Hawker Hart
Encyclopedia
The Hawker Hart was a British
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...

 two-seater biplane
Biplane
A biplane is a fixed-wing aircraft with two superimposed main wings. The Wright brothers' Wright Flyer used a biplane design, as did most aircraft in the early years of aviation. While a biplane wing structure has a structural advantage, it produces more drag than a similar monoplane wing...

 light bomber of the Royal Air Force
Royal Air Force
The Royal Air Force is the aerial warfare service branch of the British Armed Forces. Formed on 1 April 1918, it is the oldest independent air force in the world...

 (RAF), which had a prominent role during the RAF's inter-war period. The Hart was designed during the 1920s by Sydney Camm and built by Hawker Aircraft
Hawker Aircraft
Hawker Aircraft Limited was a British aircraft manufacturer responsible for some of the most famous products in British aviation history.-History:...

. It spawned several variants, including a naval version.

Design and development

In 1926, the Air Ministry
Air Ministry
The Air Ministry was a department of the British Government with the responsibility of managing the affairs of the Royal Air Force, that existed from 1918 to 1964...

 stated a requirement for a two-seat high-performance light day-bomber, to be of all-metal construction and with a maximum speed of 160 mph (258 km/h). Designs were tendered by Hawker
Hawker Aircraft
Hawker Aircraft Limited was a British aircraft manufacturer responsible for some of the most famous products in British aviation history.-History:...

, Avro
Avro
Avro was a British aircraft manufacturer, with numerous landmark designs such as the Avro 504 trainer in the First World War, the Avro Lancaster, one of the pre-eminent bombers of the Second World War, and the delta wing Avro Vulcan, a stalwart of the Cold War.-Early history:One of the world's...

 and de Havilland
De Havilland
The de Havilland Aircraft Company was a British aviation manufacturer founded in 1920 when Airco, of which Geoffrey de Havilland had been chief designer, was sold to BSA by the owner George Holt Thomas. De Havilland then set up a company under his name in September of that year at Stag Lane...

. Fairey, who had sold a squadron's worth of its wooden Fox
Fairey Fox
The Fairey Fox was a British light bomber and fighter biplane of the 1920s and 1930s. It was originally produced in Britain for the RAF, but continued in production and use in Belgium long after it was retired in Britain.-Fox I:...

 bomber in 1925, was not at first invited to tender to the specification, and was only sent a copy of the specification after protesting to the Chief of the Air Staff, Hugh Trenchard
Hugh Trenchard, 1st Viscount Trenchard
Marshal of the Royal Air Force Hugh Montague Trenchard, 1st Viscount Trenchard GCB OM GCVO DSO was a British officer who was instrumental in establishing the Royal Air Force...

.

Hawker's design was a single-bay
Interplane strut
An interplane strut is an aircraft airframe component designed to transmit lift and landing loads between wing panels on biplanes and other aircraft with multi-wing designs. They also maintain the correct angle of incidence for the connected wing panels and are often braced with wires...

 biplane
Biplane
A biplane is a fixed-wing aircraft with two superimposed main wings. The Wright brothers' Wright Flyer used a biplane design, as did most aircraft in the early years of aviation. While a biplane wing structure has a structural advantage, it produces more drag than a similar monoplane wing...

 powered by a Rolls-Royce F.XI
Rolls-Royce Kestrel
|-See also:-Bibliography:* Erfurth, Helmut. Junkers Ju 87 . Bonn, Germany: Bernard & Graefe Verlag, 2004. ISBN 1-85780-186-5....

  water-cooled V12 engine
V12 engine
A V12 engine is a V engine with 12 cylinders mounted on the crankcase in two banks of six cylinders, usually but not always at a 60° angle to each other, with all 12 pistons driving a common crankshaft....

