Northrop F-89 Scorpion

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"P-89" redirects here. For other uses, see P89 (disambiguation).

F-89 Scorpion
Formation of three F-89Ds of the 59th Fighter Squadron, Goose Bay, Labrador
Role Interceptor
Manufacturer Northrop Corporation
First flight 16 August 1948
Introduction September 1950
Retired 1969
Primary user United States Air Force
Number built 1,050 and 2 prototypes

The Northrop F-89 Scorpion is an

horizontal stabilizer, which kept it clear of the engine exhaust.[2]

The Scorpion was designed by Northrop in response to a specification issued by the

Curtiss-Wright XP-87 Blackhawk
for development, leading to an initial contract for two aircraft, designated XP-89, being approved on 13 June 1946.

On 16 August 1948, the prototype performed its

Allison J33-A-21 turbojet engines, AN/APG-33 radar, and the Hughes E-1 fire-control system. During September 1950, the Scorpion entered service with the United States Air Force
(USAF), its sole operator.

Only 18 F-89As were completed as it was quickly superseded by the more capable F-89B configuration, most of the changes being avionics-based, that arrived in June 1951. It was soon followed by the F-89C, which featured engine upgrades. During 1954, the definitive F-89D was introduced, which installed a new

Air Defense Command, later renamed the Aerospace Defense Command (ADC), through 1959, and with the Air National Guard
, into the late 1960s. The last Scorpions were withdrawn from use in 1969.

Design and development

Background

The origins of the Scorpion can be traced back to a United States Army Air Forces (USAAF) Air Technical Service Command specification ("Military Characteristics for All-Weather Fighting Aircraft") for a night fighter to replace the Northrop P-61 Black Widow. The preliminary specification, issued to aircraft manufacturers on 28 August 1945, required two engines and an armament of six guns, either 0.60-inch (15 mm) machine guns or 20 mm (0.79 in) autocannons. The revised specification was issued on 23 November; it did not specify jet propulsion, but the desired maximum speed of 530 miles per hour (460 kn; 850 km/h) was challenging to meet via alternative means. The aircraft was to be armed with aerial rockets stored internally and six guns split between two flexible mounts, four guns forward and two in the rear. Each mount had to be capable of 15° of movement from the aircraft's longitudinal axis; each mount's guns were to be automatically controlled by radar. For ground attack, it had to be capable of carrying 1,000-pound (454 kg) bombs and to be able to carry a minimum of eight rockets externally.[3] Further requirements included the ability to ascend to 35,000 feet within 12 minutes and a mission radius of 600 nautical miles.[4]

Proposals were submitted by six aircraft companies:

XA-43 attack aircraft and the Northrop N-24, one of four designs submitted by the company.[5][4]

The N-24, designed by

dihedral.[7]

Contract and redesign

On 13 June 1946, an initial $4 million contract for two aircraft, designated XP-89, along with a full-scale mock-up, was approved.

aluminum alloy, and the fuel tankage directly above the engines moved. Other changes were made in response to the results from wind tunnel and other aerodynamic tests conducted.[8] The swept wings proved less satisfactory at low speeds, and a thin straight wing was selected, instead. Delivery of the first prototype was scheduled for November 1947, 14 months after the inspection.[9] The requested alterations to the design were formalized in a series of change orders issued to Northrop.[8] Another mockup presentation took place in December 1946.[8]

Further changes included the position of the horizontal stabilizer also proved to be unsatisfactory, as it was affected by the engine exhaust, and it would be "blanked-out" by airflow from the wing at high

elevators and rudder. Moving the horizontal stabilizer forward solved the problem.[10] Another major change occurred when USAAF revised its specification to delete the rear gun installation on 8 October. Another mock-up inspection was held on 17 December, and the inspectors suggested only minor changes, though the fuselage fuel tanks were still above the engines. Northrop's efforts to protect the fuel tanks were considered sufficient, as the only alternative was redesigning the entire aircraft.[11]

The XP-89 had a thin, straight, mid-mounted wing and a crew of two seated in

flaps as needed.[14] All flying surfaces, the flaps, and the landing gear were hydraulically powered. The thin wing dictated tall, thin, high-pressure (200 psi (1,379 kPa; 14 kgf/cm2)) mainwheel tires, while the low height of the fuselage required the use of dual wheels for the nose gear.[15]

Flight testing

On 21 May 1947, the terms of the initial contract were revised and formalized, at which point the price was increased to $5,571,111.

