‘Chevaline’ – IWM London’s nuclear warhead carrier and decoy launcher

RICHARD MADDOX

IT LOOKS LIKE SOMETHING FROM A JAMES BOND STORY.

 

POLARIS CHEVALINE Penetration Aids Carrier (PAC) and the black protective nose cone for the Re-entry Body (not shown) that contained the nuclear device. The silver holes in the black panel (edged in yellow) are the exhaust ports of the manoeuvring jets and the brown tubes would have held decoys to mask the radar and other signatures of the warhead. Images © R Maddox 2018.

POLARIS CHEVALINE Penetration Aids Carrier (PAC) and the black protective nose cone for the Re-entry Body (not shown) that contained the nuclear device. The silver holes in the black panel (edged in yellow) are the exhaust ports of the manoeuvring jets and the brown tubes would have held decoys to mask the radar and other signatures of the warhead. Images © R Maddox 2018.

Called the ‘Penetration Aids Carrier’ – PAC – it’s a small manoeuvrable spaceship fitted with its own navigation system as well as a power supply and fuel for it manoeuvring jets.

Part of a UGM-27 Polaris A3T nuclear armed submarine launched ballistic missile (SLBM), its function was to move into position above the Earth before releasing its warheads and – just as important – a variety of decoys.

From 1968 to 1996 Britain relied on Polaris, a US-designed nuclear-armed submarine-launched ballistic missile (SLBM).

The system was fitted into purpose-built Royal Navy submarines to form Britain’s ultimate weapon.

The practical design and build work of building nuclear bombs was originally a closely guarded secret known to just USA and a few British scientists that had worked on Project MANHATTAN and its British equivalent Project TUBE ALLOYS. (1) (2) 

After the American attacks that ended the Second World war the Soviet Union and other nations were attempting to build nuclear weapons. The Russians received valuable information from Klaus Fuchs (3) a German-born emigré scientist working on TUBE ALLOYS. (4) (5) 

This and other perceived security lapses in Britain led to an embargo on America sharing nuclear weapons information. (6) 

This ban was only lifted in 1958 when both countries signed the 1958 Anglo-American Mutual Defence Agreement. (7) 

By then Britain had already developed its first nuclear bomb named BLUE DANUBE. First delivered in November 1953 the huge bomb – more than 24 foot/7.3 m long and weighing 10,000 lbs/4536 kg – would have to wait until the following year when the first of the RAF’s ‘V – bombers’, the Vickers Valiant came into service. (8) (9) 

The ‘nuclear club’ would gradually grow to five nations – USA, Britain, Soviet Union (now the Russian Federation), France and China over the next twenty years. (10) (11) (12) (13)(14)  These five nations would sign the 1968 Nuclear Proliferation Treaty. (15)

Since then other states have developed atomic weapons and some continue to have them in their arsenal while others have given them up.

The very destructive power of nuclear weapons and the fact that both major power blocs – Capitalist and Communist – had them and could destroy their opponents many times over, acted as a source of peace as well as ultimate deterrence through Mutually Assured Destruction. (16)

However military technology evolves with all parties trying to keep their weapons and defences ahead of both actual and potential enemies while at the same time finding and exploiting weaknesses in their defences.

In 1972 with the Soviet Union – the perceived adversary at the time – upgrading its defence systems around Moscow and the British version of Polaris becoming obsolescent, the Americans deciding to invest in a different SLBM system.

Named UGM-73 Poseidon C3, it was longer, larger and heavier than Polaris but would have been able to have been launched from existing Polaris boats. (17) (18)

But this was also the time of the Strategic Arms Limitation Talks (SALT) aimed at limiting the number of warheads the United States and the Soviet Union had in their arsenal.  The talks were held in two long rounds of negotiation leading to some limits on the number of nuclear weapons kept by each side. Although the Soviet invasion of Afghanistan in 1979 disrupted the talks sufficient progress was made for both countries to ultimately move to Strategic Arms Reduction Talks (START) beginning in 1991. (19)

Meanwhile the British government needed to make a decision about the future of Polaris – buy Posiedon and effectively scrap the missiles and the infrastructure to house and maintain them or do something else. The Royal Navy for its part favoured the Poseidon option.

