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117-553: The Fairey FC1 was a British airliner project of the 1930s. Although an order was placed for 14 FC1s in 1938, work was stopped by the outbreak of the Second World War , and no examples were built. In 1938, the British Air Ministry , eager to encourage the development of British commercial land planes, which were seen to be lagging behind foreign designs, issued a pair of specifications for new airliners,

234-402: A gas turbine engine which achieves mechanical energy from combustion, and a ducted fan that uses the mechanical energy from the gas turbine to force air rearwards. Thus, whereas all the air taken in by a turbojet passes through the combustion chamber and turbines, in a turbofan some of that air bypasses these components. A turbofan thus can be thought of as a turbojet being used to drive

351-616: A jet-powered 100-seat design at the request of Geoffrey de Havilland , involved in the first jet fighters development. After a brief contest, the Type I design was given to the Bristol Aeroplane Company , building on a "100 ton bomber " submission. This evolved into the Bristol Brabazon but this project folded in 1951 as BOAC lost interest and the first aircraft needed a costly wing re-design to accommodate

468-633: A Caravelle successor. The Super-Caravelle was a supersonic transport project of similar size and range to the Caravelle. It was merged with the similar Bristol Aeroplane Company project into the Anglo-French Concorde . The Concorde entered service in January 1967 as the second and last commercial supersonic transport , after large overruns and delays, costing £1.3 billion. All subsequent French airliner efforts were part of

585-623: A batch of nine. The Ford Trimotor had two engines mounted on the wings and one in the nose, and a slabsided body, it carried eight passengers and was produced from 1925 to 1933. It was an important early airliner in America. It was used by the predecessor to Trans World Airlines , and by other airlines long after production ceased. The Trimotor helped to popularise numerous aspects of modern aviation infrastructure, including paved runways , passenger terminals , hangars , airmail , and radio navigation . Pan Am opened up transoceanic service in

702-671: A common fuel type – kerosene-based jet fuel – is another advantage. Some variants of airliners have been developed for carrying freight or for luxury corporate use . Many airliners have also been modified for government use as VIP transports and for military functions such as airborne tankers (for example, the Vickers VC10 , Lockheed L-1011 , Boeing 707 ), air ambulance ( USAF / USN McDonnell Douglas DC-9 ), reconnaissance ( Embraer ERJ 145 , Saab 340 , and Boeing 737 ), as well as for troop-carrying roles. Modern jetliners are usually low-wing designs with two engines mounted underneath

819-419: A discordant nature known as "buzz saw" noise. All modern turbofan engines have acoustic liners in the nacelle to damp their noise. They extend as much as possible to cover the largest surface area. The acoustic performance of the engine can be experimentally evaluated by means of ground tests or in dedicated experimental test rigs. In the aerospace industry, chevrons are the "saw-tooth" patterns on

936-546: A ducted fan, with both of these contributing to the thrust . The ratio of the mass-flow of air bypassing the engine core to the mass-flow of air passing through the core is referred to as the bypass ratio . The engine produces thrust through a combination of these two portions working together. Engines that use more jet thrust relative to fan thrust are known as low-bypass turbofans ; conversely those that have considerably more fan thrust than jet thrust are known as high-bypass . Most commercial aviation jet engines in use are of

1053-555: A few experimental or military designs, all aircraft built to date have had all of their weight lifted off the ground by airflow across the wings. In terms of aerodynamics , the fuselage has been a mere burden. NASA and Boeing are currently developing a blended wing body design in which the entire airframe, from wingtip to wingtip, contributes lift. This promises a significant gain in fuel efficiency . The major manufacturers with large aircraft airliners currently in production include: The narrow-body and wide-body airliner market

1170-410: A fixed total applied fuel:air ratio, the total fuel flow for a given fan airflow will be the same, regardless of the dry specific thrust of the engine. However, a high specific thrust turbofan will, by definition, have a higher nozzle pressure ratio, resulting in a higher afterburning net thrust and, therefore, a lower afterburning specific fuel consumption (SFC). However, high specific thrust engines have

1287-932: A growth by 3.5 from 2004 to 2020 is unprecedented and highly unusual for any mature market. In 2016, the deliveries went for 38% in Asia-Pacific, 25% in Europe, 22% in North America, 7% in Middle East, 6% in South America and 2% in Africa. 1,020 narrowbodies were delivered and their backlog reach 10891: 4,991 A320neo, 644 A320ceo; 3,593 737 Max, 835 737NG, 348 CSeries, 305 C919 and 175 MC-21; while 398 widebodies were delivered : 137 Dreamliners and 99 B777 for Boeing (65%) against 63 A330 and 49 A350 for Airbus, more than 2,400 widebodies were in backlog, led by

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1404-426: A high dry SFC. The situation is reversed for a medium specific thrust afterburning turbofan: i.e., poor afterburning SFC/good dry SFC. The former engine is suitable for a combat aircraft which must remain in afterburning combat for a fairly long period, but has to fight only fairly close to the airfield (e.g. cross border skirmishes). The latter engine is better for an aircraft that has to fly some distance, or loiter for

1521-449: A higher gross weight of 5,500 lb (2,500 kg). Later aircraft were amongst the first airliners to be fitted with flaps for improved landing performance, along with downwards-facing recognition light and metal propellers, which were often retrofitted to older aircraft. It was also used in military roles; civil Dragon Rapides were impressed into military service during the Second World War . Metal airliners came into service in

1638-416: A higher nozzle pressure ratio than the turbojet, but with a lower exhaust temperature to retain net thrust. Since the temperature rise across the whole engine (intake to nozzle) would be lower, the (dry power) fuel flow would also be reduced, resulting in a better specific fuel consumption (SFC). Some low-bypass ratio military turbofans (e.g. F404 , JT8D ) have variable inlet guide vanes to direct air onto

