WE.177
Encyclopedia
WE.177 was the last air-delivered tactical nuclear weapon
of the British
Armed Forces
. There were three versions; WE.177A was a boosted fission weapon
, while WE.177B and WE.177C were thermonuclear weapons. All were delivered by fixed-wing aircraft and helicopters, although there were plans to deliver in an anti-submarine mode by Ikara missile
that never reached fruition, and all types were parachute retarded
.
The first version to be deployed, WE.177B, was delivered to the Royal Air Force
in September 1966 followed by deliveries of WE.177A to the Royal Navy beginning in 1969, and the RAF in 1971, after a delay caused by the need to produce the ET.317
warhead for the UK Polaris A3T first; and was followed by WE.177C deliveries to the RAF. The Navy weapons were retired by 1992 and all other weapons with the RAF were retired by 1998.
In May 1960 Prime Minister Harold Macmillan
signed an agreement with President Eisenhower to purchase 144 AGM-48 Skybolt
missiles for the V-bomber force. Along with the missiles, the UK would receive the design of the Skybolt's W59
warhead, which was much smaller and lighter than even the smallest UK designs of the era. The UK version would be known as RE.179.
However, the W59 primary used PBX-9404
and was considered by the British to be unsafe due to the potential for shocks to set off the PBX. Since the late 1950s they had been working on their own primary design, originally "Octopus" and then "Super Octopus", that used more explosive and less fissile material, and was shock-insensitive as well. They proposed adapting the Super Octopus design for use in RE.179, calling the new version "Cleo". Cleo designs were tested underground at the Nevada Test Site
in 1962. The secondary (or fusion elements) of RE.179 remained identical to the W59's, and were known as "Simon".
At the time, the UK's only tactical nuclear weapon was Red Beard
, a relatively large weapon of 2,000 lbs weight. While work continued on Cleo, it was decided to adapt it as a weapon of its own to replace Red Beard, as the "Improved Kiloton Weapon". The adapted version of the primary, now the only part of the physics package, became "Katie". Katie would be used in a new bomb casing to produce WE.177, replacing Red Beard with a weapon of roughly 1/3 the weight and much smaller size. WE.177 would also be used by the Royal Navy
, both for surface attack as well as a nuclear depth bomb, or NDB.
When Skybolt was cancelled, part of the resulting Nassau agreement
was the replacement of Skybolt with the Polaris missile. Polaris used its own warhead design, W58
, but given that both missiles were based on similar needs and technology, the W59 was unsurprisingly very similar. The UK decided to adapt their RE.179 for the Polaris instead of starting over with the W58, producing a smaller version known as ET.317. The need for ET.317 nuclear material was so pressing that development of the original WE.177 was halted.
WE.177 was so much better than the UK's existing weapons that it was also decided to adapt it as an interim strategic weapon while they waited for Polaris to enter service. Halting work on the original WE.177, now known as the "A" model, a new version that used the ET.317 secondary with a modified "Katie B" primary created the WE.177B. This version required a lengthened bomb casing, and was somewhat larger than WE.177A.
The original Polaris re-entry vehicle had a relatively slow (subsonic) terminal velocity, and as anti-ballistic missile
systems became an area of active study, it seemed that it would be particularly vulnerable to attack. There were also concerns that the ET.317 could be destroyed by a nearby nuclear explosion, whose X-rays could potentially damage the electronics in the trigger and whose neutron
burst could cause the primary to "fizzle" in a partial criticality. These problems led to the development of the Chevaline
system to improve the warhead's chance of avoiding ABMs, along with a new "super-hardened" primary that would be more resistant to radiation.
A side-effect of this conversion was a reduction in warheads per missile from three to two, the extra space being used by the Chevaline's decoys. As the Chevaline upgrade was carried out, the now-redundant third warheads were adapted into the new WE.177C. This conversion consisted of removing the original primary and replacing them with the WE.177A's Katie A. The new warhead was placed in existing WE.177B casings, and then ballasted to have identical weight and ballistics as the WE.177B.
Type A, B and C weapons were carried by strike aircraft, including the Avro Vulcan
, Blackburn Buccaneer
, SEPECAT Jaguar
, Panavia Tornado
, and RAF Harrier. The Royal Navy Sea Harrier carried only WE.177A, slung beneath the starboard wing. The B and C models were too large for this aircraft. At one time, eight Tornado squadrons were nuclear capable.
Three paint-schemes are known to have been used on WE.177; overall white with red and yellow bands (early paint-scheme from the 1960s) and overall green with red details (later paint-scheme from the mid-1970s onwards). The drill weapon used for loading and flight drills was Oxford blue. This was so that a live round could easily be identified, but service procedures required all training rounds to be treated and handled as if they were live. The training rounds even returned the correct indications to the carrying aircraft systems if they were 'armed' in flight. Most of the examples of WE.177 training rounds in museums have been re-painted in green, presumably to look like the original live rounds.
As with all British thermonuclear weapons, the tritium
gas used in the bomb core was purchased from the United States as part of the 1958 US-UK Mutual Defence Agreement
that permitted the US to obtain UK weapons-grade plutonium
in exchange for enriched uranium
, tritium and other specialised material uneconomical to produce in the UK in the very small quantities required. A plant codenamed Candle located adjacent to the Chapelcross nuclear power station
, near the town of Annan
, Scotland
, was built to recover tritium from time-expired service weapons returned for servicing. It was then re-cycled after re-lifing. All boosted fission weapons use tritium (which decays with time) gradually reducing the designed fission yield by approx 4.4% per year. Reduction in the fission yield of a primary will reduce the thermonuclear yield by a similar proportion, or even lead to the thermonuclear fusion stage failing to ignite. To maintain optimum yield all versions of WE.177 required servicing at intervals of three years or slightly more. Normal servicing was carried out by specialist RAF teams.
