The Type 698 was Avro’s response to the UK Government’s 1947 call for proposals for a high speed high altitude jet bomber to carry the British nuclear arsenal. It was one of three proposals chosen, and after trials with single seat scaled-down test aircraft designated Avro 707s, the first full-sized prototype (VX770) took off for the first time from Woodford on August 30th, 1952, and was demonstrated to the crowds at Farnborough two days later. The Air Ministry decided that their new bombers would constitute the “V-force”, taking their naming cue from the Vickers Valiant, and by October 1952 the Type 698 had become the Avro Vulcan.
Forty five production aircraft of the initial design, Vulcan B1s, had been delivered by mid 1959, each powered by 4 Bristol Olympus 104 engines of 13,500 pounds static thrust. These were followed between 1959 and 1965 by 89 Vulcan B2s, which had a larger, thinner wing, a number of up rated systems, and were initially powered by Bristol Olympus 201 engines of 17,000 pounds static thrust.
The aircraft was originally designed to carry Britain’s first independent nuclear weapon, Blue Danube, and that determined the size of the bomb-bay. Blue Danube, which was a pure fission weapon originally with a yield of only 10-12kt, would have filled the Vulcan’s bomb-bay and weighed in at over 10,000 lbs! As more fissile material became available it was planned to redesign the weapon to give a yield of around 40kt but there is no evidence this ever went into production. A total of 58 weapons were manufactured and it was designed to be dropped from an altitude of 50,000 ft.
By 1961, Blue Danube had been replaced as a tactical nuclear weapon by Red Beard. With a weight of 1750lbs and a yield of 15kt (Mk1 carried by the V-force) or 25kt (Mk2 for Canberra aircraft), it was considerably smaller than Blue Danube with dimensions of 12ft by 2ft 4in. diameter. Of the 110 produced, only 16 were retained in the UK, 48 being held in both Cyprus (for NEAF) and Singapore (a CENTO commitment).
The first British fusion weapon, Violet Club, whose exterior appearance was much like the Blue Danube, was never carried by the Vulcan, due to several problems. See this Wikipedia article for details.
In 1959, Blue Danube as a strategic deterrent was replaced by Yellow Sun Mk1, a boosted fission weapon. Although the Green Grass warhead was never tested it was believed to have a yield of about 400KT. Yellow Sun Mk2, a pure fusion weapon with a yield of 1.1MT, was introduced in 1961 and was withdrawn in 1970.
Although the Avro Vulcan was originally designed as an all-weather high-altitude transonic bomber with a service ceiling in excess 60,000ft, the shooting down of Gary Powers in a U2 aircraft in May 1960 made it obvious that with the rapid advances in the USSR’s surface-to-air missile systems, height alone would no longer provide protection. This led to a major modification program to the Vulcan B2s including massive strengthening measures, a camouflage paint scheme, and eventually Terrain Following Radar (TFR), to give a low level capability.
In 1963, 617 Sqn (“The Dam Busters”) aircraft based at Scampton were equipped with the Blue Steel missile. This was a highly accurate stand-off bomb with a 1.2MT yield from its Red Snow thermonuclear warhead and a range of 150 miles. Its inertial navigation system could deliver the weapon to within 300ft. of the target. However, as it used the very dangerous High Test Peroxide (HTP) as the oxidizer for its Armstrong Siddeley Stentor rocket engine, ground handling was hazardous and the missile took at least 30 minutes to prepare for flight immediately before take-off. Consequently it was never a ‘rapid reaction’ weapons system. Proposals by Avro to overcome these deficiencies using either a ram jet or an Armstrong Siddeley Viper jet engine were turned down by the U.K. Government in favour of the American Skybolt missile (see below).
The Bristol Olympus 301 engines, which each produce 20,000lbs of static thrust, were fitted to the later Vulcans which were intended to carry the Skybolt thermonuclear strategic missiles. The larger engines were required to overcome the drag and weight of the Skybolt missiles which were to be carried as external stores with one under each wing.
However, on the same day that the first successful launch of a Skybolt took place in 1962, the USA cancelled the project, and the U.K. Government opted for the Polaris submarine missile system, transferring the role of prime nuclear deterrent to the Royal Navy. Once the RN was operating Polaris, the V-Force adopted the role of low-level tactical nuclear response, equipped from 1966 with the WE-177B (and from 1969 the WE-177C) tactical thermonuclear weapon with a yield of 400KT.(Type B) or 200KT (Type C). These weapons weighed only 950 lbs. and were 133in. long with a diameter of 16.5in.
In its conventional role the Vulcan can carry up to twenty-one 1000lb high-explosive bombs.
A full history of the Vulcan Bomber can be found at: Thunder & Lightnings – Avro Vulcan – History