The Hawker Hurricane is a British single-seat fighter aircraft of the 1930s–40s that was designed and predominantly built by Hawker Aircraft Ltd for service with the RAF.
The Hurricane inflicted 60 percent of the losses sustained by the Luftwaffe in the Battle of Britain and fought in all the major theatres of the Second World War.
The Hawker Hurricane is a low-wing cantilever monoplane with retractable undercarriage and an enclosed cockpit.
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 welded.
Over this, a secondary structure composed of wooden formers and stringers covered with doped linen 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.
Camm had decided to use traditional Hawker construction techniques instead of more advanced options, such as a stressed-skin metal construction.
This form of construction resembled that of earlier biplanes and was already considered to be somewhat outdated when the Hurricane was introduced to service.
The Hurricane was initially armed with an arrangement of eight remotely operated wing-mounted Browning machine guns, intended for conducting rapid engagements.
The Hurricane was typically equipped for flying under both day and night conditions, being provided with navigation lights, Harley landing lights, complete blind-flying equipment, and two-way radios.
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.
A simple steel tube structure supported the engine; detachable cowling panels allowed access to most of the engine’s areas for maintenance.
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 Tungum alloy pipes throughout the cooling system.
Initially, the structure of the Hurricane’s cantilever wing consisted of two steel spars, which possessed considerable strength and stiffness.
The wing was described by Flight as relatively straight forward to manufacture, employing simple vertical jigs to attach the two spars, after which the wing ribs were installed using horizontal bolts, forming separate units between the front and rear spars.
Hydraulically-actuated split trailing edge flaps were fitted to the inner end of the wings.
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 ailerons, also had fabric coverings.
An all-metal, stressed-skin wing of duraluminium (a DERD specification similar to AA2024) was introduced in April 1939 and was used for all of the later marks.
The metal skinned wings allowed a diving speed that was 80 mph (130 km/h) 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.”
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.
The Hurricane had an inward-retracting undercarriage, the main undercarriage units being housed in recesses in the wing.
Hinged telescopic Vickers-built legs are attached to the bottom boom of the wing’s forward spar, but with an 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.
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.
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”.
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 demonstrated a reduction in the Hurricane’s take-off run from 1,230 to 750 ft (370 to 230 m).
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.
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 roots were coated with strips of non-slip material.
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.
The old-fashioned structure also permitted the assembly of Hurricanes with relatively basic equipment under field conditions.
Crated Hurricanes were assembled at Takoradi in West Africa and flown across the Sahara to the 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.
In contrast, the contemporary Spitfire used all-metal monocoque construction and was thus both lighter and stronger, though less tolerant to 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 fighters.
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.
Variants
Hurricane Mk I
First production version, with fabric-covered wings, a wooden two-bladed, fixed-pitch propeller (first 435) or three blade two -pitch propeller, powered by the 1,030 hp (770 kW) Rolls-Royce Merlin Mk II (first 364) or III engines and armed with eight .303 in (7.7 mm) Browning machine guns.
Produced between 1937 and 1939.
Hurricane Mk I (revised)
A revised Hurricane Mk I series built with a de Havilland or Rotol constant speed metal propeller (from mid 1940), metal-covered wings, armour and other improvements.
A total of 4,200 mark I were built, 1,924 by Hawker, 1,850 by Gloster Aircraft Company and 426 by Canadian Car and Foundry between December 1937 and July 1941.
The Canadian Car and Foundry Hurricanes were shipped to England to be fitted with engines.
Hurricane Mk IIA Series 1
Hurricane Mk I powered by the improved Merlin XX engine with two-speed supercharger.
This new engine used a coolant mix of 30 per cent glycol and 70 per cent water.
Pure glycol is flammable, so not only was the new mix safer, but the engine also ran approximately 21 °C (70 °F) cooler, which gave longer engine life and greater reliability.
The new engine was longer than the earlier Merlin and so the Hurricane gained a 4.5 in “plug” in front of the cockpit, which made the aircraft slightly more stable due to the slight forward shift in centre of gravity.