1755-508: A linkage; firstly the flap lowered below the wing and approximately parallel, making the aircraft almost a sesquiplane . This gave improved lift, but with little extra drag, and was used for landing. The flaps could be extended further for landing, now rotating downwards to 30° as a slotted flap . With the use of flaps, wing loading was reduced to the equivalent of 25 lb/sq ft and also gave a gain in lift coefficient of around 31%. The Fairey-Youngman flap and its initial downward parallel movement

1872-590: A long time, before going into combat. However, the pilot can afford to stay in afterburning only for a short period, before aircraft fuel reserves become dangerously low. The first production afterburning turbofan engine was the Pratt & Whitney TF30 , which initially powered the F-111 Aardvark and F-14 Tomcat . Low-bypass military turbofans include the Pratt & Whitney F119 , the Eurojet EJ200 ,

1989-401: A pound of thrust, more fuel is wasted in the faster propelling jet. In other words, the independence of thermal and propulsive efficiencies, as exists with the piston engine/propeller combination which preceded the turbojet, is lost. In contrast, Roth considers regaining this independence the single most important feature of the turbofan which allows specific thrust to be chosen independently of

2106-403: A pure-jet of the same thrust, and jet noise is no longer the predominant source. Turbofan engine noise propagates both upstream via the inlet and downstream via the primary nozzle and the by-pass duct. Other noise sources are the fan, compressor and turbine. Modern commercial aircraft employ high-bypass-ratio (HBPR) engines with separate flow, non-mixing, short-duct exhaust systems. Their noise

2223-569: A static thrust of 4,320 lb (1,960 kg), and had a bypass ratio of 6:1. The General Electric TF39 became the first production model, designed to power the Lockheed C-5 Galaxy military transport aircraft. The civil General Electric CF6 engine used a derived design. Other high-bypass turbofans are the Pratt & Whitney JT9D , the three-shaft Rolls-Royce RB211 and the CFM International CFM56 ; also

2340-1093: A survey by Inside MRO and Air Transport World , and this is a reason why Mitsubishi Aircraft Corporation purchased the Bombardier CRJ program. It is an entry barrier for new entrants like the Xian MA700 and Comac C919 , with no credible previous experience with the MA60 , or the Irkut MC-21 after the Sukhoi Superjet 100 . The airliner fleet went from 13,500 in 2000 to 25,700 in 2017: 16% to 30.7% in Asia/Pacific (2,158 to 7,915), 34.7% to 23.6% in USA (4,686 to 6,069) and 24% to 20.5% in Europe (3,234 to 5,272). In 2018, there were 29,398 airliners in service: 26,935 passenger transports and 2,463 freighters, while 2,754 others were stored. The largest fleet

2457-473: A turbofan engine is the ratio between the mass flow rate of the bypass stream to the mass flow rate entering the core. A bypass ratio of 6, for example, means that 6 times more air passes through the bypass duct than the amount that passes through the combustion chamber. Turbofan engines are usually described in terms of BPR, which together with overall pressure ratio, turbine inlet temperature and fan pressure ratio are important design parameters. In addition BPR

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2574-421: A turbojet engine uses all of the engine's output to produce thrust in the form of a hot high-velocity exhaust gas jet, a turbofan's cool low-velocity bypass air yields between 30% and 70% of the total thrust produced by a turbofan system. The thrust ( F N ) generated by a turbofan depends on the effective exhaust velocity of the total exhaust, as with any jet engine, but because two exhaust jets are present

2691-496: A turbojet even though an extra turbine, a gearbox and a propeller are added to the turbojet's low-loss propelling nozzle. The turbofan has additional losses from its greater number of compressor stages/blades, fan and bypass duct. Froude, or propulsive, efficiency can be defined as: η f = 2 1 + V j V a {\displaystyle \eta _{f}={\frac {2}{1+{\frac {V_{j}}{V_{a}}}}}} where: While

2808-704: A turbojet which accelerates a smaller amount more quickly, which is a less efficient way to generate the same thrust (see the efficiency section below). The ratio of the mass-flow of air bypassing the engine core compared to the mass-flow of air passing through the core is referred to as the bypass ratio . Engines with more jet thrust relative to fan thrust are known as low-bypass turbofans , those that have considerably more fan thrust than jet thrust are known as high-bypass . Most commercial aviation jet engines in use are high-bypass, and most modern fighter engines are low-bypass. Afterburners are used on low-bypass turbofans on combat aircraft. The bypass ratio (BPR) of

2925-507: Is best suited to high supersonic speeds. If it is all transferred to a separate big mass of air with low kinetic energy, the aircraft is best suited to zero speed (hovering). For speeds in between, the gas power is shared between a separate airstream and the gas turbine's own nozzle flow in a proportion which gives the aircraft performance required. The trade off between mass flow and velocity is also seen with propellers and helicopter rotors by comparing disc loading and power loading. For example,

3042-410: Is considerable potential for reducing fuel consumption for the same core cycle by increasing BPR.This is achieved because of the reduction in pounds of thrust per lb/sec of airflow (specific thrust) and the resultant reduction in lost kinetic energy in the jets (increase in propulsive efficiency). If all the gas power from a gas turbine is converted to kinetic energy in a propelling nozzle, the aircraft

3159-400: Is dominated by Airbus and Boeing, and the regional airliner market is shared between ATR Aircraft , De Havilland Canada , and Embraer . Setting up a reliable customer support network, ensuring uptime, availability and support 24/7 and anywhere, is critical for the success of airliner manufacturers. Boeing and Airbus are ranked 1 and 2 in customer satisfaction for aftermarket support by

3276-430: Is due to the speed, temperature, and pressure of the exhaust jet, especially during high-thrust conditions, such as those required for takeoff. The primary source of jet noise is the turbulent mixing of shear layers in the engine's exhaust. These shear layers contain instabilities that lead to highly turbulent vortices that generate the pressure fluctuations responsible for sound. To reduce the noise associated with jet flow,

