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85-449: The Vickers Vanguard was a short/medium-range turboprop airliner designed and produced by the British aircraft manufacturer Vickers-Armstrongs . The Vanguard was developed during the mid-to-late 1950s in response to a specification issued by British European Airways (BEA) for a 100-seat airliner; Vickers decided to design such an airliner as a follow-up to the existing Viscount series,

170-400: A Pratt & Whitney Canada PT6 , and an under-speed governor on a Honeywell TPE331 . The turboprop is also distinguished from other kinds of turbine engine in that the fuel control unit is connected to the governor to help dictate power. To make the engine more compact, reverse airflow can be used. On a reverse-flow turboprop engine, the compressor intake is at the aft of the engine, and

255-637: A hot air balloon flight from Dover to France near Calais . It was flown by Jean-Pierre Blanchard and John Jeffries . The letter was written by an American Loyalist William Franklin to his son William Temple Franklin who was serving in a diplomatic role in Paris with his grandfather Benjamin Franklin . During the first aerial flight in North America by balloon on January 9, 1793, from Philadelphia to Deptford, New Jersey , Jean-Pierre Blanchard carried

340-424: A propelling nozzle . Air enters the intake and is compressed by the compressor. Fuel is then added to the compressed air in the combustor, where the fuel-air mixture then combusts . The hot combustion gases expand through the turbine stages, generating power at the point of exhaust. Some of the power generated by the turbine is used to drive the compressor and electric generator . The gases are then exhausted from

425-505: A Viscount-like airliner capable of servicing its transcontinental routes while carrying up to 60 passengers. Recognising the potential to fulfil both airlines' requirements in a single airliner, Vickers' design team commenced work on producing such an aircraft. Vicker's initial proposal, known as the Type 870 or alternatively as the Viscount Major , was incapable of meeting BEA's criteria, and

510-460: A bombing raid. In 1941, the engine was abandoned due to war, and the factory converted to conventional engine production. The first mention of turboprop engines in the general public press was in the February 1944 issue of the British aviation publication Flight , which included a detailed cutaway drawing of what a possible future turboprop engine could look like. The drawing was very close to what

595-540: A follow-on order for three more aircraft, it would be, measured in dollar worth, the largest single export deal in postwar Britain's history at that time. The launch of the programme commenced immediately following BEA's initial order for the type. Due to the substantial growth of the airliner during the concept phase, engine supplier Rolls-Royce set about scaling up the Tyne engine from its initial output of 2,750 hp (2,000 kW) to at least 4,000 hp (3,000 kW). As

680-561: A freighter configuration, calling it the Cargoliner . Considered to be a success, the majority of Vanguards were converted into freighters during the early 1970s, those from BEA becoming the Merchantman . As a freighter, the type remained in service for many years, the final example being retired in 1996. The origins of the Vanguard can be traced back to speculative discussions between Vickers and

765-442: A governor, and overspeed governor, and a fuel-topping governor. The governor works in much the same way a reciprocating engine propeller governor works, though a turboprop governor may incorporate beta control valve or beta lift rod for beta operation and is typically located in the 12 o'clock position. There are also other governors that are included in addition depending on the model, such as an overspeed and fuel topping governor on

850-457: A letter to Vickers; these criteria included a cruise speed of 370 knots (430 mph; 690 km/h), a standard range of 1,000 miles (1,600 km), with 305 miles (490 km) in reserve fuel, the ability to accommodate up to 100 passengers, and an explicit preference for a high-wing configuration. Coincidentally, another airline, Trans-Canada Air Lines (TCA), also made contact with the manufacturer with its own list of requirements, calling for

935-443: A low-mounted wing following the adoption of a double-bubble fuselage. This type of fuselage was necessary because of the large proportion of freight which BEA needed to carry. It was considered by Vickers to be impractical if carried at the same level as the passengers due to the excessive length that would be required, but carrying the freight in a lengthy hold beneath the main cabin was a practical arrangement. Furthermore, TCA wanted

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1020-405: A low-mounted wing, which would make the aircraft easier to refuel, de-ice and service, as well as giving a statistically significant improvement in survival in the event of a water landing. By 13 April 1955, the range of design studies had been shortlisted down to five, these remaining concepts were jointly evaluated by BEA and Vickers. Of these submissions, it was recognised that the combination of