 (the engine that later became known as the Rolls-Royce Kestrel). It had, as the specification required, a metal structure, with a fuselage structure of steel-tube covered by aluminium
Aluminium
Aluminium or aluminum is a silvery white member of the boron group of chemical elements. It has the symbol Al, and its atomic number is 13. It is not soluble in water under normal circumstances....

 panels and fabric, with the wings having steel spars
Spar (aviation)
In a fixed-wing aircraft, the spar is often the main structural member of the wing, running spanwise at right angles to the fuselage. The spar carries flight loads and the weight of the wings whilst on the ground...

 and duralumin
Duralumin
Duralumin is the trade name of one of the earliest types of age-hardenable aluminium alloys. The main alloying constituents are copper, manganese, and magnesium. A commonly used modern equivalent of this alloy type is AA2024, which contains 4.4% copper, 1.5% magnesium, 0.6% manganese and 93.5%...

 ribs
Rib (aircraft)
In an aircraft, ribs are forming elements of the structure of a wing, especially in traditional construction.By analogy with the anatomical definition of "rib", the ribs attach to the main spar, and by being repeated at frequent intervals, form a skeletal shape for the wing...

, covered in fabric. The crew of two sat in individual tandem cockpits, with the pilot sitting under the wing trailing edge, and operating a single .303 in (7.7 mm) Vickers machine gun
Vickers machine gun
Not to be confused with the Vickers light machine gunThe Vickers machine gun or Vickers gun is a name primarily used to refer to the water-cooled .303 inch machine gun produced by Vickers Limited, originally for the British Army...

 mounted on the port side of the cockpit. The observer sat behind the pilot, and was armed with a single Lewis gun
Lewis Gun
The Lewis Gun is a World War I–era light machine gun of American design that was perfected and widely used by the British Empire. It was first used in combat in World War I, and continued in service with a number of armed forces through to the end of the Korean War...

 on a ring mount, while for bomb-aiming, he lay prone under the pilots seat. Up to 520 pounds (240 kg) of bombs could be carried under the aircraft's wings.

J9052
United Kingdom military aircraft serials
In the United Kingdom to identify individual aircraft, all military aircraft are allocated and display a unique serial number. A unified serial number system, maintained by the Air Ministry , and its successor the Ministry of Defence , is used for aircraft operated by the Royal Air Force , Fleet...

, the prototype Hart, first flew in June 1928, being delivered to the Aeroplane and Armament Experimental Establishment
Aeroplane and Armament Experimental Establishment
The Aeroplane and Armament Experimental Establishment was a research facility for British military aviation from 1918 to 1992.-History:...

 at RAF Martlesham Heath
RAF Martlesham Heath
RAF Martlesham Heath is a former Royal Air Force airfield in England. The field is located 1½ miles SW of Woodbridge, Suffolk.- RFC/RAF prewar use:Martlesham Heath was first used as a Royal Flying Corps airfield during World War I...

 on 8 September. It demonstrated good performance and handling, reaching 176 mph (283 km/h) in level flight and 282 mph (454 km/h) in a vertical dive. The competition culminated in the choice of the Hawker Hart in April 1929. The de Havilland Hound was rejected due to handling problems during landing and because of its part-wooden primary structure. While the Avro Antelope
Avro Antelope
|-See also:-External links:*...

 demonstrated similar performance and good handling, the Hart was preferred as it was far cheaper to maintain, a vital aspect to a programme during defence budget constraints that the British armed forces faced during the 1920s. The Fairey Fox IIM
Fairey Fox
The Fairey Fox was a British light bomber and fighter biplane of the 1920s and 1930s. It was originally produced in Britain for the RAF, but continued in production and use in Belgium long after it was retired in Britain.-Fox I:...

 (which despite the name was effectively an all-new aircraft), delayed by Fairey's late start on the design compared to the other competitors, only flew for the first time on 25 October 1929, long after the Hart had been selected.

A total of 992 aircraft were built as Harts. It became the most widely used light bomber of its time and the design would prove to be a successful one with a number of derivatives, including the Hawker Hind
Hawker Hind
-See also:-Bibliography:* Crawford, Alex. Hawker Hart Family. Redbourn, Hertfordshire, UK: Mushroom Model Publications Ltd., 2008. ISBN 83-89450-62-3....

 and Hector
Hawker Hector
-See also:-Bibliography:* Air Transport Auxiliary Ferry Pilots Notes . Elvington, York, UK: Yorkshire Air Museum, 1996. ISBN 0-9512379-8-5....

