Hurricane Mk I Hurricane Mk I (Early production) The first Mark I production machines were ready fairly quickly, with deliveries starting in December 1937. These early aircraft featured fabric-covered wings, and a wooden, two bladed, fixed
pitch propeller. Initially, the tailwheel was designed to be retractable. Early on it was discovered that the Hurricane needed a larger rudder area to improve the control characteristics during a spin. To this end, the lower part of the rudder was extended and a distinctive
ventral "keel" was added to the rear fuselage. The tailwheel was fixed in place. Early Hurricanes lacked armour or
self-sealing tanks. They used "ring and bead"
gunsights, with the ring being mounted above the instrument panel and the bead mounted on a post above the engine
cowling. The standard GM2
reflector gunsight was introduced in mid-1939, although many Hurricanes retained the "bead". Fuel capacity was 97
Imperial gallons (441 L) in two fuel tanks, each of 34.5 gal (157 L) in the wing centre-section held between the spars. The fuel was pumped from these into a reserve
gravity-feed tank which held an additional 28 gal (127 L) in the forward fuselage, just ahead of the cockpit. This was the main fuel feed to the engine. The 7 gal (32 L) oil tank was built into the forward, port centre section. Early "K" serialled Mk I models were powered by the 1,029 horsepower (768 kW)
Rolls-Royce Merlin C engine; from the "L" serial numbers the later Merlin II with 1,030 hp (768 kW) was installed. The main coolant radiator was housed in a fairing under the rear wing centre-section; the oil cooler was also incorporated into the main radiator. The aircraft handling qualities during take-off and landings were deemed excellent due to a wide-track undercarriage with relatively wide low-pressure tyres. Because of this wide, stable platform, the Hurricane was an easier aircraft to land, with less fear of nose-overs or "ground-loops" than its
RAF Fighter Command counterpart the
Supermarine Spitfire. During its operational life, the Hurricane was able to operate from all sorts of adverse airfield surfaces with ease. Large, thick wings meant that the fighter proved to be a stable gun platform. It was armed with eight
.303 in (7.7 mm)
Browning machine guns arranged in groups of four in two large gun bays incorporated into the outer wing panels. In 1937 this firepower was enough to outgun the early marks of German
Messerschmitt Bf 109, which were equipped with only four light machine guns. By the time of the
Battle of Britain, it was recognised that this relatively small-calibre armament was inadequate; during the Battle of Britain it was relatively common for
Luftwaffe aircraft to survive numerous hits from .303 in (7.7 mm) bullets and still return safely to base. Later versions of the Hurricane were equipped with 12 .303 in (7.7 mm) Brownings, and later four 20 mm (.79 in)
Hispano cannons. Hurricanes built under licence by
SABCA in Belgium had four 12.7 mm (.50 in) FN-Browning guns instead of the .303 inch armament.
Hurricane Mk I (Mid-late production) style Mk I with a de Havilland propeller unit In 1939, several changes were made to the Hurricane. The powerplant was changed to the Merlin III driving a
de Havilland or
Rotol constant speed metal propeller. Ejector exhaust stacks were fitted for added thrust. The fabric-covered wings were replaced by re-stressed metal-covered wings. An armour-glass panel was incorporated on the front of the windscreen. The "rod" aerial mast was replaced by a streamlined, tapered design. From about May 1940, of armour plate protection was added in the form of head and back armour. Starting in September 1940,
IFF equipment was installed. This weighed about and could be identified by wire aerials strung between the tailplane tips and rear fuselage. Although the added weight and the aerials reduced maximum speed by about it allowed the aircraft to be identified as "friendly" on radar. Lack of such equipment was a factor leading to the
Battle of Barking Creek. At about the same time new
VHF T/R Type 1133 radios started replacing the
HF TR9 sets. The pilots enjoyed a much clearer reception, which was a big advantage with the adoption of
Wing formations throughout the RAF in 1941. The new installation meant that the wire running between the aerial mast and rudder could be removed, as could the triangular "prong" on the mast. At the start of the war, the engine ran on the standard 87
octane aviation spirit. From March 1940 increasing quantities of 100 octane fuel, imported from the British-controlled refineries and the US, became available. This meant that during the defensive battles over
Dunkirk the Hurricane Mk I benefited from an allowable increase in supercharger "boost" from without damaging the engine. With the 12 lb "emergency boost", the Merlin III was able to generate 1,305 hp (973 kW) in a five-minute burst. If the pilot resorted to emergency boost, he had to report this on landing and it had to be noted in the engine log book. In 1939, the RAF had taken on about 500 aircraft of this later design to form the backbone of the fighter squadrons during the
Battle of France and into the Battle of Britain. The first RAF ace of the war, a young New Zealander known as
Cobber Kain, flew a Hurricane with 73 Squadron. In June 1940, another wartime ace,
Douglas Bader, was promoted to Squadron Leader and took command of 242 (Canadian) Squadron flying Hurricane Mk Is. The children's author
Roald Dahl also flew Hurricanes with 80 Squadron in Greece and later in Syria, against the Germans and
Vichy France.
