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Skybolt ALBM

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Skybolt Credit: via Andreas Parsch

AKA: AGM-48A; B-87; GAM-87; Skybolt. Status: Retired 1962. First Launch: 1962-04-19. Last Launch: 1962-12-22. Number: 6 . Thrust: 111.00 kN (24,953 lbf). Gross mass: 4,530 kg (9,980 lb). Height: 11.74 m (38.51 ft). Diameter: 1.10 m (3.60 ft). Span: 2.13 m (6.98 ft). Apogee: 20 km (12 mi).

In May 1959 Douglas was awarded the development contract for the WS-138A Skybolt missile. This was an air-launched, solid propellant, nuclear-armed missile designed as a standoff weapon for B-52H, B-70, and British Vulcan bombers. Drop tests began in January 1961, but early powered flights were dogged by failures. The first successful test came on 19 December 1962. On the same day the Kennedy administration cancelled the program, with operational repercussions for the USAF and Royal Air Force. It also created a huge political row between the United States and Britain.

The two-stage rocket used stellar-inertial navigation for precision attack of targets when penetrating Soviet air defenses. The USAF used its �interim' Hound Dog missiles in the standoff role until replaced by the SRAM Short Range Attack Missile in 1972-1976. Britain turned to Polaris submarine-launched missiles as its sole effective nuclear deterrent.

Development Cost $: 440.000 million in 1962 dollars. Maximum range: 1,610 km (1,000 mi). Boost Propulsion: Solid rocket. Maximum speed: 8,060 kph (5,000 mph). Initial Operational Capability: 1963.

Historical Essay � Andreas Parsch

Douglas GAM-87-AGM-48 Skybolt

After studies in 1958 had shown that it was feasible to air-launch ballistic missiles from high-flying strategic bombers, the USAF issued a requirement in 1959 for a long-range ALBM (Air-Launched Ballistic Missile). In May 1959, Douglas was awarded a development contract for the WS (Weapons System) 138A missile, designated GAM-87 Skybolt. Douglas subsequently awarded development subcontracts to Nortronics (guidance system), Aerojet General (propulsion), and General Electric (reentry vehicle). The GAM-87 was intended for use by the B-52H Statofortress and the British Vulcan B.2. Full-scale development was approved in February 1960, and in January 1961, the first drop tests of unpowered Skybolts occurred. Powered and guided flight tests of XGAM-87A prototypes began in April 1962, but the first five tests were all failures. The first fully successful Skybolt flight occurred on 19 December 1962, but on that same day the whole program was cancelled and the production of the operational GAM-87A stopped. Although Skybolt certainly had its technical difficulties and was well behind schedule, the cancellation was also very much influenced by economical and political factors.

The XGAM-87A was ballistic missile powered by a two-stage solid-fuel rocket motor and guided by a stellar-inertial navigation system. Each B-52H was to carry four GAM-87As, two each side-by-side on two underwing pylons. While on the pylon, the Skybolt was fitted with a tail cone to reduce aerodynamic drag. For launch, the missile was dropped from the pylon, the tail cone was ejected, and the first motor stage ignited. After first stage burnout, the Skybolt coasted for a while before the second stage ignited. First stage control was by movable tail fins, while the second stage was equipped with a gimballed nozzle.

Limited flight tests with the remaining XGAM-87A missiles continued after program cancellation, and in June 1963, the XGAM-87A was redesignated as XAGM-48A. In total, Douglas built less than 100 Skybolt missiles.

Note: Data given by several sources show slight variations. Figures given below may therefore be inaccurate!

Data for XGAM-87A (XAGM-48A):

[1] Bill Gunston: "The Illustrated Encyclopedia of Rockets and Missiles", Salamander Books Ltd, 1979
[2] Dennis R. Jenkins, Brian Rogers: "Boeing B-52G-H Stratofortress", Aerofax, 1990

Family: aircraft-launched, air-to-surface. Country: USA. Launch Sites: Cape Canaveral AMR DZ. Stages: Skybolt, Skybolt 2. Agency: Douglas. More at: 8647. Bibliography: 2, 563.

• Test mission - . Nation: USA. Agency: USAF. Apogee: 10 km (6 mi).

• No burn test - . Nation: USA. Agency: USAF. Apogee: 12 km (7 mi).

• Test mission - . Nation: USA. Agency: USAF. Apogee: 10 km (6 mi).

• Test mission - . Nation: USA. Agency: USAF. Apogee: 15 km (9 mi).

• Test mission - . Nation: USA. Agency: USAF. Apogee: 10 km (6 mi).

• Test mission - . Nation: USA. Agency: USAF. Apogee: 580 km (360 mi).