RAF Thors

From the perspective of 2007, Thor may seem “an entirely pointless exercise”, but it made a lot of sense more than half a century ago when the programme was begun. By the mid-1950s, the USA had become worried that the Soviet Union might be able to deploy an ICBM force before the equivalent US weapons were ready for service.

As an interim solution, the intermediate-range ballistic missile (IRBM) programmes were started in the USA. To speed development, Thor was intended to reuse as much Atlas technology as possible. The emphasis was to have the USSR targeted by US ballistic missiles as soon as possible.

In March 1957 the US and UK agreed that 60 Thor IRBM would be based in the UK, manned up by RAF Bomber Command personnel, but with control of the nuclear warheads remaining with USAF personnel sited at each Thor base. This dual-key arrangement was not unusual for the era.

The first active unit was No. 77 Squadron at RAF Feltwell, which became operational on 1 September 1958. The remaining squadrons were all operational by the end of 1959.

The British decision to man what was in practice a US-owned weapon system may have been intended to provide useful operational experience for the RAF, which expected to take the Blue Streak IRBM into service in the mid-1960s, but by late 1959 the UK had concluded that the usefulness of a land-based liquid-propellant strategic missile would be very limited.

Thor had a maximum range of at least 1,675 miles – the US Air Force Museum credits it with a range of 1,725 miles. This is significantly greater than the widely-reported 1,500 miles, so allowed Moscow to be targeted from launch sites in the UK.

The first Atlas D ICBMs entered service in October 1959, but was not available in other than nominal numbers until 1961. By the time that the Thors were fully deployed in December 1959, the US had only six Atlas ICBMs in service – three of which were at open launch pads at Vandenberg AFB.

The first operational patrol by a Polaris submarine took place in the winter of 1960/61. The Jupiter IRBM became operational in 1961, while the Titan 1 and Minuteman I followed in 1962.

So Thor had filled an important gap, and still provided a significant part of the west’s ballistic missile force as the Atlas and Polaris forces were built up.

By the summer of 1962, the Thor force’s usefulness was drawing to a close, and the decision was taken to take the system out of service in May 1963. The first missile came off alert in November 1962, and all were non-operational by mid-August 1963.

The short lifetime of Thor was matched by that of other US ICBMs based on cryogenic liquid propulsion. The last Jupiter IRBMs were retired in April 1963. The Atlas D ICBMs were retired in May 1964, and final Atlas F followed in March 1965 having seen less than two and a half years of operational service. Titan I was retired around the same time.

Only two of the last 22 Thor IRBMs to be test fired failed – a reliability of just over 90%. Not bad for mid-1950s missile technology!

Mercurius Cantabrigiensis

Could also have been part of a British desire to have a missile based force as well, much like the Washingtons were procured prior to the V-Bombers. Remember that this was the period in which Blue Streak was being developed and cancelled. It could have been an exercise in giving an impression of capability prior to the arrival of the Blue Streak.