Part of the safety and arming system on the WE.177 series was a simple key operated Strike Enable Facility using a cylindrical barrel key similar to those used on gaming machines. The physical safety characteristics of WE.177 were probably comparable to similar U.S. weapons, e.g. using the concept of being 'one-point-safe' http://www.osti.gov/opennet/document/guidline/pubgf.html#ZZ73 The safety and arming system was more sophisticated than on a conventional shell or bomb. The WE177 safety and arming system had three safety breaks (which varied according to delivery mode) in the arming chain whereas a conventional weapon only requires two.
The casing of WE177 was unusually robust and complicated for a British air-dropped bomb, made necessary by the requirement for the laydown options, the stresses from the opening of the drogue parachutes being particularly severe at the speed anticipated for the TSR-2
, the requirement stating a dropping speed of from Mach
(M) 0.75 to M 1.15 at a height of 50 ft http://nuclear-weapons.info/images/tna-air2-17327e23b_03.JPG for TSR-2 and M 0.75 to M 0.95 for the Buccaneer. This, together with the 'slap down' of the tail on impact required a strong, well-engineered bomb casing to ensure the enclosed warhead remained intact.
Apart from the laydown requirement, the weapon was also required to be used in a 'Dive Toss' mode from both the TSR-2 (WE.177A/B) and the RAF version of the Hawker P.1154 (WE.177A). This involved releasing the weapon after a dive from 35,000 ft, with weapon release at between 15,000 ft and 10,000 ft and, for the TSR-2, at speeds between Mach 0.80 to Mach 2.05.
Intended clearance by 1970 for other types of aircraft and delivery methods included:
Later, the following aircraft were armed with WE.177:
WE.177A weighed 272 kg (600 lb), and had a variable yield
of 10 kt or 0.5 kt. It was known to the Armed Services as "Bomb, Aircraft, HE 600lb MC". "MC" (Medium Capacity) referred to a nuclear weapon in the kiloton range. The suffix HC (High Capacity) referred to a weapon in the megaton range, although there were some anomalies.
The 0.5 kt yield was used only in the NDB
role for detonation above 130 ft (40 m) in shallow coastal waters or in oceanic deep waters to limit damage to nearby shipping. The full 10 kt yield was used below 130 ft (40 m) in deep oceanic waters where no shipping was at risk. The full 10 kt yield was also used by fixed wing aircraft for surface attack. It had air burst
, ground burst or laydown
options.
Although this variant matched the original Improved Kiloton Weapon concept with an added NDB
function, and was identified as the A model, it was not the first to be deployed due to the more pressing needs for the B models. Forty-three were deployed aboard Royal Navy surface vessels of frigate
size and larger for use by embarked helicopter
s as an anti-submarine NDB
starting in 1966. When the Navy's large aircraft carrier
s were decommissioned, twenty warheads were transferred to the RAF. The remaining weapons that were assigned to the Navy's helicopters were retired in 1992.
WE.177B weighed 457 kg (1007.5 lb), with a fixed yield of 450 kt. Although it weighed in excess of 1000 lb it was known in RAF Service as the "Bomb, Aircraft, HE 950lb MC" to differentiate it from the conventional "Bomb, Aircraft, 1000 lb GP HE", which gave rise to its popular name "950". WE.177B had airburst, impact, or laydown options.
Numbers built are still uncertain but reliable sources put the figure at 53, and all were retired by August 1998. When Polaris became operational the Vulcan force continued in a tactical role with these and other bombs. With the retirement of the Vulcans, WE.177B was carried by successor aircraft, including Tornado
.
WE.177C was deployed only by RAF Germany in the tactical strike role, and used initially by the Jaguar
and later by Tornadoes
. It was deployed probably from the early 1970s after deployment of Chevaline
had begun. WE.177C was retired by August 1998. Numbers are speculative but based on hard evidence in declassified files of the number of Polaris ET.317 warheads and spares, a figure of between 48 and 60 is likely.
as a complete unit, as the standard issue in place of the Mk-44 or Mk.46 homing torpedo carried by the Ikara
anti-submarine missile that armed some frigates of the Leander
class. Ikara performed a similar function to the U.S. Navy's Asroc missile
which could also carry a nuclear warhead. The addition of a nuclear option to Ikara was intended to significantly improve its kill probability, while providing the escort commander with an instant-response, all-weather, all-conditions weapon to deploy against time-urgent targets. Helicopter-delivered NDBs were not always immediately available due to fuel-state, other taskings, or expended weapons load. Recently declassified archives disclose that the Ikara/WE.177A proposal received serious attention for some years, although there is no evidence of actual deployment.
Other proposals to re-engineer the WE.177A warhead into two submarine-launched heavyweight torpedoes also received some attention. The Mk.24N Tigerfish
nuclear-armed torpedo had approved project status for some years but was eventually shelved. Its raison d'être was to overcome the performance shortcomings of the Tigerfish torpedo, and especially its failure to meet the dive-depth requirements needed to counter deep-diving Soviet SSNs and SSBNs that had outstripped western torpedo performance. There was also a proposal endorsed by Flag Officer Submarines (FOSM), the Royal Navy's professional head of the Submarine Service, to use the WE.177A warhead in another torpedo, the shallow-running unguided Mk.8 torpedo of World War II
vintage. A Mk.8 torpedo was chosen to sink the Argentinian warship Belgrano because it was of proven reliability, unlike the unreliable Tigerfish. This proposal did not gain approved project status although its raison d'être was similar to that for Tigerfish, and intended to counter extended delays in Tigerfish development. FOSM's proposal stated that a 10 kt nuclear detonation at the Mk.8 torpedo's running depth of approximately 40 ft (12 m) would destroy a deep-diving SSN at 2,000 ft (610 m) depth.