Allison J35-A-9 turbojets, quickly proved to be fundamentally underpowered. Initial flights were performed with conventional ailerons as the decelerons were not installed until December.[15][17]

Several months earlier, the Air Force conducted a competitive evaluation of the three existing all-weather interceptor prototypes, the

trainer.[18] The full Committee on Evaluation overruled those evaluators, preferring the Northrop design, as it had the greatest potential for development. The Air Force subsequently canceled the production contract for the F-87 to free up money for the Scorpion.[15][19]

During May 1949, the Air Force issued a cost-plus-fixed-fee contract, valued at roughly $48 million, which covered the modifications to the second prototype as well as the supply of the first 48 production standard aircraft, spare parts, tooling, ground-handling equipment, and a single static test frame.

afterburner. Other major changes included the replacement of the nose gun turret by the Hughes-designed six-gun nose, AN/ARG-33 radar, and Hughes E-1 fire-control system, permanent wingtip fuel tanks, and the ability to lower the complete engine for better maintenance access. The new nose added 3 feet (0.91 m) to the length of the aircraft. It was redesignated YF-89A to reflect its role as a pre-production testbed to evaluate equipment and changes planned for the F-89A production aircraft. The aircraft was complete by February 1950.[21]

After repairs from a

flutter developed in the elevator, and the subsequent vibrations caused the entire tail to break off.[17] Construction of the production models was suspended until the reasons for the accident were discovered. Engineering and wind tunnel tests revealed that the geometry of the rear fuselage and the engine exhaust created flutter-inducing turbulence aggravated by the exhaust's high-frequency acoustic energy. Fixes for the problem involved the addition of a "jet wake fairing" at the bottom rear of the fuselage between the engines, external ("ice tong") mass balances for the elevator, pending the design of internal mass balances,[22] and the addition of exhaust deflectors to the fuselage to reduce the turbulence and the consequent flutter.[23] These modifications were initially applied to the second prototype to validate their effectiveness.[24]

Operational history

An early F-89A

On 28 September 1950, the first F-89A was accepted by the Air Force for evaluation purposes; a further two aircraft were accepted by the end of the year.

T-31 cannon with 200 rounds per gun. The swiveling nose turret was abandoned, and 300-US-gallon (250 imp gal; 1,100 L) fuel tanks were permanently fitted to the wingtips. Underwing racks could carry 16 5-inch (130 mm) aerial rockets or up to 3,200 lb (1,451 kg) of bombs.[27]

Only 18 F-89As were completed, all of which being delivered within FY1951; they were mainly used for tests and trials, seeing little operational use.

84th Fighter-Interceptor Squadron.[28] However, the F-89B experienced considerable problems with both the engines and other systems, resulting in its withdrawal from frontline duties during 1954.[29] The improved F-89C had started to be introduced in September 1951, although the Air Force opted to halt allocations four months later due to issues. Despite repeated engine changes and other modifications, problems had persisted, compounded by the discovery of structural problems with the wings that led to the grounding of the F-89 and forced a refit of 194 -A, -B, and -C models.[30] On 22 September 1952, all Scorpions, save for those involved in flight testing, were grounded until the following year.[31] The F-89C left active service with the Air Force in 1954, it was operated by the Air National Guard as late as 1960.[32]

The definitive production model was the F-89D. While it performed its first flight on 23 October 1951, quantity production was disrupted by the issues encountered on early models, resulting in major structural modifications, after which full production was resumed during 1953.

