89D-15-NO Scorpion 
51-11318/11357 	Northrop F-89D-20-NO Scorpion 
51-11358/11407 	Northrop F-89D-25-NO Scorpion 
51-11408/11443 	Northrop F-89D-30-NO Scorpion 
52-1829/1868 	Northrop F-89D-35-NO Scorpion 
52-1869/1910 	Northrop F-89D-40-NO Scorpion 
52-1911/1961 	Northrop F-89D-45-NO Scorpion 
52-2127/2165 	Northrop F-89D-45-NO Scorpion 
53-2447/2461 	Northrop F-89D-50-NO Scorpion 
53-2462/2521 	Northrop F-89D-55-NO Scorpion 
53-2522/2581 	Northrop F-89D-60-NO Scorpion 
53-2582/2641 	Northrop F-89D-65-NO Scorpion 
53-2642/2686 	Northrop F-89D-70-NO Scorpion 
54-184/260 	Northrop F-89D-75-NO Scorpion 

Sources:

  United States Military Aircraft Since 1909, Gordon Swanborough
  and Peter M. Bowers, Smithsonian, 1989.
  
  F-89 Scorpion in Action, Aircraft Number 104, Larry Davis and 
  Dave Menard, Squadron/Signal Publications, 1990.

  Fighters of the United States Air Force, Robert F. Dorr and David 
  Donald, Temple Press Aerospace, 1990.

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

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

Joe Baugher		AT&T Bell Laboratories   	
2000 North Naperville Road      Naperville, Illinois 60566-7033