3393-413: Is quoted for turboprop and unducted fan installations because their high propulsive efficiency gives them the overall efficiency characteristics of very high bypass turbofans. This allows them to be shown together with turbofans on plots which show trends of reducing specific fuel consumption (SFC) with increasing BPR. BPR can also be quoted for lift fan installations where the fan airflow is remote from

3510-420: Is sufficient core power to drive the fan. A smaller core flow/higher bypass ratio cycle can be achieved by raising the inlet temperature of the high-pressure (HP) turbine rotor. To illustrate one aspect of how a turbofan differs from a turbojet, comparisons can be made at the same airflow (to keep a common intake for example) and the same net thrust (i.e. same specific thrust). A bypass flow can be added only if

3627-424: Is that combustion is less efficient at lower speeds. Any action to reduce the fuel consumption of the engine by increasing its pressure ratio or turbine temperature to achieve better combustion causes a corresponding increase in pressure and temperature in the exhaust duct which in turn cause a higher gas speed from the propelling nozzle (and higher KE and wasted fuel). Although the engine would use less fuel to produce

Fairey FC1 - Misplaced Pages Continue

3744-411: Is very fuel intensive. Consequently, afterburning can be used only for short portions of a mission. Unlike in the main engine, where stoichiometric temperatures in the combustor have to be reduced before they reach the turbine, an afterburner at maximum fuelling is designed to produce stoichiometric temperatures at entry to the nozzle, about 2,100 K (3,800 °R; 3,300 °F; 1,800 °C). At

3861-634: The Airbus pan-European initiative. Soon after the war, most of the Soviet fleet of airliners consisted of DC-3s or Lisunov Li-2s . These planes were in desperate need of replacement, and in 1946, the Ilyushin Il-12 made its first flight. The Il-12 was very similar in design to American Convair 240, except was unpressurized. In 1953, the Ilyushin Il-14 made its first flight, and this version

3978-555: The Airbus A300 / A310 , A330 and A350 ; the 767 , 777 and 787 . Regional airliners seat fewer than 100 passengers. These smaller aircraft are often used to feed traffic at large airline hubs to larger aircraft operated by the major mainline carriers , legacy carriers , or flag carriers ; often sharing the same livery. Regional jets include the Bombardier CRJ100/200 and Bombardier CRJ700 series , or

4095-699: The BAC 1-11 , Vickers VC10 , and Hawker Siddeley Trident . The STAC committee was formed to consider supersonic designs and worked with Bristol to create the Bristol 223 , a 100-passenger transatlantic airliner. The effort was later merged with similar efforts in France to create the Concorde supersonic airliner to share the cost. The first batch of the Douglas DC-4s went to the U.S. Army and Air Forces, and

4212-669: The Bleriot-SPAD S.33 was introduced during the early 1920s. It was commercially successful, initially serving the Paris- London route, and later on continental routes. The enclosed cabin could carry four passengers with an extra seat in the cockpit. It was further developed into the Blériot-SPAD S.46 . Throughout the 1920s, companies in Britain and France were at the forefront of the civil airliner industry. By 1921,

4329-949: The Boeing 707 and its competitor the Douglas DC-8 . They were followed by smaller models : the Douglas DC-9 and its MD-80 / MD-90 / Boeing 717 derivatives; the Boeing 727 , 737 and 757 using the 707 cabin cross-section; or the Tupolev Tu-154 , Ilyushin Il-18 , and the Ilyushin Il-62 . Currently produced narrow-body airliners include the Airbus A220 , A320 family , Boeing 737 , Embraer E-Jet family and Comac C919 , generally used for medium-haul flights with 100 to 240 passengers. They could be joined by

4446-479: The Bristol Olympus , and Pratt & Whitney JT3C engines, increased the overall pressure ratio and thus the thermodynamic efficiency of engines. They also had poor propulsive efficiency, because pure turbojets have a high specific thrust/high velocity exhaust, which is better suited to supersonic flight. The original low-bypass turbofan engines were designed to improve propulsive efficiency by reducing

4563-576: The Bristol Proteus engine. The Type II was split between the de Havilland Dove and Airspeed Ambassador conventional piston designs, and the Vickers model powered by newly developed turboprops : first flown in 1948, the VC.2 Viceroy was the first turboprop design to enter service; a commercial success with 445 Viscounts built. The Type III requirement led to the conventional Avro Tudor and

4680-822: The Cessna Caravan and Pilatus PC-12 ; or twin piston-powered aircraft made by Cessna , Piper , Britten-Norman , and Beechcraft . They often lack lavatories , stand-up cabins, pressurization , galleys , overhead storage bins, reclining seats, or a flight attendant . Until the beginning of the Jet Age , piston engines were common on propliners such as the Douglas DC-3. Nearly all modern airliners are now powered by turbine engines, either turbofans or turboprops . Gas turbine engines operate efficiently at much higher altitudes, are more reliable than piston engines, and produce less vibration and noise. The use of

4797-701: The Embraer ERJ family . Currently produced turboprop regional airliners include the Dash-8 series, and the ATR 42 / 72 . Light aircraft can be used as small commuter airliners, or as air taxis . Twin turboprops carrying up to 19 passengers include the Beechcraft 1900 , Fairchild Metro , Jetstream 31 , DHC-6 Twin Otter and Embraer EMB 110 Bandeirante . Smaller airliners include the single-engined turboprops like

Fairey FC1 - Misplaced Pages Continue

4914-771: The Fokker F.II , then the enlarged F.III . These were used by the Dutch airline KLM , including on its Amsterdam-London service in 1921. A relatively reliable aircraft for the era, the Fokkers were flying to destinations across Europe, including Bremen, Brussels, Hamburg, and Paris. The Handley Page company in Britain produced the Handley Page Type W , its first civil transport aircraft. It housed two crew in an open cockpit and 15 passengers in an enclosed cabin. Powered by two 450 hp (340 kW) Napier Lion engines,