of 1982, some Royal Navy ships had WE.177A bombs on board as they headed south. Warships and replenishment ships normally deployed with their assigned nuclear weapons during the Cold War
. However, all bombs in their floatable containers were stated by the Ministry of Defence to have been off-loaded from the escort vessels HMS Broadsword
, HMS Brilliant
, HMS Coventry
(sunk in action), and HMS Sheffield
(sunk in action), for storage in the better-protected deep magazines aboard HMS Hermes
, HMS Invincible
and the Fleet Replenishment ships RFA Fort Austin
and RFA Resource
, accompanying the Task Force. HMS Hermes and HMS Invincible then had aboard 40% and 25% respectively of the entire Royal Navy stockpile of WE.177A NDBs and there was concern at their possible loss in action, and at the consequences if a military emergency should develop simultaneously in the NATO area, where these weapons were intended for use. It is not clear if the weapons were removed from deep storage on these vessels, before the Task Force engaged in action around the Falklands Islands, although the MoD assert that these ships did not enter Falklands Islands territorial waters or any other areas subject to the Treaty of Tlatelolco
(that established the Latin America Nuclear Weapons Free Zone) that the UK was a signatory to. The MoD assert that the Task Force Commander-in-Chief was given instructions on deployment of his forces to avoid any breach of the treaty. They also state that all the nuclear weapons were returned to the UK aboard RFA Fort Austin and RFA Resource on 29 June and 20 July 1982 respectively, after the end of the Falklands War.
Trident D5 is the UK's sole remaining nuclear weapons delivery system
(see Vanguard class submarine
), believed armed with a strategic warhead also usable in the sub-strategic role formerly performed by WE.177. Various projects to produce a successor to WE.177 were abandoned.
Following retirement, a number of WE.177 training rounds were donated to museums in the United Kingdom, and one was donated to the National Atomic Museum
in Albuquerque
, New Mexico
, where it can be viewed alongside similar American weapons. Another is at RAF Hendon.
Nuclear weapon
A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either fission or a combination of fission and fusion. Both reactions release vast quantities of energy from relatively small amounts of matter. The first fission bomb test released the same amount...
of the British
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
Armed Forces
British Armed Forces
The British Armed Forces are the armed forces of the United Kingdom of Great Britain and Northern Ireland.Also known as Her Majesty's Armed Forces and sometimes legally the Armed Forces of the Crown, the British Armed Forces encompasses three professional uniformed services, the Royal Navy, the...
. There were three versions; WE.177A was a boosted fission weapon
Boosted fission weapon
A boosted fission weapon usually refers to a type of nuclear bomb that uses a small amount of fusion fuel to increase the rate, and thus yield, of a fission reaction. The neutrons released by the fusion reactions add to the neutrons released in the fission, as well as inducing the fission reactions...
, while WE.177B and WE.177C were thermonuclear weapons. All were delivered by fixed-wing aircraft and helicopters, although there were plans to deliver in an anti-submarine mode by Ikara missile
Ikara (missile)
The Ikara missile was an Australian ship-launched anti-submarine missile, named after an Australian Aboriginal word for "throwing stick". It launched an acoustic torpedo to a range of , allowing fast-reaction attacks against submarines at ranges that would otherwise require the launching ship to...
that never reached fruition, and all types were parachute retarded
Parachute
A parachute is a device used to slow the motion of an object through an atmosphere by creating drag, or in the case of ram-air parachutes, aerodynamic lift. Parachutes are usually made out of light, strong cloth, originally silk, now most commonly nylon...
.
The first version to be deployed, WE.177B, was delivered to the Royal Air Force
Royal Air Force
The Royal Air Force is the aerial warfare service branch of the British Armed Forces. Formed on 1 April 1918, it is the oldest independent air force in the world...
in September 1966 followed by deliveries of WE.177A to the Royal Navy beginning in 1969, and the RAF in 1971, after a delay caused by the need to produce the ET.317
ET.317
The ET.317 was a nuclear weapon of the British Armed Forces, developed for the British version of the UGM-27 Polaris missile....
warhead for the UK Polaris A3T first; and was followed by WE.177C deliveries to the RAF. The Navy weapons were retired by 1992 and all other weapons with the RAF were retired by 1998.
History
Harold Macmillan
Maurice Harold Macmillan, 1st Earl of Stockton, OM, PC was Conservative Prime Minister of the United Kingdom from 10 January 1957 to 18 October 1963....
signed an agreement with President Eisenhower to purchase 144 AGM-48 Skybolt
AGM-48 Skybolt
The Douglas GAM-87 Skybolt was an air-launched ballistic missile , equipped with a nuclear warhead, developed by the United States during the late 1950s. The UK joined the program in 1960, intending to use it on their V bomber force...
missiles for the V-bomber force. Along with the missiles, the UK would receive the design of the Skybolt's W59
W59
The W59 was an American thermonuclear warhead used on some Minuteman I ICBM missiles from 1962-1969.The W59 was 16.3 inches in diameter and 47.8 inches long, and it weighed 550 pounds...
warhead, which was much smaller and lighter than even the smallest UK designs of the era. The UK version would be known as RE.179.
However, the W59 primary used PBX-9404
Polymer-bonded explosive
A polymer-bonded explosive, also called PBX or plastic-bonded explosive, is an explosive material in which explosive powder is bound together in a matrix using small quantities of a synthetic polymer...
and was considered by the British to be unsafe due to the potential for shocks to set off the PBX. Since the late 1950s they had been working on their own primary design, originally "Octopus" and then "Super Octopus", that used more explosive and less fissile material, and was shock-insensitive as well. They proposed adapting the Super Octopus design for use in RE.179, calling the new version "Cleo". Cleo designs were tested underground at the Nevada Test Site
Nevada Test Site
The Nevada National Security Site , previously the Nevada Test Site , is a United States Department of Energy reservation located in southeastern Nye County, Nevada, about northwest of the city of Las Vegas...
in 1962. The secondary (or fusion elements) of RE.179 remained identical to the W59's, and were known as "Simon".
