Armstrong Whitworth AW52
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Cockpit
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A.S.52 – Specifications
- Length: 37 ft 4 in (11.4 m)
- Wingspan: 90ft (27.4 m)
- Height: 14 ft 5 in (4.4 m)
- Wing area: 1,314 ft² (122 m²)
- Airfoil: NPL.655-3-218 at root, tapering to NPL.655-3-118 at extremity of the centre section and to NPL.654-3-015 at the tips
- Empty weight: 19,660 lb (8,918 kg)
- Loaded weight: 34,150 lb (15,490 kg)
- Powerplant: 2 × Rolls-Royce Nene centrifugal-flow turbojet, 5,000 lbf (22.2 kN) each
- Maximum speed: 500 mph (434 kts, 805 km/h) at sea level
- Range: 1500 mi (2,414 km) at 330 mph (287 kts) at 36,000ft
- Service ceiling: 36,000 ft (10,973 m)
- Rate of climb: 4,800 ft/min (24.4 m/s) at sea level
- Power Plant:
1st Prototype: 2 Rolls Royce Nene engines, each of 5,000 lb. thrust.
2nd Prototype: 2 Rolls Royce Dewent engines, each of 3,500 lb. thrust.
ormance:
With Nene Engines: -
Max. Speed 500 mph at Sea Level.
Max. Rate of Climb 4,800 ft. / min. at Sea Level
One of the main reasons for the AW 52 was to provide data on laminar flow wings with boundary layer control by suction. To this end, new methods of construction were employed to provide the desired wing smoothness.
Incidentally, the new compartment was the first pressurised cabin that the firm had built and it provided much experience for future products. Another novel feature was the thermal anti-icing system for the wing leading edges which used hot gas obtained from the engine exhaust. Longitudinal control was unconventional in that intermediate moveable surfaces were provided in the wing just forward of the elevators.
In May 1949, the first aircraft was on a test flight to investigate flutter characteristics, when the pilot was forced to bale out, using the Martin Baker Seat for the first time ever in an emergency. The aircraft was destroyed.
The second prototype continued with its programme for some considerable time after, mainly at Farnborough.
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Lovely shots!
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History and Design
Armstrong Whitworth Aircraft proposed a jet-powered six or four-engine flying wing airliner design, using a laminar flow wing, during the Second World War.[1] This had to be a large aircraft in order to provide passenger head-room within the wing. The low-speed characteristics of the design were tested on a 53 ft 10 in (16.41 m) span wooden glider known as the A.W.52G; the glider was designed to be roughly half the size of the powered A.W.52, which in turn would be about half the size of the airliner. Construction of the AW.52G began in March 1943, with the glider making its maiden flight, towed by an Armstrong Whitworth Whitley bomber, on 2 March 1945. Flight testing, with tug releases from 20,000 ft (6,096 m) giving flights of around 30 min continued, mostly satisfactorily until 1947.[1] In 1944, Armstrong Whitworth received a contract that would allow them to produce two A.W.52 prototypes for evaluation, nominally as mail carrying aircraft.[1]
The A.W.52 was intended for high speeds and was an all-metal turbojet-powered aircraft, with a retractable undercarriage; aerodynamically it had much in common with the glider. Both aircraft were moderately-swept flying wings with a centre section having a straight trailing edge. The wing tips carried small (not full chord) end-plate fin and rudders, which operated differentially, with a greater angle on the outer one. Roll and pitch were controlled with elevons that extended inward from the wing tips over most (in the case of the A.W.52 about three-quarters) of the outer, swept part of the trailing edge. The elevons moved together as elevators and differentially as ailerons. They were quite complicated surfaces – which included trim tabs – and hinged not from the wing but from "correctors", which were wing-mounted; the correctors provided pitch trim. To delay tip stall, air was sucked out of a slot just in front of the elevons, by pumps powered by undercarriage-mounted fans on the glider and directly from the engine in the A.W.52. The inner centre section wing carried Fowler flaps and the upper surface of the outer section carried spoilers.
Maintenance of laminar flow over the wings was vital to the design and so they were built with great attention to surface flatness. Rather than the usual approach, where skinning is added to a structure defined by ribs, the A.W.52's wings were built in two halves (upper and lower) from the outside in, starting from pre-formed surfaces, adding stringers and ribs then joining the two halves together. The result was a surface smooth to better than 2/1000 of an inch (50 μm).[1]
The crew sat in tandem in a nacelle so that the pilot was just forward of the wing leading edge, providing a better view than in the glider. The pressurised cockpit was slightly off-set to port. The engines were mounted in the wing centre section, close to the centre line and so not disturbing the upper wing surface.[1]
The first prototype flew on 13 November 1947 powered by two Rolls-Royce Nene engines of 5,000 lbf (22.2 kN) thrust each. This was followed by the second prototype on 1 September 1948 with the lower-powered (3,500 lbf/15.5 kN) Rolls Royce Derwent. Trials were disappointing: laminar flow could not be maintained, so maximum speeds, though respectable, were less than expected. As in any tail-less aircraft, take-off and landing runs were longer than for a conventional aircraft (at similar wing loadings) because at high angles of attack, downward elevon forces were much greater than those of elevators with their large moment.[1]
The first prototype crashed without loss of life on 30 May 1949, making it the first occasion of an emergency ejection by a British pilot. Despite the termination of development, the second prototype remained flying with the Royal Aircraft Establishment until 1954
The accident
On 30 May 1949, while diving the first prototype at 320 mph (515 km/h), test pilot J.O. Lancaster encountered a pitch oscillation believed to be caused by elevon flutter. Starting at two cycles per second, it rapidly increased to incapacitating levels. With structural failure seemingly imminent, Lancaster ejected from the aircraft using its Martin-Baker Mk.1 ejection seat, becoming the first British pilot to use the apparatus in a "live" emergency.[2] It was fortunate that he was alone in the aircraft as the second crew member was not provided with an ejection seat.[1]
As luck would have it, the aircraft, left to its own devices, stopped fluttering and glided down to land itself in open country with relatively little damage. Following this incident, and in view of the disappointing results obtained, no further development of the flying-wing formula was undertaken by Armstrong Whitworth, who had now turned their attention to the more conventional A.W. 55 propeller-turbine airliner. The second A.W. 52 was handed over to the Royal Aircraft Establishment at Farnborough, where it was used for experimental flying until it was finally disposed of in June 1954.