First flew on 11 June 1940 and went into squadron service in September 1940.
Hurricane Mk IIB
(Hurricane IIA Series 2)
A few were fitted with racks allowing them to carry two 250 lb (110 kg) or two 500 lb (230 kg) bombs.
This lowered the top speed of the Hurricane to 301 mph (484 km/h), but by this point mixed sweeps of Hurricanes carrying bombs, protected by a screen of fighter Hurricanes were not uncommon.
The same racks allowed the Hurricane to carry two 45 imp gal (200 l) drop tanks instead of the bombs, nearly doubling the Hurricane’s fuel load.[148]
Hurricane Mk IIA Series 2 was equipped with a new and slightly longer propeller spinner, and 4 additional wing-mounted .303 in (7.7 mm) Browning machine guns; for a total of 12 guns.
The first aircraft were built in February 1941 and were renamed Mark IIB in April 1941.
Hurricane Mk IIB Trop
For use in North Africa the Hawker Hurricane Mk IIB (and other variants) were tropicalised.
They were fitted with Vokes and Rolls-Royce engine dust filters and the pilots were issued with a desert survival kit, including a bottle of water behind the cockpit.
Hurricane Mk IIC
(Hurricane Mk IIA Series 2)
Hurricane Mk IIA Series 1 equipped with new and slightly longer propeller spinner, and fully replaced the machine-gun armament with four 20 mm (0.79 in) Hispano Mk II cannons, two per side.
Hurricane IIA Series 2 became the Mk IIC in June 1941, using a slightly modified wing.
The new wings also included a hard point for a 500 or 250 lb (230 or 110 kg) bomb and, later in 1941, fuel tanks.
By then performance was inferior to the latest German fighters, and the Hurricane changed to the ground-attack role, sometimes referred to as the Hurribomber.
The mark also served as a night fighter and intruder with about three quarters converted to fighter bombers.
Hurricane Mk IID
Armed with two 40 mm (1.57 in) anti-tank auto cannon in a gondola-style pod, one under each wing and a single Browning machine gun in each wing loaded with tracers for aiming purposes.
The first aircraft flew on 18 September 1941 and deliveries started in 1942.
Serial-built aircraft had additional armour for the pilot, radiator and engine, and were armed with a Rolls-Royce gun with 12 rounds, later changed to the 40 mm (1.57 in) Vickers S gun with 15 rounds.
The outer wing attachments were strengthened so that 4G could be pulled at a weight of 8,540 lb (3,870 kg).
The weight of guns and armour protection marginally impaired the aircraft’s performance.
Hurricane Mk IIE
Mk IIE, this designation was used by the Ministry of Aircraft Production in 1942 and 1943 for mark II factory fitted with wing racks, the RAF used the IIB or C designation.
The Mk IIE was not an early mark Mk IV.
Hurricane Mk T.IIC
Two-seat training version of the Mk. IIC – Only two aircraft were built, for the Imperial Iranian Air Force.
Hurricane Mk III
Version of the Hurricane Mk II powered by a US Packard-built Merlin engine, intending to enable supplies of the British-built engines for other designs.
By the time production was to have started, British Merlin production had increased to the point where the idea was abandoned.
Hurricane Mk IV
The last major change to the Hurricane was the introduction of the “universal Wing”, a single design able to mount two 250 or 500 lb (110 or 230 kg) bombs, two 40 mm (1.57 in) Vickers S guns, drop tanks or eight “60 pounder” RP-3 rockets.
Two .303 in (7.7 mm) Brownings were fitted to aid aiming of the heavier armament.
Despite persistent reports actually fitted with the same Merlin XX as the mark II.
All Merlin 27 were modified to Merlin 25 and used in Mosquitoes, there were only 16 production Merlin 24 by the time over 300 mark IV had been delivered.
The individual aircraft cards held by the RAF museum reports the final mark IV had Merlin XX.
The radiator was deeper and armoured.
Additional armour was also fitted around the engine.