, being made. There were a number of Hart variants made, though only slight alterations were made. The Hart India was basically a tropicalised version of the aircraft; the Hart Special was another tropicalised version based on the Hawker Audax, a Hart variant, with desert equipment; a specialised Hart Trainer was also designed. Vickers built 114 of the latter model at Weybridge between 1931 and June 1936.

The production Hart day bomber had a single 525 hp (390 kW) Rolls-Royce Kestrel
Rolls-Royce Kestrel
|-See also:-Bibliography:* Erfurth, Helmut. Junkers Ju 87 . Bonn, Germany: Bernard & Graefe Verlag, 2004. ISBN 1-85780-186-5....

 IB 12-cylinder V-type engine; a speed of 184 mph (296 km/h) and a range of 470 mi (757 km). It was faster than most contemporary fighters, an astonishing achievement considering it was a light bomber, and had high manoeuvrability, making the Hart one of the most effective biplane bombers ever produced for the Royal Air Force. In particular, it was faster than the Bristol Bulldog
Bristol Bulldog
|-See also:-References:NotesBibliography* Andrews, C.F. The Bristol Bulldog . Leatherhead, Surrey, UK: Profile Publications Ltd., 1965.* Barnes, C.H. Bristol Aircraft Since 1910. London: Putnam, 1964....

, which had recently entered service as the RAF's front line fighter. This disparity in performance led the RAF to gradually replace the Bulldog with the Hawker Fury
Hawker Fury
The Hawker Fury was a British biplane fighter aircraft used by the Royal Air Force in the 1930s. It was originally named the Hornet and was the counterpart to the Hawker Hart light bomber.-Design and development:...

.

Demand for the bomber was such that 164 were built by Vickers-Armstrongs at its Weybridge
Weybridge
Weybridge is a town in the Elmbridge district of Surrey in South East England. It is bounded to the north by the River Thames at the mouth of the River Wey, from which it gets its name...

 factory at Brooklands
Brooklands
Brooklands was a motor racing circuit and aerodrome built near Weybridge in Surrey, England. It opened in 1907, and was the world's first purpose-built motorsport venue, as well as one of Britain's first airfields...

 between 1931 and 1936 after that company's submission of a tender, alongside the trainers mentioned above.

Operational history

The Hart entered service with No. 33 Squadron RAF
No. 33 Squadron RAF
No. 33 Squadron of the Royal Air Force operates the Puma HC.1 from RAF Benson, Oxfordshire.-Current role:The squadron is part of the RAF Support Helicopter force, which reports into the Joint Helicopter Command....

 in February 1930, replacing the larger and slower Hawker Horsley
Hawker Horsley
|-See also:-Bibliography:* Jarrett, Philip. "By Day and By Night: Hawker Horsley part 1". Aeroplane Monthly, Volume 21 No 10, Issue 246, October 1993. pp. 32–40....

. No. 12 Squadron
No. 12 Squadron RAF
No. 12 Squadron of the Royal Air Force currently operates the Tornado GR4 from RAF Lossiemouth.-History:No. 12 Squadron Royal Flying Corps was formed in February 1915 from a flight of No. 1 Squadron RFC at Netheravon. The squadron moved to France in September 1915 and operated a variety of aircraft...

 replaced its Foxes with Harts in January 1931, with a further two British-based Hart light bomber squadrons forming during 1931.

Harts were deployed to the Middle East
Middle East
The Middle East is a region that encompasses Western Asia and Northern Africa. It is often used as a synonym for Near East, in opposition to Far East...

 during the Abyssinia Crisis
Abyssinia Crisis
The Abyssinia Crisis was a diplomatic crisis during the interwar period originating in the "Walwal incident." This incident resulted from the ongoing conflict between the Kingdom of Italy and the Empire of Ethiopia...

 of 1935–1936. The Hart saw extensive and successful service on the North-West Frontier
North-West Frontier (military history)
The North-West Frontier was the most difficult area, from a military point of view, of the former British India in the Indian sub-continent. It remains the frontier of present-day Pakistan, extending from the Pamir Knot in the north to the Koh-i-Malik Siah in the west, and separating the...

