Editing Hawker Hurricane (section)

==Development==
===Background===
During the early 1930s, when [[Hawker Aircraft]] company developed the Hurricane, [[RAF Fighter Command]] had just 13 squadrons, equipped with the [[Hawker Fury]], [[Hawker Hart#Demon|Hawker Demon]], or the [[Bristol Bulldog]], all [[biplane]]s with fixed-[[Blade pitch|pitch]] wooden propellers and non-retractable undercarriages.<ref name="Bader">Bader 2004, p. 36.</ref><ref name="mason 3">Mason 1967, p. 3.</ref> At the time, there was an institutional reluctance towards change within the [[Air Staff (United Kingdom)|Air Staff]]; some senior figures{{who|date=August 2022}} were prejudiced against the adoption of [[monoplane]] fighter aircraft, while mid-level officers were typically more open-minded.<ref name="mason 3" />

In 1934 the British [[Air Ministry]] issued [[List of Air Ministry specifications#1930–1939|Specification F.5/34]] in response to demands within the [[Royal Air Force]] (RAF) for a new generation of [[fighter aircraft]]. Earlier, during 1933, British aircraft designer [[Sydney Camm]] had conducted discussions with Major John Buchanan of the Directorate of Technical Development on a monoplane based on the existing Fury.<ref name="mason 3 4">Mason 1967, pp. 3–4.</ref> Mason attributes Camm's discussions with figures within the RAF, such as Squadron Leader [[Ralph Sorley]], as having provoked the specification and some of its details, such as the preference for armaments being installed within the wings instead of within the aircraft's nose.<ref name="mason 4">Mason 1967, p. 4.</ref>

An outline of the "Fury Monoplane" armed with two guns in the wings and two in the nose and powered by the [[Rolls-Royce Goshawk|Goshawk engine]] was prepared and discussed with Roger Liptrot of the Air Ministry in December 1933.<ref>Buttler, 2005 p8</ref> The design was reworked with the PV.12, following detailed work working drawings of the "Interceptor Monoplane" were begun in May 1934. The complete design was presented to the Air Ministry on 4 September.<ref name="Buttler, 2005 p9">Buttler, 2005 p9</ref>

Camm's initial submission in response to the earlier fighter specification F.7/30 was a  development of the Fury, the [[Hawker P.V.3]],<ref group=N>PV standing for "private venture", a design manufactured by Hawker without government backing</ref><ref>Mason 1992, p. 242.</ref> However, the P.V.3 was not among the proposals which the Air Ministry selected to be built as prototype to official contract.<ref group=N>Competition included the [[Blackburn F.3]], the [[Bristol Type 123]], the [[Bristol Type 133]], the [[Supermarine Type 224]], and the [[Westland F.7/30]]</ref> After the rejection of the P.V.3 proposal, Camm started work on a new design involving a [[cantilever]] monoplane arrangement with a fixed undercarriage, armed with four machine guns and powered by the [[Rolls-Royce Goshawk]] engine. The original 1934 armament specifications for what evolved into the Hurricane were for a similar armament fitment to the [[Gloster Gladiator]]: four machine guns; two in the wings and two in the fuselage, [[Synchronization gear|synchronised]] to fire through the propeller arc. By January 1934, the proposal's detail drawings had been finished, but these failed to impress the Air Ministry enough for a prototype to be ordered.<ref>McKinstry 2010, p. 30.</ref>

Camm's response to this rejection was to further develop the design, introducing a retractable undercarriage and replacing the unsatisfactory Goshawk engine with a new Rolls-Royce design, initially designated the ''PV-12'', which went on to become famous as the [[Rolls-Royce Merlin|Merlin]]. In August 1934, a one-tenth scale model of the design was produced and sent to the [[National Physical Laboratory (United Kingdom)|National Physical Laboratory]] at [[Teddington]], where a series of [[wind tunnel]] tests confirmed the aerodynamics were satisfactory, and in September 1934 Camm again approached the Air Ministry. This time, the Ministry's response was favourable, and a prototype of the "Interceptor Monoplane" was promptly ordered.<ref>McKinstry 2010, p. 34.</ref>

