The
Douglas GAM-87 Skybolt (AGM-48 under the
1963 Tri-service system) was an
air-launched ballistic missile
An air-launched ballistic missile (ALBM) is a ballistic missile launched from an aircraft. An ALBM allows the launch aircraft to stand off at long distances from its target, keeping it well outside the range of defensive weapons like anti-aircr ...
(ALBM) developed by the United States during the late 1950s. The basic concept was to allow US
strategic bomber
A strategic bomber is a medium- to long-range Penetrator (aircraft), penetration bomber aircraft designed to drop large amounts of air-to-ground weaponry onto a distant target for the purposes of debilitating the enemy's capacity to wage war. Unl ...
s to launch their weapons from well outside the range of Soviet defenses, as much as from their targets. To do this in an air-launched form, a lightweight
thermonuclear warhead
A thermonuclear weapon, fusion weapon or hydrogen bomb (H-bomb) is a second-generation nuclear weapon design. Its greater sophistication affords it vastly greater destructive power than first-generation nuclear bombs, a more compact size, a lowe ...
was needed. Initially, the
W47 from the
Polaris missile
The UGM-27 Polaris missile was a two-stage solid-fuel rocket, solid-fueled nuclear warhead, nuclear-armed submarine-launched ballistic missile (SLBM). As the United States Navy's first SLBM, it served from 1961 to 1980.
In the mid-1950s the Navy ...
was selected, but it was later replaced by the
W59 from the
Minuteman missile.
The UK joined the Skybolt program in 1960, intending to use it on their
V bomber
The "V bombers" were the Royal Air Force (RAF) aircraft during the 1950s and 1960s that comprised the Nuclear weapons and the United Kingdom, United Kingdom's strategic nuclear strike force known officially as the V force or Bomber Command Mai ...
force. When the design added a
star tracker
A star tracker is an optical device that measures the positions of stars using photocells or a camera.
As the positions of many stars have been measured by astronomers to a high degree of accuracy, a star tracker on a satellite or spacecraft may ...
in addition to its
inertial navigation system
An inertial navigation system (INS; also inertial guidance system, inertial instrument) is a navigation device that uses motion sensors (accelerometers), rotation sensors (gyroscopes) and a computer to continuously calculate by dead reckoning th ...
(INS) this meant that it could only be carried externally where the tracker could see the sky. This requirement along with the required ground clearance on takeoff limited it to the
Avro Vulcan
The Avro Vulcan (later Hawker Siddeley Vulcan from July 1963) was a jet-powered, tailless, delta-wing, high-altitude, strategic bomber, which was operated by the Royal Air Force (RAF) from 1956 until 1984. Aircraft manufacturer A.V. Roe ...
bomber. Several design decisions in the W47 led the RAF to question its safety, so they intended to use their own
Red Snow warheads. This was a heavier warhead and would reduce the range to about , meaning the bombers would have to cross the Soviet coastline to attack
Moscow
Moscow is the Capital city, capital and List of cities and towns in Russia by population, largest city of Russia, standing on the Moskva (river), Moskva River in Central Russia. It has a population estimated at over 13 million residents with ...
.
Testing began in 1962 and was initially marked by a string of failures. These failures, along with a lack of mission after the successful development of
submarine-launched ballistic missile
A submarine-launched ballistic missile (SLBM) is a ballistic missile capable of being launched from Ballistic missile submarine, submarines. Modern variants usually deliver multiple independently targetable reentry vehicles (MIRVs), each of which ...
s (SLBMs), led to its cancellation in December 1962.
[af.mil](_blank)
/ref> The UK had decided to base its entire 1960s deterrent force on Skybolt, and its cancellation led to a major disagreement between the UK and US, known today as the " Skybolt Crisis". This was resolved by a series of meetings that led to the Royal Navy
The Royal Navy (RN) is the naval warfare force of the United Kingdom. It is a component of His Majesty's Naval Service, and its officers hold their commissions from the King of the United Kingdom, King. Although warships were used by Kingdom ...
gaining the UGM-27 Polaris
The UGM-27 Polaris missile was a two-stage solid-fueled nuclear-armed submarine-launched ballistic missile (SLBM). As the United States Navy's first SLBM, it served from 1961 to 1980.
In the mid-1950s the Navy was involved in the Jupiter missi ...
missile and construction of the s to launch them.