, British India during the inter-war period. Four Hawker Harts from the Swedish Air Force
Swedish Air Force
The Swedish Air Force is the air force branch of the Swedish Armed Forces.-History:The Swedish Air Force was created on July 1, 1926 when the aircraft units of the Army and Navy were merged. Because of the escalating international tension during the 1930s the Air Force was reorganized and expanded...

 saw action as dive bombers during the 1939-1940 Winter War
Winter War
The Winter War was a military conflict between the Soviet Union and Finland. It began with a Soviet offensive on 30 November 1939 – three months after the start of World War II and the Soviet invasion of Poland – and ended on 13 March 1940 with the Moscow Peace Treaty...

 as part of a Swedish volunteer squadron, designated F19, fighting on the Finnish side. Though obsolete compared to the United Kingdom
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...

's opposition at the start of the Second World War
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

, the Hart continued in service, mainly performing in the communications and training roles until being declared obsolete in 1943.

The Hart proved to be a successful export, seeing service with the Royal Egyptian Air Force
Egyptian Air Force
The Egyptian Air Force, or EAF , is the aviation branch of the Egyptian Armed Forces. The EAF is headed by an Air Marshal . Currently, the commander of the Egyptian Air Force is Air Marshal Reda Mahmoud Hafez Mohamed...

, Royal Indian Air Force
Indian Air Force
The Indian Air Force is the air arm of the Indian armed forces. Its primary responsibility is to secure Indian airspace and to conduct aerial warfare during a conflict...

, South African Air Force
South African Air Force
The South African Air Force is the air force of South Africa, with headquarters in Pretoria. It is the world's second oldest independent air force, and its motto is Per Aspera Ad Astra...

, Estonian Air Force
Estonian Air Force
The Estonian Air Force is the name of the unified aviation forces of Estonia.The Õhuvägi is the main arm of the Estonian aviation forces. The average size of the military formation in peacetime is about 210 men. The Estonian Air Force is tasked with dealing with political, military, economical,...

, Southern Rhodesia
Southern Rhodesia
Southern Rhodesia was the name of the British colony situated north of the Limpopo River and the Union of South Africa. From its independence in 1965 until its extinction in 1980, it was known as Rhodesia...

, Sweden
Sweden
Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....

 (where it was designated B4) and Kingdom of Yugoslavia
Kingdom of Yugoslavia
The Kingdom of Yugoslavia was a state stretching from the Western Balkans to Central Europe which existed during the often-tumultuous interwar era of 1918–1941...

.

Swedish Air Force General Bjorn Bjuggren wrote in his memoirs how his squadron developed dive-bombing techniques in the mid-1930s for their B4s. When the Hawker engineers found out, they issued a formal objection, saying that the aircraft had not been designed for that purpose; however, Swedish pilots proved that the aircraft was up to that task and dispelled their concern.

Hart

Hart I
Two-seat light bomber aircraft for the RAF. 525 hp Kestrel IB engine.

Hart SEDB
Two-seat single-engined light bomber aircraft for the RAF, powered by a 525 hp Rolls-Royce Kestrel IB, or a 510 hp Kestrel X (DR) piston engine.

Hart (India)
Tropicalised version for the RAF, used by RAF in the North West Frontier of India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...

, with larger radiator and extra equipment.

Hart (C)
Two-seat unarmed communications aircraft for the RAF, a small number were used by No. 24 Squadron RAF; eight built.

Hart Trainer (Interim)
Hart light bombers converted into training aircraft. Two built.

Hart Trainer
Two-seat dual-control trainer aircraft, with reduced sweepback on top wings to compensate for movement in cetre of gravity caused by removal of military equipment.

Hart Fighter
Two-seat fighter version for the RAF used by No. 23 Squadron RAF, with Kestrel IIS. Later redesignated as the Demon; six built.

Hart (Special)
Tropicalised version for the RAF, used by the RAF in the Middle East. Based on Audax airframe with desert equipment, and de-rated Kestrel X engine.

Estonian Hart
Export version for Estonia, equipped with an interchangeable wheel or float undercarriage; eight built.

