Encyclopedia Astronautica
Skybolt



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Skybolt
Credit: via Andreas Parsch
American strategic air-to-surface ballistic missile, development started in 1959. Program cancelled amid huge controversy in 1963 after Britain had agreed to buy the weapon in place of its own Blue Streak.

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.

Failures: 5. Success Rate: 16.67%. First Fail Date: 1962-04-19. Last Fail Date: 1962-11-28. Launch data is: incomplete. 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.

Specifications

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

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

Length 11.66 m (38 ft 3 in)
Finspan 1.68 m (5 ft 6 in)
Diameter 89 cm (35 in)
Weight 5000 kg (11000 lb)
Speed 15300 km-h (9500 mph)
Ceiling 480+ km (300+ miles)
Range 1850 km (1150 miles)
Propulsion Aerojet Genaral two-stage solid-fueled rocket
Warhead W-59 thermonuclear (1.2 MT)
Main Sources

[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


AKA: B-87; AGM-48A; Skybolt; GAM-87.
Status: Retired 1962.
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).
Thrust: 111.00 kN (24,953 lbf).
Apogee: 20 km (12 mi).
First Launch: 1962.04.19.
Last Launch: 1962.12.22.
Number: 7 .

More... - Chronology...


Associated Countries
See also
  • missile Guided self-propelled military weapon (as opposed to rocket, an unguided self-propelled weapon). More...

Associated Manufacturers and Agencies
  • Douglas American manufacturer of rockets, spacecraft, and rocket engines. Boeing Huntington Beach, Huntington Beach, CA, USA. More...

Bibliography
  • McDowell, Jonathan, Jonathan's Space Home Page (launch records), Harvard University, 1997-present. Web Address when accessed: here.
  • Parsch, Andreas, DesignationSystems.Net, Web Address when accessed: here.

Associated Launch Sites
  • AMR DZ Air-launched rocket drop zone known to have been used for 13 launches from 1958 to 1962, reaching up to 580 kilometers altitude. More...

Associated Stages

Skybolt Chronology


1962 April 19 - . Launch Site: AMR DZ. Launch Pad: 29.0 N x 79.0 W. Launch Platform: B-52G. Launch Vehicle: Skybolt. LV Configuration: Skybolt ALBM 20025. FAILURE: Failure.
  • Test mission - . Nation: USA. Agency: USAF. Apogee: 10 km (6 mi).

1962 June 29 - . Launch Site: AMR DZ. Launch Pad: 29.0 N x 79.0 W. Launch Platform: B-52. Launch Vehicle: Skybolt. LV Configuration: Skybolt ALBM 20026. FAILURE: Failure.
  • No burn test - . Nation: USA. Agency: USAF. Apogee: 12 km (7 mi).

1962 September 13 - . Launch Site: AMR DZ. Launch Pad: 29.0 N x 79.0 W. Launch Platform: B-52. Launch Vehicle: Skybolt. LV Configuration: Skybolt ALBM 20027. FAILURE: Failure.
  • Test mission - . Nation: USA. Agency: USAF. Apogee: 10 km (6 mi).

1962 September 25 - . 14:09 GMT - . Launch Site: AMR DZ. Launch Pad: 29.0 N x 79.0 W. Launch Platform: B-52. Launch Vehicle: Skybolt. LV Configuration: Skybolt ALBM 20028. FAILURE: Failure.
  • Test mission - . Nation: USA. Agency: USAF. Apogee: 15 km (9 mi).

1962 September 25 - . 14:09 GMT - . Launch Site: AMR DZ. Launch Vehicle: Skybolt. LV Configuration: Skybolt 20028.
  • PL.4 - . Nation: USA. Agency: USAF. Apogee: 100 km (60 mi).

1962 November 28 - . 18:45 GMT - . Launch Site: AMR DZ. Launch Pad: 29.0 N x 79.0 W. Launch Platform: B-52. Launch Vehicle: Skybolt. LV Configuration: Skybolt ALBM 20031. FAILURE: Failure.
  • Test mission - . Nation: USA. Agency: USAF. Apogee: 10 km (6 mi).

1962 December 22 - . 14:15 GMT - . Launch Site: AMR DZ. Launch Pad: 29.0 N x 79.0 W. Launch Platform: B-52. Launch Vehicle: Skybolt. LV Configuration: Skybolt ALBM 20032.
  • Test mission - . Nation: USA. Agency: USAF. Apogee: 580 km (360 mi).

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