5031-702: The General Electric F110 , the Klimov RD-33 , and the Saturn AL-31 , all of which feature a mixed exhaust, afterburner and variable area propelling nozzle. To further improve fuel economy and reduce noise, almost all jet airliners and most military transport aircraft (e.g., the C-17 ) are powered by low-specific-thrust/high-bypass-ratio turbofans. These engines evolved from the high-specific-thrust/low-bypass-ratio turbofans used in such aircraft in

5148-444: The swept wings , while turboprop aircraft are slow enough to use straight wings. Smaller airliners sometimes have their engines mounted on either side of the rear fuselage. Numerous advantages and disadvantages exist due to this arrangement. Perhaps the most important advantage to mounting the engines under the wings is that the total aircraft weight is more evenly distributed across the wingspan, which imposes less bending moment on

5265-628: The 1930s, the British de Havilland Dragon emerged as a short-haul, low-capacity airliner. Its relatively simple design could carry six passengers, each with 45 lb (20 kg) of luggage, on the London-Paris route on a fuel consumption of 13 gal (49 L) per hour. The DH.84 Dragon entered worldwide service. During early August 1934, one performed the first non-stop flight between the Canadian mainland and Britain in 30 hours 55 minutes, although

5382-482: The 1930s. In the United States, the Boeing 247 , and the 14-passenger Douglas DC-2 , flew during the first half of the decade, while the more powerful, faster, 21–32 passenger Douglas DC-3 first appeared in 1935. DC-3s were produced in quantity for the Second World War and were sold as surplus afterward, becoming widespread within the commercial sector. It was one of first airliners to be profitable without

5499-527: The 1960s, airliners had expanded capabilities, making a significant impact on global society, economics, and politics. During 1913, Igor Sikorsky developed the first large multi-engine airplane, the Russky Vityaz . This aircraft was subsequently refined into the more practical Ilya Muromets , being furnished with dual controls for a pilot and copilot and a comfortable cabin with a lavatory, cabin heating and lighting. This large four-engine biplane

5616-421: The 1960s. Modern combat aircraft tend to use low-bypass ratio turbofans, and some military transport aircraft use turboprops . Low specific thrust is achieved by replacing the multi-stage fan with a single-stage unit. Unlike some military engines, modern civil turbofans lack stationary inlet guide vanes in front of the fan rotor. The fan is scaled to achieve the desired net thrust. The core (or gas generator) of

5733-657: The A350 with 753 (31%) then the Boeing 787 with 694 (28%). The most important driver of orders is airline profitability , itself driven mainly by world GDP growth but also supply and demand balance and oil prices , while new programmes by Airbus and Boeing help to stimulate aircraft demand. In 2016, 38% of the 25 years old airliners had been retired, 50% of the 28 years old : there will be 523 aircraft reaching 25 years old in 2017, 1,127 in 2026 and 1,628 in 2041. Deliveries rose by 80% from 2004 to 2016, they represented 4.9% of

5850-462: The Comet took off on the world's first jetliner flight carrying fare-paying passengers and simultaneously inaugurated scheduled service between London and Johannesburg. However, roughly one year after introduction, three Comets broke up mid-flight due to airframe metal fatigue , not well understood at the time. The Comet was grounded and tested to discover the cause, while rival manufacturers heeded

5967-582: The Goliath flew 12 passengers from Toussus-le-Noble to RAF Kenley , near Croydon , despite having no permission from the British authorities to land. Dozens of early airlines subsequently procured the type. One high-profile flight, made on 11 August 1919, involved an F.60 flying eight passengers and a ton of supplies from Paris via Casablanca and Mogador to Koufa, 180 km (110 mi) north of Saint-Louis, Senegal , flying more than 4,500 km (2,800 mi). Another important airliner built in 1919

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6084-597: The Joyce Green airfield in Kent on 13 April 1919. The world's first all-metal transport aircraft was the Junkers F.13 , which also made its first flight in 1919. Junkers marketed the aircraft towards business travellers and commercial operators, and European entrepreneurs bought examples for their private use and business trips. Over 300 Junkers F 13s were built between 1919 and 1932. The Dutch Fokker company produced

6201-486: The Mediterranean area and to London . The Sud-Aviation Caravelle was developed during the late 1950s as the first short range jet airliner. The nose and cockpit layout were licensed from the de Havilland Comet , along with some fuselage elements. Entering service in mid 1959, 172 Caravelles had been sold within four years and six versions were in production by 1963. Sud Aviation then focused its design team on

6318-638: The US for military transport aircraft and the UK for heavy bombers . That such a policy was suggested or implemented have been disputed, at least by Sir Peter Masefield . British aircraft manufacturers were tied up to fulfill military requirements, and had no free capacity to address other matters though the war. The committee final report pushed four designs for the state-owned airlines British Overseas Airways Corporation (BOAC) and later British European Airways (BEA): three piston-powered aircraft of varying sizes, and

6435-464: The aerospace industry has sought to disrupt shear layer turbulence and reduce the overall noise produced. Fan noise may come from the interaction of the fan-blade wakes with the pressure field of the downstream fan-exit stator vanes. It may be minimized by adequate axial spacing between blade trailing edge and stator entrance. At high engine speeds, as at takeoff, shock waves from the supersonic fan tips, because of their unequal nature, produce noise of

6552-422: The afterburner, raising the temperature of exhaust gases by a significant degree, resulting in a higher exhaust velocity/engine specific thrust. The variable geometry nozzle must open to a larger throat area to accommodate the extra volume and increased flow rate when the afterburner is lit. Afterburning is often designed to give a significant thrust boost for take off, transonic acceleration and combat maneuvers, but

6669-441: The aircraft is going forwards, leaving a very fast wake. This wake contains kinetic energy that reflects the fuel used to produce it, rather than the fuel used to move the aircraft forwards. A turbofan harvests that wasted velocity and uses it to power a ducted fan that blows air in bypass channels around the rest of the turbine. This reduces the speed of the propelling jet while pushing more air, and thus more mass. The other penalty