Swedish Hart
Light bomber for Swedish Air Force. Four Hawker-built pattern aircraft, powered by a Bristol Pegasus IM2 radial piston engine were delivered in 1934. Following successful evaluation, 42 were built under licence in Sweden, powered by a Swedish-built NOHAB
NOHAB
NOHAB was a manufacturing company in the city of Trollhättan, Sweden.The company was founded by Antenor Nydqvist, Johan Magnus Lidström and Carl Olof Holm in 1847 as Trollhättans Mekaniska Verkstad as a manufacturer of turbines for hydraulic power plants...

 Pegasus IU2.

Audax

The Hawker Audax was a Hart variant, designed for the army co-operation role, seeing much service in the British Empire
British Empire
The British Empire comprised the dominions, colonies, protectorates, mandates and other territories ruled or administered by the United Kingdom. It originated with the overseas colonies and trading posts established by England in the late 16th and early 17th centuries. At its height, it was the...

. The first Audax flew in late 1931, and eventually, over 700 Audaxes were produced (including export). The Audax was very similar to the Hart, though had some modifications, including a hook to pick up messages. The Audax was armed with a single .303 in (7.7 mm) Lewis light machine gun and a .303 in (7.7 mm) Vickers machine gun. The Audax was powered by a version of the Kestrel engine and had a maximum speed of 170 mph (274 km/h). A number of variants of the Audax were produced, including the Audax India, a tropicalised version of the Audax for service in India; the Audax Singapore for service there.

The Audax saw service with other air forces, including the Royal Canadian Air Force
Royal Canadian Air Force
The history of the Royal Canadian Air Force begins in 1920, when the air force was created as the Canadian Air Force . In 1924 the CAF was renamed the Royal Canadian Air Force and granted royal sanction by King George V. The RCAF existed as an independent service until 1968...

, the Royal Indian Air Force, the South African Air Force
South African Air Force
The South African Air Force is the air force of South Africa, with headquarters in Pretoria. It is the world's second oldest independent air force, and its motto is Per Aspera Ad Astra...

, the Royal Egyptian Air Force, the Royal Iraqi Air Force, the Imperial Iranian Air Force
History of the Iranian Air Force
The history of the Iranian Air Force can be divided into two phases - before the Islamic Revolution, and after it.-Imperial era: The Imperial Iranian Air Force was a branch of the Imperial Iranian Armed Forces and was established by Reza Shah, the Shah of Iran, in 1920. It became operational with...

, the Straits Settlements
Straits Settlements
The Straits Settlements were a group of British territories located in Southeast Asia.Originally established in 1826 as part of the territories controlled by the British East India Company, the Straits Settlements came under direct British control as a crown colony on 1 April 1867...

 and the Southern Rhodesian Air Force. The Audax saw limited service during the Second World War, seeing service in Africa on the Kenya
Kenya
Kenya , officially known as the Republic of Kenya, is a country in East Africa that lies on the equator, with the Indian Ocean to its south-east...

-Abyssinia
Ethiopia
Ethiopia , officially known as the Federal Democratic Republic of Ethiopia, is a country located in the Horn of Africa. It is the second-most populous nation in Africa, with over 82 million inhabitants, and the tenth-largest by area, occupying 1,100,000 km2...

 border, the latter of which had been occupied by Italy. The Audax also saw service in Iraq, at RAF Habbaniya
RAF Habbaniya
Royal Air Force Station Habbaniya, more commonly known as RAF Habbaniya, was a Royal Air Force station at Habbaniyah, about west of Baghdad in modern day Iraq, on the banks of the Euphrates near Lake Habbaniyah...

, west of Baghdad
Baghdad
Baghdad is the capital of Iraq, as well as the coterminous Baghdad Governorate. The population of Baghdad in 2011 is approximately 7,216,040...

, after the uprising there, the Anglo-Iraqi War
Anglo-Iraqi War
The Anglo-Iraqi War was the name of the British campaign against the rebel government of Rashid Ali in the Kingdom of Iraq during the Second World War. The war lasted from 2 May to 31 May 1941. The campaign resulted in the re-occupation of Iraq by British armed forces and the return to power of the...

