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66-563: The Airspeed AS.57 Ambassador is a British twin piston-engined airliner that was designed and produced by the British aircraft manufacturer Airspeed Ltd. It was one of the first postwar airliners to be produced. The Ambassador was developed in response to a requirement identified by the Brabazon Committee for a twin-engined short-to-medium-haul airliner as a replacement for the ubiquitous Douglas DC-3 . Airspeed assembled

132-521: A belly landing after the port undercarriage leg failed to deploy due to a loss of hydraulic pressure. This did not seemingly deter customer confidence, as the newly created operator British European Airways (BEA) continued to openly express their preference for the type, and in September they placed a £3 million order for 20 Ambassadors. This support was so impactful that, according to aviation author H. A. Taylor, rival aircraft manufacturer Vickers

198-608: A tricycle undercarriage , a steerable nosewheel, integral fuel tanks, and other recent innovations. Distinctive external features of the Ambassador included its three low tailfins and a long pointed nose, giving it a resemblance to the larger transcontinental Lockheed Constellation . Its tricycle gear gave it a more modern appearance than contemporaries such as the DC-3 , Curtiss Commando , Avro Lancastrian and Vickers Vikings that were common on Europe's shorter airline routes. In

264-597: A capacity of 1,820 L (64 cu ft), making a total capacity of 25,480 L (900 cu ft) for the largest versions. For piston engines, an engine's capacity is the engine displacement , in other words the volume swept by all the pistons of an engine in a single movement. It is generally measured in litres (l) or cubic inches (c.i.d., cu in, or in ) for larger engines, and cubic centimetres (abbreviated cc) for smaller engines. All else being equal, engines with greater capacities are more powerful and consumption of fuel increases accordingly (although this

330-698: A circular groove in the piston head. The rings fit closely in the groove and press lightly against the cylinder wall to form a seal, and more heavily when higher combustion pressure moves around to their inner surfaces. It is common to classify such engines by the number and alignment of cylinders and total volume of displacement of gas by the pistons moving in the cylinders usually measured in cubic centimetres (cm or cc) or litres (l) or (L) (US: liter). For example, for internal combustion engines, single and two-cylinder designs are common in smaller vehicles such as motorcycles , while automobiles typically have between four and eight, and locomotives and ships may have

396-469: A cylinder to drive a reciprocating engine in a local-pollution-free urban vehicle. Torpedoes may use a working gas produced by high test peroxide or Otto fuel II , which pressurize without combustion. The 230 kg (510 lb) Mark 46 torpedo , for example, can travel 11 km (6.8 mi) underwater at 74 km/h (46 mph) fuelled by Otto fuel without oxidant . Quantum heat engines are devices that generate power from heat that flows from

462-438: A dispersed design team at Fairmile Manor, Cobham, Surrey, in 1943, which initially worked on a smaller proposal powered by Bristol Hercules radial engines ; this was quickly superseded by a larger-capacity design aimed at better fulfilling the expansion in postwar civil air travel, although several entities doubted Airspeed's projected growth in air travel. Fitted with the new but conventional Bristol Centaurus radial engines ,

528-418: A dozen cylinders or more. Cylinder capacities may range from 10 cm or less in model engines up to thousands of liters in ships' engines. The compression ratio affects the performance in most types of reciprocating engine. It is the ratio between the volume of the cylinder, when the piston is at the bottom of its stroke, and the volume when the piston is at the top of its stroke. The bore/stroke ratio

594-406: A hot to a cold reservoir. The mechanism of operation of the engine can be described by the laws of quantum mechanics . Quantum refrigerators are devices that consume power with the purpose to pump heat from a cold to a hot reservoir. In a reciprocating quantum heat engine, the working medium is a quantum system such as spin systems or a harmonic oscillator. The Carnot cycle and Otto cycle are

660-586: A key customer for the type, having placed a £3 million order for 20 aircraft in September 1948. Introducing the Ambassador to service in 1951, BEA often referred to the aircraft as the "Elizabethans", as the aircraft were used for the airline's "Elizabethan Class" passenger service. However, the type was quickly outperformed by the turboprop-powered Vickers Viscount , with BEA opting to withdraw its Ambassadors in 1958. Secondhand aircraft were operated by several other airlines, including Dan-Air and Northeast Airlines . Despite being produced in relatively small numbers,

