Editing Vickers Valiant (section)

===Background and origins===
In November 1944, the Joint Technical Warfare Committee, along with a separate committee chaired by Sir [[Henry Tizard]], examined the future potential of "weapons of war" and the accompanying Tizard Report published on 3 July 1945 made specific policy directions for the [[Royal Air Force]] (RAF) [[RAF Bomber Command|Bomber Command]].<ref name="Turpin p. 71">Turpin 2002, p. 71.</ref> After the [[World War II|Second World War]], the policy of using heavy four-engined bombers for massed raids continued into the immediate postwar period; the [[Avro Lincoln]], an updated version of the [[Avro Lancaster]], became the RAF's standard bomber.<ref>McLelland 2013, p. 18.</ref> In 1946, the [[Air Staff (United Kingdom)|Air Staff]] issued Operational Requirements OR229 and OR230 for the development of [[jet aircraft|turbojet]]-powered heavy bombers capable of carrying [[nuclear weapon]]s at high altitude and speed, without defensive armament, to act as a deterrent to hostile powers and, if deterrence failed, to perform a nuclear strike.<ref name="Turpin p. 71"/> In conjunction with this ambition, Britain set about developing its own [[nuclear weapons and the United Kingdom|atomic weapons]].<ref name = "flint 131"/>

In January 1947, the British [[Air Ministry]] issued [[Air Ministry specification|Specification B.35/46]] for an advanced jet bomber intended to carry nuclear weapons and to fly near the speed of sound at altitudes of {{cvt|50000|ft|m}}.<ref name = 'Rose 52'/> Three firms: [[Avro|A.V. Roe]], [[Handley-Page Aircraft Company|Handley-Page]] and [[Vickers-Armstrongs]] submitted advanced designs intended to meet the stringent requirements.<ref name="Aero Aug80 p397">Burnet and Morgan  ''Aeroplane Monthly'' August 1980, p. 397.</ref> While [[Short Brothers]] submitted a design, by [[Geoffrey T. R. Hill]],<ref>{{cite web|url=http://www.aerocinema.com/product/the-lost-v-bomber-2.html|title=Aerocinema-The Lost V Bomber|work=aerocinema.com|url-status=dead|archive-url=https://web.archive.org/web/20141124185209/http://aerocinema.com/product/the-lost-v-bomber-2.html|archive-date=24 November 2014}}</ref> that was judged too ambitious, the Air Staff accepted another submission from the company for a separate requirement, B.14/46, as "insurance" in case the advanced B.35/46 effort ran into trouble. Aviation authors Bill Gunston and Peter Gilchrist described Specification B.14/46 as "calling for little more than a traditional aircraft fitted with jet engines"<ref name = "bomber 72">Gunston and Gilchrist 1993, p. 72.</ref> Short submitted a conservative design to meet B.14/46, which became the [[Short Sperrin|S.A.4 Sperrin]].<ref name = 'Rose 52'/> Two prototypes were completed, the first conducting its [[maiden flight]] in 1951, but the Sperrin was ultimately relegated to research and development purposes only.<ref name="Aero Aug80 p397"/><ref name = "flint 131"/>

Vickers had emerged from World War II as one of the world's pre-eminent companies in the field of aeronautical manufacturing and development. The company operated its own secretive [[Skunk Works]]-like development organisation based at Weybridge, Surrey, which had been involved in several secret wartime development projects. It was this secretive division where the early development of the Valiant took place, including the later assembly of the initial two prototypes.<ref name = "bomber 72 73">Gunston and Gilchrist 1993, pp. 72–73.</ref> Vickers initially produced a six-engine jet bomber design proposal to meet Specification B.35/46. As progress in the development of more powerful jet engines was made, this was re-worked to a four-engine proposal in 1948.<ref name = "bomber 73">Gunston and Gilchrist 1993, p. 73.</ref> The proposed design submitted by Vickers was relatively straightforward, being less aerodynamically advanced in comparison to competing bids made by rival firms.<ref name = "bomber 72"/><ref name = "black wright 17">Blackman and Wright 2015, p. 17.</ref>

Both Handley-Page and Avro had produced advanced designs for the bomber competition. These were produced as the [[Handley Page Victor|Victor]] and the [[Avro Vulcan|Vulcan]] respectively. The Air Staff decided to award contracts to each company as a form of insurance in case one of the designs failed. The submissions became known as the [[V bomber]]s, or V-class, with the aircraft given names that started with the letter "V".<ref>Downey 1985, p. 5.</ref> Vickers' submission had initially been rejected as not being as advanced as the Victor and the Vulcan,<ref name = 'Rose 52'>Rosemeyer 2009, p. 52.</ref><ref name = "bomber 72"/> but Vickers' chief designer [[George Edwards (aviation)|George Edwards]] lobbied the Air Ministry on the basis that it would be available much sooner than the competition, going so far as to promise that a prototype would be flown by the end of 1951, that subsequent production aircraft would be flown prior to the end of 1953, and that serial deliveries would commence during early 1955. Gaining the bomber contract was considered of crucial importance to the future of aircraft manufacturing at Vickers.<ref name = "bomber 73"/> "Edwards was supremely confident that Weybridge could deliver the aircraft as specified .. " and "..committed to the brochure performance figures and dates because he thought they knew how to do it". He resisted being pushed to try to more closely match the Victor and Vulcan height and speed requirements or to change equipment from that originally specified as these distractions would jeopardize his promised delivery dates.<ref>Gardner 2006, p. 92.</ref>

Although developing three different aircraft types in response to a single Operational Requirement (OR) was costly, events such as the [[Berlin Blockade]] had led to a sense of urgency in providing a deterrent to the Soviet Union from possible acts of aggression in Western Europe.<ref>Rosemeyer 2009, pp. 52–53.</ref><ref name = "bomber 72"/>

In April 1948, the Air Staff issued a specification with the designation B.9/48 written around the Type 660 Vickers design; and an 'Instruction to Proceed' was received by Vickers on 16 April 1948.<ref name = "bomber 73"/>

In February 1949, two prototypes of the Vickers 660 series were ordered. The first was to be fitted with four [[Rolls-Royce Limited|Rolls-Royce]] [[Rolls-Royce Avon|RA.3 Avon]] [[turbojet]] engines, while the second was to be fitted with four [[Armstrong Siddeley Sapphire]] engines and was designated the Type 667.<ref name="Andrews Vickers p438">Andrews and Morgan 1988, p. 438.</ref>