1105-410: A mode typically consisting of zero to negative thrust, is used for all ground operations aside from takeoff. The Beta mode is further broken down into 2 additional modes, Beta for taxi and Beta plus power. Beta for taxi as the name implies is used for taxi operations and consists of all pitch ranges from the lowest alpha range pitch, all the way down to zero pitch, producing very little to zero-thrust and

1190-469: A monologue by a veteran pilot, preserving the atmosphere of these pioneering times: "We used to fly on the Paris route, from Hounslow to Le Bourget and get through as best as you could. Later we moved on to Croydon . (...) We carried the much advertised Air Mails. That meant the machines had to fly whether there were passengers to be carried or not. It was left to the discretion of the pilot whether or not

1275-452: A more powerful engine, which led to the adoption of the newly-developed Rolls-Royce Tyne engine. This powerplant was capable of generating a nominal 4,000 hp (3,000 kW), in comparison to the Viscount's Rolls-Royce Dart of about 1,700 hp (1,300 kW). The Tyne engine enabled the Vanguard to be operated at a substantially greater service ceiling and cruising speed. The Vanguard

1360-565: A personal letter from George Washington to be delivered to the owner of whatever property Blanchard happened to land on, making the flight the first delivery of air mail in the United States. The first official air mail delivery in the United States took place on August 17, 1859, when John Wise piloted a balloon starting in Lafayette, Indiana , with a destination of New York . Weather issues forced him to land near Crawfordsville, Indiana , and

1445-422: A range of 2,600 miles (4,200 km) so that the airliner would be acceptable to TCA as well. The Type 900 was a further revision of the design, featuring an expanded payload capacity of 21,000 lb (9,500 kg) and carry up to 93 passengers. Following some relatively minor revisions, which largely bolstered the gross weight upwards, that were made to better suit the design to the needs of global customers,

1530-581: A small amount of air by a large degree, a low disc loading (thrust per unit disc area) increases the aircraft's energy efficiency , and this reduces the fuel use. Propellers work well until the flight speed of the aircraft is high enough that the airflow past the blade tips reaches the speed of sound. Beyond that speed, the proportion of the power that drives the propeller that is converted to propeller thrust falls dramatically. For this reason turboprop engines are not commonly used on aircraft that fly faster than 0.6–0.7 Mach , with some exceptions such as

1615-455: A specific kind of airmail letter which is its own envelope; see aerogram . Some forms of airletter, such as aerogram , may forbid enclosure of other material so as to keep the weight down. The choice to send a letter by air is indicated either by a handwritten note on the envelope , by the use of special labels called airmail etiquettes (blue stickers with the words "air mail" in French and in

1700-575: A test-bed not intended for production. It first flew on 20 September 1945. From their experience with the Trent, Rolls-Royce developed the Rolls-Royce Clyde , the first turboprop engine to receive a type certificate for military and civil use, and the Dart , which became one of the most reliable turboprop engines ever built. Dart production continued for more than fifty years. The Dart-powered Vickers Viscount

1785-406: A turboprop counterpart. It was around this time that Vickers' design team also discarded notions of adopting a swept wing , largely due to its providing little benefit at the envisioned airliner's 350-knot (400 mph; 640 km/h) cruise speed, as well as its inferior performance during the approach stage of flight. Despite BEA's initial preference for a high-mounted wing, the company opted for

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1870-485: Is coupled to the turbine through a reduction gear that converts the high RPM /low torque output to low RPM/high torque. This can be of two primary designs, free-turbine and fixed. A free-turbine turboshaft found on the Pratt & Whitney Canada PT6 , where the gas generator is not connected to the propeller. This allows for propeller strike or similar damage to occur without damaging the gas generator and allowing for only

1955-421: Is different from nominal airmail in its branding, price, and priority of service. Specific instances of a letter being delivered by air long predate the introduction of Airmail as a regularly scheduled service available to the general public. Although homing pigeons had long been used to send messages (an activity known as pigeon mail ), the first mail to be carried by an air vehicle was on January 7, 1785, on