6786-474: The average stage loading and to maintain LP turbine efficiency. Reducing core flow also increases bypass ratio. Bypass ratios greater than 5:1 are increasingly common; the Pratt & Whitney PW1000G , which entered commercial service in 2016, attains 12.5:1. Further improvements in core thermal efficiency can be achieved by raising the overall pressure ratio of the core. Improvements in blade aerodynamics can reduce

6903-570: The capacity of airliners needed to be increased to achieve more favourable economics. The English company de Havilland , built the 10-passenger DH.29 monoplane, while starting work on the design of the DH.32, an eight-seater biplane with a more economical but less powerful Rolls-Royce Eagle engine. For more capacity, DH.32 development was replaced by the DH.34 biplane, accommodating 10 passengers. A commercially successful aircraft, Daimler Airway ordered

7020-601: The end of the First World War, large numbers of ex-military aircraft flooded the market. One such aircraft was the French Farman F.60 Goliath , which had originally been designed as a long-range heavy bomber ; a number were converted for commercial use into passenger airliners starting in 1919, being able to accommodate a maximum of 14 seated passengers. and around 60 were built. Initially, several publicity flights were made, including one on 8 February 1919, when

7137-448: The engine and doesn't flow past the engine core. Considering a constant core (i.e. fixed pressure ratio and turbine inlet temperature), core and bypass jet velocities equal and a particular flight condition (i.e. Mach number and altitude) the fuel consumption per lb of thrust (sfc) decreases with increase in BPR. At the same time gross and net thrusts increase, but by different amounts. There

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7254-427: The engine must generate enough power to drive the fan at its rated mass flow and pressure ratio. Improvements in turbine cooling/material technology allow for a higher (HP) turbine rotor inlet temperature, which allows a smaller (and lighter) core, potentially improving the core thermal efficiency. Reducing the core mass flow tends to increase the load on the LP turbine, so this unit may require additional stages to reduce

7371-416: The engine, from the gas generator, to a ducted fan which produces a second, additional mass of accelerated air. The transfer of energy from the core to bypass air results in lower pressure and temperature gas entering the core nozzle (lower exhaust velocity), and fan-produced higher pressure and temperature bypass-air entering the fan nozzle. The amount of energy transferred depends on how much pressure rise

7488-524: The exhaust velocity to a value closer to that of the aircraft. The Rolls-Royce Conway , the world's first production turbofan, had a bypass ratio of 0.3, similar to the modern General Electric F404 fighter engine. Civilian turbofan engines of the 1960s, such as the Pratt & Whitney JT8D and the Rolls-Royce Spey , had bypass ratios closer to 1 and were similar to their military equivalents. The first Soviet airliner powered by turbofan engines

7605-411: The fan is designed to produce (fan pressure ratio). The best energy exchange (lowest fuel consumption) between the two flows, and how the jet velocities compare, depends on how efficiently the transfer takes place which depends on the losses in the fan-turbine and fan. The fan flow has lower exhaust velocity, giving much more thrust per unit energy (lower specific thrust ). Both airstreams contribute to

7722-751: The first commercial plane to circumnavigate the globe during December 1941 and January 1942. In the United Kingdom, the Brabazon Committee was formed in 1942 under John Moore-Brabazon, 1st Baron Brabazon of Tara to forecast advances in aviation technology and the air transport needs of the postwar British Empire (in South Asia, Africa, and the Near and Far East ) and Commonwealth ( Australia , Canada , New Zealand ). For British use, multi-engine aircraft types were allegedly split between

7839-450: The first fan rotor stage. This improves the fan surge margin (see compressor map ). Since the 1970s, most jet fighter engines have been low/medium bypass turbofans with a mixed exhaust, afterburner and variable area exit nozzle. An afterburner is a combustor located downstream of the turbine blades and directly upstream of the nozzle, which burns fuel from afterburner-specific fuel injectors. When lit, large volumes of fuel are burnt in

7956-740: The first scheduled international airline service from London to Paris. One aircraft was sold to the River Plate Aviation Company in Argentina , to operate a cross-river service between Buenos Aires and Montevideo . Meanwhile, the competing Vickers converted its successful First World War era bomber, the Vickers Vimy , into a civilian version, the Vimy Commercial. It was redesigned with a larger-diameter fuselage (largely of spruce plywood), and first flew from

8073-557: The first, Specification 14/38 for a long-range airliner, and the second, 15/38, for a short/medium haul aircraft. Specification 14/38 was issued to Short Brothers only, who produced their S.32 design to meet it, while 15/38 was issued to a number of companies, including Fairey Aviation and General Aircraft Limited . Fairey's proposal, the FC1, was chosen as the winner of the competition in October 1938, and an order placed for two prototypes and twelve production aircraft, to be used by British Airways Ltd. on 12 November 1938. The FC1

8190-602: The fleet at the end of 2012 and 11.3% at the end of 2001. Since it began, the jet airliner market had a recurring pattern of seven years of growth followed by three years of deliveries falling 30–40%, except a steady growth from 2004 due to the economic rise of China going from 3% of world market in 2001 to 22% in 2015, expensive jet fuel till 2014 stimulating old jets replacement allowed by low interest rates since 2008, and strong airline passenger demand since. In 2004, 718 Airbus and Boeings were delivered, worth $ 39.3 billion; 1,466 are expected in 2017, worth $ 104.4 billion:

8307-407: The fleet in 2004 and 5.9% in 2016, down from 8% previously. Oil prices and airshow orders are trending together. Turbofan A turbofan or fanjet is a type of airbreathing jet engine that is widely used in aircraft propulsion . The word "turbofan" is a combination of references to the preceding generation engine technology of the turbojet and the additional fan stage. It consists of

8424-483: The fuel consumption of the turbojet. It achieves this by pushing more air, thus increasing the mass and lowering the speed of the propelling jet compared to that of the turbojet. This is done mechanically by adding a ducted fan rather than using viscous forces. A vacuum ejector is used in conjunction with the fan as first envisaged by inventor Frank Whittle . Whittle envisioned flight speeds of 500 mph in his March 1936 UK patent 471,368 "Improvements relating to

