Editing Hawker Hurricane (section)

==Design==
[[File:Hawker Hurricanes at Lille-Seclin - Royal Air Force 1939-1945 Fighter Command C460.jpg|thumb|Mk.I in France, November 1939, showing original fabric-covered outer wing and two-bladed propeller]]

The Hawker Hurricane is a low-wing [[cantilever]] [[monoplane]]  with retractable undercarriage and an enclosed cockpit.<ref name = "fli 38 468">''Flight'' 12 May 1938, p. 468.</ref> The primary structure of the fuselage was a [[Warren truss]] box-girder with high-tensile steel [[longerons]] and [[duralumin]] cross-bracing, which were mechanically fastened rather than being [[welding|welded]].<ref name = "fli 38 469">''Flight'' 12 May 1938, p. 469.</ref> Over this, a secondary structure composed of wooden [[former]]s and [[stringer (aircraft)|stringers]] covered with [[aircraft dope|doped linen]] gave the fuselage a rounded section. The majority of the external surfaces were linen, except for a section between the cockpit and the engine cowling which used lightweight metal panels instead.<ref name = "fli 38 469 470">''Flight'' 12 May 1938, pp. 469, 470.</ref> Camm had decided to use traditional Hawker construction techniques instead of more advanced options, such as a stressed-skin metal construction.<ref name = "fli 38 467 468">''Flight'' 12 May 1938, pp. 467, 468.</ref>  This form of construction resembled that of earlier biplanes and was already considered to be somewhat outdated when the Hurricane was introduced to service .<ref name = "fli 38 467 470">''Flight'' 12 May 1938, pp. 467–470.</ref>  The Hurricane was initially armed with an arrangement of eight remotely-operated wing-mounted Browning machine guns, intended for conducting rapid engagements.<ref name = "fli 38 468 473">''Flight'' 12 May 1938, pp. 468, 473.</ref> The Hurricane was typically equipped for flying under both day and night conditions, being provided with navigation lights, Harley [[landing light]]s, complete blind-flying equipment, and two-way [[radio]]s. Upon its entry to service, much of the performance data was intentionally concealed from the general public, but it was known that the type possessed a speed range of 6:1.<ref name = "fli 38 473"/> A simple steel tube structure supported the engine; detachable cowling panels allowed access to most of the engine's areas for maintenance.<ref name = "fli 38 472"/> Installed underneath the fuselage, the liquid-cooled radiator has a rectangular opening to its aft; this is covered by a hinged flap, allowing the pilot to control the cooling level. An atypical feature for the era was the use of [[UNS C69100|Tungum alloy]] pipes throughout the cooling system.<ref name = "fli 38 472">''Flight'' 12 May 1938, p. 472.</ref>

[[File:hurricane in planform arp.jpg|thumb|Underside view of ''R4118'', a preserved Hurricane from the [[Battle of Britain]]]]
Initially, the structure of the Hurricane's [[cantilever]] wing consisted of two steel spars, which possessed considerable strength and stiffness.<ref name = "fli 38 469 471">''Flight'' 12 May 1938, pp. 469–471.</ref> The wing was described by  [[Flight International|''Flight'']] as  relatively straightforward to manufacture, employing simple vertical [[jig (tool)|jig]]s to attach the two spars, after which the wing ribs were installed using horizontal bolts, forming separate units between the front and rear spars. [[Hydraulics|Hydraulically]]-actuated split [[trailing edge]] [[flap (aeronautics)|flap]]s were fitted to the inner end of the wings.<ref name = "fli 38 471"/> This wing was predominantly fabric-covered, like the fuselage, although some lightweight metal sheets were used on the inner wing and its [[leading edge]]. The majority of the [[flight control surfaces]], such as the Frise-type [[aileron]]s, also had fabric coverings.<ref name = "fli 38 471">''Flight'' 12 May 1938, p. 471.</ref>

An all-metal, stressed-skin wing of [[duralumin]]ium (a DERD specification similar to AA2024) was introduced in April 1939 and was used for all of the later marks.<ref name=greatac /> "The metal skinned wings allowed a diving speed that was {{cvt|80|mph}} higher than the fabric-covered ones. They were very different in construction but were interchangeable with the fabric-covered wings; one trials Hurricane, ''L1877'', was even flown with a fabric-covered port wing and metal-covered starboard wing. The great advantage of the metal-covered wings over the fabric ones was that the metal ones could carry far greater stress loads without needing as much structure."<ref name="Hiscock p. 12">Hiscock 2003, p. 12.</ref> Several fabric-wing Hurricanes were still in service during the Battle of Britain, although a good number had had their wings replaced during servicing or after repair. Changing the wings required only three hours work per aircraft.<ref name="Hiscock p. 12"/>