2040-407: Is that it can also be used to generate reverse thrust to reduce stopping distance on the runway. Additionally, in the event of an engine failure, the propeller can be feathered , thus minimizing the drag of the non-functioning propeller. While the power turbine may be integral with the gas generator section, many turboprops today feature a free power turbine on a separate coaxial shaft. This enables

2125-421: Is typically accessed by moving the power lever to a beta for taxi range. Beta plus power is a reverse range and produces negative thrust, often used for landing on short runways where the aircraft would need to rapidly slow down, as well as backing operations and is accessed by moving the power lever below the beta for taxi range. Due to the pilot not being able to see out of the rear of the aircraft for backing and

2210-500: Is unavailable. It is usually impossible to know this by examining an envelope, and such items are not considered "airmail." Generally, airmail would take a guaranteed and scheduled flight and arrive first, while air-speeded mail would wait for a non-guaranteed and merely available flight and would arrive later than normal airmail. A letter sent via airmail may be called an aerogramme , aerogram , air letter or simply airmail letter . However, aerogramme and aerogram may also refer to

2295-638: The Bombay-Calcutta line to the exhibition. The letters bore an official frank "First Aerial Post, U.P. Exhibition, Allahabad. 1911". The aircraft used was a Humber-Sommer biplane , and it made the journey in thirteen minutes. The first official American airmail delivery was made on September 23, 1911, by pilot Earle Ovington under the authority of the United States Post Office Department . The first official air mail in Australia

2380-635: The London suburb of Hendon , North London , and the Postmaster General 's office in Windsor, Berkshire , on September 9, 1911, as part of the celebrations for King George V 's coronation and at the suggestion of Sir Walter Windham , who based his proposal on the successful experiment he had overseen in India. The service ran for just under a month, transporting 35 bags of mail in 16 flights; four pilots operated

2465-571: The Middle East . On 25 December 1918, the Latécoère Airlines (later becoming the famed Aéropostale ) became the first civilian international airmail service, when mail was flown from Toulouse , France, to Barcelona , Spain. Less than 2 months later, on 19 February 1919, the airmail service was extended to Casablanca , Morocco, making the Latécoère Airlines the first transcontinental airmail service. In June 1919, Alcock and Brown completed

2550-616: The P-3 Orion , and the C-130 Hercules military transport aircraft. The first turbine-powered, shaft-driven helicopter was the Kaman K-225 , a development of Charles Kaman 's K-125 synchropter , which used a Boeing T50 turboshaft engine to power it on 11 December 1951. December 1963 saw the first delivery of Pratt & Whitney Canada's PT6 turboprop engine for the then Beechcraft 87, soon to become Beechcraft King Air . 1964 saw

2635-830: The Piper Meridian , Socata TBM , Pilatus PC-12 , Piaggio P.180 Avanti , Beechcraft King Air and Super King Air . In April 2017, there were 14,311 business turboprops in the worldwide fleet. Between 2012 and 2016, the ATSB observed 417 events with turboprop aircraft, 83 per year, over 1.4 million flight hours: 2.2 per 10,000 hours. Three were "high risk" involving engine malfunction and unplanned landing in single‑engine Cessna 208 Caravans , four "medium risk" and 96% "low risk". Two occurrences resulted in minor injuries due to engine malfunction and terrain collision in agricultural aircraft and five accidents involved aerial work: four in agriculture and one in an air ambulance . Jane's All

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2720-580: The Royal Air Force pioneered the first scheduled international airmail service between Folkestone, Kent and Cologne, Germany . The service operated between December 1918 and mid-1919; its purpose was to provide troops of the British Army stationed in Germany with a fast mail service. (see more at British Forces Post Office ) Throughout the 1920s the Royal Air Force continued to develop air routes through

2805-590: The Tupolev Tu-114 can reach 470 kn (870 km/h; 540 mph). Large military aircraft , like the Tupolev Tu-95 , and civil aircraft , such as the Lockheed L-188 Electra , were also turboprop powered. The Airbus A400M is powered by four Europrop TP400 engines, which are the second most powerful turboprop engines ever produced, after the 11 MW (15,000 hp) Kuznetsov NK-12 . In 2017,

