Overall Pressure Ratio
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Overall Pressure Ratio
In aeronautical engineering, overall pressure ratio, or overall compression ratio, is the ratio of the stagnation pressure as measured at the front and rear of the compressor of a gas turbine engine. The terms ''compression ratio'' and ''pressure ratio'' are used interchangeably. Overall compression ratio also means the ''overall cycle pressure ratio'' which includes intake ram. History of overall pressure ratios Early jet engines had limited pressure ratios due to construction inaccuracies of the compressors and various material limits. For instance, the Junkers Jumo 004 from World War II had an overall pressure ratio 3.14:1. The immediate post-war Snecma Atar improved this marginally to 5.2:1. Improvements in materials, compressor blades, and especially the introduction of multi-spool engines with several different rotational speeds, led to the much higher pressure ratios common today. Modern civilian engines generally operate between 40 and 55:1. The highest in-service is th ...
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Aeronautical Engineering
Aerospace engineering is the primary field of engineering concerned with the development of aircraft and spacecraft. It has two major and overlapping branches: Aeronautics, aeronautical engineering and Astronautics, astronautical engineering. Avionics engineering is similar, but deals with the electronic engineering, electronics side of aerospace engineering. "Aeronautical engineering" was the original term for the field. As flight technology advanced to include vehicles operating in outer space, the broader term "aerospace engineering" has come into use. Aerospace engineering, particularly the astronautics branch, is often colloquially referred to as "rocket science". Overview Flight vehicles are subjected to demanding conditions such as those caused by changes in atmospheric pressure and temperature, with structural loads applied upon vehicle components. Consequently, they are usually the products of various technological and engineering disciplines including aerodynamics, A ...
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Pratt & Whitney TF30
The Pratt & Whitney TF30 (company designation JTF10A) is a military low-bypass turbofan engine originally designed by Pratt & Whitney for the subsonic F6D Missileer fleet defense fighter, but this project was cancelled. It was later adapted with an afterburner for supersonic designs, and in this form it was the world's first production afterburning turbofan, going on to power the F-111 and the F-14A Tomcat, as well as being used in early versions of the A-7 Corsair II without an afterburner. First flight of the TF30 was in 1964 and production continued until 1986. Design and development In 1958, the Douglas Aircraft Company proposed a short-range, four-engined jet airliner to fill the gap below its new DC-8 intercontinental, known internally as the Model 2067. Intended to be marketed as DC-9, it was not directly related to the later twin-engined Douglas DC-9.Connors 2010, p. 341 Pratt & Whitney (P&W) had offered its JT8A turbojet for the airliner, but Douglas preferred to go wi ...
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McDonnell Douglas MD-11
The McDonnell Douglas MD-11 is an American tri-jet wide-body airliner manufactured by American McDonnell Douglas (MDC) and later by Boeing. Following DC-10 development studies, the MD-11 program was launched on December 30, 1986. Assembly of the first prototype began on March 9, 1988. It rolled out in September 1989 and made its maiden flight on January 10, 1990. FAA certification was achieved on November 8. The first delivery was to Finnair on December 7, 1990, and it entered service on December 20. It retains the basic trijet configuration of the DC-10 with updated GE CF6-80C2 or PW4000 turbofan engines. It has a slightly wider wing with winglets, and its MTOW was increased by % to . Its fuselage is stretched by % to to accommodate 298 passengers in three classes over a range of up to . It features a glass cockpit that eliminates the need for a flight engineer. The MD-11 failed to meet its range and fuel burn targets. The last of 200 aircraft was built in October 2000 af ...