At the time, the UK's only tactical nuclear weapon was Red Beard
Red Beard (nuclear weapon)
Red Beard was the first British tactical nuclear weapon. It was carried by the English Electric Canberra and the V bombers of the Royal Air Force, and by the Blackburn Buccaneers, Sea Vixens and Supermarine Scimitars of the Royal Navy's Fleet Air Arm...
, a relatively large weapon of 2,000 lbs weight. While work continued on Cleo, it was decided to adapt it as a weapon of its own to replace Red Beard, as the "Improved Kiloton Weapon". The adapted version of the primary, now the only part of the physics package, became "Katie". Katie would be used in a new bomb casing to produce WE.177, replacing Red Beard with a weapon of roughly 1/3 the weight and much smaller size. WE.177 would also be used by the Royal Navy
Royal Navy
The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...
, both for surface attack as well as a nuclear depth bomb, or NDB.
When Skybolt was cancelled, part of the resulting Nassau agreement
Nassau agreement
The Nassau Agreement, concluded on 22 December 1962, was a treaty negotiated between President John F. Kennedy for the United States and Prime Minister Harold Macmillan for the United Kingdom...
was the replacement of Skybolt with the Polaris missile. Polaris used its own warhead design, W58
W58
The W58 was an American thermonuclear warhead used on the Polaris A-3 submarine launched ballistic missile. Three W58 warheads were fitted as multiple warheads on each Polaris A-3 missile....
, but given that both missiles were based on similar needs and technology, the W59 was unsurprisingly very similar. The UK decided to adapt their RE.179 for the Polaris instead of starting over with the W58, producing a smaller version known as ET.317. The need for ET.317 nuclear material was so pressing that development of the original WE.177 was halted.
WE.177 was so much better than the UK's existing weapons that it was also decided to adapt it as an interim strategic weapon while they waited for Polaris to enter service. Halting work on the original WE.177, now known as the "A" model, a new version that used the ET.317 secondary with a modified "Katie B" primary created the WE.177B. This version required a lengthened bomb casing, and was somewhat larger than WE.177A.
The original Polaris re-entry vehicle had a relatively slow (subsonic) terminal velocity, and as anti-ballistic missile
Anti-ballistic missile
An anti-ballistic missile is a missile designed to counter ballistic missiles .A ballistic missile is used to deliver nuclear, chemical, biological or conventional warheads in a ballistic flight trajectory. The term "anti-ballistic missile" describes any antimissile system designed to counter...
systems became an area of active study, it seemed that it would be particularly vulnerable to attack. There were also concerns that the ET.317 could be destroyed by a nearby nuclear explosion, whose X-rays could potentially damage the electronics in the trigger and whose neutron
Neutron
The neutron is a subatomic hadron particle which has the symbol or , no net electric charge and a mass slightly larger than that of a proton. With the exception of hydrogen, nuclei of atoms consist of protons and neutrons, which are therefore collectively referred to as nucleons. The number of...
burst could cause the primary to "fizzle" in a partial criticality. These problems led to the development of the Chevaline
Chevaline
Chevaline was a system to improve the penetrability of the British Polaris missile warheads. Devised as an answer to the improved Soviet defences around Moscow, the system was intended to increase the probability that at least one warhead would penetrate the city's anti-ballistic missile defences,...
system to improve the warhead's chance of avoiding ABMs, along with a new "super-hardened" primary that would be more resistant to radiation.
A side-effect of this conversion was a reduction in warheads per missile from three to two, the extra space being used by the Chevaline's decoys. As the Chevaline upgrade was carried out, the now-redundant third warheads were adapted into the new WE.177C. This conversion consisted of removing the original primary and replacing them with the WE.177A's Katie A. The new warhead was placed in existing WE.177B casings, and then ballasted to have identical weight and ballistics as the WE.177B.
Type A, B and C weapons were carried by strike aircraft, including the Avro Vulcan
Avro Vulcan
The Avro Vulcan, sometimes referred to as the Hawker Siddeley Vulcan, was a jet-powered delta wing strategic bomber, operated by the Royal Air Force from 1956 until 1984. Aircraft manufacturer A V Roe & Co designed the Vulcan in response to Specification B.35/46. Of the three V bombers produced,...
, Blackburn Buccaneer
Blackburn Buccaneer
The Blackburn Buccaneer was a British low-level subsonic strike aircraft with nuclear weapon delivery capability serving with the Royal Navy and the Royal Air Force between 1962 and 1994, including service in the 1991 Gulf War...
, SEPECAT Jaguar
SEPECAT Jaguar
The SEPECAT Jaguar is an Anglo-French jet ground attack aircraft, originally used by the British Royal Air Force and the French Armée de l'Air in the close air support and nuclear strike role, and still in service with several export customers, notably the Indian Air Force and the Royal Air Force...
, Panavia Tornado
Panavia Tornado
The Panavia Tornado is a family of twin-engine, variable-sweep wing combat aircraft, which was jointly developed and manufactured by the United Kingdom, West Germany and Italy...
, and RAF Harrier. The Royal Navy Sea Harrier carried only WE.177A, slung beneath the starboard wing. The B and C models were too large for this aircraft. At one time, eight Tornado squadrons were nuclear capable.
Three paint-schemes are known to have been used on WE.177; overall white with red and yellow bands (early paint-scheme from the 1960s) and overall green with red details (later paint-scheme from the mid-1970s onwards). The drill weapon used for loading and flight drills was Oxford blue. This was so that a live round could easily be identified, but service procedures required all training rounds to be treated and handled as if they were live. The training rounds even returned the correct indications to the carrying aircraft systems if they were 'armed' in flight. Most of the examples of WE.177 training rounds in museums have been re-painted in green, presumably to look like the original live rounds.
