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Aircraft Noise
Aircraft noise pollution refers to noise produced by aircraft in flight that has been associated with several negative stress-mediated health effects, from sleep disorders to cardiovascular disorders. Governments have enacted extensive controls that apply to aircraft designers, Aerospace manufacturer, manufacturers, and operators, resulting in improved procedures and cuts in pollution. Mechanisms of sound pollution Aircraft noise is noise pollution produced by an aircraft or its components, whether on the ground while parked such as auxiliary power units, while taxiing, on run-up from propeller and jet exhaust, during takeoff, underneath and lateral to departure and arrival paths, over-flying while en route, or during landing. A moving aircraft including the jet engine or Propeller (aircraft), propeller causes Compression (physics), compression and rarefaction of the air, producing motion of air molecules. This movement propagates through the air as pressure waves. If these p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Supersonic Speed
Supersonic speed is the speed of an object that exceeds the speed of sound (Mach number, Mach 1). For objects traveling in dry air of a temperature of 20 °C (68 °F) at sea level, this speed is approximately . Speeds greater than five times the speed of sound (Mach 5) are often referred to as hypersonic. Flights during which only some parts of the air surrounding an object, such as the ends of rotor blades, reach supersonic speeds are called transonic. This occurs typically somewhere between Mach 0.8 and Mach 1.2. Sounds are traveling vibrations in the form of pressure waves in an elastic medium. Objects move at supersonic speed when the objects move faster than the speed at which sound propagates through the medium. In gases, sound travels longitudinally at different speeds, mostly depending on the molecular mass and temperature of the gas, and pressure has little effect. Since air temperature and composition varies significantly with altitude, th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mitsubishi MRJ
The Mitsubishi SpaceJet (, originally named ''Mitsubishi Regional Jet'') was a regional jet project by Japanese company Mitsubishi Aircraft Corporation (MAC), a Mitsubishi Heavy Industries (MHI) subsidiary. MHI first announced the concept in June 2007, then targeting certification for 2012, as the first Japanese airliner since the 1962 NAMC YS-11. After a delayed development, the maiden flight of the MRJ90 took place on 11 November 2015. In June 2019, Mitsubishi rebranded the Mitsubishi Regional Jet (MRJ, ) program as the SpaceJet. As flight testing took longer than expected, the scheduled entry into service was further pushed back until development was first paused in October 2020, and subsequently cancelled altogether in February 2023. The airframe was made mainly in aluminium with a carbon fibre composite empennage. The low-wing twinjet was powered by underwing Pratt & Whitney PW1000Gs, and was the first program to select the geared turbofan. The M90 (originally named MR ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bombardier CSeries
The Airbus A220 is a family of five-abreast narrow-body airliners by Airbus Canada Limited Partnership (ACLP). It was originally developed by Bombardier Aviation and had two years in service as the Bombardier CSeries. The program was launched on 13 July 2008. The smaller A220-100 (formerly CS100) Maiden flight, first flew on 16 September 2013, received an initial type certificate from Transport Canada on 18 December 2015, and entered service on 15 July 2016 with launch operator Swiss Global Air Lines. The longer A220-300 (formerly CS300) first flew on 27 February 2015, received an initial type certificate on 11 July 2016, and entered service with airBaltic on 14 December 2016. Both launch operators recorded better-than-expected fuel burn and dispatch reliability, as well as positive feedback from passengers and crew. In July 2018, the aircraft was rebranded as the A220 after Airbus acquired a majority stake in the programme through a joint venture that became ACLP in June 20 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pratt & Whitney PW1000G
The Pratt & Whitney PW1000G family, also marketed as the Pratt & Whitney GTF (geared turbofan), is a family of high-bypass geared turbofan engines produced by Pratt & Whitney. The various models can generate 15,000 to 33,000 Pound (force), pounds-force (67 to 147 Newton (unit), kilonewtons) of thrust. As of 2025, they are used on the Airbus A220, Airbus A320neo family, and Embraer E-Jet E2. They were also used on new Yakovlev MC-21, Yakovlev MC-21s until exports to Russia were stopped as part of the International sanctions during the Russian invasion of Ukraine, international sanctions during the invasion of Ukraine. Following years of development and testing on various demonstrators, the program officially launched in 2008 with the PW1200G destined for the later-canceled Mitsubishi SpaceJet. The first successful flight test occurred later that year. The PW1500G variant, designed for the A220, became the first certified engine in 2013. P&W is estimated to have spent $10 billion to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Turbofan
A turbofan or fanjet is a type of airbreathing jet engine that is widely used in aircraft engine, 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 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 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 Propel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Line Source
