Saturday, July 20, 2013

Skybolt: The First (and only) USAF ALBM: Air Force work on air launched ballistic missiles began in earnest by the late 1950s, and was spurred by several factors. Many (incorrectly) regarded the ballistic missile as a replacement for manned bombers (just as SAMs were to have replaced interceptors) but combining the two did have its attractions. ICBMs could not be recalled after firing, or launched and then kept in a holding position; bombers had these capabilities, as well as being capable of use in conventional strikes, and assuming successful completion of a mission and recovery, could be used again. The aircraft, however, were increasingly vulnerable to air defenses, whereas missile warheads were essentially unstoppable. There was a political aspect as well, as it was becoming apparent that the Navy's Polaris system had the potential for being an almost invulnerable nuclear deterrent force, while the Strategic Air Command was restricted to operating fixed land-based missiles and vulnerable bombers. Developing a mobile strike force using bombers and ALBMs meant that the USAF would have a chance to compete with Polaris for defense dollars.

Although conventional aircraft obviously could not maintain standing patrols for months at a time as submarines could, SAC's airborne alert program had much the same effect, using rotating flights to keep a portion of the force in the air at any given time. There were also long-range plans for nuclear powered bombers that while not having the on-station endurance of a submarine, could mount patrols of very long duration while carrying ALBMs.

Martin's Bold Orion ALBM prototype program was run in 1959, and used three-stage missiles of various configurations, with the launch aircraft being a refitted B-47 Stratojet. A series of launches were made, with the final shot being acknowledged as the first known ASAT test, as the missile's trajectory came close enough (several miles) to the orbit of an Explorer satellite that the "bird" could have been destroyed had the Orion been carrying a warhead.

There was another late 1950s ALBM demonstrator program, this time using the Convair B-58 Hustler as a launch platform. Lockheed would design and build the High Virgo demonstrator missiles, which would be carried and launched from the Hustler's centerline station, which normally carried the aircraft's fuel/bomb pod.

 Like Bold Orion, High Virgo was basically a lash-up of existing solid-fuel stages. An attempt at an ASAT test is said to have been made during the High Virgo launches, but apparently did not succeed. Despite the early work on ALBMs done by Lockheed and Martin, the contract for an operational-type weapon went to Douglas, in 1960. Developed under the WS-138 program, the Skybolt was to be a two stage solid-fuel missile capable of carrying a W59 warhead in a Mk.7 reentry vehicle some 1,500 miles. Launch aircraft would (at least initially) be late-model B-52s, which would carry four missiles externally with a pair of missiles on each underwing pylon.

Although Skybolt was intended primarily as a weapon for the B-52G/H force, refitting older models of the Stratofortress to carry the missile was also considered. Of SAC's other bombers, the B-47 was in the process of being retired, the B-58 was not earmarked as a carrier, and extensive changes to the design would have been necessary to match the weapon to an operational version of the B-70.

The British joined the Skybolt program early on; RAF Bomber Command badly needed such a weapon, as its "V-Bombers" were far fewer in number than SAC's huge force, and as such needed a standoff weapon to keep the limited number of aircraft as effective as possible. The Vulcan B.2 would have carried four missiles, and a single B.2 test ship was used to conduct compatibility and dummy drop tests. The Handley-Page Victor B.2 was another potential carrier, and there was even a proposal for a missile platform version of the Vickers VC.10 airliner armed with the Skybolt.

The first Skybolt launch took place on the afternoon of April 19, 1962, with the B-52 launch aircraft staging from Eglin AFB, Florida. A single Skybolt was carried under the right wing, with an inert example fitted on the port launcher. The launch and first stage ignition took place as planned, but a failure of the second stage meant that the planned 1,000 mile range for this first shot was not achieved. The second Skybolt test, on June 29, failed completely when the first stage did not ignite.

Skybolt's high cost, coupled with the troubled development program, made it a prime target for cancellation. During a conference between President Kennedy and British Prime Minister Harold MacMillan in the Bahamas in December 1962, Kennedy let it be known that the US would not in the end buy Skybolt for SAC, although the program could be continued by the British. Becoming the sole customer for Skybolt would have driven costs too high, and MacMillan settled on an alternative offered by Kennedy, namely the supply of Polaris SLBMs.

Although the Polaris decision would preserve Britain's nuclear deterrent, the fact that a new ALBM would not be forthcoming meant that the V-Bomber force would have a limited lifespan ahead of it, at least in its original strategic role. The British-developed Blue Steel ASM would be bought in limited numbers, but that weapon's range and speed could not compare with those of Skybolt, and development of a more capable Mk.2 version had been abandoned. Given the cancellation, there was no justification seen in proceeding with the Vulcan B.3 design, which could have carried a triple load of missiles under each wing. However, vestiges of the Skybolt system were to survive to the end of the Vulcan B.2's service life in the bomber role, as at least some aircraft had provisions for the missiles, and these were used to haul conventional weapons to the Falklands.

Ironically, a final Skybolt test launch in December was hailed by some as a success, although it was later revealed that the missile did not carry a representative warhead. There was considerable political furor over the Skybolt cancellation, especially given the Kennedy Adminstration's lack of enthusiasm for bomber related programs, in particular the B-70. Critics contended that without the B-70 or Skybolt, the future of the manned strategic bomber was in doubt.

In the late 1970s, nearly two decades after the cancellation of Skybolt, the USAF was again looking at putting small ballistic missiles on strategic bombers. Like Skybolt, the Longbow missile was to be a two-stage weapon, but would be far smaller than the older missile, although thanks to advances in propellant technology the range would actually be greater. Although Longbow could have been pushed as part of the early 1980s US nuclear buildup, the program was not picked up, as there were other systems such as Pershing II and GLCM that had already reached the hardware stage.

Bibliography
Magazine Articles
"USAF Concern Over Skybolt" Aviation Week August 15, 1960 p.27

Irving Stone "Skybolt ALBM Gets Priority for 1964 Availability" Aviation Week October 3, 1960 p.26-28 4 illustrations

"Britain Finances Vulcan-Skybolt Work" Aviation Week January 2, 1961 p.16

"Coming: A Deadly B-52 Loaded With Missiles" U.S. News & World Report January 16, 1961 p.8

[Photo: Skybolt] advertisement U.S. News & World Report May 8, 1961 p.25

"Skybolt ALBM Has New Configuration" Aviation Week June 5, 1961 p.42 1  illustration

[Photo: Skybolt] advertisement Aviation Week June 5, 1961 p.112

"B-52H Makes Test of Skybolt Compatibility" Aviation Week June 19, 1961 p.33 1 illustration

"Skybolt Successfully Air-Launched From B-52G" Aviation Week & Space Technology April 30, 1962 p.28-29 6 illustrations

"RAF Vulcan Tested With Dummy Skybolts" Aviation Week & Space Technology April 9, 1962 p.118 1 illustration

Photo: B-52H w/Skybolts Aviation Week & Space Technology March 12, 1962 p.73

"Skybolt - What Now?" Air Pictorial February 1963 p.32-33. One photo of a Vulcan with a Skybolt test vehicle mounted.

 "Two New Ballistic Missiles Scrutinized" Aviation Week & Space Technology January 29, 1979 p.101+ 3 illustrations

Newspaper Articles

"Skybolt: A Promising New Weapon" The New York Times April 21, 1962 p.4 c.4 2 illustrations

"Two U.S. Missiles Score In New Tests" The New York Times June 30, 1962 p.5 c.2

Web Resources
A restored Skybolt mockup at the Air Force Space & Missile Museum
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