8541-400: The gas generator cycle. The working substance of the thermodynamic cycle is the only mass accelerated to produce thrust in a turbojet which is a serious limitation (high fuel consumption) for aircraft speeds below supersonic. For subsonic flight speeds the speed of the propelling jet has to be reduced because there is a price to be paid in producing the thrust. The energy required to accelerate

8658-443: The gas inside the engine (increase in kinetic energy) is expended in two ways, by producing a change in momentum ( i.e. a force), and a wake which is an unavoidable consequence of producing thrust by an airbreathing engine (or propeller). The wake velocity, and fuel burned to produce it, can be reduced and the required thrust still maintained by increasing the mass accelerated. A turbofan does this by transferring energy available inside

8775-429: The gross thrust of the engine. The additional air for the bypass stream increases the ram drag in the air intake stream-tube, but there is still a significant increase in net thrust. The overall effective exhaust velocity of the two exhaust jets can be made closer to a normal subsonic aircraft's flight speed and gets closer to the ideal Froude efficiency . A turbofan accelerates a larger mass of air more slowly, compared to

8892-409: The high-bypass type, and most modern fighter engines are low-bypass. Afterburners are used on low-bypass turbofan engines with bypass and core mixing before the afterburner. Modern turbofans have either a large single-stage fan or a smaller fan with several stages. An early configuration combined a low-pressure turbine and fan in a single rear-mounted unit. The turbofan was invented to improve

9009-474: The hot nozzle to convert to kinetic energy. Turbofans represent an intermediate stage between turbojets , which derive all their thrust from exhaust gases, and turbo-props which derive minimal thrust from exhaust gases (typically 10% or less). Extracting shaft power and transferring it to a bypass stream introduces extra losses which are more than made up by the improved propulsive efficiency. The turboprop at its best flight speed gives significant fuel savings over

9126-701: The in-development Irkut MC-21 . The larger wide-body aircraft , or twin-aisle as they have two separate aisles in the cabin, are used for long-haul flights. The first was the Boeing 747 quadjet, followed by the trijets: the Lockheed L-1011 and the Douglas DC-10 , then its MD-11 stretch. Then other quadjets were introduced: the Ilyushin Il-86 and Il-96 , the Airbus A340 and the double-deck A380 . Twinjets were also put into service:

9243-583: The intended destination had originally been Baghdad in Iraq . British production of the Dragon ended in favour of the de Havilland Dragon Rapide , a faster and more comfortable successor. By November 1934, series production of the Dragon Rapide had commenced. De Havilland invested into advanced features including elongated rear windows, cabin heating, thickened wing tips, and a strengthened airframe for

9360-682: The journey time replied; "It is intended to speed up progressively the time-table of the Empire Service by an extension of night flying and also, in due course, by the construction of aircraft, prototype production orders for which have already been placed for 14 aircraft being constructed by Fairey's, for completion in 1941 or 1942, to be used on this and other routes." Data from Fairey Aircraft since 1915 General characteristics Performance Airliner Regional airliners typically seat fewer than 100 passengers and may be powered by turbofans or turboprops . These airliners are

9477-684: The late 1920s and early 1930s, based on a series of large seaplanes – the Sikorsky S-38 through Sikorsky S-42 . By the 1930s, the airliner industry had matured and large consolidated national airlines were established with regular international services that spanned the globe, including Imperial Airways in Britain, Lufthansa in Germany, KLM in the Netherlands, and United Airlines in America. Multi-engined aircraft were now capable of transporting dozens of passengers in comfort. During

9594-402: The lessons learned while developing their own aircraft. The improved Comet 2 and the prototype Comet 3 culminated in the redesigned Comet 4 series which debuted in 1958 and had a productive career over 30 years, but sales never fully recovered. By the 1960s, the UK had lost the airliner market to the US due to the Comet disaster and a smaller domestic market, not regained by later designs like

9711-417: The mechanical power produced by the turbine. In a bypass design, extra turbines drive a ducted fan that accelerates air rearward from the front of the engine. In a high-bypass design, the ducted fan and nozzle produce most of the thrust. Turbofans are closely related to turboprops in principle because both transfer some of the gas turbine's gas power, using extra machinery, to a bypass stream leaving less for

9828-498: The more ambitious Bristol Britannia , although both aircraft suffered protracted developments, with the latter entering service with BOAC in February 1957, over seven years following its order. The jet-powered Type IV became the de Havilland Comet in 1949. It featured an aerodynamically clean design with four de Havilland Ghost turbojet engines buried in the wings, a pressurised fuselage, and large square windows. On 2 May 1952,

9945-529: The non- mainline counterparts to the larger aircraft operated by the major carriers, legacy carriers , and flag carriers , and are used to feed traffic into the large airline hubs. These regional routes then form the spokes of a hub-and-spoke air transport model. The lightest aircraft are short-haul regional feeder airliner type aircraft that carry a small number of passengers are called commuter aircraft, commuterliners, feederliners, and air taxis , depending on their size, engines, how they are marketed, region of

10062-483: The number of extra compressor stages required, and variable geometry stators enable high-pressure-ratio compressors to work surge-free at all throttle settings. The first (experimental) high-bypass turbofan engine was the AVCO-Lycoming PLF1A-2, a Honeywell T55 turboshaft-derived engine that was first run in February 1962. The PLF1A-2 had a 40 in diameter (100 cm) geared fan stage, produced

10179-536: The planes. American planes were allegedly more comfortable and had superior flight decks than those produced in Europe. In 1936, the French Air Ministry requested transatlantic flying boats that could hold at least 40 passengers, leading to three Latécoère 631s introduced by Air France in July 1947. However, two crashed and the third was removed from service over safety concerns. The SNCASE Languedoc

