Hawker HURRICANE Mk II B
Design of the Hurricane had begun in 1934, and its first flight had been made, from Hawker's establishment within the confines of the historic Brooklands motor racing circuit at Weybridge in Surrey, on November 6, 1935. Sydney Camm's design team at nearby Kingston upon Thames already had long experience of fighter design for the RAF, and drew heavily upon this experience to produce what was at first seen as a "Monoplane Fury" -- the Fury being the elegant biplane that still epitomized the equipment of Fighter Command upon its formation within the RAF in, July 1936, Such advanced features as an enclosed cockpit and retractable undercarriage were combined with traditional methods of construction using a tubular metal structure and fabric covering, that meant that the Hurricane could be easily and rapidly produced in existing facilities -- an advantage not enjoyed by the Spitfire with its advanced stressed-skin construction and complex shapes.
In February 1936, the prototype Hurricane (as yet unnamed), powered by an early Merlin C producing 900hp and driving a Watts fixed-pitch two-bladed wooden propeller, was tested at the Aircraft and Armament Experimental Establishment (A & AEE) at Martlesham Heath, giving Service pilots their first opportunity to experience the improvements in performance and handling that were to become available.
At a weight of 5,6721b (2,572kg), the prototype demonstrated a speed of 315mph (506km/h) at the Merlin's rated altitude of 16,200ft (4, 937m)with 61b/sq in boost, After taking off into a 5mph (8km/h) wind with a run of 795ft (242m) to reach the 81mph (180km/h) lift-off speed, the Hurricane climbed to 15,000ft (4,570m) in 5.7 minutes and to 20,000ft (6,100m) in 8.4 min. Service ceiling was 34,500ft (10,515m) and the estimated absolute ceiling was 35,400ft (10,800m).
Convinced that the RAF would buy the new fighter in the prevailing mood of rearmament, the Hawker company decided, in March 1936, to proceed with the production drawings and to make plans for large scale production. Three months later in July, that action was vindicated when the Air Ministry confirmed that 600 Hurricanes were to be included in its expansion Plan F (which also provided for 300 Spitfires). By the time the Battle of Britain began, every single fighter in the hands of the RAF counted, and the early launch of Hurricane production had helped to ensure that just enough machines were in fact available to Fighter Command.
Even so! meeting the RAF's rapidly expanding needs proved to be no simple matter and the Plan F target of 600 Hurricanes to be delivered bv March 1939 was missed by some six months. There had been a succession of relatively minor but time consuming problems with prototype development, especially related to the Merlin, and the early intention to fit the Merlin F (Mk I) in the production Hurricane was changed to make use of the improved Merlin G; (Mk II)- which required a redesign of the installation and the front fuselage profile before production could begin. The cockpit canopy also produced its share of problems, with five failures recorded on the prototype before a satisfactory design was evolved.
The first production Hurricane I flew at Brooklands on October 12th 1937, fitted with an early example of the Rolls Royce Merlin II that was rated at 1.030 hp at 16,250 feet (4,955m). This power unit drove a fixed pitch two bladed propellor and at a weight of 5,459lb (2,476kg) the aircraft attained a maximum speed of 318 mph (512 kph) at 17,400 feet (5,305m).
In January 1939, the Merlin II gave way to the Merlin III and with the fitting of a constant speed three bladed propellor and it was this amended specifications that was adopted and all Hurricane Mark I's were constructed using this configuration. Other alterations/additions being the armament which was four Browning .303 machine guns mounted in the wings, metal stressed- skin covered the wings instead of fabric which also covered the fuselage.
By the 27th September 1939, Hawker had delivered 497 Hurricanes to the RAF against the initial order of 3,500 and was enough to equip 18 Fighter Command squadrons. But despite the need to bring Britain's fighter strength to its potential, quite a number of Hurricanes were exported to other countries. 15 went to Turkey, another 15 went to Finland, 12 went to Romania while 1 went to Poland.
During late 1939 and early 1940, 1,924 Hurricanes had been constructed by the Hawker works while Gloster Aircraft who also took on construction built 1,850. Hawker also put out tenders for the construction of the Hurricane overseas. One of these successful tenderer's was the Canadian Car and Foundry Works (CCF) and a licence was issued for the construction of both the Hurricane and the Sea Hurricane. A total of 1,451 machines were built and of these, 60 were flying by 10th January 1940. The Canadian company built the Hurricane in a number of different versions. The original accepted design of the Mark I, the Mark X which were powered by the Merlin 28 engine and built by the Packard Car Co, the Mark XI which was built with Canadian equipment and the Mark XII's that now incorporated the Merlin 29 engine and 12 Browning guns. (8 guns in the Mark XIIA).