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Airbus A300
The Airbus A300 is a wide-body airliner developed and manufactured by Airbus. In September 1967, aircraft manufacturers in the United Kingdom, France, and West Germany signed a memorandum of understanding to develop a large airliner. West Germany and France reached an agreement on 29 May 1969 after the British withdrew from the project on 10 April 1969. European collaborative aerospace manufacturer Airbus Industrie was formally created on 18 December 1970 to develop and produce it. The prototype first flew on 28 October 1972. The first twin-engine widebody airliner, the A300 typically seats 247 passengers in two classes over a range of 5,375 to 7,500 km (2,900 to 4,050 nmi). Initial variants are powered by General Electric CF6-50 or Pratt & Whitney JT9D turbofans and have a three-crew flight deck. The improved A300-600 has a two-crew cockpit and updated CF6-80C2 or PW4000 engines; it made its first flight on 8 July 1983 and entered service later that year. The A ...
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Boeing 767
The Boeing 767 is an American wide-body aircraft developed and manufactured by Boeing Commercial Airplanes. The aircraft was launched as the 7X7 program on July 14, 1978, the prototype first flew on September 26, 1981, and it was certified on July 30, 1982. The original 767-200 entered service on September 8, 1982, with United Airlines, and the extended-range 767-200ER in 1984. It was stretched into the in October 1986, followed by the 767-300ER in 1988, the most popular variant. The 767-300F, a production Cargo aircraft, freighter version, debuted in October 1995. It was stretched again into the 767-400ER from September 2000. To complement the larger Boeing 747, 747, it has a seven-abreast cross-section, accommodating smaller LD2 unit load device, ULD cargo containers. The 767 is Boeing's first wide-body twinjet, powered by General Electric CF6, Rolls-Royce RB211, or Pratt & Whitney JT9D turbofans. JT9D engines were eventually replaced by Pratt & Whitney PW4000, PW4000 engi ...
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Boeing 747
The Boeing 747 is a large, long-range wide-body airliner designed and manufactured by Boeing Commercial Airplanes in the United States between 1968 and 2022. After introducing the 707 in October 1958, Pan Am wanted a jet times its size, to reduce its seat cost by 30%. In 1965, Joe Sutter left the 737 development program to design the 747, the first twin-aisle airliner. In April 1966, Pan Am ordered 25 Boeing 747-100 aircraft and in late 1966, Pratt & Whitney agreed to develop the JT9D engine, a high-bypass turbofan. On September 30, 1968, the first 747 was rolled out of the custom-built Everett Plant, the world's largest building by volume. The first flight took place on February 9, 1969, and the 747 was certified in December of that year. It entered service with Pan Am on January 22, 1970. The 747 was the first airplane dubbed "Jumbo Jet", the first wide-body airliner. The 747 is a four-engined jet aircraft, initially powered by Pratt & Whitney JT9D turbofan engin ...
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General Electric CF6
The General Electric CF6, US military designations F103 and F138, is a family of high-bypass turbofan engines produced by GE Aviation. Based on the TF39, the first high-power high-bypass jet engine, the CF6 powers a wide variety of civilian airliners. The basic engine core also powers the LM2500 and LM6000 marine and power generation turboshafts. It is gradually being replaced by the newer GEnx family. Development After developing the TF39 for the C-5 Galaxy in the late 1960s, GE offered a more powerful variant for civilian use, the CF6, and quickly found interest in two designs being offered for a recent Eastern Airlines contract, the Lockheed L-1011 and the McDonnell Douglas DC-10. Lockheed eventually selected the Rolls-Royce RB211, but the latter stuck with the CF6 and entered service in 1971. It was also selected for versions of the Boeing 747. Since then, the CF6 has powered versions of the Airbus A300, A310 and A330, Boeing 767, and McDonnell Douglas MD-11. The high b ...
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Boeing 777
The Boeing 777, commonly referred to as the Triple Seven, is an American long-range wide-body airliner developed and manufactured by Boeing Commercial Airplanes. It is the world's largest twinjet. The 777 was designed to bridge the gap between Boeing's other wide body airplanes, the twin-engined 767 and quad-engined 747, and to replace older DC-10s and L-1011 trijets. Developed in consultation with eight major airlines, with a first meeting in January 1990, the program was launched in October, with an order from United Airlines. The prototype was rolled out in April 1994, and first flew in June. The 777 entered service with the launch customer, United Airlines, in June 1995. Longer range variants were launched in 2000, and were first delivered in 2004. It can accommodate a ten–abreast seating layout and has a typical 3-class capacity of 301 to 368 passengers, with a range of . It is recognizable for its large-diameter turbofan engines, six wheels on each main landing g ...
