| Hart | |
|---|---|
 | |
| Hawker Hart | |
| Role | Light bomber |
| Manufacturer | Hawker Aircraft Limited |
| Designed by | Sydney Camm |
| First flight | June 1928 |
| Introduced | 1930 |
| Primary user | Royal Air Force |
| Variants | Hawker Hind Hawker Hector |
Contents
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Design and development
In 1926, the Air Ministry 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, Avro and de Havilland.[1] Fairey, who had sold a squadron's worth of its wooden Fox 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.[2][3]Hawker's design was a single-bay biplane powered by a Rolls-Royce F.XI water-cooled V12 engine (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 panels and fabric, with the wings having steel spars and duralumin ribs, 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 mounted on the port side of the cockpit. The observer sat behind the pilot, and was armed with a single Lewis gun on a ring mount, while for bomb-aiming, he lay prone under the pilots seat.[4] Up to 520 pounds (240 kg) of bombs could be carried under the aircraft's wings.[5]
J9052, the prototype Hart, (a Hart being a male Red Deer) first flew in June 1928, being delivered to the Aeroplane and Armament Experimental Establishment at RAF Martlesham Heath 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.[6][7] 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 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 (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.[6]
A total of 992 aircraft were built as Harts.[8][N 1] 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 and Hector, 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.[9]
The production Hart day bomber had a single 525 hp (390 kW) Rolls-Royce Kestrel IB 12-cylinder V-type engine; a speed of 184 mph (296 km/h) and a range of 470 mi (757 km).[10] 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, 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.[11]
Demand for the bomber was such that 164 were built by Vickers-Armstrongs at its Weybridge factory at Brooklands 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 in February 1930, replacing the larger and slower Hawker Horsley. No. 12 Squadron replaced its Foxes with Harts in January 1931, with a further two British-based Hart light bomber squadrons forming during 1931.[12]Harts were deployed to the Middle East during the Abyssinia Crisis of 1935–1936. The Hart saw extensive and successful service on the North-West Frontier, British India during the inter-war period. Four Hawker Harts from the Swedish Air Force saw action as dive bombers during the 1939-1940 Winter War as part of a Swedish volunteer squadron, designated F19, fighting on the Finnish side. Though obsolete compared to the United Kingdom's opposition at the start of the Second World War, the Hart continued in service, mainly performing in the communications and training roles until being declared obsolete in 1943.[13]
The Hart proved to be a successful export, seeing service with the Royal Egyptian Air Force, Royal Indian Air Force, South African Air Force, Estonian Air Force, Southern Rhodesia, Sweden (where it was designated B4) and Kingdom of Yugoslavia.
Swedish Air Force General Bjorn Bjuggren wrote in his memoirs how his squadron developed dive-bombing techniques in the mid-1930s for their B4s. [N 2] 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.[14]
Variants
Hart
- Hart I
- Two-seat light bomber aircraft for the RAF. 525 hp Kestrel IB engine.[15]
- 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.[16]
- Hart (India)
- Tropicalised version for the RAF, used by RAF in the North West Frontier of India, with larger radiator and extra equipment.[17]
- Hart (C)
- Two-seat unarmed communications aircraft for the RAF, a small number were used by No. 24 Squadron RAF; eight built.[18]
- Hart Trainer (Interim)
- Hart light bombers converted into training aircraft. Two built.[19]
- 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.[20]
- 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.[21]
- 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.[22][23]
- Estonian Hart
- Export version for Estonia, equipped with an interchangeable wheel or float undercarriage; eight built.[24][25]
- 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 Pegasus IU2.[24][25]
Audax
The Hawker Audax was a Hart variant, designed for the army co-operation role, seeing much service in the British Empire. 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, the Royal Indian Air Force, the South African Air Force, the Royal Egyptian Air Force, the Royal Iraqi Air Force, the Imperial Iranian Air Force, the Straits Settlements and the Southern Rhodesian Air Force. The Audax saw limited service during the Second World War, seeing service in Africa on the Kenya-Abyssinia border, the latter of which had been occupied by Italy. The Audax also saw service in Iraq, at RAF Habbaniya, west of Baghdad, after the uprising there, the Anglo-Iraqi War; influenced by Axis 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 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 1937–1938 Avro built 24 modernised Audaxes for the Egyptian government, powered by 750 hp (560 kW) Armstrong Siddeley Panther VIA 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.
- 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.
- 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 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
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 with two .303 in (7.7 mm) Vickers machine guns in the nose. Large numbers of the type were fitted with an 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. It saw only brief second line operations during the Second World War.
Production of the Demon was by Hawker and by Boulton Paul Aircraft, 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; 64 built.
- Australian Demon II
- Two-seat training version for the RAAF, standard Demon fitted with dual controls.
- Turret Demon
- Two-seat fighter version, fitted with a Frazer-Nash 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 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 the 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
Main article: Hawker Hind
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 (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 Navy being used on the seaplane cruiser HMS Gotland, which carried six Ospreys. Ospreys were also sold to the air forces of Portugal and the Spanish Republican Air Force.- 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
- Four aircraft fitted with a Swedish-built NOHAB Bristol Mercury radial piston engine; four built for Sweden.
Operators
Main article: Operators of Hawker Hart and variants
Hawker Hart
Afghanistan
Canada
Egypt
Estonia
British India
South Africa
Southern Rhodesia
Sweden
United Kingdom
Kingdom of Yugoslavia
Hawker Audax
Hawker Demon
Hawker Hardy
- United Kingdom
- Southern Rhodesia
Belgium (one aircraft, ex-RAF K4316)
Hawker Hartebees
Hawker Osprey
Specifications (Hart (Kestrel IB powered day bomber))
Data from The British Bomber since 1914[8]
General characteristics- Crew: 2
- Length: 29 ft 4 in (8.94 m)
- Wingspan: 37 ft 3 in (11.36 m)
- Height: 10 ft 5 in (3.18 m)
- Wing area: 349.5 ft² (32.5 m²)
- Airfoil: RAF 28[10]
- Empty weight: 2,530 lb (1,150 kg)
- Max takeoff weight: 4,596 lb (2,089 kg)
- Powerplant: 1× Rolls-Royce Kestrel IB water-cooled V12 engine, 510 hp (380 kW)
- Maximum speed: 161 kn (185 mph, 298 km/h) at 13,000 ft
- Stall speed: 39 kn (45 mph, 72 km/h) [29]
- Range: 374 nmi (430 mi, 692 km)
- Service ceiling: 22,800 ft (6,950 m)
- Wing loading: 13.2 lb/ft² (64.3 kg/m²)
- Power/mass: 0.11 hp/lb (0.182 kW/kg)
- Climb to 10,000 ft 8 minutes, 30 seconds
- Guns: 1 × synchronised forward firing .303 in (7.7 mm) Vickers machine gun, 1 × .303 in (7.7 mm) Lewis Gun on Scarff ring in rear cockpit.
- Bombs: Up to 500 lb (227 kg) bombs under wings.
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