Because of the weather conditions in Canada and especially Nova Scotia where many of them were based, the normal retractable undercarriage was dispensed with and fixed ski's were used in there place. This allowed the aircraft to take off and land on snow and ice.
During 1939 and 1940, 24 Hurricane Mark I's were delivered to Yugoslavia, and Belgium was also granted a licence to build the fighter although 20 had been acquired from Britain only 15 of these had been delivered.
Hurricane Mark II through to Mark V
June 11th 1940 a Hurricane Mark I was fitted with a two stage supercharged Rolls Royce Merlin XX engine that at sea level was rated at 1,300hp rising to 1,460hp at 6,250 feet. After numerous tests the aircraft was given the designation of Mark II, the improved power plant being the only difference from the Mark I. This first model of the MkII was known as the Series I. Further modifications took place as designers tried to make improvements to the Hurricane. The next model was given the title of Mark II Series 2. The fuselage was given added strengthening which was needed to accommodate the redesigned wings that incorporated attachment points for external stores. A bay was also introduced into the fuselage that also increased the length by a additional 7 inches (7.7mm).
In November 1940, the Mark II Series 2 was given additional firepower by the inclusion of 12 .303 machine guns mounted in the wings. This version was known as the Hurricane IIB.
The Hurricane IIC followed by having four 20mm Hispano cannons also mounted in the wings.
Many of these versions flew during the Battle of Britain with a number of Mark II's being fitted with drop-tanks, some being fitted with light to medium bombs while other had increased stores such as additional room for bullets for the machine guns.
After the Battle of Britain, the Hurricane was further developed, mostly up to and including 1942 even though it was relieved as a front line attack aircraft in the air to air war, and was used mainly as a ground attack aircraft. The Mark IIC served until June 1942 when the Hurricane IID appeared which was basically a IIC but with two 40mm cannons and two .303 machine guns.
The Hurricane II gave way to the Hurricane III with a Packard Merlin power plant, then came the Hurricane IV, the first prototype flying on 14th March 1943 which had been previously known as the Hurricane IIE, but after the designation change was fitted with reinforced under wing attachments to carry bombs and rockets and was given the new Merlin 24 engines that put out 1,620hp. A further alteration saw the Mk V which was a Mk IV but given even more power by the fitting of the 1,700hp Merlin 32 engines and having four bladed propellors.
In all, 8,406 Hurricane II's were produced, with 3,000 going to the Soviet Union. In all, only 794 Hurricane IV's were made.
In conclusion, the Hurricane was a fighting plane that pilots agreed would be having a great future. At the time when the first prototype took to the skies, it had performance not yet seen in combat aircraft. Many were, even in the mid-thirties, were looking towards the Spitfire which was already in prototype stages and being based on earlier designs that had won the Schnieder Trophy race and it looked as if it was a race to see what aircraft would be first in production.
But the Spitfire was taking longer to produce
in the early stages, and it was the Hurricane that entered service first.
In the hands of a skilled pilot, the Hurricane could achieve great success. In fact during the Battle of Britain between July and October 1940, 1.720 of them took part and had the honour of claiming 80% of enemy aircraft shot down by Fighter Command.
The Hurricane's performance was increasing all the time. It was believed that if the Battle of Britain had continued longer, the performance difference between the Mk IIA and the Bf109 was constantly being reduced. Had the Mk II's been powered by the Merlin 32's during the Battle of Britain, then many feel sure that it would have been a certain match for the Bf109.
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As expected the first Mk.I production machines were ready fairly quickly, and deliveries started in October 1937. They mounted the 1,030 hp (768 kW) Rolls Royce Merlin Mk.II or III engine and were armed with eight .303-in Browning machine guns. These early planes were rather simple, with fabric-covered wings, a wooden fixed-pitch propeller, and without armour or self-sealing tanks.
These issues were addressed in 1939. The new Mk.I included a deHavilland or Rotol constant-speed metal propeller, ejector exhaust stacks for added thrust, metal-covered wings, armour and other changes. At the start of the war the RAF had taken on about 500 of this later design, and it formed the backbone of the fighter squadrons during the Battle of France and into the Battle of Britain.