In July 1934, at a meeting chaired by Air Commodore [[Arthur Tedder, 1st Baron Tedder|Arthur Tedder]] (director of training), the Air Ministry Science Officer Captain [[Frederick William Hill|F.W. "Gunner" Hill]] presented his calculation showing that future fighters must carry no fewer than eight machine guns, each capable of firing 1,000 rounds per  minute.<ref>Keith CH. ''I Hold My Aim''. George Allen and Unwin Ltd, London, 1946</ref>/{{page needed|date=November 2021}} Hill's assistant in making his calculations was his 13-year-old daughter [[Hazel Hill]]. Of the decision to place eight machine guns in fighters, [[Claude Hilton Keith]], at the time assistant director of armament research and development, said "The battle was brisk and was carried into very high quarters before the implementing authority was given. My Branch had made out a sound case for 8-gun fighters and if this recommendation had not been accepted and we had been content with half-measures, it might indeed have gone ill for us during the late summer of 1940". Present at the meeting was Squadron Leader [[Ralph Sorley]] of the Air Ministry's Operational Requirements branch, who played an important role in the decision. In November 1934, the Air Ministry issued Specification F.5/34 which called for new fighter aircraft to be armed with a total of eight guns. However, by this time, work had progressed too far to immediately modify the planned four-gun installation. By January 1935, a wooden mock-up had been finished, and although a number of suggestions for detail changes were made, construction of the prototype was approved, and a new specification (F.36/34) was written around the design. In July 1935, this specification was amended to include installation of eight guns.<ref name="mason 4" /><ref>McKinstry 2010, p. 40.</ref>

The mock-up conference with Air Ministry staff was on 10 January 1935 at Kingston. The ministry order to purchase a prototype to the September proposal was placed on 21 February 1935. At the time the armament was two Vickers Mark V machine guns in the fuselage and one [[M1919 Browning machine gun|Browning machine gun]] in each wing. Work on stressed skin outer wings to replace the fabric covered ones began in July and the contract was altered in August to include another set of wings with eight guns in them; the guns were to be either [[Vickers]] or Brownings.<ref name="Buttler, 2005 p9"/> These wings were delivered in June 1936.<ref name="Buttler, 2005 p9"/>

===Prototype and trials===
[[File:Hurricane mockup.jpg|thumb|An early mock-up for the Hurricane's fuselage, showing side fuselage-mounted [[Synchronization gear|synchronised]] machine gun, like earlier British biplane fighters.]]

By the end of August 1935, work on the airframe had been completed at Hawker's [[Kingston upon Thames]] facility and the aircraft components were transported to [[Brooklands]], [[Surrey]], where Hawker had an assembly shed; the prototype was fully re-assembled on 23 October 1935.<ref name="mason 4" /> Ground testing and taxi trials took place over the following two weeks. On 6 November 1935 the prototype ''K5083'' took to the air for the first time at the hands of Hawker's chief [[test pilot]], [[Flight Lieutenant]] [[George Bulman (pilot)|George Bulman]].<ref name=greatac>Cacutt 1989, pp. 204–212.</ref> Bulman was assisted by two other pilots in subsequent flight testing; [[Philip Lucas]] flew some of the experimental test flights, while [[John Stuart Hindmarsh|John Hindmarsh]] conducted the firm's production flight trials.<ref>Bader 2004, pp. 37, 40.</ref> As completed, the prototype had been fitted with [[ballast]] to represent the aircraft's armament prior to the acceptance of the final multi-gun wing armament.<ref>{{cite book |last=Mason |first=Francis K. |date=1962 |title=The Hawker Hurricane |location=London |publisher=MacDonald |page=21 }}</ref>

By March 1936, the prototype had completed ten flying hours, covering all major portions of the flight envelope. Early testing had gone reasonably well, especially in light of the trial status of the Merlin engine, which had yet to achieve full flight certification at this time and thus severe restrictions had been imposed upon use of the engine.<ref name="mason 4" /> In early 1936, the prototype was transferred to [[RAF Martlesham Heath]], [[Suffolk]], to participate in initial service trials under the direction of Squadron Leader D.F. Anderson. Sammy Wroath, later to be the founding commandant of the [[Empire Test Pilots' School]], was the RAF test pilot for the Hurricane: his report was favourable, stating that: "The aircraft is simple and easy to fly and has no apparent vices" and proceeded to praise its control response.<ref>McKinstry 2010, p. 52.</ref>