10296-468: The project was abandoned due to a lack of customer demand and its high development costs. Rival planes include the Martin 2-0-2 and Martin 4-0-4 , but the 2-0-2 had safety concerns and was unpressurized, while the 4-0-4 only sold around 100 units. During the postwar years, engines became much larger and more powerful, and safety features such as deicing, navigation, and weather information were added to

10413-622: The project. The project was cancelled on 17 October 1939 following the outbreak of the Second World War in September. Fairey proposed restarting the project after the end of the war in 1945, fitting more modern engines, but nothing came of the proposal. The then Secretary of State for Air when asked in the House of Commons , questions regarding the journey from London to Singapore made by Imperial Airways, if there were any modern aircraft being constructed for Imperial Airways by which might reduce

10530-414: The propulsion of aircraft", in which he describes the principles behind the turbofan, although not called as such at that time. While the turbojet uses the gas from its thermodynamic cycle as its propelling jet, for aircraft speeds below 500 mph there are two penalties to this design which are addressed by the turbofan. Firstly, energy is wasted as the propelling jet is going much faster rearwards than

10647-605: The prototype first flew on 4 December 1919, shortly after it was displayed at the 1919 Paris Air Show at Le Bourget . It was ordered by the Belgian firm Sabena , a further ten Type Ws were produced under license in Belgium by SABCA . In 1921 the Air Ministry ordered three aircraft, built as the W.8b, for use by Handley Page Transport , and later by Imperial Airways , on services to Paris and Brussels . In France,

10764-399: The same helicopter weight can be supported by a high power engine and small diameter rotor or, for less fuel, a lower power engine and bigger rotor with lower velocity through the rotor. Bypass usually refers to transferring gas power from a gas turbine to a bypass stream of air to reduce fuel consumption and jet noise. Alternatively, there may be a requirement for an afterburning engine where

10881-502: The sole requirement for bypass is to provide cooling air. This sets the lower limit for BPR and these engines have been called "leaky" or continuous bleed turbojets (General Electric YJ-101 BPR 0.25) and low BPR turbojets (Pratt & Whitney PW1120). Low BPR (0.2) has also been used to provide surge margin as well as afterburner cooling for the Pratt & Whitney J58 . Propeller engines are most efficient for low speeds, turbojet engines for high speeds, and turbofan engines between

10998-723: The support of postal or government subsidies. Long-haul flights were expanded during the 1930s as Pan American Airways and Imperial Airways competed on transatlantic travel using fleets of flying boats , such as the British Short Empire and the American Boeing 314 . Imperial Airways' order for 28 Empire flying boats was viewed by some as a bold gamble. At the time, flying boats were the only practical means of building aircraft of such size and weight as land-based aircraft would have unfeasibly poor field performance. One Boeing 314, registration NC18602 , became

11115-536: The technology and materials available at the time. The first turbofan engine, which was only run on a test bed, was the German Daimler-Benz DB 670 , designated the 109-007 by the German RLM ( Ministry of Aviation ), with a first run date of 27 May 1943, after the testing of the turbomachinery using an electric motor, which had been undertaken on 1 April 1943. Development of the engine

11232-497: The thrust equation can be expanded as: F N = m ˙ e v h e − m ˙ o v o + B P R ( m ˙ c ) v f {\displaystyle F_{N}={\dot {m}}_{e}v_{he}-{\dot {m}}_{o}v_{o}+BPR\,({\dot {m}}_{c})v_{f}} where: The cold duct and core duct's nozzle systems are relatively complex due to

11349-673: The trailing edges of some jet engine nozzles that are used for noise reduction . The shaped edges smooth the mixing of hot air from the engine core and cooler air flowing through the engine fan, which reduces noise-creating turbulence. Chevrons were developed by GE under a NASA contract. Some notable examples of such designs are Boeing 787 and Boeing 747-8  – on the Rolls-Royce Trent 1000 and General Electric GEnx engines. Early turbojet engines were not very fuel-efficient because their overall pressure ratio and turbine inlet temperature were severely limited by

11466-428: The turbine inlet temperature is not too high to compensate for the smaller core flow. Future improvements in turbine cooling/material technology can allow higher turbine inlet temperature, which is necessary because of increased cooling air temperature, resulting from an overall pressure ratio increase. The resulting turbofan, with reasonable efficiencies and duct loss for the added components, would probably operate at

11583-476: The two flows may combine within the ducts, and share a common nozzle, which can be fitted with afterburner. Most of the air flow through a high-bypass turbofan is lower-velocity bypass flow: even when combined with the much-higher-velocity engine exhaust, the average exhaust velocity is considerably lower than in a pure turbojet. Turbojet engine noise is predominately jet noise from the high exhaust velocity. Therefore, turbofan engines are significantly quieter than

11700-418: The two. Turbofans are the most efficient engines in the range of speeds from about 500 to 1,000 km/h (270 to 540 kn; 310 to 620 mph), the speed at which most commercial aircraft operate. In a turbojet (zero-bypass) engine, the high temperature and high pressure exhaust gas is accelerated when it undergoes expansion through a propelling nozzle and produces all the thrust. The compressor absorbs

11817-510: The use of two separate exhaust flows. In high bypass engines, the fan is situated in a short duct near the front of the engine and typically has a convergent cold nozzle, with the tail of the duct forming a low pressure ratio nozzle that under normal conditions will choke creating supersonic flow patterns around the core . The core nozzle is more conventional, but generates less of the thrust, and depending on design choices, such as noise considerations, may conceivably not choke. In low bypass engines

11934-433: The wings and allows for a lighter wing structure. This factor becomes more important as aircraft weight increases, and no in-production airliners have both a maximum takeoff weight more than 50 tons and engines mounted on the fuselage. The Antonov An-148 is the only in-production jetliner with high-mounted wings (usually seen in military transport aircraft ), which reduces the risk of damage from unpaved runways. Except for