2890-403: The Tupolev Tu-95 . However, propfan engines, which are very similar to turboprop engines, can cruise at flight speeds approaching 0.75 Mach. To maintain propeller efficiency across a wide range of airspeeds, turboprops use constant-speed (variable-pitch) propellers. The blades of a constant-speed propeller increase their pitch as aircraft speed increases. Another benefit of this type of propeller

2975-457: The aeroplane generated immediate interest in using them for mail transport. An unofficial airmail flight was conducted by Fred Wiseman, who carried three letters between Petaluma and Santa Rosa , California, on February 17, 1911. The world's first official airmail flight came the next day, at a large exhibition in the United Provinces of Agra and Oudh , British India . The organizer of

3060-587: The pilot would sign them as well. The first stamps designated specifically for airmail were issued by Italy in 1917, and used on experimental flights; they were produced by overprinting special delivery stamps. Austria also overprinted stamps for airmail in March 1918, soon followed by the first definitive stamp for airmail, issued by the United States in May 1918. A postal service may sometimes opt to transport some regular mail by air, perhaps because other transportation

3145-519: The Soviet Union had the technology to create the airframe for a jet-powered strategic bomber comparable to Boeing's B-52 Stratofortress , they instead produced the Tupolev Tu-95 Bear, powered with four Kuznetsov NK-12 turboprops, mated to eight contra-rotating propellers (two per nacelle) with supersonic tip speeds to achieve maximum cruise speeds in excess of 575 mph, faster than many of

3230-417: The Vanguard's production line was coming online at Vickers' Weybridge facility, BEA recognised that, due to the typically short length of its routes, a higher density economy seating configuration could be adopted without impacting performance. Accordingly, on 23 July 1957, Vickers announced a new model, the Type 953 , which could handle payloads of up to 29,000 lb (13,000 kg), which greatly improved

3315-486: The Vanguard's specifics. The Vanguard was brought into revenue service on 17 December 1960, around the same time as the commercial availability of a new generation of jet-powered airliners; as a result, these competitors quickly overshadowed its performance and led to the type being largely ignored by the market. Only 44 aircraft were ever built, the type having been ordered by BEA and TCA. After only about ten years' service, TCA experimentally converted one of its Vanguards to

3400-408: The Viscount, while also being considerably faster throughout all operational stages. Out of BEA's internal analysis of various options, which studied both turboprop and pure jet propulsion arrangements, it became clear that a larger aircraft that could accommodate bigger payloads was highly desirable. On 19 April 1953, BEA's chief executive, Peter Masefield , outlined the company's requirements in

3485-580: The World's Aircraft . 2005–2006. Air mail For about the first half century of its existence, transportation of mail via aircraft was usually categorized and sold as a separate service (airmail) from surface mail. Today it is often the case that mail service is categorized and sold according to transit time alone, with mode of transport (land, sea, air) being decided on the back end in dynamic intermodal combinations. Thus even "regular" mail may make part of its journey on an aircraft. Such "air-speeded" mail

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3570-420: The additional expansion in the turbine system, the residual energy in the exhaust jet is low. Consequently, the exhaust jet produces about 10% of the total thrust. A higher proportion of the thrust comes from the propeller at low speeds and less at higher speeds. Turboprops have bypass ratios of 50–100, although the propulsion airflow is less clearly defined for propellers than for fans. The propeller

3655-456: The aircraft including Gustav Hamel , who flew the first service in his Blériot , covering the 21 miles between Hendon and Windsor in just 18 minutes. The service was eventually terminated due to constant and severe delays caused by bad weather conditions. Similar services were intermittently run in other countries before the war , including in Germany , France and Japan , where airmail provision

3740-583: The aircraft, registered G-APEP , to Brooklands Museum on 17 October 1996. These airlines operated the Vickers Vanguard: ♠ original operators Data from Vickers Aircraft since 1908 General characteristics Performance Related development Aircraft of comparable role, configuration, and era Turboprop A turboprop is a turbine engine that drives an aircraft propeller . A turboprop consists of an intake , reduction gearbox , compressor , combustor , turbine , and