FFAR rockets.[35][36] A total of 682 F-89Ds were built.[37] In August 1956, a pair of F-89D interceptors were scrambled from Oxnard Air Force Base to shoot down a runaway F6F-5K drone leading to the so-called Battle of Palmdale.[38]

Proposed re-engined F-89s, designated F-89E and F-89F, were not built, nor was a proposed F-89G that would have used Hughes MA-1 fire control and GAR-1/GAR-2 Falcon air-to-air missiles like the Convair F-106 Delta Dart.[39]

F-89H showing its GAR-1/2 Falcon missiles extended from the wingtip pods

The subsequent F-89H, which entered service in 1956, had an E-9 fire control system like that of the early F-102 and massive new wingtip pods, each holding three Falcons (usually three

supersonic interceptors, so it was phased out of USAF service by 1959.[41]

The final variant was the F-89J, which was based on the F-89D, but replaced the standard wingtip missile pod/tanks with 600-US-gallon (500 imp gal; 2,300 L) fuel tanks and fitted a pylon under each wing for a single

Semi Automatic Ground Environment (SAGE) air-defense system.[43][44]

A total of 1,050 Scorpions of all variants were produced.

Variants

XF-89
First prototype, powered by two 4,000 lbf (17.79 kN)
Allison J35-A-9 engines.[45]
XF-89A
Second prototype. Fitted with more powerful 5,100 lbf (22.69 kN) dry (6,800 lbf (30.25 kN) wet)
Allison J35-A-21A engines and revised, pointed nose with cannon armament.[45]
F-89A
First production version, eight built. Fitted with a revised tailplane and six cannon armaments.[45]
DF-89A
F-89As converted into drone control aircraft.
F-89B
Second production version with upgraded avionics. 40 built.[45]
DF-89B
F-89Bs converted into drone control aircraft.
F-89C
Third production version with more powerful 5,600 lbf (24.91 kN) dry (7,400 lbf (32.92 kN) wet)
Allison J35-A-33 engines. 164 built.[45][46]
YF-89D
Conversion of one F-89B to test new avionics and armament of F-89D.[45]
F-89D
Main production version, which saw the deletion of the six 20-millimeter cannons in favor of 104 rockets in wing pods, installation of a new Hughes E-6 fire-control system, AN/APG-40 radar, and the AN/APA-84 computer. This new system allowed a lead-collision attack in place of the previous lead-pursuit-curve technique. A total of 682 were built.[35][45]
YF-89E
One-off prototype to test the 7,000 lbf (31.14 kN) dry (9,500 lbf (42.26 kN) wet)
Allison YJ71-A-3 engine, converted from an F-89C.[45][47]
F-89F
Proposed version with revised fuselage and wings, powered by 10,200 lbf (45.37 kN) dry (14,500 lbf (64.50 kN) wet)
Allison J71-A-7 engines, never built.[47][48]
F-89G
Proposed version equipped with Hughes MA-1 fire control and GAR-1/GAR-2 Falcon air-to-air missiles, never built.
YF-89H
Modified F-89D to test features of F-89H. Three converted.[49]
F-89H
Version with E-9 fire control system, six Hughes GAR-1/GAR-2 Falcon missiles, and 42 Folding Fin Aircraft Rockets (FFAR). 156 built.[49][50]
Northrop F-89J in 1972
F-89J
Conversion of F-89D with underwing hardpoints for two MB-1 (later AIR-2) Genie nuclear-armed rocket and four Falcon missiles, and carrying either the standard F-89D rocket/fuel pod or pure fuel tanks. 350 were converted from F-89Ds.[51]

Operators

see also: F-89 Scorpion units of the United States Air Force
 United States

Aircraft on display

Joint Base Elmendorf-Richardson
F-89J, AF Serial No. 52-2129, on display at the Air Power Park and Museum in Hampton, Virginia
F-89J, AF Ser. No. 53-2547
F-89B
F-89D
F-89H
F-89J

Specifications (F-89D)

3-view line drawing of the Northrop F-89 Scorpion
3-view line drawing of the Northrop F-89 Scorpion

Data from Scorpion with a Nuclear Sting[78]

