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Airspeed AS.57 Ambassador

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In 1943, the British government formed a committee under the chairmanship of Lord Brabazon of Tara to identify post-war civil aviation requirements. In its February 1943 report, they recommended a twin-engined, unpressurised design in the 14.5 tonnes gross weight class, short to medium-range piston-engined aircraft for British operators and for sale to European airlines.


The Airspeed AS.57 Ambassador was designed by a team headed by Arthur Hagg, their work taking shape on the drawing-board while the UK was still at war. Spanning 115ft and 81ft long, the Ambassador had two Bristol Centaurus 661s, each developing 2,700 hp and driving a 16ft 6in-diameter four-bladed de Havilland propeller.
A normal capacity of 47 passengers was envisaged with an all- up weight would be 52,500 lb, with ranges of 720 and 1,560 miles at cruising speeds of 280 and 220 mph respectively.


There was capacity for future "stretch", and the wings were designed with strongpoints to accommodate a future powerplant change to four propeller turbines of the Rolls-Royce Dart type.


By the time the British Ministry of Aircraft production ordered two prototypes from Airspeed Ltd., immediately after the end of the World War II, the design had grown. The Ambassador would be pressurised and have a maximum gross weight of almost 24 tonnes, offering seating for 47 passengers. The Ambassador was a high-wing monoplane with triple fins, retractable nosewheel.


The Ambassador was of cantilever high-wing monoplane configuration of all-metal construction, with its fuselage stressed for cabin pressurisation. The three-finned tail unit was car-ried high on an upswept aft fuselage, and the retractable tricycle landing gear incorporated twin wheels on each unit.


The prototype (G-AGUA) powered by two 2.600 hp Centaurus 631 radials, was first flown on 10 July 1947 from Christchurch. In 1948 the first (and also the only) order for 20 Ambassador 2s was received from British Euro-pean Airways. The second prototype (G-AKRD) flew on 26 August 1948; two static-test airframes were built, followed by one pre-production Ambassador (G-ALFR) which was used to obtain the C of A and for route proving by BEA - British European Airways. Airspeed AS57 Ambassador G-ALFR had the definitive Centaurus 661 powerplant, and was flown first in May 1950.

 

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On 13 March 1952, the first British European Airways service London-Paris was inaugurated, with 47 seats and 2,012kW Centaurus 661. BEA called its fleet "Elizabethans" in honour of the newly crowned Queen Elizabeth 1, during their six years of operation. In 1954, after two years' service, BEA requested clearance of an increased maximum take-off weight from 52,500 lb to 55,000 lb. This was achieved.


After service with BEA the Ambassador passed to several independent airlines including BKS, Dan-Air and Globe Air of Switzerland - some serving as freighters and horse transports. Three were used for a time by Butler Air Transport in Australia, and one was owned by the King of Morocco.


The second AS.57 prototype (G-AKRD) was later used for development testing of the Bristol Proteus 705, Rolls-Royce Tyne and Rolls-Royce Dart turbo-props, and was still airworthy in 1969.


The third prototype (G-ALFR), was used for testing of the Napier Eland turboprop, but was later converted to airline standards and sold to Dan Air.


Only 23 Airspeed Ambassadors were produced.

Engine: 2 x Bristol Centaurus 661 two-row sleeve-valve radial piston, 1939-kW (2,600-hp)
Wing span: 35.05m (115 ft 0 in)
Length: 24.69m (81 ft 0in)
Height: 5.59m (l8ft 4in)  
Wing area: 111.48sq.m (1,200 sq.ft.)
Max take-off 23814 kg (52,500 lb) - 55000.0 lb / 24947.0 kg
Empty equipped weight: 16230 kg (35,781 lb)
Max. speed : 271 kts / 502 km/h
Maximum cruising speed: 438 km/h (272 mph)
Economic cruising speed: 399 km/h (248 mph)
Range with maximum payload: 1159 km (720 miles).
Range w/max.fuel: 1930 km / 1199 miles
Service ceiling : 36089 ft / 11000 m
Crew: 3
Pax cap: 47

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