The Hurricane had an inward-retracting [[landing gear|undercarriage]], the main undercarriage units being housed in recesses in the wing.<ref name = "fli 38 472"/> Hinged telescopic Vickers-built legs are attached to the bottom boom of the wing's forward spar, but with an [[Landing gear#Rearwards and sideways retraction|angled pivot]]  to allow the strut to be perpendicular to the thrust line when extended and angle rearwards when retracted to clear the forward spar. A hydraulic jack actuated the undercarriage.<ref name = "fli 38 472"/> Two separate hydraulic systems, one being power-operated and the other hand-operated, are present for the deployment and retraction of the undercarriage; in the event of both failing, pilots can release the retaining catches holding the undercarriage in place, deploying the wheels to the 'down' position using weight alone. A wide wheel-track was used to allow for considerable stability during ground movements and to enable tight turns to be performed.<ref name = "fli 38 471 472">''Flight'' 12 May 1938, pp. 471–472.</ref>

The prototype and early production Hurricanes were fitted with a Watts two-bladed fixed-pitch wooden propeller. ''Flight'' commented of this arrangement: "Many have expressed surprise that the Hurricane is not fitted with variable-pitch airscrews".<ref name = "fli 38 473">''Flight'' 12 May 1938, p. 473.</ref> The original two-bladed propeller was found to be inefficient at low airspeeds and the aircraft required a long ground run to get airborne, which caused concern at Fighter Command. Accordingly, trials with a [[de Havilland]] [[Variable-pitch propeller (aeronautics)|variable-pitch propeller]] demonstrated a reduction in the Hurricane's take-off run from {{cvt|1230|to|750|ft}}. Deliveries of these began in April 1939: this was later replaced by the hydraulically operated constant-speed [[Rotol]] propeller, which came into service in time for the Battle of Britain.<ref>McKnstry 2010, p. 87.</ref>

{{quote box
| align = right
| quote = Then, with tail trimmer set, throttle and mixture lever fully forward... and puffs of grey exhaust smoke soon clearing at maximum r.p.m. came the surprise! There was no sudden surge of acceleration, but with a thunderous roar from the exhausts just ahead on either side of the windscreen, only a steady increase in speed... In retrospect that first Hurricane sortie was a moment of elation, but also of relief. Apart from the new scale of speeds that the pilot had to adapt to, the Hurricane had all the qualities of its stable, secure biplane predecessor the [[Hawker Hart|Hart]], but enhanced by livelier controls, greater precision and all this performance.
| source = [[Roland Beamont]] describing his first flight in a Hurricane as a trainee pilot.<ref>Beamont January 1994, pp. 17, 18.</ref>
| width = 26%
}}
Camm's priority was to provide the pilot with good all-round visibility. To this end, the cockpit was mounted reasonably high in the fuselage, creating a distinctive "hump-backed" silhouette. Pilot access to the cockpit was aided by a retractable "[[stirrup]]" mounted below the trailing edge of the port wing. This was linked to a spring-loaded hinged flap which covered a handhold on the fuselage, just behind the cockpit. When the flap was shut, the footstep retracted into the fuselage. In addition, both [[wing root]]s were coated with strips of non-slip material.<ref>Simmons 2013, ch. "Hundreds of Hurricanes"</ref>

An advantage of the steel-tube structure was that cannon shells could pass right through the wood and fabric covering without exploding. Even if one of the steel tubes were damaged, the repair work required was relatively simple and could be done by ground crew at the airfield. Damage to a [[stressed skin]] structure, as used by the Spitfire, required more specialised equipment to repair.<ref>[http://www.airspacemag.com/history-of-flight/spits_and_canes.html "Best of Battle of Britain."]''[[Air & Space]],'' February–March 2008, p. 4. {{Webarchive|url=https://web.archive.org/web/20131029201855/http://www.airspacemag.com/history-of-flight/spits_and_canes.html |date=29 October 2013 }}</ref> The old-fashioned structure also permitted the assembly of Hurricanes with relatively basic equipment under field conditions. Crated Hurricanes were assembled at [[Sekondi-Takoradi|Takoradi]] in West Africa and flown across the Sahara to the [[Mediterranean and Middle East theatre of World War II|Middle East theatre]] and, to save space, some [[Royal Navy]] aircraft carriers carried their reserve Sea Hurricanes dismantled into their major assemblies, which were slung up on the hangar bulkheads and deckhead for reassembly when needed.{{citation needed|date=November 2020}}

In contrast, the contemporary Spitfire used all-metal [[monocoque]] construction and was thus both lighter and stronger, though less tolerant of bullet damage. With its ease of maintenance, widely set landing gear and benign flying characteristics, the Hurricane remained in use in theatres of operations where reliability, easy handling and a stable gun platform were more important than performance, typically in roles like ground attack. One of the design requirements of the original specification was that both the Hurricane and the Spitfire were also to be used as [[night fighter]]s. The Hurricane proved to be a relatively simple aircraft to fly at night, and shot down several German aircraft on night raids. From early 1941 the Hurricane was also used as an "intruder" aircraft, patrolling German airfields in France at night to catch bombers taking off or landing.{{citation needed|date=November 2020}}