General characteristics

  • Crew: 2
  • Length: 53 ft 9.5 in (16.396 m)
  • Wingspan: 59 ft 8.5 in (18.199 m)
  • Height: 17 ft 6 in (5.33 m)
  • Wing area: 606 sq ft (56.3 m2)
  • Aspect ratio: 5.88
  • Airfoil: NACA 0009-64[79]
  • Empty weight: 25,194 lb (11,428 kg)
  • Gross weight: 37,190 lb (16,869 kg)
  • Max takeoff weight: 42,241 lb (19,160 kg)
  • Powerplant: 2 ×
    afterburning turbojet
    engines, 5,440 lbf (24.2 kN) thrust each dry, 7,200 lbf (32 kN) with afterburner

Performance

  • Maximum speed: 645 mph (1,038 km/h, 560 kn) at 10,600 ft (3,231 m)
  • Ferry range: 1,366 mi (2,198 km, 1,187 nmi)
  • Service ceiling: 49,200 ft (15,000 m)
  • Rate of climb: 7,440 ft/min (37.8 m/s)

Armament

  • 2 × pods of 52 2.75 in (70 mm) "Mighty Mouse"
    Mk 4/Mk 40 Folding-Fin Aerial Rockets, for a total of 104.[35]

Avionics

  • Hughes E-6 fire-control system
  • AN/APG-40 radar
  • AN/APA-84 computer

See also

Aircraft of comparable role, configuration, and era

Related lists

References

Citations

  1. ^ Kinsey 1992, p. 3.
  2. ^ Knaack 1978, p. 82.
  3. ^ Blazer and Dorio 1993, pp. 1–3.
  4. ^ a b c Knaack 1978, p. 83.
  5. ^ Air International July 1988, pp. 44–45.
  6. ^ a b Air International July 1988, p. 45.
  7. ^ Isham and McLaren, p. 9.
  8. ^ a b c d e f g h Knaack 1978, p. 84.
  9. ^ Blazer and Dorio 1993, pp. 5–7, 9.
  10. ^ Isham and McLaren, pp. 9–10.
  11. ^ Blazer and Dorio 1993, pp. 6–8.
  12. ^ a b Davis and Menard 1990, p. 5.
  13. ^ Air International July 1988, pp. 45–46.
  14. ^ Davis and Menard 1990, p. 4.
  15. ^ a b c Air International July 1988, p. 46.
  16. ^ Blazer and Dorio 1993, pp. 9–10.
  17. ^ a b c d Knaack 1978, p. 85.
  18. ^ a b Blazer and Dorio 1993, p. 12.
  19. ^ Knaack 1978, pp. 84-85.
  20. ^ Blazer and Dorio 1993, p. 25.
  21. ^ Blazer and Dorio 1993, p. 16.
  22. ^ Blazer and Dorio 1993, pp. 15–16, 19.
  23. ^ Davis and Menard 1990, p. 7.
  24. ^ Knaack 1978, pp. 85-86.
  25. ^ a b Knaack 1978, p. 86.
  26. ^ Knaack 1978, pp. 86-87.
  27. ^ a b Air International July 1988, pp. 47–48.
  28. ^ a b Knaack 1978, p. 87.
  29. ^ Knaack 1978, p. 88.
  30. ^ Knaack 1978, pp. 88–89.
  31. ^ Knaack 1978, p. 89.
  32. ^ Knaack 1978, p. 90.
  33. ^ Knaack 1978, pp. 90-91.
  34. ^ Knaack 1978, p. 91.
  35. ^ a b c Air International August 1988, pp. 88–89.
  36. ^ Knaack 1978, pp. 91-92.
  37. ^ Knaack 1978, p. 93.
  38. ^ Rasmussen, Cecilia (11 September 2005). "'Battle of Palmdale': Sound, Fury and 1 Lost Plane". Los Angeles Times. Retrieved 16 February 2015.
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  40. ^ Knaack 1978, p. 95.
  41. ^ a b Knaack 1978, p. 96.
  42. ^ Knaack 1978, p. 97.
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Bibliography

External links

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