524 built by Hawker between December 1942 and March 1944.
Hurricane Mk V
The final variant to be produced – Only one was built and 2 mark IV converted, and the variant never reached production.
This was planned to be powered by a Merlin 27 but also tested with a Merlin 32 boosted engine to give 1,700 hp (1,300 kW) at low level and was intended as a dedicated ground-attack aircraft to use in Burma.
All three prototypes had four-bladed propellers.
Speed was 326 mph (525 km/h) at 500 ft (150 m), which is comparable with the Hurricane I despite being one and a half times as heavy.
Hurricane Mk X
Canadian-built variant – Canadian Car and Foundry report building a total of 975 mark II airframes for Holland (1), the RAF (575) and RCAF (400), between July 1941 and May 1943.
The mark X designation has been used by the RAF for Canadian Car and Foundry built mark I but it is usually defined as mark II airframes fitted with a Merlin 28.
About two thirds of the Canadian Car and Foundry built mark II airframes shipped to Britain did so without an engine, the remainder being fitted with Merlin 28 in Canada, but the engine was near automatically removed upon arrival and a Merlin XX fitted instead and the aircraft called mark II by the RAF.
Apart from some test flights in Canada and England no Hurricane flew powered by a Merlin 28.
Canada only imported 285 Merlin 28 for Hurricanes, all of which were shipped to Britain either as a separate engine or attached to a Hurricane.
Hurricane Mk XI
Canadian-built variant – Designation used for 150 aircraft from the RCAF mark XII order sent to Britain, these aircraft had their Merlin 29 removed and were either shipped without an engine or fitted with a Merlin 28.
Fitted with Merlin XX on arrival in Britain and called mark II by the RAF.
Hurricane Mk XII
Canadian-built variant,
Single-seat fighter and fighter-bomber.
Powered by a 1,300 hp (970 kW) Packard Merlin 29.
Initially armed with 12 0.303 in (7.7 mm) machine guns, but this was later changed to four 20 mm (0.79 in) cannon.
Hurricane Mk XIIA
Canadian-built variant
Single seat fighter/fighter bomber
An order for 400 mark II airframes for the RCAF powered by a 1,300 hp (970 kW) Packard Merlin 29, armed with eight 0.303 in (7.7 mm) machine guns, production starting in June 1942.
150 sent to Britain in 1943 either engineless or fitted with a Merlin 28.
Also a batch of 30 RAF order mark II airframes retained in Canada in late 1941 and initially fitted with Merlin III became mark XII when later fitted with Merlin 29.
Holland standard Hurricane.
Canadian built variant.
RAF serial airframe AM270 was completed around early March 1942 to Dutch standards, including US built Merlin, instruments and gun sight, as the prototype of an order for the Netherlands East Indies (KM/KNIL). Given the Dutch serial HC3-287, its subsequent fate is unclear beyond being used by Canadian Car and Foundry for test flying.
Sea Hurricane Mk IA
The Sea Hurricane Mk IA was a Hurricane Mk I modified by General Aircraft Limited.
These conversions numbered approximately 250 aircraft.
They were modified to be carried by CAM ships (catapult-armed merchantman), whose ships’ crews were Merchant Marine and whose Hurricanes were crewed and serviced by RAF personnel, or Fighter Catapult Ships, which were Naval Auxiliary Vessels crewed by naval personnel and aircraft operated by the Fleet Air Arm.
These ships were equipped with a catapult for launching an aircraft, but without facilities to recover them.
Consequently, if the aircraft were not in range of a land base, pilots had to bail out or to ditch.
Both of these options had their problems, there was always a chance of striking part of the fuselage when bailing out, and a number of pilots had been killed in this way.
Ditching the Hurricane in the sea called for skill as the radiator housing acted as a water brake, pitching the nose of the fighter downwards when it hit the water, while also acting as a very efficient scoop, helping to flood the Hurricane so that a quick exit was necessary before the aircraft sank.
Then the pilot had to be picked up by a ship.