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General Electric GE90
The General Electric GE90 is a family of high-bypass turbofan aircraft engines built by GE Aviation for the Boeing 777, with thrust ratings from . It entered service with British Airways in November 1995. It is one of three options for the 777-200, -200ER, and -300 versions, and the exclusive engine of the -200LR, -300ER, and 777F. It was the largest jet engine, until being surpassed in January 2020 by its successor, the GE9X, which has a larger diameter fan. The GE90, however, is still more powerful than its successor, the GE9X. Development The GE90 was developed from the NASA 1970s Energy Efficient Engine, a prototype variant of the General Electric CF6. GE's GE36 Un-Ducted Fan (propfan) was meant to replace the CFM International CFM56 high-bypass turbofan which was initially uncompetitive against the rival IAE V2500. However, when the V2500 ran into technical problems, sales of the CFM56 took off. GE was not interested in having the GE36 cannibalize the CFM56, and whil ...
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Airbus A350 XWB
The Airbus A350 is a flight length, long-range, wide-body aircraft, wide-body twinjet, twin-engine jet airliner developed and produced by Airbus Commercial Aircraft, Airbus. The first A350 design proposed by Airbus in 2004, in response to the Boeing 787 Dreamliner, would have been a development of the Airbus A330, A330 with composite wings and new engines. As market support was inadequate, in 2006, Airbus switched to a clean-sheet "XWB" (eXtra Wide Body) design, powered by two Rolls-Royce Trent XWB turbofan engines. The prototype first flew on 14 June 2013 from Toulouse in France. Type certification from the European Aviation Safety Agency (EASA) was obtained in September 2014, followed by certification from the Federal Aviation Administration (FAA) two months later. The A350 is the first Airbus aircraft largely made of carbon-fiber-reinforced polymers. It has a new fuselage designed around a nine-abreast economy cross-section, up from the eight-abreast A330/A340. It has a ...
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Rolls-Royce Trent XWB
The Rolls-Royce Trent XWB is a high bypass turbofan produced by Rolls-Royce plc. In July 2006, the Trent XWB was selected to power exclusively the Airbus A350. The first engine was run on 14 June 2010, it first flew on an A380 testbed on 18 February 2012, it was certified in early 2013, and it first flew on an A350 on 14 June 2013. It had its first in-flight shutdown on 11 September 2018 as the fleet accumulated 2.2 million flight hours. It keeps the characteristic three-shaft layout of the Rolls-Royce Trent, with a 3.00 m (118 in) fan, an IP and HP spool. The engine has a 9.6:1 Bypass ratio and a 50:1 Pressure ratio. It is the most powerful among the Trent family. Development By 2004 Airbus had been facing pressure from customers to develop a competitor to the Boeing 787 Dreamliner, then in October 2005 launched the A350, at the time an improved A330. Rolls-Royce initially offered a conventional bleed air engine variant of the Trent 1000 with a throttle-push to st ...
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Boeing 777X
The Boeing 777X is the latest series of the long-range, wide-body, twin-engine jetliners in the Boeing 777 family from Boeing Commercial Airplanes. The 777X features new GE9X engines, new composite wings with folding wingtips, greater cabin width and seating capacity, and technologies from the Boeing 787. The 777X was launched in November 2013 with two variants: the 777-8 and the 777-9. The 777-8 provides seating for 384 passengers and has a range of 8,730 nmi (16,170 km) while the 777-9 has seating for 426 passengers and a range of over 7,285 nmi (13,500 km). The 777X program was proposed in the early 2010s with assembly at the Boeing Everett Factory and the wings built at a new building adjacent to the Everett factory. , there are 341 total orders for the 777X passenger and freighter versions from eight identified customers and other buyers. The 777-9 first flew on January 25, 2020, with deliveries delayed multiple times and expected to commence in 2025. ...
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