Tuesday, December 26, 2023

Nuclear-armed stinger from Hawthorne: the Northrop F-89J

In 1955, the Douglas Aircraft Company began full-scale development of a short-range unguided air-to-air rocket to carry a 1.5 kiloton W25 nuclear warhead, the MB-1 Genie, after it became clear that traditional World War II-era US fighter armament would be inadequate to repel a bombing attack by squadrons of the Soviet Union's new gas turbine powered strategic bombers, the Myasishchev M-4, Tupolev Tu-16, and Tupolev Tu-95. The MB-1 Genie obviated the need for precise accuracy when targeting enemy bombers because it was designed with a large nuclear blast radius. Beginning in March 1956, Northrop modified numerous F-89D Scorpion all-weather interceptors from the F-89D-35 to -75 production blocks to carry the MB-1 Genie under Project Bellboy, and the company designation N-160 was allocated to this scheme. The resulting Genie-armed Scorpion, designated F-89J, carried two MB-1 Genies below launching rails that were mounted on the underwing pylons and had the standard wingtip missile pod/tanks replaced with 600 gallon (2,271 liter) fuel tanks, although a few F-89Js retained the wingtip tanks of the F-89D. Later, the F-89J received an extra modification by adding two more underwing pylons inboard of the launching rails for the Genie to carry four Falcon air-to-air missiles tipped with non-nuclear warheads. The F-89J was equipped with the Hughes MG-12 fire-control system (a upgraded and more advanced development of the E-5 fire control system installed on the F-89D), which could allow it to attack enemy bombers at much higher altitudes by making it easier for the crew to launch the Genie rockets while in a nose-up, climbing altitude. During interception of an enemy bomber formation, the MG-12 fire-control radar tracked a target and assigned a Genie to its target, after which the pilot armed the nuclear warhead and fired the Genie at the bomber pack before pulling the interceptor into a tight turn to escape the nuclear detonation and then proceeding to use remote control to allow the Genie's nuclear warhead to explode and destroy enemy bombers.

Left: Two F-89Js (serial numbers 52-1848 and 52-1862) in flight, 1958
Right: An F-89J (serial number 52-1949) at the March Field Air Museum, photographed by me on December 17, 2022.

In November 1956, the US Air Force began taking deliveries of the F-89J, the 84th Fighter Interceptor Squadron based at Hamilton AFB in Novato, California being the first unit to receive the F-89J, and standing active alerts of the F-89J with the Genie started on January 1, 1957. A total of 350 F-89Ds were converted to F-89J standard, with modifications completed by February 1958, and the US Air Force assigned the system code WS-205G (Weapons System 205G) to the F-89J. On July 19, 1957, as part of Operation Plumbbob, the F-89J carried out the first and only live firing of a Genie (codenamed John) when an F-89J with serial number 53-2547 fired an MB-1 Genie over the Yucca Flats Nuclear Test Site in southern Nevada, with the rocket's warhead detonating at an altitude of 15,000 feet (4,500 meters). To prove that the Genie was safe for use over populated areas in the event that Soviet bombers would penetrate US airspace, a group of five Air Force officers volunteered to stand uncovered in their light summer uniforms underneath the blast, and they were apparently spared from the effects of the blast after the live-firing test of the Genie over the Yucca Flats.

Despite proving to the US Air Force that a live-firing of a nuclear-armed unguided air-to-air rocket was feasible, the F-89J was destined to have a brief operational career with the Air Defense Command, and beginning in July 1959 it was replaced in ADC units by the supersonic F-101B Voodoo and F-106 Delta Dart, which also carried the Genie air-to-air rocket. The F-89Js were then transferred to the Air National Guard, operating with ANG until late 1968, when they were retired. In an interesting footnote, in 1963 ten F-89Js were stripped of their nose radars, fitted with additional underwing fuel tanks, and eventually used for testing Nike missile defenses in Japan, being redesignated DF-89J.  

References:

Balzer, G., and Dario, M., 1993. Northrop F-89 Scorpion. Leicester, UK: Aerofax.

Chong, T., 2016. Flying Wings & Radical Things: Northrop's Secret Aerospace Projects & Concepts 1939-1994. Forest Lake, MN: Specialty Press.

Davis, L., and Menard, D., 1990. F-89 Scorpion in Action (Aircraft Number 104). Carrollton, TX: Squadron/Signal Publications.

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