A line source, as opposed to a point source, area source, or volume source, is a source of air, noise, water contamination or electromagnetic radiation that emanates from a linear (one-dimensional) geometry. The most prominent linear sources are roadway air pollution, aircraft air emissions, roadway noise, certain types of water pollution sources that emanate over a range of river extent rather than from a discrete point, elongated light tubes, certain dose models in medical physics and electromagnetic antennas. While point sources of pollution were studied since the late nineteenth century, linear sources did not receive much attention from scientists until the late 1960s, when environmental regulations for highways and airports began to emerge. At the same time, computers with the processing power to accommodate the data processing needs of the computer models required to tackle these one-dimensional sources became more available. In addition, this era of the 1960s saw ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computer Model
Computer simulation is the running of a mathematical model on a computer, the model being designed to represent the behaviour of, or the outcome of, a real-world or physical system. The reliability of some mathematical models can be determined by comparing their results to the real-world outcomes they aim to predict. Computer simulations have become a useful tool for the mathematical modeling of many natural systems in physics (computational physics), astrophysics, climatology, chemistry, biology and manufacturing, as well as human systems in economics, psychology, social science, health care and engineering. Simulation of a system is represented as the running of the system's model. It can be used to explore and gain new insights into new technology and to estimate the performance of systems too complex for analytical solutions. Computer simulations are realized by running computer programs that can be either small, running almost instantly on small devices, or large-scale p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tail Rotor
The tail rotor is a smaller rotor mounted vertically or near-vertically at the tail of a traditional single-rotor helicopter, where it rotates to generate a propeller-like horizontal thrust in the same direction as the main rotor's rotation. The tail rotor's position and distance from the helicopter's center of mass allow it to develop enough thrust leverage to counter the reactional torque exerted on the fuselage by the spinning of the main rotor. Without the tail rotor or other anti-torque mechanisms (e.g. NOTAR), the helicopter would be constantly spinning in the opposite direction of the main rotor when flying. Tail rotors are simpler than main rotors since they require only collective changes in pitch to vary thrust. The pitch of the tail rotor blades is adjustable by the pilot via the anti-torque pedals, which also provide directional control by allowing the pilot to rotate the helicopter around its vertical axis. Its drive system consists of a shaft powered from ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Helicopter Rotor
On a helicopter, the main rotor or rotor system is the combination of several rotary wings (rotor blades) with a control system, that generates the aerodynamic lift (force), lift force that supports the weight of the helicopter, and the thrust that counteracts aerodynamic drag in forward flight. Each main rotor is mounted on a vertical mast over the top of the helicopter, as opposed to a helicopter tail rotor, which connects through a combination of drive shaft(s) and gearboxes along the tail boom. The blade pitch is typically controlled by the pilot using the helicopter flight controls. Helicopters are one example of rotary-wing aircraft (rotorcraft). The name is derived from the Greek words ''helix'', helik-, meaning spiral; and ''pteron'' meaning wing. Design principles Overview The helicopter rotor is powered by the engine, through the transmission, to the rotating mast. The mast is a cylindrical metal shaft that extends upward from—and is driven by—the transmission. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aerodynamics
Aerodynamics () is the study of the motion of atmosphere of Earth, air, particularly when affected by a solid object, such as an airplane wing. It involves topics covered in the field of fluid dynamics and its subfield of gas dynamics, and is an important domain of study in aeronautics. The term ''aerodynamics'' is often used synonymously with gas dynamics, the difference being that "gas dynamics" applies to the study of the motion of all gases, and is not limited to air. The formal study of aerodynamics began in the modern sense in the eighteenth century, although observations of fundamental concepts such as aerodynamic drag were recorded much earlier. Most of the early efforts in aerodynamics were directed toward achieving Aircraft#Heavier-than-air – aerodynes, heavier-than-air flight, which was first demonstrated by Otto Lilienthal in 1891. Since then, the use of aerodynamics through mathematical analysis, empirical approximations, wind tunnel experimentation, and computer si ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Noise Research Program On Hangar Apron - GPN-2000-001457
Noise is sound, chiefly unwanted, unintentional, or harmful sound considered unpleasant, loud, or disruptive to mental or hearing faculties. From a physics standpoint, there is no distinction between noise and desired sound, as both are vibrations through a medium, such as air or water. The difference arises when the brain receives and perceives a sound. Acoustic noise is any sound in the acoustic domain, either deliberate (e.g., music or speech) or unintended. In contrast, Noise (electronics), noise in electronics may not be audible to the human ear and may require instruments for detection. In audio engineering, noise can refer to the unwanted residual electronic noise signal that gives rise to acoustic noise heard as a Hiss (electromagnetic), hiss. This signal noise is commonly measured using A-weighting or ITU-R 468 weighting. In experimental sciences, noise can refer to any random fluctuations of data that hinders perception of a signal. Measurement Sound is measured bas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
