Array ( [0] => {{Short description|Means of creating force leading to movement}} [1] => {{Redirect|Powerplant|facilities that generate electricity|Power station|other uses|Power plant (disambiguation)}} [2] => {{more citations needed|date=August 2017}} [3] => [[File:Armadillo Aerospace Pixel Hover.jpg|thumb|[[Armadillo Aerospace]]'s quad [[rocket]] vehicle showing [[shock diamond]]s in the exhaust plume from its propulsion system]] [4] => '''Propulsion''' is the generation of [[force]] by any combination of pushing or pulling to modify the translational [[motion]] of an object, which is typically a [[rigid body]] (or an articulated rigid body) but may also concern a [[fluid]].{{cite book|title=A Dictionary of Aviation |first=David W. |last=Wragg |isbn=0-85045-163-9 |publisher=Frederick Fell, Inc. |publication-place=New York |date=1974 |edition=1st American |page=216}} The term is derived from two Latin words: ''[[wikt:pro|pro]]'', meaning'' before'' or ''forward''; and ''[[wikt:pellere|pellere]]'', meaning ''to drive''.{{cite web| url = http://www.grc.nasa.gov/WWW/k-12/airplane/bgp.html| title = Beginner's Guide to Propulsion NASA}} [5] => A '''propulsion system''' consists of a source of mechanical power, and a ''propulsor'' (means of converting this power into propulsive force). [6] => [7] => Plucking a guitar string to induce a [[vibration|vibratory]] translation is technically a form of propulsion of the guitar string; this is not commonly depicted in this vocabulary, even though human muscles are considered to propel the fingertips. The motion of an object moving through a [[gravitational field]] is affected by the field, and within some frames of reference physicists speak of the gravitational field generating a force upon the object, but for [[general relativity|deep theoretic reasons]], physicists now consider the curved path of an object moving freely through space-time as shaped by gravity as a natural movement of the object, unaffected by a propulsive force (in this view, the falling apple is considered to be unpropelled, while the observer of the apple standing on the ground is considered to be propelled by the reactive force of the Earth's surface). [8] => [9] => [[Biology|Biological]] propulsion systems use an animal's muscles as the power source, and limbs such as [[wing]]s, [[fin]]s or [[leg]]s as the propulsors. A [[technology|technological]] system uses an [[engine|engine or motor]] as the power source (commonly called a '''powerplant'''), and [[wheel and axle|wheels and axles]], [[propeller]]s, or a [[propulsive nozzle]] to generate the force. Components such as [[clutch]]es or [[gearbox]]es may be needed to connect the motor to axles, wheels, or propellers. A technological/biological system may use human, or trained animal, muscular work to power a mechanical device. [10] => [11] => Small objects, such as [[bullet]]s, propelled at high speed are known as [[projectile]]s; larger objects propelled at high speed, often into [[ballistic flight]], are known as [[rocket]]s or [[missile]]s. [12] => [13] => Influencing rotational motion is also technically a form of propulsion, but in speech, an automotive mechanic might prefer to describe the hot gasses in an engine cylinder as propelling the piston (translational motion), which ''drives'' the crankshaft (rotational motion), the crankshaft then ''drives'' the wheels (rotational motion), and the wheels propel the car forward (translational motion). In common speech, propulsion is associated with spatial displacement more strongly than locally contained forms of motion, such as rotation or vibration. As another example, internal stresses in a [[rotation|rotating]] [[Baseball (ball)|baseball]] cause the surface of the baseball to travel along a sinusoidal or helical trajectory, which would not happen in the absence of these interior forces; these forces meet the technical definition of propulsion from [[Newtonian mechanics]], but are not commonly spoken of in this language. [14] => [15] => == Vehicular propulsion == [16] => [17] => ===Air propulsion=== [18] => {{main|Powered aircraft}} [19] => [[File:Tupolev Tu-95 in flight.jpg|thumb|left|A [[turboprop]]-engined [[Tupolev Tu-95]] ]] [20] => [21] => An aircraft propulsion system generally consists of an [[aircraft engine]] and some means to generate thrust, such as a [[propeller (aircraft)|propeller]] or a [[propulsive nozzle]]. [22] => [23] => An aircraft propulsion system must achieve two things. First, the thrust from the propulsion system must balance the drag of the airplane when the airplane is cruising. And second, the thrust from the propulsion system must exceed the drag of the airplane for the airplane to accelerate. The greater the difference between the thrust and the drag, called the excess thrust, the faster the airplane will accelerate. [24] => [25] => Some [[aircraft]], like airliners and [[cargo planes]], spend most of their life in a cruise condition. For these airplanes, excess thrust is not as important as high engine