3825-408: The airline British European Airways (BEA) conducted as early as 1953, the same year in which the commercially successful Vickers Viscount airliner first entered revenue service. Even at this early stage, the two firms had envisioned the introduction of a successor to the Viscount entering service around 1959. This envisioned successor airliner would possess economics 10 per cent greater than those of

3910-414: The amount of debris reverse stirs up, manufacturers will often limit the speeds beta plus power may be used and restrict its use on unimproved runways. Feathering of these propellers is performed by the propeller control lever. The constant-speed propeller is distinguished from the reciprocating engine constant-speed propeller by the control system. The turboprop system consists of 3 propeller governors ,

3995-474: The aviation display, Sir Walter Windham , was able to secure permission from the postmaster general in India to operate an airmail service in order to generate publicity for the exhibition and to raise money for charity. Mail from people across the region was gathered in at Holy Trinity Church and the first airmail flight was piloted by Henri Pequet , who flew 6,500 letters a distance of 13 km (8.1 mi) from Allahabad to Naini —the nearest station on

4080-450: The basic model not entirely fulfilling its requirements, such as the level of capacity for air mail . Vickers recognised that a high-density seating configuration, accommodating up to 139 passengers to be carried, would likely be attractive to more operators, and designed the Type 952 model for this market. Following a particularly vigorous evaluation, during early January 1957, TCA announced that it had placed an order for 20 Type 952s. With

4165-453: The definitive Type 950 proposal emerged. On 20 July 1960, BEA placed an initial order for 20 Type 950s, the type becoming subsequently known as the Vanguard ; the airline publicly announced the order and its intended plan for the new airliner to succeed the Viscount in its fleet. At the time, TCA was, while intensely interested in the airliner, not yet willing to commit itself, partially due to

4250-407: The exhaust is situated forward, reducing the distance between the turbine and the propeller. Unlike the small-diameter fans used in turbofan engines, the propeller has a large diameter that lets it accelerate a large volume of air. This permits a lower airstream velocity for a given amount of thrust. Since it is more efficient at low speeds to accelerate a large amount of air by a small degree than

4335-493: The first jet aircraft and comparable to jet cruising speeds for most missions. The Bear would serve as their most successful long-range combat and surveillance aircraft and symbol of Soviet power projection through to the end of the 20th century. The USA used turboprop engines with contra-rotating propellers, such as the Allison T40 , on some experimental aircraft during the 1950s. The T40-powered Convair R3Y Tradewind flying-boat

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4420-546: The first deliveries of the Garrett AiResearch TPE331 , (now owned by Honeywell Aerospace ) on the Mitsubishi MU-2 , making it the fastest turboprop aircraft for that year. In contrast to turbofans , turboprops are most efficient at flight speeds below 725 km/h (450 mph; 390 knots) because the jet velocity of the propeller (and exhaust) is relatively low. Modern turboprop airliners operate at nearly

4505-455: The first transatlantic airmail flight. The first airmail service established officially by an airline occurred in Colombia , South America, on 19 October 1920. Scadta , the first airline of the country, flew landing river by river delivering mail in its destinations. Australia's first airmail contract was awarded to Norman (later Sir) Brearley's Western Australian Airlines (WAA). The first airmail

4590-537: The flight should be cancelled in bad weather; the pilots were dead keen on flying in the most impossible conditions. Sanderson got killed this way at Douinville. And all he had in the machine was a couple of picture postcards from trippers in Paris, sent to their families as a curiosity. That was the Air Mail. No passengers or anything—just the mail". In the aftermath of the war, the Royal Engineers (Postal Section) and

4675-458: The future Rolls-Royce Trent would look like. The first British turboprop engine was the Rolls-Royce RB.50 Trent , a converted Derwent II fitted with reduction gear and a Rotol 7 ft 11 in (2.41 m) five-bladed propeller. Two Trents were fitted to Gloster Meteor EE227 — the sole "Trent-Meteor" — which thus became the world's first turboprop-powered aircraft to fly, albeit as

4760-452: The larger upper portion was a more spacious interior, along with an increase in cargo capacity below the floor of the main cabin. A low-mounted straight wing was also adopted for the type, despite considerations towards shoulder-mounted and swept-wing alternatives. Aviation author C. F. Andrews observed the design to be orthodox in practically every respect. The Vanguard's larger and heavier fuselage presented an obvious need to be combined with

