Editing Vickers Valiant (section)

==Development==
===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>

===Prototypes===
[[File:Vickers Valiant Farnborough 1951.jpg|thumb|First prototype at the [[Farnborough Airshow]], 1951]]
On 18 May 1951, the first prototype, [[United Kingdom military aircraft serials|serial number]] WB210 took to the air for its maiden flight,<ref name="Andrews Vickers p439">Andrews and Morgan 1988, p. 439.</ref> within the deadline that George Edwards had promised, only 27 months since the contract had been issued. This was several months before the competing Short Sperrin; the Sperrin had straight (not swept) wings and was not ordered.  The Valiant pilot was [[Joseph Summers|Captain Joseph "Mutt" Summers]], who had also been the original test pilot on the [[Supermarine Spitfire]], and wanted to add another "first" to his record before he retired. His co-pilot on the first flight was Gabe "Jock" Bryce, who succeeded Summers as Vickers' chief test pilot upon his retirement shortly after.<ref name="Turpin p. 72">Turpin 2002, p. 72.</ref><ref name = "black wright 10">Blackman and Wright 2015, p. 10.</ref><ref>McLelland 2013, p. 68.</ref> The next month, the Vickers Type 660 was given the official name of "Valiant", reusing the name given to the [[Vickers 131 Valiant|Vickers Type 131]] general-purpose biplane of 1931.{{#tag:ref|Traditionally, RAF bombers had been named after towns and cities, for example Lancaster, [[Handley Page Halifax|Halifax]] and [[English Electric Canberra|Canberra]], but new jet aircraft technology reflected a new tradition. The name also fitted in with a tradition of alliteration in aircraft names.|group=N}} The name Valiant had been selected by a survey of Vickers employees.<ref name="Jones p31,3">Jones 2007, pp. 31, 33.</ref>

On 11 January 1952, the first Valiant prototype was lost while making internal noise measurements for the [[Vickers V-1000|V.1000]] programme. Testing included engine shutdowns and re-lights,<ref>Andrews 1965, p. 4.</ref> one of which caused a fire in the starboard wing; most of the crew managed to escape the aircraft safely, except for the co-pilot, who struck the tail after ejecting.<ref name="Flight p13">''Flight'' 4 July 1958, p. 13.</ref><ref>Blackman and Wright 2015, pp. 11–16.</ref>

On 11 April 1952, the second prototype WB215 made its maiden flight, after modifications to the fuel system.<ref name="Andrews Vickers p440">Andrews and Morgan 1988, p. 440.</ref> It was fitted with more powerful RA.7 Avon engines with {{convert|7500|lbf|kN}} thrust each, rather than the originally planned Sapphires. It also featured more rounded [[Components of jet engines#Air intakes|air inlet]]s, replacing the narrow slot-type intakes of the first prototype, to feed sufficient air to the more powerful engines. The short delay until the second prototype became available meant that loss of the prototype did not compromise the development schedule.<ref name="Turpin p74">Turpin 2002, p. 74.</ref><ref name="Jones p34">Jones 2007, p. 34.</ref><ref name = "black wright 17"/>

===The Valiant B2===
One of the three prototypes was the B.2 version.<ref name="Jones p26">Jones 2007, p. 26.</ref> The B.2 was intended to serve as a [[Pathfinder (RAF)|Pathfinder]] aircraft, flying at low level to mark targets for the main bomber force. To cope with increased air turbulence at low level, the B.2 had a strengthened airframe. In particular, the wing was strengthened with the removal of the cut-outs in the wing structure into which the main wheels retracted, allowing the wing torsion box structure to be uninterrupted and giving more room for internal fuel storage. Instead, the main landing gear, which had four wheels instead of the two wheels of the B.1, retracted backwards into large [[Aircraft fairing|fairing]]s set into the rear of the wings.<ref name = "bomber 77 78">Gunston and Gilchrist 1993, pp. 77–78.</ref> The B.2 had a lengthened fuselage with a total length of {{convert|112|ft|9|in|m|abbr=on}}, in contrast to a length of {{convert|108|ft|3|in|abbr=on}} for the Valiant B.1, with the extra length giving room for more avionics.<ref name="Jones p32,6">Jones 2007, pp. 32, 36.</ref>