History
Background
The US Air Force
The United States Air Force (USAF) is the Air force, air service branch of the United States Department of Defense. It is one of the six United States Armed Forces and one of the eight uniformed services of the United States. Tracing its ori ...
had built up an enormous fleet of strategic bomber
A strategic bomber is a medium- to long-range Penetrator (aircraft), penetration bomber aircraft designed to drop large amounts of air-to-ground weaponry onto a distant target for the purposes of debilitating the enemy's capacity to wage war. Unl ...
s during the 1950s, only to see them threatened by the possibility of a surprise attack by Soviet ICBM
An intercontinental ballistic missile (ICBM) is a ballistic missile with a range (aeronautics), range greater than , primarily designed for nuclear weapons delivery (delivering one or more Thermonuclear weapon, thermonuclear warheads). Conven ...
s. As the US bombers were located at only a small number of air bases, a relatively small fleet of missiles could attack all of them at once. The US had been developing its own ICBMs as well, but early models, like the SM-65 Atlas
The SM-65 Atlas was the first operational intercontinental ballistic missile (ICBM) developed by the United States and the first member of the Atlas rocket family. It was built for the U.S. Air Force by the Convair Division of General ...
, required some time to prepare to launch from their surface launchers and were vulnerable to sneak air attack. A carefully timed attack from Soviet bombers against US missiles and their ICBMs against US bomber fields could inflict serious damage.
The one weapon system that was not open to attack was the US Navy
The United States Navy (USN) is the naval warfare, maritime military branch, service branch of the United States Department of Defense. It is the world's most powerful navy with the largest Displacement (ship), displacement, at 4.5 millio ...
's Polaris missile
The UGM-27 Polaris missile was a two-stage solid-fuel rocket, solid-fueled nuclear warhead, nuclear-armed submarine-launched ballistic missile (SLBM). As the United States Navy's first SLBM, it served from 1961 to 1980.
In the mid-1950s the Navy ...
system. The Polaris equipped submarines could cruise in large areas of the Atlantic or Pacific where the Soviet fleet was unable to find them, and launch their missiles with impunity. If the goal of the nuclear force was to maintain deterrence by ensuring that a counterstrike would be launched, Polaris met this goal in a way the existing Air Force fleet could not. This fact was more worrying to the Air Force than the Soviet arsenal and generated a number of internal reports on how to deal with this threat to their dominance in the strategic field.[
]
WS-199 and WS-138
In response, in 1957 the Air Force began studying solutions to the "Puzzle of Polaris" under the WS-199 program. WS-199 was a grab-bag effort, studying anything that might improve the survivability of the Air Force strike capability. Primary among the concepts were two air-launched ballistic missiles, Bold Orion and High Virgo. These systems would give the Air Force a method somewhat similar to the Navy's; in times of high alert, the bomber force would be sent to holding positions far outside the range of any Soviet defenses, and then launch their missiles on command. Using aerial refueling
Aerial refueling ( en-us), or aerial refuelling ( en-gb), also referred to as air refueling, in-flight refueling (IFR), air-to-air refueling (AAR), and tanking, is the process of transferring aviation fuel from one aircraft (the tanker) to an ...
, a bomber might be expected to be able to loiter for as long as a day.
This system had a major advantage compared to Polaris, as the aircraft could be sent radio instructions to retarget the missiles before launch. In theory, the bombers could be used as a second-strike weapon, attacking only those targets that had been missed in a first-strike, or alternately, being switched from counterforce to countervalue targets or vice versa. Ground-based systems like Atlas and Polaris lacked this ability, and could only be retargeted with a significant amount of effort. Even the latest Air Force design, the LGM-30 Minuteman
The LGM-30 Minuteman is an American land-based intercontinental ballistic missile (ICBM) in service with the Air Force Global Strike Command. , the LGM-30G (Version 3) is the only land-based ICBM in service in the United States and represents th ...
, required changes in targeting data to be loaded from magnetic tape in a process that took several weeks.
WS-199 was generally successful, but the two ALBMs had a shorter range than desired. The Air Force tendered bids for a longer-range version in early 1959. Douglas Aircraft
The Douglas Aircraft Company was an American aerospace and defense company based in Southern California. Founded in 1921 by Donald Wills Douglas Sr., it merged with McDonnell Aircraft in 1967 to form McDonnell Douglas, where it operated as a di ...
received the prime contract in May, and in turn subcontracted to Northrop for the guidance system, Aerojet
Aerojet was an American rocket and missile propulsion manufacturer based primarily in Rancho Cordova, California, with divisions in Redmond, Washington, Orange and Gainesville in Virginia, and Camden, Arkansas. Aerojet was owned by GenCorp, ...
for the propulsion system, and General Electric
General Electric Company (GE) was an American Multinational corporation, multinational Conglomerate (company), conglomerate founded in 1892, incorporated in the New York (state), state of New York and headquartered in Boston.