4845-594: The last BA passenger flight with the type was on 16 June 1974. TCA initiated Vanguard schedules on 1 February 1961 with two flights from Toronto and Montreal via intermediate stops to Vancouver. The fleet was also used on services from Toronto and Montreal to New York and Nassau, Bahamas. Tyne engine reliability was a concern to the airline in the early 1960s. It had a Constellation on stand-by at Dorval Airport in Montreal and at Toronto to take Vanguard passengers in case an engine failed to start. In 1966, Air Canada removed all

4930-404: The last weeks of trials with BEA in early 1960 uncovered some engine-related difficulties, necessitating a brief delay while the compressor rotor was modified. With the issue resolved, the Vanguard entered revenue service with TCA on 1 February 1961, and with BEA one month later. However, by the time of the Vanguard's entry to service, the attitudes of the travelling public had shifted in favour of

5015-551: The low-mounted wing and the double-bubble fuselage represented the optimum configuration, having offered the best capacity and versatility amongst other attributes. This conceptual aircraft, referred to as the Type 870 Scheme 16a , could accommodate 88 passengers, a cruising speed of 360 knots (420 mph; 680 km/h) at 25,000 ft (7,600 m), and payload of 20,000 lb (9,100 kg). While BEA were interested in relatively short, sub-1000 mile, routes, its fuel tanks were progressively enlarged over several revisions to give

5100-569: The mail reached its final destination via train. In 1959, the U.S. Postal Service issued a 7 cent stamp commemorating the event. Balloons also carried mail out of Paris and Metz during the Franco-Prussian War (1870), drifting over the heads of the Germans besieging those cities. Balloon mail was also carried on an 1877 flight in Nashville, Tennessee . Starting in 1903 the introduction of

5185-657: The most widespread turboprop airliners in service were the ATR 42 / 72 (950 aircraft), Bombardier Q400 (506), De Havilland Canada Dash 8 -100/200/300 (374), Beechcraft 1900 (328), de Havilland Canada DHC-6 Twin Otter (270), Saab 340 (225). Less widespread and older airliners include the BAe Jetstream 31 , Embraer EMB 120 Brasilia , Fairchild Swearingen Metroliner , Dornier 328 , Saab 2000 , Xian MA60 , MA600 and MA700 , Fokker 27 and 50 . Turboprop business aircraft include

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5270-443: The new bypass jet engines which did not use propellers. Passengers typically preferred the additional speed, even at the disadvantage of greater operating costs and thus higher ticket prices, that came with jet-powered airliners. As such, the turboprop-powered Vanguard did not sell well, although those examples that were introduced typically performed well in numerous capacities, and often had lengthy service lives. The Vickers Vanguard

5355-823: The onboard electrical systems were a major advance over the previous generation of airliners; amongst other capabilities, the engines could be started without the aid of a ground support cart. The Vanguard possessed relatively docile stall characteristics, in part due to the dihedral positioning of its horizontal stabiliser, which kept it clear of the jet efflux from the engines and aided longitudinal stability. However, acceptable stalling behaviour only came after an extensive programme of over 2,000 stalls to correct initial very violent tendencies which included rolling inverted. The Vanguard entered service with BEA and TCA in late 1960. BEA operated its first Vanguard schedule on 17 December from Heathrow to Paris. Following delivery of its full fleet of six V951 and 14 V953 aircraft by 30 March 1962,

5440-554: The operating costs for BEA's preferred model; the airline quickly converted its order to six Type 951s and 14 Type 953s. On 20 January 1959, the first Type 950 prototype G-AOYW conducted its maiden flight . The flight, a transfer to Wisley three miles away, had been planned for December but the engines were returned to Rolls-Royce for minor work. Proper flight testing was then carried out from Wisley. While development proceeded relatively smoothly, apart from over 2,000 flights being required to resolve unacceptable stalling characteristics,