726-540: A large number of unusual varieties of piston engines that have various claimed advantages, many of which see little if any current use: Ministry of Aircraft Production The Minister of Aircraft Production was, from 1940 to 1945, the British government minister at the Ministry of Aircraft Production, one of the specialised supply ministries set up by the British Government during World War II . It

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792-480: A month, with the number of heavy bombers – a priority – doubling to a monthly average of 458 by 1944. Production Efficiency Boards were established to monitor production and remove inefficiency with, in extreme cases, the ministry taking direct control of factories. Joint Production Committees were set up in each factory to aid an exchange of views between management and workers, with Cripps making over five hundred visits to factories in order to meet staff. Cripps left

858-403: A reciprocating engine is proportional to the volume of the combined pistons' displacement. A seal must be made between the sliding piston and the walls of the cylinder so that the high pressure gas above the piston does not leak past it and reduce the efficiency of the engine. This seal is usually provided by one or more piston rings . These are rings made of a hard metal, and are sprung into

924-484: A sequence of strokes that admit and remove gases to and from the cylinder. These operations are repeated cyclically and an engine is said to be 2-stroke , 4-stroke or 6-stroke depending on the number of strokes it takes to complete a cycle. The most common type is 4-stroke, which has following cycles. The reciprocating engine developed in Europe during the 18th century, first as the atmospheric engine then later as

990-414: A standard configuration, the Ambassador could accommodate up to 47 passengers; somewhat unusually, its passenger cabin could be either pressurised or not as the customer preferred. To reduce cabin noise levels, considerable effort went into soundproofing and general furnishings; Taylor described the Ambassador as being particularly quiet for a piston engine airliner, although also noting it could not equal

1056-433: Is inside a cylinder , into which a gas is introduced, either already under pressure (e.g. steam engine ), or heated inside the cylinder either by ignition of a fuel air mixture ( internal combustion engine ) or by contact with a hot heat exchanger in the cylinder ( Stirling engine ). The hot gases expand, pushing the piston to the bottom of the cylinder. This position is also known as the bottom dead center (BDC), or where

1122-586: Is not to be confused with fuel efficiency , since high efficiency often requires a lean fuel-air ratio, and thus lower power density. A modern high-performance car engine makes in excess of 75 kW/L (1.65 hp/in ). Reciprocating engines that are powered by compressed air, steam or other hot gases are still used in some applications such as to drive many modern torpedoes or as pollution-free motive power. Most steam-driven applications use steam turbines , which are more efficient than piston engines. The French-designed FlowAIR vehicles use compressed air stored in

1188-412: Is not true of every reciprocating engine), although power and fuel consumption are affected by many factors outside of engine displacement. Reciprocating engines can be characterized by their specific power , which is typically given in kilowatts per litre of engine displacement (in the U.S. also horsepower per cubic inch). The result offers an approximation of the peak power output of an engine. This

1254-807: Is on display at the Imperial War Museum , Duxford near Cambridge having undergone major restoration by the Duxford Aviation Society. The restoration was completed in April 2013 and the aircraft is presently part of the Duxford Collection. Data from Airspeed aircraft since 1931 , British Civil Aircraft since 1919 Volume 1 General characteristics Performance Aircraft of comparable role, configuration, and era Related lists Reciprocating engine There may be one or more pistons. Each piston

1320-394: Is the fictitious pressure which would produce the same amount of net work that was produced during the power stroke cycle. This is shown by: where A p {\displaystyle A_{p}} is the total piston area of the engine, S {\displaystyle S} is the stroke length of the pistons, and V d {\displaystyle V_{d}}

1386-459: Is the ratio of the diameter of the piston, or " bore ", to the length of travel within the cylinder, or "stroke". If this is around 1 the engine is said to be "square". If it is greater than 1, i.e. the bore is larger than the stroke, it is "oversquare". If it is less than 1, i.e. the stroke is larger than the bore, it is "undersquare". Cylinders may be aligned in line , in a V configuration , horizontally opposite each other, or radially around