[[File:Hawker Hurricane before maiden flight 1935.jpg|thumb|''K5083'', the prototype, photographed before its first flight in November 1935]]
In the course of RAF trials, despite the problems with the Merlin engine, which had suffered numerous failures and necessitating several changes, enthusiastic reports were produced on the aircraft and its performance. The trials had proved the aircraft to possess a maximum level speed of {{cvt|315|mph}} at an altitude of {{cvt|16200|ft}}, climb to  {{cvt|15000|ft}} in 5.7 minutes, and a stalling speed of {{cvt|57|mph}} (only marginally higher than the Gladiator biplane), the last achieved using its [[Flap (aeronautics)|flaps]].<ref name="mason 4" />

In the course of further testing, it was found that the Hurricane had poor [[Spin (aerodynamics)|spin]] recovery characteristics, in which all [[rudder]] authority could be lost due to shielding of the rudder.<ref name="mason 5" /> Hawker's response to the issue was to request that spinning tests be waived, but the Air Ministry refused the request;<ref>McKinstry 2010, p. 64.</ref> the situation was resolved by the [[Royal Aircraft Establishment]] (RAE), who established that the aerodynamic problem had been caused by a breakdown of the airflow over the lower fuselage, and could be cured by the addition of a small ventral [[aircraft fairing|fairing]] and extension of the bottom of the rudder. This discovery had come too late for the changes to be incorporated in the first production aircraft, but were introduced upon the 61st built and all subsequent aircraft.<ref>Mason 1992, p. 254.</ref>

In early 1936, the Hawker [[board of directors]] had decided, in the absence of official authorisation and at company expense, to proceed with the issue of the design drawings to the production design office and to start tooling-up for a production line capable of producing a batch of 1,000 Hurricanes.<ref>"World Encyclopedia of Aero Engines – 5th edition" by [[Bill Gunston]], Sutton Publishing, 2006, p. 188.</ref><ref name="mason 4 5">Mason 1967, pp. 4–5.</ref>

===Production===
[[File:Women assembling Hawker Hurricanes 1942.jpg|thumb|Hurricane production line, 1942]]
In June 1936 the Air Ministry placed its first order for 600 aircraft.<ref name="mason 5" /> On 26 June 1936 the Air Ministry approved the type name of "Hurricane" that had been proposed by Hawker, and an informal naming ceremony occurred the following month during an official visit by [[King Edward VIII]] to Martlesham Heath.<ref name="mason 5">Mason 1967, p. 5.</ref><ref>{{citation |url=http://www.flightglobal.com/pdfarchive/view/1936/1936%20-%201976.html |title=The King Inspects his Air Force |work=[[Flight International|Flight]] |date=16 July 1936 |page=83 |archive-url=https://web.archive.org/web/20171010211309/http://www.flightglobal.com/pdfarchive/view/1936/1936%20-%201976.html   |archive-date=  10 October 2017  }}.</ref>

It was significantly cheaper to produce than the [[Supermarine Spitfire]] and took 10,300 man hours per airframe to produce, compared to 15,200 for the Spitfire, which had many parts formed by hand, with [[English wheel]]s.<ref name="postan">Postan 1952, p. Chapter IV, footnote 89.</ref> As war was looking likely, and time was of the essence in providing the RAF with an effective fighter, the authorities expected there to be problems with the more advanced Spitfire, while the Hurricane made use of well proven manufacturing techniques.<ref name="postan" /> The service squadrons were also already experienced in maintaining aircraft structurally similar to the Hurricane.<ref name="postan" /> A fabric-covered wing was initially adopted in order to accelerate production, while a higher-performing stressed-skin metal wing was introduced in late 1939.<ref name="mason 5" />

The first production Hurricane I first flew on 12 October 1937, flown by Flight Lieutenant Philip Lucas and powered by a Merlin II engine. While a contract for 600 Hurricanes was received on 2 June 1936, deliveries lagged by roughly six months due to a decision in December 1936 to replace the Merlin I with the improved Merlin II, which resulted in many detail alterations.