5525-485: The power section (turbine and gearbox) to be removed and replaced in such an event, and also allows for less stress on the start during engine ground starts. Whereas a fixed shaft has the gearbox and gas generator connected, such as on the Honeywell TPE331 . The propeller itself is normally a constant-speed (variable pitch) propeller type similar to that used with larger aircraft reciprocating engines , except that

5610-460: The principal difference from which being an expanded airframe that provided considerably more internal volume. Another key innovation was the Tyne engine, which was roughly twice as powerful as the Viscount's Rolls-Royce Dart engine, and allowed for increases in both cruising speed and altitude. Throughout the design process, the needs of two airlines, BEA and Trans-Canada Air Lines (TCA), heavily shaped

5695-522: The propeller to rotate freely, independent of compressor speed. Alan Arnold Griffith had published a paper on compressor design in 1926. Subsequent work at the Royal Aircraft Establishment investigated axial compressor-based designs that would drive a propeller. From 1929, Frank Whittle began work on centrifugal compressor-based designs that would use all the gas power produced by the engine for jet thrust. The world's first turboprop

5780-403: The propeller-control requirements are very different. Due to the turbine engine's slow response to power inputs, particularly at low speeds, the propeller has a greater range of selected travel in order to make rapid thrust changes, notably for taxi, reverse, and other ground operations. The propeller has 2 modes, Alpha and Beta. Alpha is the mode for all flight operations including takeoff. Beta,

5865-421: The rear and 108 tourist, but this was changed to 139 all-tourist, in which configuration the Vanguard had very low operating costs per seat-mile. On flights up to 300 miles (480 km), such as from London to Paris, Brussels and Amsterdam, the type could match the block times of the pure jets which were being introduced in the early 1960s. The remaining BEA fleet passed to British Airways (BA) on 1 April 1974 and

5950-511: The remainder at Heathrow using kits from ATEL. A large forward cargo door measuring 139 by 80 inches (350 by 200 cm) was incorporated. The Merchantmen continued in service with BA until late 1979 when the remaining five were sold. Air Bridge Carriers purchased several of the Merchantmen and operated them until 1992, when it changed its name to Hunting Cargo Airlines . Hunting Cargo operated its last V953C flight on 30 September 1996 and donated

6035-585: The same speed as small regional jet airliners but burn two-thirds of the fuel per passenger. Compared to piston engines, their greater power-to-weight ratio (which allows for shorter takeoffs) and reliability can offset their higher initial cost, maintenance and fuel consumption. As jet fuel can be easier to obtain than avgas in remote areas, turboprop-powered aircraft like the Cessna Caravan and Quest Kodiak are used as bush airplanes . Turboprop engines are generally used on small subsonic aircraft, but

6120-630: The seats from one of its aircraft and refitted for pure cargo work, in which role it could carry 42,000 lb (19,000 kg) of freight. Known by the airline as the "Cargoliner", it was the only such conversion, but survived to be the last Canadian Vanguard to be retired in December 1972. BEA operated nine Vanguards modified to the V953C "Merchantman" all-cargo layout from 1969, with the first two conversions being designed and carried out by Aviation Traders Engineering Ltd (ATEL) at Southend Airport . BEA modified

6205-415: The turbine. In contrast to a turbojet or turbofan , the engine's exhaust gases do not provide enough power to create significant thrust, since almost all of the engine's power is used to drive the propeller. Exhaust thrust in a turboprop is sacrificed in favor of shaft power, which is obtained by extracting additional power (beyond that necessary to drive the compressor) from turbine expansion. Owing to

6290-452: The type took over many of BEA's busier European and UK trunk routes. The aircraft received names of famous Royal Navy warships; the first (registered G-APEA) was named " Vanguard ", however by the time that the aircraft were delivered, BEA had adopted its new "red square" livery, which saw the end of naming and none of the Vanguards actually carried a name. Initial seating was 18 first-class at

6375-475: Was a turboprop-powered airliner designed for short- and medium-range services. The principal difference between the Vanguard and the preceding Viscount was in the construction of the fuselage ; the Vanguard lower fuselage was similar to that of the Viscount but the top section had a larger-diameter giving a double bubble cross-section (somewhat similar to the Boeing Stratocruiser ). The primary result of