Tritium
Tritium is a radioactive isotope of hydrogen. The nucleus of tritium contains one proton and two neutrons, whereas the nucleus of protium contains one proton and no neutrons...
gas used in the bomb core was purchased from the United States as part of the 1958 US-UK Mutual Defence Agreement
1958 US-UK Mutual Defence Agreement
The 1958 US–UK Mutual Defence Agreement is a bilateral treaty between the United States and the United Kingdom on nuclear weapons cooperation.It was signed after the UK successfully tested its first hydrogen bomb during Operation Grapple. While the U.S...
that permitted the US to obtain UK weapons-grade plutonium
Plutonium
Plutonium is a transuranic radioactive chemical element with the chemical symbol Pu and atomic number 94. It is an actinide metal of silvery-gray appearance that tarnishes when exposed to air, forming a dull coating when oxidized. The element normally exhibits six allotropes and four oxidation...
in exchange for enriched uranium
Enriched uranium
Enriched uranium is a kind of uranium in which the percent composition of uranium-235 has been increased through the process of isotope separation. Natural uranium is 99.284% 238U isotope, with 235U only constituting about 0.711% of its weight...
, tritium and other specialised material uneconomical to produce in the UK in the very small quantities required. A plant codenamed Candle located adjacent to the Chapelcross nuclear power station
Chapelcross nuclear power station
Chapelcross was a Magnox nuclear power plant located near the town of Annan in Dumfries and Galloway in south west Scotland. It was the sister plant to Calder Hall in Cumbria, England, both commissioned and originally operated by the United Kingdom Atomic Energy Authority.The primary purpose of...
, near the town of Annan
Annan, Dumfries and Galloway
The royal burgh of Annan is a well-built town, red sandstone being the material mainly used. Each year in July, Annan celebrates the Royal Charter and the boundaries of the Royal Burgh are confirmed when a mounted cavalcade undertakes the Riding of the Marches. Entertainment includes a...
, Scotland
Scotland
Scotland is a country that is part of the United Kingdom. Occupying the northern third of the island of Great Britain, it shares a border with England to the south and is bounded by the North Sea to the east, the Atlantic Ocean to the north and west, and the North Channel and Irish Sea to the...
, was built to recover tritium from time-expired service weapons returned for servicing. It was then re-cycled after re-lifing. All boosted fission weapons use tritium (which decays with time) gradually reducing the designed fission yield by approx 4.4% per year. Reduction in the fission yield of a primary will reduce the thermonuclear yield by a similar proportion, or even lead to the thermonuclear fusion stage failing to ignite. To maintain optimum yield all versions of WE.177 required servicing at intervals of three years or slightly more. Normal servicing was carried out by specialist RAF teams.
Part of the safety and arming system on the WE.177 series was a simple key operated Strike Enable Facility using a cylindrical barrel key similar to those used on gaming machines. The physical safety characteristics of WE.177 were probably comparable to similar U.S. weapons, e.g. using the concept of being 'one-point-safe' http://www.osti.gov/opennet/document/guidline/pubgf.html#ZZ73 The safety and arming system was more sophisticated than on a conventional shell or bomb. The WE177 safety and arming system had three safety breaks (which varied according to delivery mode) in the arming chain whereas a conventional weapon only requires two.
The casing of WE177 was unusually robust and complicated for a British air-dropped bomb, made necessary by the requirement for the laydown options, the stresses from the opening of the drogue parachutes being particularly severe at the speed anticipated for the TSR-2
BAC TSR-2
The British Aircraft Corporation TSR-2 was a cancelled Cold War strike and reconnaissance aircraft developed by the British Aircraft Corporation for the Royal Air Force in the late 1950s and early 1960s...
, the requirement stating a dropping speed of from Mach
Mach number
Mach number is the speed of an object moving through air, or any other fluid substance, divided by the speed of sound as it is in that substance for its particular physical conditions, including those of temperature and pressure...
(M) 0.75 to M 1.15 at a height of 50 ft http://nuclear-weapons.info/images/tna-air2-17327e23b_03.JPG for TSR-2 and M 0.75 to M 0.95 for the Buccaneer. This, together with the 'slap down' of the tail on impact required a strong, well-engineered bomb casing to ensure the enclosed warhead remained intact.
Apart from the laydown requirement, the weapon was also required to be used in a 'Dive Toss' mode from both the TSR-2 (WE.177A/B) and the RAF version of the Hawker P.1154 (WE.177A). This involved releasing the weapon after a dive from 35,000 ft, with weapon release at between 15,000 ft and 10,000 ft and, for the TSR-2, at speeds between Mach 0.80 to Mach 2.05.
Intended clearance by 1970 for other types of aircraft and delivery methods included:
- Handley Page VictorHandley Page VictorThe Handley Page Victor was a British jet bomber aircraft produced by the Handley Page Aircraft Company during the Cold War. It was the third and final of the V-bombers that provided Britain's nuclear deterrent. The other two V-bombers were the Avro Vulcan and the Vickers Valiant. Some aircraft...
Mk.2 - WE.177A/B - Laydown, Ballistic, Retarded. - Avro VulcanAvro VulcanThe Avro Vulcan, sometimes referred to as the Hawker Siddeley Vulcan, was a jet-powered delta wing strategic bomber, operated by the Royal Air Force from 1956 until 1984. Aircraft manufacturer A V Roe & Co designed the Vulcan in response to Specification B.35/46. Of the three V bombers produced,...
- WE.177A/B - Laydown, Ballistic, Retarded. - Vickers ValiantVickers ValiantThe Vickers-Armstrongs Valiant was a British four-jet bomber, once part of the Royal Air Force's V bomber nuclear force in the 1950s and 1960s...
Mk B.1, P.R., K.1., P.R.K.1 - WE.177A - Laydown, Ballistic, Retarded. - TSR-2 - WE.177 A/B - Laydown, Ballistic, Retarded, Loft, Dive Toss.
