Gloster Gladiator I

The Gloster Gladiator is a British biplane fighter. It was used by the Royal Air Force (RAF) and the Fleet Air Arm (FAA) (as the Sea Gladiator variant) and was exported to a number of other air forces during the late 1930s.

Developed privately as the Gloster SS.37, it was the RAF's last biplane fighter aircraft, and was rendered obsolete by newer monoplane designs even as it was being introduced. Though often pitted against more formidable foes during the early days of the Second World War, it acquitted itself reasonably well in combat.

The Gladiator saw action in almost all theatres during the Second World War, with a large number of air forces, some of them on the Axis side. The RAF used it in France, Norway, Greece, the defence of Malta, the Middle East, and the brief Anglo-Iraqi War (during which the Royal Iraqi Air Force was similarly equipped). Other countries deploying the Gladiator included China against Japan, beginning in 1938; Finland (along with Swedish volunteers) against the Soviet Union in the Winter War and the Continuation War; Sweden as a neutral noncombatant (although Swedish volunteers fought for Finland against USSR as stated above); and Norway, Belgium, and Greece resisting Axis invasion of their respective lands.

South African pilot Marmaduke "Pat" Pattle was the top Gladiator ace with 15 victories with the type.Mason 1966, p. 10.

Design and development

Origins

During the 1920s, Britain's air defences had been based around interceptor aircraft capable of flying only for short ranges and at speeds of , but by 1930, figures within the Air Ministry were keen to supersede these aircraft. In particular, some dissatisfaction had arisen with the level of reliability experienced with the 'one pilot, two machine guns' design formula previously used; the guns were often prone to jams and being unreliable.Mason 1966, p. 3. The Air Ministry's technical planning committee formulated Specification F.7/30, which sought a new aircraft capable of a maximum speed of at least , an armament of no fewer than four machine guns, and such handling that that same fighter could be used by both day and night squadrons. Gloster, being already engaged with development of the Gloster Gauntlet, did not initially respond to the specification, which later proved to be beneficial.Mason 1966, pp. 3-4.

The specification had also encouraged the use of the new Rolls-Royce Goshawk evaporatively cooled inline engine; many of the submissions produced by various aviation companies in response accordingly featured the Goshawk engine.Mason 1966, p. 4. However, the Goshawk engine proved to be unreliable, mainly due to its overcomplex and underdeveloped cooling system, and unsuited to use on fighter aircraft and this outcome stalled development of the aircraft intended to use it. A further stumbling point for many of the submitted designs was the placement of the machine gun breeches within arm's reach of the pilot. At the same time, the development of monoplane fighters such as the Hawker Hurricane and Supermarine Spitfire cast doubt over the future viability of the requirement altogether.

Gloster recognised that instead of developing an all-new design from scratch, the existing Gauntlet fighter could be used as a basis for a contender to meet Specification F.7/30. Development of what would become the Gladiator began as a private venture, internally designated as the SS.37, at Gloster, by a design team headed by H.P. Folland, who soon identified various changes to increase the aircraft's suitability to conform with the demands of the specification. Making use of wing-design techniques developed by Hawker Aircraft, the new fighter adopted single-bay wings in place of the two-bay wings of the Gauntlet, and two pairs of interplane struts were also dispensed with as a drag-reduction measure. The Bristol Mercury M.E.30 radial engine, capable of generating , was selected to power the SS.37, which provided a performance boost over the preceding Gauntlet. Another design choice was the fitting of a cantilever main undercarriage, which incorporated Dowty internally sprung wheel struts.Lumsden 1992, p.10.James 1971, p. 206.

Prototype

In spring 1934, Gloster embarked on the construction of a single SS.37 prototype. On 12 September 1934, the SS.37 prototype conducted its maiden flight, piloted by Gloster chief test pilot Gerry Sayer. Initially powered by a Mercury IV engine, the prototype was quickly re-equipped with a more powerful Mercury VIS engine. During flight tests, the prototype attained a top speed of while carrying the required four machine guns (two synchronised Vickers guns in the fuselage and two Lewis guns under the lower wing). According to aviation author Francis K. Mason, the Air Ministry were sceptical about the aircraft achieving such performance from a radial engine design, so funded a protracted series of evaluation trials.

On 3 April 1935, the prototype was transferred to the RAF, receiving the designation ''K5200'', and commenced operational evaluations of the type. Around the same time, Gloster proceeded to plan a further improved version, featuring an Mercury IX engine, a two-blade wooden fixed-pitch propeller, improved wheel discs, and a fully enclosed cockpit.James 1971, pp. 206–207. ''K5200'' was later used to trial modifications for production aircraft, such as the addition of a sliding hood for the pilot.