; influenced by Axis
Axis Powers
The Axis powers , also known as the Axis alliance, Axis nations, Axis countries, or just the Axis, was an alignment of great powers during the mid-20th century that fought World War II against the Allies. It began in 1936 with treaties of friendship between Germany and Italy and between Germany and...

 forces, but the Audax ended its service by 1945. A derivative of the Audax, the Hawker Hartebees, a light bomber, was built for the South African Air Force with modifications made from the Audax. Sixty-five of these aircraft were built, the majority in South Africa. The aircraft saw action in East Africa
East Africa
East Africa or Eastern Africa is the easterly region of the African continent, variably defined by geography or geopolitics. In the UN scheme of geographic regions, 19 territories constitute Eastern Africa:...

 during clashes against Italy who occupied Abyssinia.

A.V.Roe and Co. built 287 Audaxes as part of the RAF expansion scheme during 1935–1937. These did not warrant an Avro type number, but between 1937 and 1938 Avro built 24 modernised Audaxes for the Egyptian government, powered by 750 hp (560 kW) Armstrong Siddeley Panther VIA
Armstrong Siddeley Panther
|-See also:-Bibliography:* Lumsden, Alec. British Piston Engines and their Aircraft. Marlborough, Wiltshire: Airlife Publishing, 2003. ISBN 1-85310-294-6....

 radials. Acknowledging the amount of redesign work done, these were designated the Avro Type 674.

Audax I
Two-seat army co-operation aircraft for the RAF, powered by a 530 hp (395 kW) Rolls-Royce Kestrel IB, or 580 hp Kestrel X piston engine.

Audax (India)
Tropicalised version for the RAF, used by the RAF in India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...

.

Audax (Singapore)
Tropicalised version for the RAF, powered by a Rolls-Royce Kestrel V piston engine, used by the RAF in Singapore and British Malaya
British Malaya
British Malaya loosely described a set of states on the Malay Peninsula and the Island of Singapore that were brought under British control between the 18th and the 20th centuries...

.

Canadian Audax
Modified version of the Audax I for the RCAF; one built for Canada.

Egyptian Audax
Six aircraft fitted with the 750 hp Armstrong Siddeley Panther
Armstrong Siddeley Panther
|-See also:-Bibliography:* Lumsden, Alec. British Piston Engines and their Aircraft. Marlborough, Wiltshire: Airlife Publishing, 2003. ISBN 1-85310-294-6....

 radial piston engine, plus 18 aircraft fitted with the Panther X radial piston engine; 34 built for Egypt.

Iraqi Audax
24 aircraft fitted with the Bristol Pegasus IIM2 radial piston engine, plus 10 aircraft fitted with the Pegasus VIP8 radial piston engine; 34 built for Iraq.

Persian Audax
30 aircraft fitted with the Pratt & Whitney Hornet S2B radial piston engine, plus 26 aircraft fitted with the Bristol Pegasus IIM or IIM2 radial piston engine; 56 built for Persia.

Hartbees
Hawker built pattern aircraft; four built and exported to South Africa.

Hartebees I
Two-seat general-purpose, ground surpport aircraft for the South African Air Force, powered by a 608 hp (453 kW) Rolls-Royce Kestrel VFP piston engine; 65 aircraft built under licence in South Africa.

Demon

The Hawker Demon was a fighter variant of the Hart light bomber. It was developed as when the Hart entered service, it was virtually uninterceptable by the RAF's fighters, which was demonstrated in air defence exercises where they were sometimes instructed to restrict their height and speed in order to give the RAF's Siskins and Bulldogs a chance. While the Hawker Fury
Hawker Fury
The Hawker Fury was a British biplane fighter aircraft used by the Royal Air Force in the 1930s. It was originally named the Hornet and was the counterpart to the Hawker Hart light bomber.-Design and development:...

 offered better performance, it was expensive and was only available in small numbers, so when a fighter version of the Hart was suggested, the Air Ministry selected the type as an interim fighter until higher performance dedicated fighters could be bought in larger numbers. The new fighter variant added a second Vickers machine gun, while the coaming of the rear cockpit was angled to give a better field of fire, and a supercharged
Supercharger
A supercharger is an air compressor used for forced induction of an internal combustion engine.The greater mass flow-rate provides more oxygen to support combustion than would be available in a naturally aspirated engine, which allows more fuel to be burned and more work to be done per cycle,...