- CanberraEnglish Electric CanberraThe English Electric Canberra is a first-generation jet-powered light bomber manufactured in large numbers through the 1950s. The Canberra could fly at a higher altitude than any other bomber through the 1950s and set a world altitude record of 70,310 ft in 1957...
Mk.B.15 & B.16 - WE.177A - Laydown, Ballistic, Retarded, Loft. - Blackburn BuccaneerBlackburn BuccaneerThe Blackburn Buccaneer was a British low-level subsonic strike aircraft with nuclear weapon delivery capability serving with the Royal Navy and the Royal Air Force between 1962 and 1994, including service in the 1991 Gulf War...
Mk.2 - WE.177A - Laydown, Loft, Retarded. - Sea Vixen MK.2 - WE.177A - Laydown, Loft, Retarded.
- WaspWestland WaspThe Westland Wasp was a British small first-generation, gas-turbine powered, shipboard anti-submarine helicopter. Produced by Westland Helicopters, it came from the same P.531 programme as the British Army Westland Scout, and was based on the earlier piston-engined Saunders-Roe Skeeter...
- WE.177A - Depth Charge. - WessexWestland WessexThe Westland Wessex is a British turbine-powered version of the Sikorsky S-58 "Choctaw", developed under license by Westland Aircraft , initially for the Royal Navy, and later for the Royal Air Force...
HAS.3 - WE.177A - Depth Charge. - Wessex HUS - WE.177A - Depth Charge.
- IkaraIkara (missile)The Ikara missile was an Australian ship-launched anti-submarine missile, named after an Australian Aboriginal word for "throwing stick". It launched an acoustic torpedo to a range of , allowing fast-reaction attacks against submarines at ranges that would otherwise require the launching ship to...
- WE.177A - Depth Charge. - P.1154 - WE.177A - Depth Charge. (RN)
- P.1154 - WE.177A - Laydown, Loft, Dive Toss. (RAF)
- Nimrod - WE.177A - Depth Charge.
Later, the following aircraft were armed with WE.177:
- Panavia TornadoPanavia TornadoThe Panavia Tornado is a family of twin-engine, variable-sweep wing combat aircraft, which was jointly developed and manufactured by the United Kingdom, West Germany and Italy...
- WE.177 A/B/C - Laydown, Loft, Retarded - SEPECAT JaguarSEPECAT JaguarThe SEPECAT Jaguar is an Anglo-French jet ground attack aircraft, originally used by the British Royal Air Force and the French Armée de l'Air in the close air support and nuclear strike role, and still in service with several export customers, notably the Indian Air Force and the Royal Air Force...
- WE.177A - Laydown, Loft, Retarded - Harrier and Sea Harrier - WE.177A - Laydown, Loft, Retarded
WE.177A
Variable yield
Variable yield — or dial-a-yield — is an option available on most modern nuclear weapons. It allows the operator to specify a weapon's yield, or explosive power, allowing a single design to be used in different situations...
of 10 kt or 0.5 kt. It was known to the Armed Services as "Bomb, Aircraft, HE 600lb MC". "MC" (Medium Capacity) referred to a nuclear weapon in the kiloton range. The suffix HC (High Capacity) referred to a weapon in the megaton range, although there were some anomalies.
The 0.5 kt yield was used only in the NDB
Nuclear Depth Bomb
A Nuclear Depth Bomb is the nuclear equivalent of the conventional depth charge and can be used in Anti-Submarine Warfare for attacking submerged submarines...
role for detonation above 130 ft (40 m) in shallow coastal waters or in oceanic deep waters to limit damage to nearby shipping. The full 10 kt yield was used below 130 ft (40 m) in deep oceanic waters where no shipping was at risk. The full 10 kt yield was also used by fixed wing aircraft for surface attack. It had air burst
Air burst
An air burst is the detonation of an explosive device such as an anti-personnel artillery shell or a nuclear weapon in the air instead of on contact with the ground or target or a delayed armor piercing explosion....
, ground burst or laydown
Laydown delivery
Laydown delivery is a mode of deploying a free-fall nuclear weapon in which the bomb's fall is slowed by parachute so that it actually lands on the ground before detonating. Laydown delivery requires that the weapon's case be reinforced so that it can survive the impact, and generally involves a...
options.
Although this variant matched the original Improved Kiloton Weapon concept with an added NDB
Nuclear Depth Bomb
A Nuclear Depth Bomb is the nuclear equivalent of the conventional depth charge and can be used in Anti-Submarine Warfare for attacking submerged submarines...
function, and was identified as the A model, it was not the first to be deployed due to the more pressing needs for the B models. Forty-three were deployed aboard Royal Navy surface vessels of frigate
Frigate
A frigate is any of several types of warship, the term having been used for ships of various sizes and roles over the last few centuries.In the 17th century, the term was used for any warship built for speed and maneuverability, the description often used being "frigate-built"...
size and larger for use by embarked helicopter
Helicopter
A helicopter is a type of rotorcraft in which lift and thrust are supplied by one or more engine-driven rotors. This allows the helicopter to take off and land vertically, to hover, and to fly forwards, backwards, and laterally...
s as an anti-submarine NDB
Nuclear Depth Bomb
A Nuclear Depth Bomb is the nuclear equivalent of the conventional depth charge and can be used in Anti-Submarine Warfare for attacking submerged submarines...
starting in 1966. When the Navy's large aircraft carrier
Aircraft carrier
An aircraft carrier is a warship designed with a primary mission of deploying and recovering aircraft, acting as a seagoing airbase. Aircraft carriers thus allow a naval force to project air power worldwide without having to depend on local bases for staging aircraft operations...
s were decommissioned, twenty warheads were transferred to the RAF. The remaining weapons that were assigned to the Navy's helicopters were retired in 1992.