In June 1935, production plans for the aircraft were proposed; two weeks later, a production specification, Specification F.14/35, had been rapidly drawn up, partially prompted by events in continental Europe, such as the invasion of Abyssinia by Fascist Italy and the rise of Adolf Hitler to power in Germany, in response to which the British government mandated an urgent expansion of the RAF to counter the emerging threats. This culminated in an initial order for 23 aircraft. On 1 July 1935, the aircraft formally received the name ''Gladiator''.Lumsden 1992, p. 12.

Production

Manufacturing of the Gladiator was started at Gloster's Hucclecote facility. Production of the initial batch was performed simultaneously, leading to many aircraft being completed around the same time. On 16 February 1937, ''K6129'', the first production Gladiator, was formally accepted by the RAF; on 4 March 1937, ''K6151'', the last aircraft of the initial batch, was delivered. In September 1935, a follow-up order of 180 aircraft was also received from the Air Ministry;James 1971, p. 207. this order had the proviso that all aircraft had to be delivered before the end of 1937.

The first version, the Gladiator Mk I, was delivered from July 1936, becoming operational in January 1937. The Mk II soon followed, the main differences being a slightly more powerful Mercury VIIIAS engine with Hobson mixture control boxes and a partly automatic boost-control carburettor, driving a Fairey fixed-pitch three-blade metal propeller, instead of the two-blade wooden one of the Mark I. All MK II Gladiators also carried Browning 0.303-inch machine guns (licence-manufactured by the BSA company in Birmingham) in place of the Vickers-Lewis combination of the MK I. A modified Mk II, the Sea Gladiator, was developed for the Fleet Air Arm, with an arrestor hook, catapult attachment points, a strengthened airframe, and an underbelly fairing for a dinghy lifeboat, all for operations aboard aircraft carriers.Barber 2008, p. 6 Of the 98 aircraft built as, or converted to, Sea Gladiators, 54 were still in service by the outbreak of the Second World War.

The Gladiator was the last British biplane fighter to be manufactured, and the first to feature an enclosed cockpit. It possessed a top speed of about , yet even as the Gladiator was introduced, it was already being eclipsed by new-generation monoplane fighters, such as the RAF Hawker Hurricane and Supermarine Spitfire, and the ''Luftwaffe'' Messerschmitt Bf 109. In total, 747 aircraft were built (483 RAF, 98 RN), with 216 being exported to 13 countries, some of which were from the total allotted to the RAF. Gladiators were sold to Belgium, China, Egypt, Finland, Free France, Greece, Iraq, Ireland, Latvia, Lithuania, Norway, Portugal, South Africa, and Sweden.

Operational history

Introduction to service

In February 1937, No. 72 Squadron, based at Tangmere, became the first squadron to be equipped with the Gladiator; No. 72 operated the type until April 1939, longer than any other home-based frontline unit.Mason 1966, p. 5. Between March and April 1937, No. 3 Squadron at Kenley also received Gladiators from the remainder of the first production batch, replacing their obsolete Bristol Bulldogs. Initial service with the type proved the Vickers guns to be problematical; the Gladiator was quickly armed with .303 in (7.7 mm) Browning machine guns, which were substantially more popular, leading to the other guns often only being resorted to if deemed necessary. On 27 March 1937, No. 54 Squadron at Hornchurch became the first unit to receive Browning-armed Gladiators.

By September 1937, all eight Gladiator squadrons had achieved operational status and had formed the spearhead of London's air defences.Mason 1966, pp. 5-6. Difficulties with introducing the type had been experienced. Although the Gladiator was typically well-liked by pilots, the accident rate during operational training on the type was so high that a small replacement batch of 28 Gladiator Mk IIs was hurriedly produced. Most accidents were caused by pilots being caught out by the fighter's increased wing loading, and many aviators had little experience in landing aircraft with such a wide flap area. The aircraft had a tendency to stall more abruptly, frequently dropping a wing while doing so. The Gladiator very easily entered a flat spin, and great skill was needed to recover.Håkan & Slongo 2012.

During 1938, the RAF had begun to receive its first deliveries of the Hurricane and Spitfire monoplanes; an emphasis was soon placed on quickly re-equipping half of the Gladiator squadrons with either of these monoplane types.Mason 1966, p. 6. By the outbreak of the Second World War, the Gladiator had largely been replaced by the Hurricane and Spitfire in front-line RAF service. The introduction of these aircraft had been eased by the presence of the Gladiator, squadrons that had operated Gladiators prior to converting to the monoplane types experienced a noticeably improved accident record than those who converted from older types such as the Gauntlet. Experiences such as operating the Gladiator's landing flaps and familiarisation with its sliding hood have been attributed to having favourably impacted pilot conversion.

Although by 1941, all Gladiators had been withdrawn from front-line duties defending the British Isles, a need to defend Britain's trade routes throughout the overseas territories of the British Empire had been recognised, so the RAF redeployed many of its Gladiators to the Middle East to defend the theatre and the crucial Suez Canal. The Gladiator saw considerable action during early stages of the war, including participating in the action in the French and Norwegian campaigns, in addition to various peripheral campaigns.