 Kestrel IS engine was fitted. Evaluation of an initial batch of six aircraft, known as Hart Fighters by one flight of 23 Squadron
No. 23 Squadron RAF
No. 23 Squadron was a squadron of the Royal Air Force. Until October 2009, it operated the Boeing Sentry AEW1 Airborne Warning And Control System aircraft from RAF Waddington, Lincolnshire.-First World War:...

 during 1931 was successful, and larger orders followed for the fighter Hart, now known as the Hawker Demon.

Over 200 Hawker Demons were built for the RAF. The Demon were powered by varying types of the Kestrel engine. It had an armament of a single rear .303 in (7.7 mm) Lewis Gun
Lewis Gun
The Lewis Gun is a World War I–era light machine gun of American design that was perfected and widely used by the British Empire. It was first used in combat in World War I, and continued in service with a number of armed forces through to the end of the Korean War...

 with two .303 in (7.7 mm) Vickers machine guns in the nose. Large numbers of the type were fitted with a hydraulically powered turret in the rear, which had been tested on the Hawker Hart. The Demon was also sold to the Royal Australian Air Force
Royal Australian Air Force
The Royal Australian Air Force is the air force branch of the Australian Defence Force. The RAAF was formed in March 1921. It continues the traditions of the Australian Flying Corps , which was formed on 22 October 1912. The RAAF has taken part in many of the 20th century's major conflicts...

. It saw only brief second line operations during the Second World War.

Production of the Demon was by Hawker and by Boulton Paul Aircraft
Boulton Paul Aircraft
Boulton Paul Aircraft Ltd was a British aircraft manufacturer that was created in 1934, although its origins lay in 1914, and lasted until 1961...

, Norwich.

Hart Two-Seat Fighter
Two-seat fighter version of the Hart for the RAF. Later redesignated as the Hart Fighter.

Demon I
Two-seat fighter aircraft for the RAF.

Australian Demon I
Two-seat fighter aircraft for the RAAF, similar to RAF version but fitted with a 600 hp (447 kW) Rolls Royce Kestrel V engine; 54 built (the first 18 delivered as general-purpose fighters in 1935 and an additional 36 for army co-operation duties delivered in 1936).

Australian Demon II
Two-seat training version for the RAAF, standard Demon fitted with dual controls and provision for target towing, 10 built

Turret Demon
Two-seat fighter version, fitted with a Frazer-Nash
Nash & Thomson
Nash & Thompson was a British engineering firm that specialised in the production of hydraulically-operated gun turrets for aircraft. The company was also an important manufacturer of hydraulic powered radar scanners, used on radar systems such as H2S and AI Mark VIII.- History :Nash & Thompson was...

 gun turret in the rear cockpit.

Hardy

The Hawker Hardy was general-purpose variant of the Hawker Hart tropicalised to meet Air Ministry Specification G.23/33 as a Wapiti replacement in Iraq. The prototype was a production Hart which was modified with a modified radiator, a message pick-up hook, water containers and a desert survival kit. The prototype first flew on 7 September 1934, and the first production aircraft were delivered to 30 Squadron
No. 30 Squadron RAF
No. 30 Squadron of the Royal Air Force operates the second generation C-130J Hercules from RAF Brize Norton, Oxfordshire. The squadron operates alongside No. 24 Squadron and No. 47 Squadron all flying the Hercules.-History:...

 in January 1935. The Hardy saw some service during the Second World War, in Africa and the Middle East; the Hardys performing a number of operations against Italian-occupied Abyssinia as well as other areas of Africa. The Hardy also saw service with Southern Rhodesia. The last operational sortie by a Hardy was on 9 May 1941 and most of the survivors were scrapped, although some continued in service as communications aircraft. On 14 May 1941, the Belgian Colonial authorities obtained a Hawker Hardy from the South African Air Force. Painted in Belgian colours, the machine was used for observation missions, but unfortunately overturned while landing at Gambela airfield on 26 May 1941, effectively writing off the aircraft.