Comparative aircraft Although some of the basic design elements of the aircraft were from an earlier generation, the Hurricane proved to be a match, to an extent, for the German Messerschmitt Bf 109E. In his book,
Duel of Eagles, British ace
Peter Townsend, who flew Hurricanes with
85 Squadron during the Battle of Britain, provides examples demonstrating how the Hurricane's superior turning ability could offset the Bf 109's higher speed. This small turning circle often allowed a well-flown Hurricane to get onto the tail of a 109 even more quickly than a Spitfire. Working against the Hurricane was the aircraft's relatively slow acceleration and a top speed some slower, depending on altitude. This meant that the 109 pilot often held the initiative when it came to breaking off or attacking during combat. At higher altitudes especially, the Hurricane was hard-pressed to keep up with a well-flown 109, or even a
Bf 110. Hurricane IIC (LF363) Lower down the situation was a little more even. The Merlin engine gave more power at low altitude than the
Daimler-Benz DB 601 (DB601A-1) used in the Bf 109, on account of a different supercharger design. The DB601A-1 did not start to outperform the Merlin III and XII until above . The Merlin's only serious drawback was a tendency to cut out during negative-
g manoeuvres and inverted flight, on account of
fuel starvation from the
carburettor. This was temporarily fixed with "
Miss Shilling's orifice", a simple modification. A direct-injection carburettor later solved the problem and eventually, some versions of the Merlin used direct
fuel injection. When attacking
Luftwaffe bombers, it was discovered that the Hurricane's fuel tanks were vulnerable to defensive machine gun fire. The greatest hazard was with the unprotected gravity-feed fuel tank in front of the cockpit which could rupture when hit, allowing a jet of flame to penetrate the cockpit through the instrument panel, causing serious burns to the pilot. The wooden and fabric rear fuselage was also far more likely to catch fire than the metal fuselages of its contemporaries. This issue was of such concern to
Air Vice Marshal Hugh Dowding that he had Hawker retrofit the fuselage tanks of Hurricanes with a fire-resistant material called "Linatex" as a matter of priority. The wing tanks had already been fitted with a covering of this sealant, but the fuselage tank was considered to be too small a target. Hurricanes were soon being modified at the rate of 75 per month. In one month of combat, 10 July 1940 to 11 August, defensive fire from bombers hit 25 Hurricanes and 25 Spitfires; as a result, 11 Hurricanes were shot down compared to two Spitfires. The biggest advantages of the Hurricane were that it was a relatively easy aircraft to fly, which was a boon when it came to squadrons being flooded with inexperienced pilots, and it was a steady gun platform. The closely grouped .303 in (7.7 mm) Brownings created a superior pattern of fire to those of the Spitfire, which were spaced out along the wings, and the armament was more quickly serviced. In spite of its vulnerabilities during the Battle of Britain, the Hurricane shot down the majority of the planes claimed by the RAF (1,593 out of 2,739 in total). Hurricanes were sometimes directed against slower bombers whilst the Spitfires attacked German fighters. By the close of the Battle of Britain in late 1940, production of the Spitfire had increased to the point where all squadrons could be supplied with them. In June 1940, the first Hurricane Mk I "Tropical" versions appeared. These featured a Vokes air filter in a large "chin" fairing under the engine cowling. Many of these aircraft were ferried to North Africa and
Malta via
France and the
Mediterranean using fixed, cylindrical 40-gallon fuel tanks under each wing to extend the range. The tropical filter and fuel tanks were to be used on later variants of the Hurricane.
Hurricane Mk II The improved Merlin XX (Mk.20) engine appeared in 1940 featuring a new two-speed
supercharger that could have its
impeller speed changed by the pilot depending on the outside air pressure (altitude). At about (effective), it would be switched to a higher speed gearing ("FS ratio" – Full Supercharge) for added compression, while below that, at its lower speed gearing, ("MS ratio" – Moderate Supercharge), it "robbed" less power from the engine. The result was more power at both lower and higher altitudes, dramatically increasing the overall performance of the engine with it peaking at . Because of the new engine, the bay immediately in front of the cockpit was lengthened by . The carburettor air intake under the forward centre-section was redesigned and moved back . The more powerful engine was cooled by a 70% to 30% water
glycol mix, rather than pure glycol used for earlier Merlin versions. This and the increased cooling requirements required a larger
radiator and a redesigned, circular oil cooler housed in a deeper, slightly wider "bath".