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1452-425: Is the total displacement volume of the engine. Therefore: Whichever engine with the larger value of MEP produces more net work per cycle and performs more efficiently. In steam engines and internal combustion engines, valves are required to allow the entry and exit of gases at the correct times in the piston's cycle. These are worked by cams, eccentrics or cranks driven by the shaft of the engine. Early designs used

1518-423: Is then fed through one or more, increasingly larger bore cylinders successively, to extract power from the steam at increasingly lower pressures. These engines are called compound engines . Aside from looking at the power that the engine can produce, the mean effective pressure (MEP), can also be used in comparing the power output and performance of reciprocating engines of the same size. The mean effective pressure

1584-452: The D slide valve but this has been largely superseded by piston valve or poppet valve designs. In steam engines the point in the piston cycle at which the steam inlet valve closes is called the cutoff and this can often be controlled to adjust the torque supplied by the engine and improve efficiency. In some steam engines, the action of the valves can be replaced by an oscillating cylinder . Internal combustion engines operate through

1650-650: The Royal Jordanian Air Force , also procured Ambassadors for private purposes. The initial popularity of the Ambassador, with its pressurised cabin and good soundproofing , was soon eclipsed by the arrival of turboprop -powered aircraft such as the Vickers Viscount and, some years later, the Lockheed Electra , which featured more reliable engines and faster speeds. One Elizabethan, Christopher Marlowe ( G-ALZO , c/n 5226)

1716-572: The Type 2 . The British manufacturer Airspeed Ltd. was interested in this requirement and established a small design team to work on the project from a dispersed office in Fairmile Manor at Cobham in Surrey in 1943. This effort was headed by ex- de Havilland aeronautical engineer Arthur Hagg, who had joined the company earlier that year. Early concepts included an unpressurised aircraft in

1782-475: The steam engine . These were followed by the Stirling engine and internal combustion engine in the 19th century. Today the most common form of reciprocating engine is the internal combustion engine running on the combustion of petrol , diesel , liquefied petroleum gas (LPG) or compressed natural gas (CNG) and used to power motor vehicles and engine power plants . One notable reciprocating engine from

1848-501: The 14.5- ton gross weight class to be powered by a pair of Bristol Hercules radial engines . Work on the endeavour was taken as far as possible without impacting Airspeed's wartime production activity, as the Second World War was still raging. In response to changes in planner's preferences, dictating that the interim aircraft be procured so that airliners such as the in-development Ambassador had more development time, thus

1914-586: The Air Ministry, interaction was informal, characterised by personal intervention, crisis management and application of willpower to improve output. "Few records were kept, the functions of most individuals were left undefined and business was conducted mainly over the telephone". One important change made within days of the creation of the ministry was it taking over the RAF 's storage units and Maintenance Units which were found to have accepted 1,000 aircraft from

1980-432: The Ambassador commenced during 1950, leading to the first production standard aircraft, destined for BEA, performing its first flight on 12 January 1951. The Airspeed Ambassador was an all-metal twin-engine airliner, designed to serve short-to-medium haul routes. It was relatively advanced for the era, being relatively aerodynamically clean, having a high aspect–ratio wing with hoped-for near- Laminar flow characteristics,

2046-464: The Ambassador was designed to accommodate four Napier Nomad turbo-compound engines , a then-recent innovation. Its fuselage was compatible with pressurisation , this being an optional feature offered to customers. On 10 July 1947, the first prototype Ambassador conducted its maiden flight at Christchurch with chief test pilot George Errington at the controls; a total of three prototypes were built. Early on, British European Airways (BEA) emerged as

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2112-463: The Ambassador was operational for longer than had been anticipated by planners. The origins of the Ambassador can be traced to 1943 and the work of the Brabazon Committee , which sought to define what types of aircraft would be desired by the postwar civil aviation sector. One of the committee's recommendations was a twin-engined short-to-medium-haul replacement for the Douglas DC-3 , known as

2178-511: The Ambassador were being conducted by a joint team of Airspeed and BEA employees, while official BEA training commenced in August of that year. The flagship of BEA's fleet was G-ALZN , appropriately named "RMA Elizabethan". The first "Elizabethan" scheduled flight was from Heathrow Airport to Paris Le Bourget on 13 March 1952, soon the type was used across BEA's main UK routes. According to Taylor,