[[File:Royal Air Force Training Command, 1939-1940. C851.jpg|thumb|Trainee aircraft fitters working on instructional Hurricanes 1939–1940]]
Merlin I production ended after 180 were built. This engine had been prioritised for the [[Fairey Battle]] light bomber and the [[Hawker Henley]], a failed competitor to the Battle briefly adapted as a target tug which shared common elements with the Hurricane design.<ref name="mason 5" /> By the following December, the first four aircraft to enter service with the RAF had joined [[No. 111 Squadron RAF|No. 111 Squadron]], stationed at [[RAF Northolt]]. By February 1938, No. 111 Squadron had received 16 Hurricanes.<ref name="mason 5" /> Upon the outbreak of the Second World War, over 550 Hurricanes had been produced equipping 18 squadrons, with 3,500 more on order.<ref>Bader 2004, p. 41.</ref><ref name="mason 7" />

During 1940, [[Max Aitken, 1st Baron Beaverbrook|Lord Beaverbrook]], the [[Minister of Aircraft Production]], established the [[Civilian Repair Organisation]] through which a number of manufacturers were to repair and overhaul battle-damaged aircraft including Hurricanes. Some of these were later sent to training units or to other air forces. Factories involved included the [[Austin Motor Company|Austin Aero Company]]'s [[Cofton Hackett#Austin Aero Works|Cofton Hackett plant]] and David Rosenfield Ltd, based at [[Barton-upon-Irwell|Barton]] aerodrome near [[Manchester]].{{cn|date=August 2023}}

The [[Canadian Car and Foundry]] of [[Fort William, Ontario]], Canada was a major Hurricane manufacturer, producing them from November 1938 after receiving their  initial contract for 40 Hurricanes. The facility's chief engineer, [[Elsie MacGill]], became known as the "Queen of the Hurricanes".<ref name="mason 7" /> The initiative was commercially driven, but was endorsed by the British government. Hawker recognised that a major conflict was inevitable after the [[Munich Agreement|Munich Crisis]] of 1938 and drew up preliminary plans to expand Hurricane production at a new factory in Canada. Under this plan, samples, pattern aircraft, and design documents stored on [[microfilm]] were shipped to Canada. In 1938/39 the RCAF ordered 24 Hurricanes to equip one fighter squadron, 20 of which were delivered, and two were supplied to Canadian Car and Foundry as pattern aircraft but one probably did not arrive, while the other was returned to Britain in 1940. The first Hurricane built at Canadian Car and Foundry was completed in February 1940.<ref name="mason 7" /> Canadian-built Hurricanes shipped to Britain participated in the [[Battle of Britain]].<ref name="mason 7" />

Overall, some 14,487 Hurricanes and Sea Hurricanes were produced in England and Canada.<ref name="Thetford 1994, p. 232">Thetford 1994, p. 232</ref><!--page ref may be wrong since I have 1982 edition--> The majority of Hurricanes, 9,986 were built by Hawker (who produced the type at Brooklands from December 1937 to October 1942 and Langley from October 1939 to July 1944), while Hawker's sister company, the [[Gloster Aircraft Company]], constructed 2,750. The Austin Aero Company completed 300 Hurricanes. Canada Car and Foundry produced 1,451 Hurricanes.<ref>{{Cite web|url=https://ingeniumcanada.org/aviation/collection-research/artifact-hawker-hurricane-xii.php|title=Hawker Hurricane XII – Canada Aviation and Space Museum|website=ingeniumcanada.org|language=en-CA|access-date=2018-05-21}}</ref> However those shipped to Britain were often incomplete airframes and about 80% were delivered without an engine.

In 1939, production of 100 Hurricanes was initiated in [[Yugoslavia]] by [[Zmaj aircraft|Zmaj]] and [[Rogožarski]].<ref name="mason 6 7" /> Of these, 20 were built by Zmaj by April 1941. Recognising that the supply of British-made Merlin engines might not be guaranteed, it was decided to fit one of the Yugoslavian Hurricanes with a [[Daimler-Benz DB 601]] engine instead. This aircraft was flown in 1941.<ref name="mason 7" /> In 1938, a contract for 80 Hurricanes was placed with Fairey's Belgian subsidiary [[Avions Fairey]] SA for the [[Belgian Air Force]], and it was intended to arm these aircraft with four {{cvt|13.2|mm|2}} [[M1919 Browning machine gun|Browning machine guns]]. Three were built and two flown with this armament by the time of the [[German invasion of Belgium (1940)|German invasion of Belgium]] in May 1940, with at least 12 more constructed by Avions Fairey armed with the conventional eight rifle calibre machine gun armament.<ref name="mason 7" /><ref name="Half pt 4 p34">''Air International'', July 1987, p. 34.</ref>