Over the year ...
for the reentry vehicle. The system was initially known as WS-138A and was given the official name GAM-87 Skybolt in 1960.
British involvement
At the same time, the Royal Air Force
The Royal Air Force (RAF) is the Air force, air and space force of the United Kingdom, British Overseas Territories and Crown Dependencies. It was formed towards the end of the World War I, First World War on 1 April 1918, on the merger of t ...
(RAF) was having problems with their MRBM
A medium-range ballistic missile (MRBM) is a type of ballistic missile with medium range, this last classification depending on the standards of certain organizations. Within the U.S. Department of Defense, a medium-range missile is defined ...
missile project, the Blue Streak, which was long overdue. Even if this was successful it faced the serious problem of basing. No fixed land-based missile system could be credibly installed in the British Isles; they were well within the range of Soviet air strikes. The limited land mass available meant it would be relatively easy for missile sites to be spotted no matter what security measures were taken, and flying time for a jet bomber from the coast to any potential inland location would be on the order of minutes.
This left the deterrent based on their own bomber force, the V bomber
The "V bombers" were the Royal Air Force (RAF) aircraft during the 1950s and 1960s that comprised the Nuclear weapons and the United Kingdom, United Kingdom's strategic nuclear strike force known officially as the V force or Bomber Command Mai ...
fleet, which the RAF had already long concluded would be unable to penetrate Soviet defenses by about 1960. The RAF was in the process of introducing their own stand-off missile, the ranged Mach 3 Blue Steel. While capable, the missile flew at altitudes and speeds that left it vulnerable to improving SAMs, and it had a number of reliability and serviceability issues that made it less than ideal. A faster, longer-ranged version was being talked about, Blue Steel II, but it would be some time before it could enter service.
The long-range Skybolt would eliminate the need for both the Blue Streak and the Blue Steel II. Blue Steel II was canceled in December 1959 and the British Cabinet decided in February 1960 to cancel Blue Streak as well. Prime Minister Macmillan met President Eisenhower
Dwight David "Ike" Eisenhower (born David Dwight Eisenhower; October 14, 1890 – March 28, 1969) was the 34th president of the United States, serving from 1953 to 1961. During World War II, he was Supreme Commander of the Allied Expeditionar ...
in March 1960 and agreed to purchase 144 Skybolts for the RAF. By agreement, British funding for research and development was limited to that required to modify the V bombers to take the missile, but the British were allowed to fit their own warheads. In exchange, the Americans were given nuclear submarine basing facilities in Scotland. Following the agreement, the Blue Streak program was formally canceled in April 1960 and in May 1960 an agreement for an initial order of 100 Skybolts was concluded.
Avro
Avro (an initialism of the founder's name) was a British aircraft manufacturer. Its designs include the Avro 504, used as a trainer in the First World War, the Avro Lancaster, one of the pre-eminent bombers of the Second World War, and the d ...
was made an associate contractor to manage the Skybolt program for the United Kingdom and four different schemes were submitted to find a platform for the missile. A number of different aircraft were considered, including a variant of the Vickers VC10
The Vickers VC10 is a retired mid-sized, narrow-body long-range British jet airliner designed and built by Vickers-Armstrongs (Aircraft) Ltd and first flown at Brooklands, Surrey, in 1962. The VC10 is often compared to the larger Soviet Ily ...
airliner and two of the current V bombers, the Avro Vulcan
The Avro Vulcan (later Hawker Siddeley Vulcan from July 1963) was a jet-powered, tailless, delta-wing, high-altitude, strategic bomber, which was operated by the Royal Air Force (RAF) from 1956 until 1984. Aircraft manufacturer A.V. Roe ...
and Handley Page Victor
The Handley Page Victor was a British jet-powered strategic bomber developed and produced by Handley Page during the Cold War. It was the third and final ''V bomber'' to be operated by the Royal Air Force (RAF), the other two being the Vickers ...
. It was decided to use the Vulcan to initially carry two missiles each on hardpoints outboard of the main landing gear.
Development and testing
During development, it was decided that the system could not reach the required accuracy at the desired range without improvements to the guidance system. This led to the introduction of a star tracker
A star tracker is an optical device that measures the positions of stars using photocells or a camera.
As the positions of many stars have been measured by astronomers to a high degree of accuracy, a star tracker on a satellite or spacecraft may ...
platform that would enhance the existing inertial navigation system
An inertial navigation system (INS; also inertial guidance system, inertial instrument) is a navigation device that uses motion sensors (accelerometers), rotation sensors (gyroscopes) and a computer to continuously calculate by dead reckoning th ...
