F-89 Scorpion walk around photosAlmost
forgotten in the shadow of the later Century Series interceptors,
Northrop's F-89 Scorpion was the USAF's first jet interceptor designed
as such from the outset, rather than being an adaptation of a day
fighter. Development of a jet powered all-weather fighter began not
long after V-J Day, as it was recognized that the P-61 Black Widow
would soon be obsolete in an age of jets. Northrop's N-24 proposal
encompassed a number of design alternatives, with a swept wing version
being chosen in the spring of 1946. This twin TG-180/J35 powered
aircraft was to have been armed with a quartet of 20mm cannon in a
revolving nose cannon, but this configuration was soon to give way to a
straight-wing iteration with fixed guns.
The first XF-89 flight took place
on 16 August 1948, and within several months of that event the USAF had
cancelled orders for the competing Curtiss F-87 Blackhawk. However,
despite the Northrop aircraft's official favor, all was not well with
the program, as the Scorpion proved to have structural weaknesses, and
was underpowered. Originally, 48 F-89As had been contracted for, but
this figure was reduced to eleven as costs to fix the problems
F-89B: First operational Scorpion, equipping the 84th FIS in the summer of 1951.
flown in October 1951; differed primarily from the B-model in having
internal mass balancers for the elevators, as well as higher
pressurization for the cockpit. A series of F-89C crashes in 1952 led
to the discovery of structural weakness in the wing attach point. This
necessitated a delay to the Scorpion program, as a strctural
refinforcement of the attachments and the wings, and the fitting of
fins to the tip tanks had to be carried out.
The most numerous Scorpion model, the F-89D was a major redesign –
driven by both the need to improve the Scorpion's shortcomings, as well
as to provide a heavier armament, as taking down nuclear-armed bombers
demanded something more potent than machine guns. The D-model deleted
the nose cannon in favor of large wingtip pods that each contained 104
"Mighty Mouse" FFARs. The pods still retained some fuel, and to make up
for the lost wingtip fuel, an additional tank was fitted internally in
the space once used by the cannon.The APG-40 radar was combined with an
APA-84 ballistics computer to form the E-6 fire control system. Early
aircraft were flown with -33A engines, while later blocks had -41s, and
ultimately the -35. Even the -35 would still experience problems at
high altitude, and the powerplants were later brought up to -35A
An F-89B was reworked as the YF-89D testbed, this flying in October
1951, and by early 1953 the first production aircraft were being handed
over; it would, however be until early 1954 that the model would enter
The F-89D was also considered as a platform for the Hughes
Falcon AAM, and test firings were conducted from three aircraft
(52-1830, 52-1938, and 53-2449) starting in the fall of 1953, but
carriage would be the role of the F-89H.
E-9 fire control system, reconfigured wingtip pods each carrying 21
FFARs and three Falcons. A total of 156 new-build aircraft were bought. Operational from the spring of 1956 starting with the 445th FIS at Wurtsmith AFB.
F-89J: Rebuild of 350 F-89Ds with the Hughes MG-12, and the capability to carry a pair of Douglas Genie rockets underwing. An
additional pair of pylons for Falcon carriage were fitted, and either
the fuel/rocket pods or the original fuel-only wing tanks could be
carried. Entered service in
early 1957 with the 84th FIS; retired from active USAF service by 1960,
the F-89J was the last Scorpion to remain with Air National Guard
squadrons, with Guard units in Maine and Iowa retaining their aircraft
This designation applied to two
Scorpion derivative proposals, only one of which actually flew. The
original use of the model type was for a J47 powered single-seat escort
fighter model that never made it to the hardware stage, while the later
YF-89E was the conversion of a single F-89C with Allison YJ-71 engines.
Proposal for a much revised aircraft with a substantially enlarged fuselage, General Electric J73 engines, and large pods on a new wing carrying fuel, three Falcons, and 21 FFARs. Only made it to the mockup stage.
Proposal for a J65 Sapphire-engined aircraft with better altitude capability.
The F-89F & X did not quite mark the
end of the Scorpion's design evolution, as Northrop investigated mating
a J67-powered Scorpion fuselage with a delta wing; this study later
evolved into a whole series of designs that only shared the "Delta
Scorpion" name in common with the earlier proposal.