6460-649: Was briefly established in 1912, only to meet with similar practical difficulties. The range, speed and lifting capacity of aircraft were transformed through technological innovation during the war, allowing the first practical air mail services to finally become a reality when the war ended. For instance, the first regularly scheduled airmail service in the United States was inaugurated on May 15, 1918. The route, which ran between Washington, D.C. , and New York City , with an intermediate stop in Philadelphia, Pennsylvania ,

6545-486: Was carried between Geraldton and Derby in Western Australia on December 5, 1921. Since stamp collecting was already a well-developed hobby by this time, collectors followed developments in airmail service closely, and went to some trouble to find out about the first flights between various destinations, and to get letters onto them. The authorities often used special cachets on the covers , and in many cases

6630-463: Was carried by French pilot Maurice Guillaux. On July 16–18, 1914, he flew his Blériot XI aircraft from Melbourne to Sydney, a distance of 584 miles (940 km), carrying 1785 specially printed postcards, some Lipton's Tea and some O.T. Lemon juice. At the time, this was the longest such flight in the world. The world's first scheduled airmail post service took place in the United Kingdom between

6715-754: Was designed by aviation pioneer Augustus Post . The field used for this service is marked by a plaque in West Potomac Park . In 1925, the U.S. Postal service issued contracts to fly airmail between designated points. By 1931, 85% of domestic airline revenue was from airmail. In Germany, dirigibles of the 1920s and 1930s were used extensively to carry airmail; it was known as Zeppelin mail , or dirigible mail. The German Zeppelins were especially visible in this role, and many countries issued special stamps for use on Zeppelin mail. The 1928 book So Disdained by Nevil Shute —a novel based on this author's deep interest in and thorough knowledge of aviation—includes

6800-557: Was designed by the Hungarian mechanical engineer György Jendrassik . Jendrassik published a turboprop idea in 1928, and on 12 March 1929 he patented his invention. In 1938, he built a small-scale (100 Hp; 74.6 kW) experimental gas turbine. The larger Jendrassik Cs-1 , with a predicted output of 1,000 bhp, was produced and tested at the Ganz Works in Budapest between 1937 and 1941. It

6885-460: Was of axial-flow design with 15 compressor and 7 turbine stages, annular combustion chamber. First run in 1940, combustion problems limited its output to 400 bhp. Two Jendrassik Cs-1s were the engines for the world's first turboprop aircraft – the Varga RMI-1 X/H . This was a Hungarian fighter-bomber of WWII which had one model completed, but before its first flight it was destroyed in

6970-604: Was one of the fastest turboprop airliners to ever be built, including much later designs such as the Saab 2000 and de Havilland Canada Dash 8 . A pilot report describes maintaining 10,000 ft (3,000 m) altitude with three engines at idle power and propellers feathered and the port outer engine at maximum cruise power. The flight deck of the Vanguard was particularly spacious for the era. The flying controls were designed with manual operation in mind and were aerodynamically balanced. In spite of this arrangement, according to Andrews,

7055-635: Was operated by the U.S. Navy for a short time. The first American turboprop engine was the General Electric XT31 , first used in the experimental Consolidated Vultee XP-81 . The XP-81 first flew in December 1945, the first aircraft to use a combination of turboprop and turbojet power. The technology of Allison's earlier T38 design evolved into the Allison T56 , used to power the Lockheed Electra airliner, its military maritime patrol derivative

7140-499: Was quickly dismissed. On 14 May 1951, Vickers met with Rolls-Royce representatives to discuss potential engines for their envisioned airliner; the meeting led to the decision to adopt the in-development Rolls-Royce Tyne powerplant for its revised proposal. While considerations towards adopting a turbojets engine were made, a study performed in November 1953 found that such an engine would produce inferior performance over shorter routes to

7225-593: Was the first turboprop aircraft of any kind to go into production and sold in large numbers. It was also the first four-engined turboprop. Its first flight was on 16 July 1948. The world's first single engined turboprop aircraft was the Armstrong Siddeley Mamba -powered Boulton Paul Balliol , which first flew on 24 March 1948. The Soviet Union built on German World War II turboprop preliminary design work by Junkers Motorenwerke, while BMW, Heinkel-Hirth and Daimler-Benz also worked on projected designs. While

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