China

In October 1937, the Chinese Central Government ordered 36 Gladiator Is, which were delivered in two crated batches to Guangzhou via Hong Kong. The Chinese Gladiators used the American M1919 Browning machine gun to fire American .30-06 Springfield ammunition, the main ammunition of the new Chinese Nationalist Air Force. By February 1938, these aircraft had been assembled into two squadrons and the Chinese pilots familiarised themselves with them. The Gloster Gladiator had its combat début on 24 February 1938.Thomas 2002, p. 11. That day, in the Nanking area, Chinese-American Capt John Wong Sun-Shui (nicknamed 'Buffalo') shot down an Mitsubishi A5M "Claude" naval fighter, the first victim of a Gladiator. Wong is believed to have shot down a second A5M as the wrecks of two Japanese fighters were found. During that clash, Chinese Gladiators lost two of their number.

Chinese Gladiators scored several more victories over Japanese aircraft from 1938 to 1940 during the Second Sino-Japanese War. In China, Gladiators were used extensively before the start of 1940 by the 28th, 29th, and 32nd squadrons of the 3rd Group. Chinese aviators considered the Gladiator an excellent fighter in its class, but pilots soon found it increasingly difficult to hold their own against the modern A5M, and because of a lack of spare parts due to an arms embargo, the surviving Gladiators were mostly relegated to training.Thomas 2002, p. 13. When newer Japanese aircraft such as the Mitsubishi A6M Zero entered the theatre, the Gladiators' days were numbered. "Buffalo" Wong, the first Gladiator flying ace and first American fighter ace of the war, was eventually shot down in combat with A6M Zeros on 14 March 1941 and died two days later from his injuries.Thomas 2002, p. 12. Arthur Chin and he were among a group of 15 Chinese Americans who formed the original group of American volunteer combat aviators in China.

The Finnish Winter War and Continuation War

During the Winter War, the Finnish Air Force (FAF) obtained 30 Mk II fighters from the UK. Ten of the aircraft were donated, while the other 20 were bought by the FAF; all were delivered between 18 January and 16 February 1940, the first entering service on 2 February 1940.Perttula, Pentti
"Finnish Air Force Aircraft: Gloster Gladiator."
''Backwoods Landing Strip – Finnish Air Force Aircraft'', 2007. Retrieved 12 April 2009. The Finnish Gladiators served until 1945, but they were outclassed by modern Soviet fighters during the Continuation War, and the aircraft was mostly used for reconnaissance from 1941. The Finnish Air Force obtained 45 aerial victories by 22 pilots with the aircraft during the Winter War and one victory during the Continuation War. Twelve Gladiators were lost in combat during the Winter War and three during the Continuation War. Two pilots became aces with this aircraft: Oiva Tuominen (6.5 victories with Gladiators) and Paavo Berg (five victories).

Besides the FAF Gladiators, the Swedish Voluntary Air Force, responsible for the air defence of northernmost Finland during the later part of the Winter War, was also equipped with Gladiator fighters, known as J8s (Mk Is) and J8As (Mk IIs). The Flying Regiment F 19 arrived in Finnish Lapland on 10 January 1940 and remained there until the end of hostilities. It fielded 12 Gladiator Mk II fighters, two of which were lost during the fighting and five Hawker Hart dive bombers, plus a Raab-Katzenstein RK-26 liaison aircraft and a Junkers F.13 transport aircraft. The aircraft belonged to and were crewed by the Swedish Air Force but flew with Finnish nationality markings. The Swedish Gladiators scored eight aerial victories and destroyed four aircraft on the ground. One concern was expressed when F 19's executive officer Captain Björn Bjuggren wrote in his memoirs, that the tracer rounds of the Gladiator's machine guns would not ignite the gasoline when penetrating the fuel tanks of Soviet bombers.

The Phoney War

At the beginning of the Second World War, during what was known as the " Phoney War", Britain deployed the British Expeditionary Force (BEF) into France to fight alongside the French army. As part of this force, RAF units operating various aircraft were dispatched to contribute, including two Gladiator squadrons. Initial air operations on either side were limited by the winter weather; however, immediately following Germany's commencement of the Manstein Plan and its invasion of the Low Countries on 10 May 1940, the BEF's Gladiators participated in the Dyle Plan, an unsuccessful counterattack on German forces.

From 10 May 1940 to 17 May, the Gladiators were in continuous demand on the front line, quickly losing numerous aircraft and their crews in the rapid action.Mason 1966, pp. 6-7. On 18 May 1940, a Luftwaffe bombing raid destroyed many of the BEF's Gladiators and Hurricanes on the ground at Vitry-en-Artois, shortly after which the BEF's withdrawal to Dunkirk

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