WE.177B
Numbers built are still uncertain but reliable sources put the figure at 53, and all were retired by August 1998. When Polaris became operational the Vulcan force continued in a tactical role with these and other bombs. With the retirement of the Vulcans, WE.177B was carried by successor aircraft, including Tornado
Panavia Tornado
The Panavia Tornado is a family of twin-engine, variable-sweep wing combat aircraft, which was jointly developed and manufactured by the United Kingdom, West Germany and Italy...
.
WE.177C
WE.177C weighed 457 kg (1007.5 lb), with a fixed yield of 200 kt.WE.177C was deployed only by RAF Germany in the tactical strike role, and used initially by the Jaguar
SEPECAT Jaguar
The SEPECAT Jaguar is an Anglo-French jet ground attack aircraft, originally used by the British Royal Air Force and the French Armée de l'Air in the close air support and nuclear strike role, and still in service with several export customers, notably the Indian Air Force and the Royal Air Force...
and later by Tornadoes
Panavia Tornado
The Panavia Tornado is a family of twin-engine, variable-sweep wing combat aircraft, which was jointly developed and manufactured by the United Kingdom, West Germany and Italy...
. It was deployed probably from the early 1970s after deployment of Chevaline
Chevaline
Chevaline was a system to improve the penetrability of the British Polaris missile warheads. Devised as an answer to the improved Soviet defences around Moscow, the system was intended to increase the probability that at least one warhead would penetrate the city's anti-ballistic missile defences,...
had begun. WE.177C was retired by August 1998. Numbers are speculative but based on hard evidence in declassified files of the number of Polaris ET.317 warheads and spares, a figure of between 48 and 60 is likely.
| Variant | Weight | Est. Yield | Operational | Est. Numbers http://www.nuclear-weapons.info/vw.htm#WE.177 |
|---|---|---|---|---|
| WE.177A | 282 kg | ½ or 10 kt | 1969–1992 | 107 |
| WE.177B | 457 kg | 450 kt | 1966–1995 | 53 |
| WE.177C | 457 kg | 200 kt | ~1980 - 1998 | 159 |
| Total | 319 |
Further development proposals
There were several proposals to adapt WE.177A for other delivery systems. One was to use the WE.177A NDBNuclear Depth Bomb
A Nuclear Depth Bomb is the nuclear equivalent of the conventional depth charge and can be used in Anti-Submarine Warfare for attacking submerged submarines...
as a complete unit, as the standard issue in place of the Mk-44 or Mk.46 homing torpedo carried by the Ikara
Ikara (missile)
The Ikara missile was an Australian ship-launched anti-submarine missile, named after an Australian Aboriginal word for "throwing stick". It launched an acoustic torpedo to a range of , allowing fast-reaction attacks against submarines at ranges that would otherwise require the launching ship to...
anti-submarine missile that armed some frigates of the Leander
Leander
Leander, from the Hero and Leander myth, is a character from Greek myth, and has given his name to several individuals, at least one city and a number of warships and warship classes of the Royal Navy:-With the given name:...
class. Ikara performed a similar function to the U.S. Navy's Asroc missile
ASROC
ASROC is an all-weather, all sea-conditions anti-submarine missile system. Developed by the United States Navy in the 1950s, it was deployed in the 1960s, updated in the 1990s, and eventually installed on over 200 USN surface ships, specifically cruisers, destroyers, and frigates...
which could also carry a nuclear warhead. The addition of a nuclear option to Ikara was intended to significantly improve its kill probability, while providing the escort commander with an instant-response, all-weather, all-conditions weapon to deploy against time-urgent targets. Helicopter-delivered NDBs were not always immediately available due to fuel-state, other taskings, or expended weapons load. Recently declassified archives disclose that the Ikara/WE.177A proposal received serious attention for some years, although there is no evidence of actual deployment.
Other proposals to re-engineer the WE.177A warhead into two submarine-launched heavyweight torpedoes also received some attention. The Mk.24N Tigerfish
Mark 24 Tigerfish
The Mk 24 Tigerfish torpedo was a heavyweight acoustic homing torpedo used by the Royal Navy for several years. The early Mod0 and Mod1 variants were unreliable and unsuccessful, and were issued to the RN even though they failed Fleet Weapon Acceptance...
nuclear-armed torpedo had approved project status for some years but was eventually shelved. Its raison d'être was to overcome the performance shortcomings of the Tigerfish torpedo, and especially its failure to meet the dive-depth requirements needed to counter deep-diving Soviet SSNs and SSBNs that had outstripped western torpedo performance. There was also a proposal endorsed by Flag Officer Submarines (FOSM), the Royal Navy's professional head of the Submarine Service, to use the WE.177A warhead in another torpedo, the shallow-running unguided Mk.8 torpedo of World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
vintage. A Mk.8 torpedo was chosen to sink the Argentinian warship Belgrano because it was of proven reliability, unlike the unreliable Tigerfish. This proposal did not gain approved project status although its raison d'être was similar to that for Tigerfish, and intended to counter extended delays in Tigerfish development. FOSM's proposal stated that a 10 kt nuclear detonation at the Mk.8 torpedo's running depth of approximately 40 ft (12 m) would destroy a deep-diving SSN at 2,000 ft (610 m) depth.
Falklands War
During the Falklands warFalklands War
The Falklands War , also called the Falklands Conflict or Falklands Crisis, was fought in 1982 between Argentina and the United Kingdom over the disputed Falkland Islands and South Georgia and the South Sandwich Islands...
of 1982, some Royal Navy ships had WE.177A bombs on board as they headed south. Warships and replenishment ships normally deployed with their assigned nuclear weapons during the Cold War
Cold War
The Cold War was the continuing state from roughly 1946 to 1991 of political conflict, military tension, proxy wars, and economic competition between the Communist World—primarily the Soviet Union and its satellite states and allies—and the powers of the Western world, primarily the United States...