Armstrong Whitworth Aircraft proposed a jet-powered six or four-engine flying wing airliner design, using a laminar flow wing, during the Second World War.[1] This had to be a large aircraft in order to provide passenger head-room within the wing. The low-speed characteristics of the design were tested on a 53 ft 10 in (16.41 m) span wooden glider known as the A.W.52G; the glider was designed to be roughly half the size of the powered A.W.52, which in turn would be about half the size of the airliner. Construction of the AW.52G began in March 1943, with the glider making its maiden flight, towed by an Armstrong Whitworth Whitley bomber, on 2 March 1945. Flight testing, with tug releases from 20,000 ft (6,096 m) giving flights of around 30 min continued, mostly satisfactorily until 1947.[1] In 1944, Armstrong Whitworth received a contract that would allow them to produce two A.W.52 prototypes for evaluation, nominally as mail carrying aircraft.[1]
The A.W.52 was intended for high speeds and was an all-metal turbojet-powered aircraft, with a retractable undercarriage; aerodynamically it had much in common with the glider. Both aircraft were moderately-swept flying wings with a centre section having a straight trailing edge. The wing tips carried small (not full chord) end-plate fin and rudders, which operated differentially, with a greater angle on the outer one. Roll and pitch were controlled with elevons that extended inward from the wing tips over most (in the case of the A.W.52 about three-quarters) of the outer, swept part of the trailing edge. The elevons moved together as elevators and differentially as ailerons. They were quite complicated surfaces – which included trim tabs – and hinged not from the wing but from "correctors", which were wing-mounted; the correctors provided pitch trim. To delay tip stall, air was sucked out of a slot just in front of the elevons, by pumps powered by undercarriage-mounted fans on the glider and directly from the engine in the A.W.52. The inner centre section wing carried Fowler flaps and the upper surface of the outer section carried spoilers.
Maintenance of laminar flow over the wings was vital to the design and so they were built with great attention to surface flatness. Rather than the usual approach, where skinning is added to a structure defined by ribs, the A.W.52's wings were built in two halves (upper and lower) from the outside in, starting from pre-formed surfaces, adding stringers and ribs then joining the two halves together. The result was a surface smooth to better than 2/1000 of an inch (50 μm).[1]
The crew sat in tandem in a nacelle so that the pilot was just forward of the wing leading edge, providing a better view than in the glider. The pressurised cockpit was slightly off-set to port. The engines were mounted in the wing centre section, close to the centre line and so not disturbing the upper wing surface.[1]
The first prototype flew on 13 November 1947 powered by two Rolls-Royce Nene engines of 5,000 lbf (22.2 kN) thrust each. This was followed by the second prototype on 1 September 1948 with the lower-powered (3,500 lbf/15.5 kN) Rolls Royce Derwent. Trials were disappointing: laminar flow could not be maintained, so maximum speeds, though respectable, were less than expected. As in any tail-less aircraft, take-off and landing runs were longer than for a conventional aircraft (at similar wing loadings) because at high angles of attack, downward elevon forces were much greater than those of elevators with their large moment.[1]
The first prototype crashed without loss of life on 30 May 1949, making it the first occasion of an emergency ejection by a British pilot. Despite the termination of development, the second prototype remained flying with the Royal Aircraft Establishment until 1954
The accident
On 30 May 1949, while diving the first prototype at 320 mph (515 km/h), test pilot J.O. Lancaster encountered a pitch oscillation believed to be caused by elevon flutter. Starting at two cycles per second, it rapidly increased to incapacitating levels. With structural failure seemingly imminent, Lancaster ejected from the aircraft using its Martin-Baker Mk.1 ejection seat, becoming the first British pilot to use the apparatus in a "live" emergency.[2] It was fortunate that he was alone in the aircraft as the second crew member was not provided with an ejection seat.[1]
As luck would have it, the aircraft, left to its own devices, stopped fluttering and glided down to land itself in open country with relatively little damage. Following this incident, and in view of the disappointing results obtained, no further development of the flying-wing formula was undertaken by Armstrong Whitworth, who had now turned their attention to the more conventional A.W. 55 propeller-turbine airliner. The second A.W. 52 was handed over to the Royal Aircraft Establishment at Farnborough, where it was used for experimental flying until it was finally disposed of in June 1954.
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