12051-511: The world, and seating configurations. The Beechcraft 1900 , for example, has only 19 seats. When the Wright brothers made the world's first sustained heavier-than-air flight , they laid the foundation for what would become a major transport industry. Their flight, performed in the Wright Flyer during 1903, was just 11 years before what is often defined as the world's first airliner. By

12168-701: The world, with an experience base of over 10 million service hours. The CF700 turbofan engine was also used to train Moon-bound astronauts in Project Apollo as the powerplant for the Lunar Landing Research Vehicle . A high-specific-thrust/low-bypass-ratio turbofan normally has a multi-stage fan behind inlet guide vanes, developing a relatively high pressure ratio and, thus, yielding a high (mixed or cold) exhaust velocity. The core airflow needs to be large enough to ensure there

12285-447: Was a four-engined low-winged monoplane with a pressurized cabin accommodating 26 passengers and a crew of 5. A nosewheel undercarriage was fitted and four Bristol Taurus radial engines were to power the aircraft. To achieve long range, the aircraft was designed for efficient cruising with the engines at half power. This required careful streamlining, both for the shaping of the fuselage and also for careful surface finishing. Drag

12402-559: Was abandoned with its problems unsolved, as the war situation worsened for Germany. Later in 1943, the British ground tested the Metrovick F.3 turbofan, which used the Metrovick F.2 turbojet as a gas generator with the exhaust discharging into a close-coupled aft-fan module comprising a contra-rotating LP turbine system driving two co-axial contra-rotating fans. Improved materials, and the introduction of twin compressors, such as in

12519-622: Was based on the C-97 Stratofreighter military transport, it had a double deck and a pressurized fuselage. Convair produced the Convair 240 , a 40-person pressurized airplane; 566 examples flew. Convair later developed the Convair 340 , which was slightly larger and could accommodate between 44 and 52 passengers, of which 311 were produced. The firm also commenced work on the Convair 37 , a relatively large double-deck airliner that would have served trans continental routes; however,

12636-660: Was derived from the General Electric J85/CJ610 turbojet 2,850 lbf (12,700 N) to power the larger Rockwell Sabreliner 75/80 model aircraft, as well as the Dassault Falcon 20 , with about a 50% increase in thrust to 4,200 lbf (19,000 N). The CF700 was the first small turbofan to be certified by the Federal Aviation Administration (FAA). There were at one time over 400 CF700 aircraft in operation around

12753-526: Was equipped with much more powerful engines. The main contribution that the Soviets made in regards to airliners was the Antonov An-2 . This plane is a biplane, unlike most of the other airliners, and sold more units than any other transport plane. The most common airliners are the narrow-body aircraft , or single-aisles. The earliest jet airliners were narrowbodies: the initial de Havilland Comet ,

12870-473: Was further adapted into an early bomber aircraft , preceding subsequent transport and bomber aircraft. It first flew on 10 December 1913 and took off for its first demonstration flight with 16 passengers aboard on 25 February 1914. However, it was never used as a commercial airliner due to the onset of the First World War which led to military applications being prioritised. In 1919, shortly after

12987-532: Was in Asia-Pacific with 8,808 (5% stored), followed by 8,572 in North America (10% stored), 7,254 in Europe (9% stored), 2,027 in Latin America, 1,510 in Middle East and 1,347 in Africa. Narrowbody are dominant with 16,235, followed by 5,581 Widebodies, 3,743 Turboprops, 3,565 Regional jets and 399 Others. By the end of 2018, there were 1,826 parked or in storage jetliners out of 29,824 in service (6.1%): 1,434 narrowbodies and 392 widebodies, down from 9.8% of

13104-660: Was named the C-54 Skymaster . Some ex-military DC-6s were later converted into airliners, with both passenger and cargo versions flooding the market shortly after the war's end. Douglas also developed a pressurized version of the DC-4, which it designated the Douglas DC-6 . Rival company Lockheed produced the Constellation , a triple-tailed aircraft with a wider fuselage than the DC-4. The Boeing 377 Stratocruiser

13221-477: Was reduced by the small size of the wings and their high wing loading of 32 lb/sq ft. This would otherwise make the aircraft difficult to handle, especially with a high landing speed, but this was countered by the new development of the Fairey-Youngman flap . The Fairey-Youngman flap was patented in 1941. These flaps were large, around 1/3rd of the wing chord. Their movement went in two phases, controlled by

13338-539: Was superseded for other aircraft by the Fowler flap , which too had an initial parallel movement, although rearward sliding. Fairey did use this flap design for other aircraft though, such as the Fairey Barracuda dive bomber, as the design could be modified to also tilt the extended flap upwards, acting as a dive brake . Charles Richard Fairey is said to have spent at least £1 million out of his own pocket on

13455-480: Was the Airco DH.16 ; a redesigned Airco DH.9A with a wider fuselage to accommodate an enclosed cabin seating four passengers, plus pilot in an open cockpit. In March 1919, the prototype first flew at Hendon Aerodrome . Nine aircraft were built, all but one being delivered to the nascent airline, Aircraft Transport and Travel , which used the first aircraft for pleasure flying, and on 25 August 1919, it inaugurated

13572-587: Was the Tupolev Tu-124 introduced in 1962. It used the Soloviev D-20 . 164 aircraft were produced between 1960 and 1965 for Aeroflot and other Eastern Bloc airlines, with some operating until the early 1990s. The first General Electric turbofan was the aft-fan CJ805-23 , based on the CJ805-3 turbojet. It was followed by the aft-fan General Electric CF700 engine, with a 2.0 bypass ratio. This

13689-452: Was the first French post-war airliner. Accommodating up to 44 seats, 40 aircraft were completed for Air France between October 1945 and April 1948. Air France withdrew the last Languedoc from its domestic routes in 1954, being replaced by later designs. First flying in February 1949, the four-engined Breguet Deux-Ponts was a double-decker transport for passengers and cargo. Air France used it on its busiest routes, including from Paris to

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