Post by Diarist on May 26, 2014 3:22:13 GMT 1
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. 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.
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. Up to 520 pounds (240 kg) of bombs could be carried under the aircraft's wings.
J9052, the prototype Hart, 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 miles per hour (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 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.
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 and Hector, being made. There were a number of Hart variants made, though only slight alterations were made. The Hart India was a tropicalised version of the aircraft; the Hart Special was a tropicalised Hawker Audax, a Hart variant, with desert equipment; a specialised Hart Trainer was also built which dispensed with the gunners ring. Vickers built 114 of the latter model at Weybridge.
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). 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.
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.
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.
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 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 Kestrel IS engine was fitted. Evaluation of an initial batch of six aircraft, known as Hart Fighters by one flight of 23 Squadron during 1931 was successful, and larger orders followed for the fighter Hart, now known as the Hawker Demon. First Flight on February 10, 1933.
305 Hawker Demons were built including 232 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 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.
Hardy
The Hawker Hardy was a 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.
Hind
An improved Hawker Hart bomber defined by Specification G.7/34, was purchased by RAF as interim aircraft while more modern monoplane bombers such as the Fairey Battle were still in development. Structural elements were a mixture of steel and duralumin with the wings being fabric covered while the main differences compared to the earlier Hart was a new powerplant, (the Rolls Royce Kestrel V) and the inclusion of refinements from the earlier derivatives such as the cut-down rear cockpit developed for the Demon. The prototype (Serial number K2915) was constructed very rapidly due to Hawker's development work for other proposals, and made its first flight on September 12, 1934.
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 103 being built.
Source: Wikipedia - en.wikipedia.org/wiki/Hawker_Hart
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. 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.
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. Up to 520 pounds (240 kg) of bombs could be carried under the aircraft's wings.
J9052, the prototype Hart, 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 miles per hour (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 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.
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 and Hector, being made. There were a number of Hart variants made, though only slight alterations were made. The Hart India was a tropicalised version of the aircraft; the Hart Special was a tropicalised Hawker Audax, a Hart variant, with desert equipment; a specialised Hart Trainer was also built which dispensed with the gunners ring. Vickers built 114 of the latter model at Weybridge.
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). 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.
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.
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.
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 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 Kestrel IS engine was fitted. Evaluation of an initial batch of six aircraft, known as Hart Fighters by one flight of 23 Squadron during 1931 was successful, and larger orders followed for the fighter Hart, now known as the Hawker Demon. First Flight on February 10, 1933.
305 Hawker Demons were built including 232 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 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.
Hardy
The Hawker Hardy was a 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.
Hind
An improved Hawker Hart bomber defined by Specification G.7/34, was purchased by RAF as interim aircraft while more modern monoplane bombers such as the Fairey Battle were still in development. Structural elements were a mixture of steel and duralumin with the wings being fabric covered while the main differences compared to the earlier Hart was a new powerplant, (the Rolls Royce Kestrel V) and the inclusion of refinements from the earlier derivatives such as the cut-down rear cockpit developed for the Demon. The prototype (Serial number K2915) was constructed very rapidly due to Hawker's development work for other proposals, and made its first flight on September 12, 1934.
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 103 being built.
Source: Wikipedia - en.wikipedia.org/wiki/Hawker_Hart