2244-589: The Ambassador's performance gave BEA a competitive edge over its rivals. By December 1955, the "Elizabethan Class" had reached 2,230 flying hours annually, per aircraft, the highest in BEA's fleet. However, the rival Vickers Viscount , which was introduced in 1953, was even more popular with BEA's passengers than the Ambassador. Rival airlines, such as Air France , had also quickly introduced the Viscount, and thus held an advantage over BEA's Elizabethan service. Accordingly,

2310-489: The World War II era was the 28-cylinder, 3,500  hp (2,600 kW) Pratt & Whitney R-4360 Wasp Major radial engine. It powered the last generation of large piston-engined planes before jet engines and turboprops took over from 1944 onward. It had a total engine capacity of 71.5 L (4,360 cu in), and a high power-to-weight ratio . The largest reciprocating engine in production at present, but not

2376-458: The adoption of the new turbopropeller engines. By the end of 1945, work had commenced on building structural test sections and jigs . On 10 July 1947, the first prototype, registered G-AGUA , conducted the type's maiden flight , flown by chief test pilot George B.S. Errington. After the generally successful first flight, the prototype underwent a month of alterations, including deleting the spring tab and replacing it with geared tabs fitted to

2442-578: The aircraft programmes set bore little relation to expected aircraft production. Beaverbrook deliberately inserted an extra margin of 15 per cent over and above the very best that British industry could be expected to produce. The extra margin was added to provide an out-of-reach target to British industry so that it would push as hard as possible to increase production. The ministry was characterised by, for its time, highly unorthodox methods of management, including its initial location at Beaverbrook's home, Stornoway House . Personnel were recruited from outside

2508-551: The airline decided to withdraw the type despite its relative youth, with BEA's final scheduled Ambassador flight on 30 July 1958. There were no further sales of the Ambassador. Aviation authors Bill Gunston and Peter Masefield laid this lack of success largely upon attitudes within de Havilland 's management following its takeover of Airspeed in 1951; they allegedly preferred to use Airspeed's factory at Christchurch Airfield to produce military jets designed by de Havilland. One example of de Havilland's undermining of potential sales

2574-477: The crankshaft. Opposed-piston engines put two pistons working at opposite ends of the same cylinder and this has been extended into triangular arrangements such as the Napier Deltic . Some designs have set the cylinders in motion around the shaft, such as the rotary engine . In some steam engines, the cylinders may be of varying size with the smallest bore cylinder working the highest pressure steam. This

2640-512: The cylinder by this stroke . The exception is the Stirling engine , which repeatedly heats and cools the same sealed quantity of gas. The stroke is simply the distance between the TDC and the BDC, or the greatest distance that the piston can travel in one direction. In some designs the piston may be powered in both directions in the cylinder, in which case it is said to be double-acting . In most types,

2706-474: The department. Fraser, whose pre-war career had been with Imperial Chemical Industries , was first appointed director-general of equipment production, before moving to the aircraft production post, which he held throughout the rest of the war. In 1945, Ben Lockspeiser was appointed director-general. The first minister, Lord Beaverbrook, pushed for aircraft production to have priority for raw materials over virtually all other types of munitions production. This

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2772-646: The design was revised substantially to expand its capacity. By 1944, it was a considerably larger design than the DC-3, with improved comfort and space. While Airspeed's management believed that postwar demands would demand greater passenger capacities, several figures, including those within the British Overseas Airways Corporation (BOAC) and the Air Ministry , were less enthusiastic with their projections. The company also promoted

2838-475: The economics of higher utilisation rates and elevated cruise speeds, whereas conventional wisdom amongst airlines was to avoid increasing speeds to reduce fuel consumption. For the Ambassador, Airspeed opted to pursue a cruising altitude of 20,000 ft, relatively high for the era. A comprehensive mockup was completed by November 1944, largely for promotional purposes, while the projected operating cost figures were released during early 1945. Immediately following