The prototype B.2, serial number WJ954 first flew on 4 September 1953.<ref name="AndrewsVickers p445">Andrews and Morgan 1988, p. 445.</ref> Finished in a gloss black night operations paint scheme, it became known as the "Black Bomber". Its performance at low level was superior to that of the B.1 (or any other V-bomber), particularly at [[sea level#Aviation|sea level]],<ref name = "bomber 77"/> with the aircraft being cleared for {{convert|580|mph|abbr=on}} at low level (with speeds of up to {{convert|640|mph|abbr=on}} being reached in testing). This was compared to the B.1 sea-level limit of {{convert|414|mph|abbr=on|round=5}}. The Air Ministry ordered 17 production B.2 aircraft, which were to be powered by [[Rolls-Royce Conway]] [[turbofan]]s. Although the Valiant B.2 low-level capabilities were significant, the programme was terminated because the World War 2 "Pathfinder concept" was considered obsolete in the nuclear era.<ref name = "bomber 78">Gunston and Gilchrist 1993, p. 78.</ref> The B.2 prototype was used for tests for a few years, including the clearance of rocket-assisted take-offs, for the Valiant B.1 at hot or high airfields, using two Super-Sprite rocket motors. It also did extensive taxiing tests to investigate the cause of brake judder which caused a fatigue failure of the landing gear. It was scrapped in 1958.<ref>Trubshaw and Edmondson 1998, p. 37.</ref><ref name="Jones p36-7">Jones 2007, pp. 36–37.</ref><ref name="Osprey p83-4">Brookes 2012, pp. 83–84.</ref><ref name = "black wright 20"/>

===Production===
[[File:Vickers Valian B.1 WZ393 90 Sqn SGT 10.06.57.jpg|thumb|Valiant B(PR)K.1 WZ393 of 90 Squadron in original all-metal finish displaying at Blackpool Squires Gate airport in 1957]]
In April 1951, an initial production order for 25 Valiant B.1 (Bomber Mark 1) aircraft was placed by the Ministry of Supply on behalf of the RAF.<ref name="Aero Aug80 p400">Burnet and Morgan ''Aeroplane Monthly'' August 1980, p. 400.</ref> The timing of this order was key to establishing production quickly. Due to shortages of [[steel]] and other materials while setting up an assembly line at Brooklands, substantial portions of the production [[Jig (tool)|jigs]] for the Valiant were made from [[concrete]].<ref name = "bomber 77">Gunston and Gilchrist 1993, p. 77.</ref> The first five Valiants produced were completed to a pre-production standard, the first being WP199. On 21 December 1953, the production aircraft conducted its first flight; this had again occurred within the schedule that Edwards had promised.<ref name="Jones p37">Jones 2007, p. 37.</ref><ref name = "bomber 77"/>

On 8 February 1955, this first production Valiant was delivered to the RAF.<ref name="Osprey p12">Brookes 2012, p. 12.</ref><ref name = "flint 131">Flintham 2008, p. 131.</ref> Britain's "V-bomber" force, as it had been nicknamed in October 1952, formally entered operational service on that day. The Victor and Vulcan would soon follow the Valiant into service, for a total of three types of nuclear-armed strategic bombers in RAF service. In September 1957, the final Valiant was delivered.<ref name = "hub and sim 26"/> All production aircraft had been delivered on time and below budget.<ref name = "bomber 78"/>

A total of 108 Valiants were manufactured, including the sole B.2 prototype. In addition to its principal role as part of Britain's [[nuclear deterrent]], the Valiant bomber also dropped high explosive bombs. The bombers were followed into service by a strategic reconnaissance version and a multi-purpose version capable conventional bombing, [[aerial reconnaissance]] and [[aerial refueling|aerial refuelling]]. 18 squadron operated 6 Valiants with [[electronic countermeasure]]s equipment.<ref name = "black wright 19 20">Blackman and Wright 2015, pp. 19–20.</ref> Valiants of 90 and 214 squadrons were used for air refuelling through the addition of a Hose Drum Unit (HDU) in the bomb bay, mounted on the same suspension units that were also used for bombs.  This meant that for refuelling, the bomb-bay doors had to be opened so that the refuelling hose could be streamed (unlike later tankers where the HDU was flush with the under fuselage rather than inside a bomb bay). Several Valiants were also used for testing and development purposes, such as its use as a flying testbed during trials of the [[Blue Steel (missile)|Blue Steel]] nuclear-armed [[standoff missile]], which was later added to the arsenal of munitions the other V-bombers were equipped with.<ref name = "black wright 24 26">Blackman and Wright 2015, pp. 24–26.</ref><ref name = "flint 133">Flintham 2008, p. 133.</ref>

Unlike the Vulcan and Victor, the Valiant did not see the production of a more capable mark 2 model.<ref name = "flint 131"/> In 1962 the Valiant bomber squadrons were switched to a low-level flight profile in order to avoid enemy Surface-to-Air (SAM) defence systems. In 1964 [[Fatigue (material)|fatigue]] was discovered due to the increased air turbulence in low level flying and led to the type's premature retirement. Vic Flintham observed that: "There is a fine irony to the situation, for Vickers had produced the Type 673 B Mk 2 version designed as a fast, low-level pathfinder... The Air Ministry was not interested..."<ref name = "flint 133"/> The Valiant was Vickers' last purpose-built military aircraft. It was followed by the [[Vickers Vanguard|Vanguard]], a passenger turboprop designed in 1959, and the [[Vickers VC10]], a jet passenger aircraft in 1962, also used as a military transport and tanker by the RAF.<ref name = "flint 131"/>