Almost 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. The XF-89 was lost in February 1950 when its tailplane came apart in flight; the breakup resulted in the death of the aircraft’s backseater.
YF-89A: Having been started as an XF-89, the second prototype Scorpion was finished to an enhanced standard with redesigned intakes and a stretched nose. Following the XF-89 crash, the YF was reworked with new exhausts and new, permanently affixed wingtip tanks.
F-89A: Eight aircraft with mass balances on the elevators, -21 engines (later -21A) new tip tanks, the ability to carry bombs or rockets underwing in the strike role, an an APG-33 radar and six T-31/M24A1 20mm cannon in the nose.
F-89B: First operational Scorpion, equipping the 84th FIS in the summer of 1951. The B closely followed the F-89A, but with some avionics differences, and the external mass balances were eventually replaced by internally mounted ones.
F-89C: First 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, which necessitated a delay to the Scorpion program, as a structural reinforcement of the attachments and the wings, and the fitting of fins to the tip tanks had to be carried out. One F-89C was fitted with the T110 rocket gun for launching 2.75″ FFARs from the nose, while another example tested a quartet of Oerliken 30mm cannon.
F-89D: 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 2.75-inch “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 standard.
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 frontline service.
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 operational Falcon carriage would be the role of the F-89H.
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 until 1969.
F-89E: 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.
F-89F: 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.
F-89X: 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.
REFERENCES & RESOURCES
Tony Chung “Flying Wings & Radical Things: Northrop’s Secret Aerospace Projects & Concepts 1939-1994” ISBN 978-1-58007-229-8
An outstanding book that includes coverage of such one-off and never built Scorpion variants as the RF-89A recce model with five cameras and pods for photoflash bombs, a 3-view and model photo of a swept-wing derivative, YF-84E J71 testbed, F-89F three-view, F-89C test aircraft with Martin and Oerlikon nose guns, the PD-1875 outgrowth with engines in wing pods, the PD-1887 swept wing version, and the F-89X improved interceptor with Sapphire engines and armed with up to ten Falcons and two Genies.
- Photo: F-89s on the Hawthorne assembly line Aviation Week October 23, 1950 p.18
- “F-89 May Put Northrop in Black” Aviation Week November 6, 1950 p.18
- “F-89 Scorpion’s Deadly Sting” Aviation Week February 19, 1951 p.14 Photos showing ground test of an F-89A’s 20mm cannon.
- Photo: frontal shot of an F-89C fitted with T-110 rocket guns. Aviation Week November 8, 1954 p.9
- Northrop ad, depicting a pair of F-89s chasing a target drone. Aviation Week March 14, 1955 p.197
- “The Black Knights of Keflavik” Flight 24 February 1956 a look at the F-89s of the 57th FIS; includes a cockpit photo
- Photos showing close-up detail of an XF-89H’s wingtip pods, with rockets and GAR-1 Falcons Flight 21 September 1956 p.520
- Connecticut Hard Rubber Company ad, with a close-up photo of a Falcon installation on an F-89H Aviation Week January 14, 1957 p.87
- Tony Grand “The Scorpion, Plumbob Joh, and the UFO” Scale Aviation Modeller International May 2008 Building the 1/72 F-89D kit from Academy.
- Lloyd S. Jones U.S. Fighters: Army-Air Force 1925 to 1980s p.239-240: F-89C scale 3-view plans, artist’s illustration of the F-89F
- Chris Bishop, editor The Encyclopedia of 20th Century Air Warfare color 3-view of a 59th FIS F-89D in high-viz arctic markings
- Dan B. McCarthy “Death of a Scorpion” Warbirds International Jan/Feb 2012 details the disposal and scrapping of a JF-89C
- Jezz Coleman “Silver Sting” Model Aircraft March 2017 Building the 1/72 Revell Scorpion kit as an F-89D.
- Jim Winchester American Military Aircraft: A History of Innovation p.365: color profile of an F-89D of the 59th FIS
Tony Buttler American Secret Projects: Fighters & Interceptors 1945-1978 p.27: 3-view of the early swept-wing F-89 proposal
Gerald Balzer, Mike Dario Aerofax Datagraph 8: Northrop F-89 Scorpion Includes 1/100th scale F-89J plans
Martin W. Bowman Fast Jet Fighters 1948-1978 p.52: photo of a Vermont ANG F-89D
Boneyard Almanac: 20th Century Picture Book p.38: photo of F-89J 53-2522, ex Minn ANG