2904-662: The end of April 1941. He was succeeded by John Moore-Brabazon , who was replaced in February 1942 by John Llewellin , who served until November 1942. Sir Stafford Cripps became the Minister of Aircraft Production on 22 November 1942, serving for two and a half years until the end of the war in Europe. He made a number of changes, including replacing unrealistic production targets, deliberately set too high to encourage effort, with realistic forecasts for each type of aircraft. Production levels were maintained at over 2,000 aircraft

2970-582: The end of the conflict, the British Ministry of Aircraft Production placed an order with the company to produce a pair of prototypes . While the first prototype was to be un pressurised and powered by a pair of Bristol Centaurus radial engines , it was envisioned that the second prototype would feature a reinforced fuselage compatible with pressurisation and a wing that could accommodate four Napier Nomad turboprop engines. Several officials, including company chairman Alan Samuel Butler , favored

3036-518: The gills were reinstated. Engine-out climb performance was enhanced by being able to feather the propeller using a zero-torque signal from the engine. During 1952, British European Airways (BEA) introduced the first of its 20 strong fleet of Ambassadors to revenue service, the airline referred to them as the "Elizabethan Class" in honour of the newly crowned Queen Elizabeth II . The planned 1951 introduction date had been pushed to 1952 to address development issues. By May 1951, intense proving trials of

3102-462: The industry but issued only 650 to squadrons. These management and organisational changes bore results almost immediately; in the first four months of 1940, 2,729 aircraft were produced of which 638 were fighters, while in the following four months crucial to the Battle of Britain during May to August 1940, production rose to 4,578 aircraft, of which 1,875 were fighters. This production rate achieved

3168-604: The largest ever built, is the Wärtsilä-Sulzer RTA96-C turbocharged two-stroke diesel engine of 2006 built by Wärtsilä . It is used to power the largest modern container ships such as the Emma Mærsk . It is five stories high (13.5 m or 44 ft), 27 m (89 ft) long, and weighs over 2,300 metric tons (2,535 short tons ; 2,264 long tons ) in its largest 14 cylinders version producing more than 84.42 MW (113,209 bhp). Each cylinder has

3234-416: The linear movement of the piston is converted to a rotating movement via a connecting rod and a crankshaft or by a swashplate or other suitable mechanism. A flywheel is often used to ensure smooth rotation or to store energy to carry the engine through an un-powered part of the cycle. The more cylinders a reciprocating engine has, generally, the more vibration-free (smoothly) it can operate. The power of

3300-418: The lower noise levels of turboprop -powered airliners such as the Vickers Viscount . It was typically powered by conventional Bristol Centaurus radial engines , although individual aircraft were reengined with various powerplants, including turboprops. To increase cruise performance, designers made great efforts to minimise drag , using a NACA laminar-flow wing section. The predicted low-drag performance

3366-410: The ones most studied. The quantum versions obey the laws of thermodynamics . In addition, these models can justify the assumptions of endoreversible thermodynamics . A theoretical study has shown that it is possible and practical to build a reciprocating engine that is composed of a single oscillating atom. This is an area for future research and could have applications in nanotechnology . There are

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3432-421: The only aircraft in history to perform such an aerial display with one engine out throughout. This was a deliberate choice, with the inactive engine's propeller being feathered prior to taking off and remaining so until after landing. The first prototype performed the majority of flight testing through late 1948. A total of three prototypes were constructed for the test programme. The second Ambassador, G-AKRD ,

3498-472: The outer rudders and locking the inner rudder; reversible propellers were also installed. During September 1947, the prototype made its first public display alongside elements of the second prototype, including its cockpit and control system, at the Society of British Aircraft Constructors (SBAC) show at Radlett . On 22 November 1947, the programme received a setback when the prototype was forced to perform

3564-482: The personal direction of the Minister, for a time it operated from his private home. The initial Chief Executive of the Ministry was Air Chief Marshal Sir Wilfrid Freeman , who left after frustrations with Lord Beaverbrook's working methods but returned in October 1942 and served until 1945. The Director-General of Aircraft Production from April 1943 was Eric Fraser , who remained the most senior non-elected figure in