. For this role, the system had to be capable of tracking bright stars in direct sunlight, a challenging requirement. Star trackers have to be provided with a relatively accurate location in order to point their trackers at selected stars. Over a long flight, the INS would drift too much to provide the needed accuracy. Instead, the tracker has to be able to track the stars during flight, continually updating the INS.
This change meant that the missile could only be carried in locations where the front of the missile could continually observe the sky. This had always been the case on the USAF's B-52
The Boeing B-52 Stratofortress is an American long-range, subsonic, jet-powered strategic bomber. The B-52 was designed and built by Boeing, which has continued to provide support and upgrades. It has been operated by the United States Ai ...
bombers, where they were carried under the narrow-chord wings and the nose projected out in front. But this presented a problem for some of the UK designs, especially the Victor, where the layout of the wing, engines and landing gear left the mounting point behind the massive wing's leading edge. As Valiant had limited range, the decision was made to move forward only with Vulcan, where its mounting points allowed the nose of the missile to project in front of this aircraft's delta wing
A delta wing is a wing shaped in the form of a triangle. It is named for its similarity in shape to the Greek uppercase letter delta (letter), delta (Δ).
Although long studied, the delta wing did not find significant practical applications unti ...
.
By 1961, several test articles were ready for testing from B-52s, with drop tests starting in January. In January 1961 a Vulcan visited the Douglas plant at Santa Monica, California, to ensure the modifications to the aircraft were electrically compatible with the missile. In Britain, compatibility trials with mockups started on the Vulcan.
Testing started with unpowered drop tests to ensure safe separating from the launch aircraft. Powered tests started in April 1962, but the test series went badly, with the first five trials ending in failure. The first fully successful flight occurred on 19 December 1962.
Cancellation
By this point, the value of the Skybolt system in the US had been seriously eroded. The Polaris had recently gone into service, with overall capabilities similar to Skybolt, but with "loiter" times on the order of months instead of hours. The US Air Force was well into the process of developing the Minuteman missile, whose improved accuracy reduced the need for any bomber attacks. Robert McNamara
Robert Strange McNamara (; June 9, 1916 – July 6, 2009) was an American businessman and government official who served as the eighth United States secretary of defense from 1961 to 1968 under presidents John F. Kennedy and Lyndon B. Johnson ...
was particularly opposed to the bomber force and repeatedly stated he felt that the combination of SLBMs and ICBMs would render them useless. He pressed for the cancellation of Skybolt as unnecessary.
The British had canceled all other projects to concentrate fully on Skybolt. When McNamara informed them that they were considering canceling the program in November 1962, a firestorm of protest broke out in the House of Commons. Jo Grimond
Joseph Grimond, Baron Grimond, (; 29 July 1913 – 24 October 1993) was a British politician, leader of the Liberal Party for eleven years from 1956 to 1967 and again briefly on an interim basis in 1976.
Grimond was a long-term supporter of ...
noted "Does not this mark the absolute failure of the policy of the independent deterrent? Is it not the case that everybody else in the world knew this, except the Conservative Party in this country?"["Hansard 17 December 1962, SKYBOLT MISSILE (TALKS)"]
, Hansard
''Hansard'' is the transcripts of parliamentary debates in Britain and many Commonwealth of Nations, Commonwealth countries. It is named after Thomas Curson Hansard (1776–1833), a London printer and publisher, who was the first official printe ...
, 17 December 1962 President Kennedy officially cancelled the program on 22 December 1962.
As the political row grew into a major crisis, an emergency meeting between parties from the US and UK was called, leading to the Nassau agreement
The Nassau Agreement, concluded on 21 December 1962, was an agreement negotiated between President of the United States, John F. Kennedy, and Harold Macmillan, the Prime Minister of the United Kingdom, to end the Skybolt Crisis. A series of meeti ...
. Over the next few days a new plan was hammered out that saw the UK purchase the Polaris
Polaris is a star in the northern circumpolar constellation of Ursa Minor. It is designated α Ursae Minoris (Latinisation of names, Latinized to ''Alpha Ursae Minoris'') and is commonly called the North Star or Pole Star. With an ...
SLBM, but equipped with British warheads that lacked the dual-key system. The UK would thus retain its independent deterrent force, although its control passed from the RAF largely to the Royal Navy
The Royal Navy (RN) is the naval warfare force of the United Kingdom. It is a component of His Majesty's Naval Service, and its officers hold their commissions from the King of the United Kingdom, King. Although warships were used by Kingdom ...