More than 80 modifications were needed to convert a Hurricane into a Sea Hurricane, including new radios to conform with those used by the Fleet Air Arm and new instrumentation to read in knots rather than miles per hour.
The majority of the aircraft modified had suffered wear-and-tear serving with front line squadrons, so much so that at least one example used during trials broke up under the stress of a catapult launching.
CAM Sea Hurricanes were launched operationally on eight occasions and the Hurricanes shot down six enemy aircraft for the loss of one Hurricane pilot killed.
Sea Hurricane Mk IB
Hurricane Mk I version equipped with catapult spools plus an arrester hook.
From July 1941 they operated from HMS Furious and from October 1941, they were used on merchant aircraft carrier (MAC) ships, which were large cargo vessels with a flight deck fitted, enabling aircraft to be launched and recovered.
Apart from the conversions in Britain 50 Sea Hurricane IB were built in Canada and delivered in late 1941 and early 1942.
Initially fitted with a Merlin III, they became Mk XIIA when later fitted with a Merlin 29.
Sea Hurricane Mk IC
Reported to be a Hurricane Mk I version equipped with catapult spools, an arrester hook and the four-cannon wing.
The Sea Hurricane I used during Operation Pedestal had their Merlin III engines modified to accept 16 psi (110 kPa) boost, and could generate more than 1,400 hp (1,000 kW) at low altitude.
Sea Hurricane Mk IIC
60 built by Hawker between November 1942 and May 1943, version equipped with naval radio gear; other standard mark IIC were converted and used on fleet carriers.
The Merlin XX engine on the Sea Hurricane generated 1,460 hp (1,090 kW) at 6,250 ft (1,900 m) and 1,435 hp (1,070 kW) at 11,000 ft (3,400 m).
Top speed was 322 mph (518 km/h) at 13,500 ft (4,100 m) and 342 mph (550 km/h) at 22,000 ft (6,700 m).
Note the RAF reports as of end June 1944 a total of 378 conversions to Sea Hurricane I, less any conversions back to standard Hurricanes, and no conversions to Sea Hurricane II
Sea Hurricane Mk XII
50 Canadian built Sea Hurricane I delivered in late 1941 and early 1942. Initially fitted with Merlin III as mark I, they became Mk XII when fitted with Merlin 29.
Hillson F.40 (a.k.a. F.H.40)
A full-scale version of the Hills & Son Bi-mono slip-wing Biplane/monoplane, using a Hawker Hurricane Mk I returned from Canada as RCAF ser no 321 (RAF serial L1884).
Taxi and flight trials carried out at RAF Sealand during May 1943, and at the Aeroplane and Armament Experimental Establishment, Boscombe Down from September 1943.
The upper wing was not released in flight before the program was terminated due to poor performance.
Hurricane Photo Reconnaissance
The Service Depot at Heliopolis in Egypt converted several Hurricanes Is for photo reconnaissance.
The first three were converted in January 1941.
Two carried a pair of F24 cameras with 8-inch focal length lenses.
The third carried one vertical and two oblique F24s with 14-inch focal length lenses mounted in the rear fuselage, close to the trailing edge of the wing, and a fairing was built up over the lenses aft of the radiator housing.
A further five Hurricanes were modified in March 1941, and two were converted in a similar manner in Malta during April 1941.
During October 1941 a batch of six Hurricane IIs was converted to PR Mark II status and a final batch, thought to be of 12 aircraft, was converted in late 1941.
The PR Mark II was said to be capable of slightly over 350 mph (560 km/h) and was able to reach 38,000 ft (12,000 m).
Hurricane Tac R
For duties closer to the front lines some Hurricanes were converted to Tactical Reconnaissance (Tac R) aircraft.
An additional radio was fitted for liaison with ground forces who were better placed to direct the Hurricane.
Some Hurricane Tac R aircraft also had a vertical camera fitted in the rear fuselage, so to compensate for the extra weight either one or two Brownings or two cannons would be omitted.
Externally these aircraft were only distinguishable by the missing armament.