Hardy I
Two-seat general-purpose aircraft for the RAF, 47 built excluding one prototype modified from a Hart.

Hind

The Hawker Hind was a derivative of the Hart and was intended to replace it. The Hawker Hector
Hawker Hector
-See also:-Bibliography:* Air Transport Auxiliary Ferry Pilots Notes . Elvington, York, UK: Yorkshire Air Museum, 1996. ISBN 0-9512379-8-5....

 was a variant of the Hind and was used in the army co-operation role. It saw only limited service during the Second World War with the Royal Air Force. Hectors were also sold to Ireland
Republic of Ireland
Ireland , described as the Republic of Ireland , is a sovereign state in Europe occupying approximately five-sixths of the island of the same name. Its capital is Dublin. Ireland, which had a population of 4.58 million in 2011, is a constitutional republic governed as a parliamentary democracy,...

.

Osprey

The Hawker Osprey was the navalised carrier-borne version of the Hart, performing in the fighter and reconnaissance roles. The Osprey had a single Rolls-Royce Kestrel II engine, and had a max speed of 168 mph (270 km/h). Its armament consisted of a single forward .303 in (7.7 mm) Vickers machine gun and one .303 in (7.7 mm) Lewis gun. The Osprey joined the Fleet Air Arm
Fleet Air Arm
The Fleet Air Arm is the branch of the British Royal Navy responsible for the operation of naval aircraft. The Fleet Air Arm currently operates the AgustaWestland Merlin, Westland Sea King and Westland Lynx helicopters...

 (FAA) in 1932, with just over 100 being built, and ended its career in 1944 after serving as a trainer for FAA pilots during her career in the Second World War. The Osprey was also sold to the Swedish Air Force
Swedish Air Force
The Swedish Air Force is the air force branch of the Swedish Armed Forces.-History:The Swedish Air Force was created on July 1, 1926 when the aircraft units of the Army and Navy were merged. Because of the escalating international tension during the 1930s the Air Force was reorganized and expanded...

 being used on the seaplane cruiser , which carried six Ospreys. Ospreys were also sold to the air forces of Portugal and the Spanish Republican Air Force
Spanish Republican Air Force
The Spanish Republican Air Force, , was the air arm of the Second Spanish Republic, the legally established government of Spain between 1931 and 1939...

.

Osprey I
Two-seat fleet spotter and reconnaissance aircraft, power by a 630 hp (470 kW) Rolls-Royce Kestrel IIMS inline piston engine; 37 built.

Osprey II
Two-seat fleet spotter and reconnaissance aircraft, powered by a 630 hp (470 kW) Rolls-Royce Kestrel IIMS piston engine, equipped with redesigned floats; 14 built.

Osprey III
Tho-seat fleet spotter and reconnaissance aircraft, powered by a 630 hp (470 kW) Rolls-Royce Kestrel IIMS piston engine, equipped with a dinghy stowed away in the starboard upper wing; 26 built.

Osprey IV
Two-seat fleet spotter and reconnaissance aircraft, powered by a Rolls-Royce Kestrel V inline piston engine.

Portuguese Osprey
One aircraft fitted with a Rolls-Royce Kestrel IIMS piston engine; one built for Portugal.

Spanish Osprey
One aircraft fitted with a Hispano-Suiza 12Xbrs engine; one built for Spain.

Swedish Osprey
Six aircraft fitted with a Swedish-built NOHAB
NOHAB
NOHAB was a manufacturing company in the city of Trollhättan, Sweden.The company was founded by Antenor Nydqvist, Johan Magnus Lidström and Carl Olof Holm in 1847 as Trollhättans Mekaniska Verkstad as a manufacturer of turbines for hydraulic power plants...

 Bristol Mercury radial piston engine; six built for the Swedish Air Force who gave them the military designation S 9H (with floats) and S 9 (on wheels).

Operators

Specifications (Hart (Kestrel IB powered day bomber))

External links

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