. The Polaris, a much better weapon system for the UK, was a major "scoop" and has been referred to as "almost the bargain of the century". The RAF kept a tactical nuclear capability with the WE.177 which armed V bombers and later the Panavia Tornado
The Panavia Tornado is a family of twin-engine, variable-sweep wing multi-role combat aircraft, jointly developed and manufactured by Italy, the United Kingdom and Germany. There are three primary #Variants, Tornado variants: the Tornado IDS ...
force.
A B-52G launched the last XGAM-87A missile at the Atlantic Missile Range a day after the program was canceled. In June 1963, the XGAM-87A was redesignated as XAGM-48A.
Description
The GAM-87 was powered by a two-stage solid-fuel rocket motor. The missile was fitted with a tailcone to reduce drag while on the pylon, which was ejected shortly after being dropped from the plane. After first stage burnout, the Skybolt coasted for a while before the second stage ignited. First stage control was by eight movable tail fins, while the second stage was equipped with a gimballed nozzle.
Guidance was entirely by inertial platform. The current position was constantly updated from the host aircraft through accurate fixes, meaning that the accuracy of the platform inside the missile was not as critical.
B-52s were to carry four missiles, two under each wing on the weapons pylon with a dual launcher adapter with the missiles slightly staggered (inboard missile slightly ahead of the outboard missile). The Vulcan carried two missiles, one each on smaller underwing pylons.
Survivors
* Royal Air Force Museum Midlands, Shropshire, England
* National Museum of the United States Air Force
The National Museum of the United States Air Force (formerly the United States Air Force Museum) is the official museum of the United States Air Force located at Wright-Patterson Air Force Base, northeast of Dayton, Ohio. The NMUSAF is ...
, Dayton, Ohio
Dayton () is a city in Montgomery County, Ohio, United States, and its county seat. It is the List of cities in Ohio, sixth-most populous city in Ohio, with a population of 137,644 at the 2020 United States census, 2020 census. The Dayton metro ...
, United States
* Air Force Space & Missile Museum
The Cape Canaveral Space Force Museum (formerly the Air Force Space and Missile Museum) is located at Cape Canaveral Launch Complex 26, Launch Complex 26 at Cape Canaveral Space Force Station, Florida. It includes artifacts from the early American ...
, Cape Canaveral Air Force Station
Cape Canaveral Space Force Station (CCSFS) is an installation of the United States Space Force's Space Launch Delta 45, located on Cape Canaveral in Brevard County, Florida.
Headquartered at the nearby Patrick Space Force Base, the sta ...
, Florida, United States
See also
* List of military aircraft of the United States
Lists of military aircraft of the United States cover current and former military aircraft of the United States Armed Forces.
By designation
* List of United States Air Force aircraft designations (1919–1962)
*List of United States Navy aircraft ...
* List of missiles by nation
This list of missiles by country displays the names of missiles in order of the country where they originate (were developed), with the countries listed alphabetically and annotated with their continent (and defence alliance, if applicable). In ca ...
* AGM-28 Hound Dog
The North American Aviation AGM-28 Hound Dog was a supersonic, turbojet, turbojet-propelled, Thermonuclear weapon, nuclear armed, air-launched cruise missile developed in 1959 for the United States Air Force. It was primarily designed to be capab ...
* AGM-69 SRAM
The Boeing AGM-69 SRAM (Short-Range Attack Missile) was a air-to-surface missile with a nuclear warhead. It had a range of up to , and was intended to allow US Air Force strategic bombers to penetrate Soviet airspace by neutralizing surface-t ...
References
Bibliography
*
Further reading
* Neustadt, Richard E. ''Report to JFK: The Skybolt Crisis in Perspective''. Ithaca, NY: Cornell University Press, 1999. .
*Matthew Jones. 2019.
Prelude to the Skybolt Crisis: The Kennedy Administration's Approach to British and French Strategic Nuclear Policies in 1962.
''Journal of Cold War Studies''.
*Ken Young (2004) The Skybolt Crisis of 1962: Muddle or Mischief?, Journal of Strategic Studies, 27:4, 614–635
External links
Encyclopedia Astronautica
{{DEFAULTSORT:Gam-87 Skybolt
Cold War air-to-surface missiles of the United States
Ballistic missiles of the United States
Nuclear missiles of the United States
Nuclear air-to-surface missiles
Abandoned military rocket and missile projects of the United States
Air-launched ballistic missiles
United Kingdom–United States military relations
Nuclear weapons of the United Kingdom