The UK government considered a variety of options and chose to update Polaris with a British designed and built decoy package to give the warheads the best chance of finding their target. Work started on the CHEVALINE project in the mid-1970s. (20)

The physical size and design of the Polaris missile – and the four Resolution class submarines that were built to launch them as part of the Royal Navy’s Continuously At Sea Deterrent (CASD) force – meant that one of the warheads in each missile was removed to make space for the CHEVALINE decoys .

There were a variety of them. Some decoys would form a cloud to hide the real warheads in a manner similar to Second World War ‘WINDOW’, while others would act as targets to lure enemy anti-ballistic-missile missiles (ABMs) away from nuclear devices.

A REAR VIEW OF THE PENETRATION AIDS CARRIER (PAC). Image © R Maddox 2018.

A REAR VIEW OF THE PENETRATION AIDS CARRIER (PAC). Image © R Maddox 2018.

Today with Trident missiles and their Vanguard class submarines coming to the end of their useful lives as deterrents, the UK has decided to invest in a new class of submarine to continue the Continuous at Sea Deterrent patrols.

These patrols enable at least one of the nuclear missile submarines is at sea 24 hours a day each day of the year. (21)

The new Dreadnought submarines will be the largest submarines ever built for the Royal Navy and are due to enter service around 2030. (22)

SOURCES

(1) http://www.atomicarchive.com/History/british/index.shtml – retrieved 10 November 2018

(2) https://www.bbc.co.uk/news/uk-wales-33540282 – retrieved 10 November 2018

(3) https://www.mi5.gov.uk/klaus-fuchs – retrieved 10 November 2018

(4) https://www.atomicheritage.org/profile/klaus-fuchs – retrieved 10 November 2018

(5) https://www.atomicheritage.org/history/soviet-atomic-program-1946 – retrieved 10 November 2018

(6) https://www.bbc.com/timelines/z33fycw – retrieved 10 November 2018

(7) https://www.tandfonline.com/doi/abs/10.1080/01402390802024726?journalCode=fjss20 – retrieved 10 November 2018

(8) https://rafbarnham-nss.weebly.com/blue-danube.html – retrieved 10 November 2018

(9) http://www.bbc.co.uk/ahistoryoftheworld/objects/Ycm_vFKhQHOnipak_UHL2w – retrieved 10 November 2018

(10) https://www.history.com/topics/world-war-ii/atomic-bomb-history – retrieved 10 November 2018

(11) https://www.atomicheritage.org/history/british-nuclear-program – retrieved 10 November 2018

(12) https://www.atomicheritage.org/history/soviet-atomic-program-1946 – retrieved 10 November 2018

(13) https://www.atomicheritage.org/history/french-nuclear-program – retrieved 10 November 2018

(14) https://www.atomicheritage.org/history/soviet-atomic-program-1946 – retrieved 10 November 2018

(15) https://www.cfr.org/backgrounder/growing-nuclear-club – retrieved 10 November 2018

(16) https://www.thoughtco.com/mutually-assured-destruction-1221190 – retrieved 10 November 2018

(17) http://www.navweaps.com/Weapons/WMUS_Poseidon.php – retrieved 10 November 2018

(18) https://fas.org/nuke/guide/usa/slbm/c-3.htm – retrieved 10 November 2018

(19) https://history.state.gov/milestones/1969-1976/salt – retrieved 10 November 2018

(20) http://www.nationalarchives.gov.uk/cabinetpapers/themes/skybolt-polaris-missiles.htm – retrieved 10 November 2018

(21)  https://www.royalnavy.mod.uk/news-and-latest-activity/operations/global/continuous-at-sea-deterrent – retrieved 10 November 2018

(22)  https://www.gov.uk/government/publications/successor-submarine-programme-factsheet/successor-submarine-programme-factsheet – retrieved 10 November 2018

 

 

 

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