3630-423: The piston forms the largest volume in the cylinder. The piston is returned to the cylinder top (top dead center) (TDC) by a flywheel , the power from other pistons connected to the same shaft or (in a double acting cylinder ) by the same process acting on the other side of the piston. This is where the piston forms the smallest volume in the cylinder. In most types the expanded or " exhausted " gases are removed from

3696-533: The type's disposal by BEA, secondhand Ambassadors helped to establish the scheduled and charter flight operations of Dan-Air , an important airline in the development of the package holiday . The type was also used in the UK by Autair and BKS Air Transport . Secondhand Ambassadors were also flown for short periods by other airlines including Butler Air Transport (Australia), Globe Air (Switzerland) and Norrønafly (Norway). Multiple entities, such as Royal Dutch Shell and

3762-622: Was a headquarters in London and twelve regions, each with a controller and resident Ministry representatives in most of the larger factories. The department was formed in May 1940 by the Prime Minister, Winston Churchill , to produce large numbers of aircraft to fight the Battle of Britain . The first minister was Lord Beaverbrook ; under his control the Ministry presided over an enormous increase in British aircraft production. Initially under

3828-455: Was close to cancelling development of the Viscount over fears that airlines held a preference for advanced piston-powered airliners over the unfamiliar turboprop. During flight testing, it was found that the aircraft possessed particularly favourable low speed characteristics. Having been explored in depth beforehand, this was dramatically displayed at the 1948 Farnborough Airshow , becoming

3894-473: Was initially used for BEA proving trials, and in 1955 it also supported the development trials of the Napier Eland turbine engine. During 1958, intensive simulated airline flying, to pave the way for BEA Vanguards, was performed using two Tyne-powered Ambassadors. During the latter stage of development, some issues were uncovered. The wing, which had been designed to induce laminar flow characteristics,

3960-477: Was needed in the summer and autumn of 1940 but it distorted the supply system of the war economy . It eventually came to be replaced by a quota system , with each supply ministry being allocated a certain amount of raw materials imports to be distributed amongst various projects within the ministries' purviews. Beaverbrook continued to push hard for increases in aircraft production until he left to become Minister of Supply . Controversially, under Beaverbrook's tenure

4026-411: Was not completely realized, however, due to structural features for wing construction, propeller slipstream over the inner wing, and increased skin roughness in actual service conditions. The engine nacelles were initially designed with inwardly-opening louvres for exhaust gases and cooling air rather than the usual outwardly opening "gills". However, these proved inadequate for cooling the engine, thus

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4092-503: Was relatively unconventional in its design; testing revealed that it lacked sufficient strength, and redesigning the wing was not straightforward. Technical assistance was provided by de Havilland and the issue was proven to be resolved in December 1949. Three minor accidents during demonstration flights, while causing no serious damage, often delayed testing and did not inspire confidence amongst potential customers. Quantity production of

4158-545: Was responsible for aircraft production for the British forces, primarily the Royal Air Force , but also the Fleet Air Arm . During the war, British aircraft production quickly expanded to be the largest industry in the country, involving hundreds of private firms and employing nearly two million workers. The Ministry was set up to co-ordinate the activity of this industry to maximise aircraft production. There

4224-610: Was the first to feature pressurisation and was equipped with a full passenger cabin configuration for demonstration flights. This second prototype was subsequently used by the Bristol Aeroplane Company from 1953 for flight-testing the Bristol Proteus 705 turbine engine. From March 1958, it was used by Rolls-Royce for testing the Dart and Tyne turboprops. The third prototype and first Ambassador 2 G-ALFR

4290-491: Was the recall of the Sales Director to de Havilland's headquarters at Hatfield Aerodrome ( Hertfordshire , England) from Australia, despite his reportedly being near to finalizing an order from Trans-Australia Airlines for 12 Ambassadors. Taylor observed that prospective customers were often sceptical that Airspeed, being a relatively small company, could be relied upon for technical support and components. Following

4356-461: Was two and a half times German fighter production and the ministry repaired and returned to service nearly 1,900 aircraft. The result of this effort and management style was that while the number of German fighters available for operations over England fell from 725 to 275, the RAF's complement rose from 644 at the beginning of July 1940 to 732 at the beginning of October. Beaverbrook left the ministry at

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