Although it may have been an older design, the Hurricane was still a worthy fighter on its own and a reasonable match for the Messerschmitt Bf 109 it faced. Much of this was the result of the use of the very impressive Rolls Royce Merlin engine, which also powered the Spitfire. The Merlin (using 100 octane fuel) gave more power at low altitude than the Daimler-Benz DB 601 used in the Bf 109. Above 15000 ft, the DB601A-1 had the edge on the Merlin III and XII, though.
During the Battle of Britain the Hurricane accounted for the majority of the planes shot down by the RAF, being vectored against the slower bombers whilst the Spitfires kept the defending German fighters occupied, but their day was already over. By the close of the Battle of Britain in late 1940, production of the Spitfire had ramped up to the point where all squadrons could be supplied with new machines. Deliveries of the Spitfire were now outpacing the Hurricane, as it turned out that its all metal construction allowed it to be produced even faster than the mixed-construction Hurricane.
Rolls-Royce was improving the Merlin even before the war started, and in 1940 started production of the Merlin XX (Mk.20). The XX featured a new two-speed supercharger, that could have its impeller-speed changed by the pilot depending on the outside air pressure (altitude). At about 18,000ft (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 overall performance of the engine, peaking at 1,280hp (954 kW).
Although by this time production of the Spitfire had started to ramp up, a Merlin XX powered Hurricane Mk.I was built and first flew on 11 June 1940. The initial Mark II, retroactively to be known as the Mark IIA Series 1, 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 cannon. Their first experiments used two Oerlikon 20mm anti-aircraft cannons in pods, one under each wing, but the wooden wings were deemed to fragile to handle the large and somewhat temperamental fitting. A more reasonable fit was made with four 20mm cannons, two in each wing, but the weight was enough to seriously impact performance. Fitting the cannons also proved to be a problem, as the cannon was designed to be drum fed and fired through the propeller shaft, and a suitable belt-feed mechanism hadn't yet been worked out.
With the new Merlin XX, performance was good enough to keep the aging Hurricane in production. Hawker soon introduced the new Mark IIA Series 2 with either of two wings, one mounting twelve Brownings, the other four Hispano cannon. The first Series 2's arrived in October, also sporting a new and slightly longer propeller spinner.
These were later to become the Mark IIB in April 1941 and Mark IIC in June, respectively, using a slightly modified wing. The Mk.IIC used drums for the cannons to avoid the problems with the earlier attempts and belt feeds, limiting their ammunition. The new wings also included a hardpoint for a 500 lb or 250 lb bomb, and later in 1941, fuel tanks. By this point the design was falling well behind the latest German fighters in terms of performance, and the Hurricane was re-tasked in the fighter-bomber role, sometimes referred to as the Hurribomber.
Mk.IIs were used in therole, where it was quickly learned that destroying German tanks was terribly difficult; the cannons didn't have the performance needed, while bombing them was almost impossible. The solution was to equip the plane with a 40mm cannon in a pod under each wing, reducing the other armament to a single Browning in each wing for spotting.
The layout was originally tested on a converted Mk.IIB, and flew on 18 September 1941. New-build version of what was known as the Mk.IID started in 1942, including additional armor for the pilot, radiator, and engine. The planes were initially supplied with a Rolls-Royce gun with 12 rounds, but soon upgraded to the Vickers S gun with 15 rounds.
Yet another wing modification was introduced in the Mk.IIE, but the changes soon became extensive enough that it was renamed the Mk.IV after the first 250 had been delivered.
The Mk.III was a Mk.II equipped with a Packard-built Merlin engine, intending to free up supplies of the British-built engines for other designs. By the time production was to have started, Merlin production had increased to the point where the idea was abandoned.
The last major update to the Hurricane was to "rationalize" the wing, equipping it with a single design able to mount two bombs, two 40mm guns or eight "60 pounder" rockets. The new design also mounted the upgraded Merlin 24 or 27 equipped with dust filters for desert work, delivering 1,620 hp (1,208 kW).
Two Hurricane "Mark Vs" were built as conversions of Mark IVs, and featured a Merlin 32 engine driving a four-bladed propeller. As the ground-attack role moved to the more capable Hawker Typhoon, production of the Hurricane instead ended, and only a handful were delivered with the Merlin 32.
By this time, the Hurricane was no longer equipping frontline fighter squadrons in the United Kingdom itself. However, it still saw extensive service overseas in the fighter role, playing a prominent role in the Middle East and Far East. It was also critical to the defence of Malta, helping to see the island through some of its darkest days.