Hurricane IIA Series 1 Although, by this time, production of the
Spitfire had started to increase, a prototype of a Merlin XX-powered Hurricane Mk I was built and first flew on 11 June 1940. The initial Mark II is often known as by the unofficial designation
Mark IIA Series 1, while later Mark IIs had their wing centre sections strengthened. The Mark II went into squadron service in September 1940 at the peak of the Battle of Britain. Hawker had long experimented with improving the armament of the fighter by fitting cannons. Their first experiments used two
Oerlikon cannons in pods, one under each wing, (one aircraft was tested during 1940 with 151 Squadron) but the extra weight and drag seriously compromised the aircraft's performance and manoeuvrability, and the limited amount of ammunition carried coupled with the frequent stoppages suffered by the drum-fed guns, meant the arrangement was unsatisfactory. A more reliable fit was made with four Hispano Mk II cannon, two in each wing, but the weight was enough to seriously reduce performance. The Hispanos were designed for a rigid, engine-based mounting and it was quickly found that the wings flexing in flight led to problems with the weapons twisting in their mounts as they fired, which caused gun jamming through misaligned shells. Changes made both to the Hispanos and to their mountings cured this problem. Small blisters on the upper wing surfaces were needed to clear the Hispano breeches and feed motors. The first sets of Hispano wings were modified from standard Mark I eight gun wings.
Hurricane IIB Trials with 12 .303 in (7.7 mm) Brownings (four per wing in the original gun-bays and two more in new gun-bays outboard of the landing lights) were done in June and July 1940, production began at Hawker and Austin in February 1941. These aircraft also featured a new longer propeller spinner. using a slightly modified wing. Trials with a pair of external cannons as armament had begun in May 1939, then the internal arrangement in June to August 1940. In November 1940 thirty sets of Hurricane IIC (Four cannon) wings were built by semi-tooled and hand methods in the experimental shop, using wings damaged in the region of the gun bay. Test flights with external fuel tanks began in May 1940, the first Mark II trials in June 1941. Test flights carrying bombs began in April 1941, the first Mark II trials with bombs were in February 1942, most Mark II were built as able or converted to carry external stores.
Hurricane T IIC The
T Mk IIC was a dedicated two-seat training version of the Mk. IIC created by Hawker in 1946. Although a successful design, only two aircraft were built for the
Imperial Iranian Air Force.
Hurricane IID Mk IIs were used in
ground support, where it was quickly learned that destroying German tanks was difficult. The cannons did not have the performance needed, while bombing the tanks was almost impossible. The solution was to equip the aircraft with a 40 mm cannon in a pod under each wing, reducing the other armament to a single Browning in each wing loaded with tracers for aiming purposes. The Hurricanes of
No. 6 Squadron, the first squadron equipped with this armament, were so effective that the squadron was nicknamed the "Flying Can Openers". A winged can-opener became an unofficial squadron emblem, and is painted on present-day aircraft of 6 Squadron. The layout was originally tested on a converted Mk IIB and flew on 18 September 1941. A new-build version of what was known as the
Mk IID started in January 1942, including additional armour for the pilot, radiator and engine. The aircraft were initially supplied with a
Rolls-Royce gun and carried 12 rounds, but soon changed to the 40 mm (1.57 in)
Vickers S gun with 15 rounds. The weight of guns and armour protection had a marginal effect on the aircraft's performance. The IID was used in anti-tank operations in limited numbers during the
North African campaign where, provided enemy
flak and fighters were absent, they proved accurate and highly effective against armoured vehicles and all motor transport.
Hurricane IIE The
Mk IIE. This designation was used by parts of the RAF in 1941 (starting with BE221 in September) and then the
Ministry of Aircraft Production in 1942 for Mark II factory fitted with wing racks, 270 delivered according to the Ministry, 230 IIB and 40 IIC, the RAF used the
Mk IIBB or IICB designation to denote racks fitted. The Mk IIE was NOT an early mark Mk IV.
Hurricane Mk III The
Mk III was a Mk II equipped with a
Packard-built Merlin engine, intending to provide 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
Mk IV. The last major change to the Hurricane was to "rationalise" the wing, configuring it with 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, two 40 mm (1.57 in) Rolls-Royce B.H. type guns, two SBC (small bomb containers), SCI (smoke curtain installation), two 45 or 90 gallon drop tanks, or eight
"60 pounder" RP-3 rockets. Some sources say that the new design also mounted the improved Merlin 24 or 27 engines of 1,620 hp (1,208 kW) but the RAF Form 78 shows otherwise. 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 and despite many Hurricane IV exports Merlin 24 exports were rare, and in accordance with the overseas
Avro York fleet. The individual aircraft cards held by the RAF museum reports the final Mark IV had a Merlin XX. Mark IV loss reports note the engine as Merlin XX. They were equipped with dust filters for desert operations and an additional 350 lb (159 kg) of armour plating was added to the radiator housing, cockpit, and fuel tanks. The Mk IV was used in ground-attack missions in the European theatre until the early days of 1944, before being replaced by the more modern
Hawker Typhoon.
Hurricane Mk V One prototype and another two Hurricane Mk Vs were built as conversions of Mk IVs, and featured a Merlin 27 engine driving a four-bladed propeller, also tested with a Merlin 32. The ground attack role moved to the more capable
Hawker Typhoon. By this time, the Hurricane was no longer a frontline fighter in the United Kingdom. However, it still saw extensive service overseas as a fighter, playing a prominent role in the
Middle East and
Far East. It was also critical to the defence of
Malta during 1941 and early 1942. ==Canadian production==