. However, all bombs in their floatable containers were stated by the Ministry of Defence to have been off-loaded from the escort vessels HMS Broadsword
HMS Broadsword (F88)
HMS Broadsword was the lead ship and first Batch 1 unit of the Type 22 frigates of the Royal Navy.-Service:While on sea trials, Broadsword was called into service as the command ship during the large rescue operation required after storms struck the 1979 Fastnet race.Broadsword took part in the...
, HMS Brilliant
HMS Brilliant (F90)
HMS Brilliant was a Type 22 frigate of the Royal Navy.She was part of the Task Force that took part in the Falklands War, with Captain John Coward in command...
, HMS Coventry
HMS Coventry (D118)
HMS Coventry was a Type 42 destroyer of the Royal Navy. Laid down by Cammell Laird and Company, Limited, at Birkenhead on 29 January 1973, she was launched on 21 June 1974 and accepted into service on 20 October 1978 at a cost of £37,900,000.She was sunk by Argentine Air Force A-4 Skyhawks on 25...
(sunk in action), and HMS Sheffield
HMS Sheffield (D80)
HMS Sheffield was the second Royal Navy ship to be named after the city of Sheffield in Yorkshire. She was a Type 42 Guided Missile Destroyer laid down by Vickers Shipbuilding and Engineering at Barrow-in-Furness on 15 January 1970, launched on 10 June 1971 and commissioned on 16 February 1975.An...
(sunk in action), for storage in the better-protected deep magazines aboard HMS Hermes
HMS Hermes (R12)
HMS Hermes was a Centaur-class British aircraft carrier, the last of the postwar conventional aircraft carriers commissioned into the Royal Navy.-Construction and modifications:...
, HMS Invincible
HMS Invincible (R05)
HMS Invincible was a British light aircraft carrier, the lead ship of three in her class in the Royal Navy. She was launched on 3 May 1977 and is the seventh ship to carry the name. She saw action in the Falklands War when she was deployed with , she took over as flagship of the British fleet when...
and the Fleet Replenishment ships RFA Fort Austin
RFA Fort Austin (A386)
RFA Fort Austin is a fleet stores ship of the Royal Fleet Auxiliary.Fort Austin was laid down at Scott Lithgow in 1975, launched in 1978 and commissioned in 1979. These ships were designed to carry a wide range of stores to support other ships; ammunition, food, explosives...
and RFA Resource
RFA Resource (A480)
RFA Resource was an armament stores ship of the Royal Fleet Auxiliary.-Falklands War:RFA Resource served in the Falklands War. The ship was captained at that time by Captain Bruce Seymour....
, accompanying the Task Force. HMS Hermes and HMS Invincible then had aboard 40% and 25% respectively of the entire Royal Navy stockpile of WE.177A NDBs and there was concern at their possible loss in action, and at the consequences if a military emergency should develop simultaneously in the NATO area, where these weapons were intended for use. It is not clear if the weapons were removed from deep storage on these vessels, before the Task Force engaged in action around the Falklands Islands, although the MoD assert that these ships did not enter Falklands Islands territorial waters or any other areas subject to the Treaty of Tlatelolco
Treaty of Tlatelolco
The Treaty of Tlatelolco is the conventional name given to the Treaty for the Prohibition of Nuclear Weapons in Latin America and the Caribbean...
(that established the Latin America Nuclear Weapons Free Zone) that the UK was a signatory to. The MoD assert that the Task Force Commander-in-Chief was given instructions on deployment of his forces to avoid any breach of the treaty. They also state that all the nuclear weapons were returned to the UK aboard RFA Fort Austin and RFA Resource on 29 June and 20 July 1982 respectively, after the end of the Falklands War.
Retirement
Reliable, recently published sources based upon recent research in declassified files in The National Archives, put eventual total numbers of all versions of WE.177 at between 200-250. All Royal Navy WE.177A weapons were retired in 1992. By August 1998 all RAF stock of all versions, had been withdrawn and dismantled. In the early 1990s the US withdrew all nuclear weapons that were assigned to British forces under NATO nuclear weapons sharing arrangements.Trident D5 is the UK's sole remaining nuclear weapons delivery system
Nuclear weapons and the United Kingdom
The United Kingdom was the third country to test an independently developed nuclear weapon, in October 1952. It is one of the five "Nuclear Weapons States" under the Nuclear Non-Proliferation Treaty, which the UK ratified in 1968...
(see Vanguard class submarine
Vanguard class submarine
The Vanguard class are the Royal Navy's current nuclear ballistic missile submarines , each armed with up to 16 Trident II Submarine-launched ballistic missiles...
), believed armed with a strategic warhead also usable in the sub-strategic role formerly performed by WE.177. Various projects to produce a successor to WE.177 were abandoned.
Following retirement, a number of WE.177 training rounds were donated to museums in the United Kingdom, and one was donated to the National Atomic Museum
National Atomic Museum
The National Museum of Nuclear Science & History is a national repository of nuclear science information chartered by the 102nd United States Congress under Public Law 102-190, and located in Albuquerque, New Mexico. "The mission of the National Atomic Museum is to serve as America's resource for...
in Albuquerque
Albuquerque, New Mexico
Albuquerque is the largest city in the state of New Mexico, United States. It is the county seat of Bernalillo County and is situated in the central part of the state, straddling the Rio Grande. The city population was 545,852 as of the 2010 Census and ranks as the 32nd-largest city in the U.S. As...
, New Mexico
New Mexico
New Mexico is a state located in the southwest and western regions of the United States. New Mexico is also usually considered one of the Mountain States. With a population density of 16 per square mile, New Mexico is the sixth-most sparsely inhabited U.S...
, where it can be viewed alongside similar American weapons. Another is at RAF Hendon.