efficiency and low fuel usage. Since thrust depends on both the amount of gas moved and the velocity, we can generate high thrust by accelerating a large mass of gas by a small amount, or by accelerating a small mass of gas by a large amount. Because of the aerodynamic efficiency of propellers and fans, it is more fuel efficient to accelerate a large mass by a small amount, which is why high-bypass turbofans and turboprops are commonly used on cargo planes and airliners. [26] => [27] => Some aircraft, like [[fighter planes]] or experimental high speed aircraft, require very high excess thrust to accelerate quickly and to overcome the high drag associated with high speeds. For these airplanes, engine efficiency is not as important as very high thrust. Modern [[combat aircraft]] usually have an afterburner added to a [[low bypass turbofan]]. Future [[hypersonic aircraft]] may use some type of ramjet or rocket propulsion. [28] => [29] => ===Ground=== [30] => [[File:Opel Ampera (front quarter).jpg|thumb|Wheels are commonly used in ground propulsion]] [31] => {{main|Ground propulsion}} [32] => Ground propulsion is any mechanism for propelling solid bodies along the ground, usually for the purposes of [[transportation]]. The propulsion system often consists of a combination of an [[engine|engine or motor]], a [[gearbox]] and [[wheel and axle]]s in standard applications. [33] => [34] => ===Maglev=== [35] => [[File:Transrapid-emsland.jpg|thumb|[[Transrapid]] 09 at the [[Emsland test facility]] in [[Germany]]]] [36] => {{main|Maglev}} [37] => Maglev (derived from '''mag'''netic '''lev'''itation) is a system of transportation that uses [[magnetic levitation]] to suspend, guide and propel vehicles with magnets rather than using mechanical methods, such as [[wheel and axle|wheels, axles and bearings]]. With maglev a vehicle is levitated a short distance away from a guide way using magnets to create both lift and thrust. Maglev vehicles are claimed to move more smoothly and quietly and to require less maintenance than wheeled [[mass transit]] systems. It is claimed that non-reliance on friction also means that acceleration and deceleration can far surpass that of existing forms of transport. The power needed for levitation is not a particularly large percentage of the overall energy consumption; most of the power used is needed to overcome air resistance ([[drag (physics)|drag]]), as with any other high-speed form of transport. [38] => [39] => ===Marine=== [40] => [[Image:Two Main Engines, V12.jpg|thumb|250px|A view of a ship's engine room]] [41] => {{main|Marine propulsion}} [42] => Marine propulsion is the mechanism or system used to generate [[thrust]] to move a [[ship]] or [[boat]] across water. While [[paddle]]s and [[sail]]s are still used on some smaller boats, most modern ships are propelled by mechanical systems consisting of a motor or engine turning a [[propeller]], or less frequently, in jet drives, an [[impeller]]. Marine engineering is the discipline concerned with the design of marine [[propulsion system]]s. [43] => [44] => [[Steam engine]]s were the first mechanical engines used in marine propulsion, but have mostly been replaced by [[two-stroke engine|two-stroke]] or [[four-stroke engine|four-stroke]] diesel engines, outboard motors, and [[gas turbine engine]]s on faster ships. [[nuclear marine propulsion|Nuclear reactors]] producing steam are used to propel [[warship]]s and [[icebreaker]]s, and there have been attempts to utilize them to power commercial vessels. [[Electric motor]]s have been used on [[submarine]]s and [[electric boat]]s and have been proposed for energy-efficient propulsion.{{cite web |url=http://www.ivt.ntnu.no/imt/electricship/ |title=Energy Efficient - All Electric Ship |access-date=2009-11-25 |url-status=dead |archive-url=https://web.archive.org/web/20090517060017/http://www.ivt.ntnu.no/imt/electricship/ |archive-date=2009-05-17 }} Recent development in liquified natural gas (LNG) fueled engines are gaining recognition for their low emissions and cost advantages. [45] => [46] => ===Space=== [47] => [[Image:Shuttle Main Engine Test Firing.jpg|thumb|left|A remote camera captures a close-up view of a [[Space Shuttle main engine]] during a test firing at the [[John C. Stennis Space Center]] in [[Hancock County, Mississippi]]]] [48] => {{main|Spacecraft propulsion}} [49] => [50] => Spacecraft propulsion is any method used to accelerate [[spacecraft]] and artificial [[satellite]]s. There are many different methods. Each method has drawbacks and advantages, and spacecraft propulsion is an active area of research. However, most spacecraft today are propelled by forcing a gas from the back/rear of the vehicle at very high speed through a [[rocket engine nozzle|supersonic de Laval nozzle]]. This sort of [[engine]] is called a [[rocket engine]]. [51] => [52] => All current spacecraft use chemical rockets ([[bipropellant rocket|bipropellant]] or [[solid rocket|solid-fuel]]) for launch, though some (such as the [[Pegasus rocket]] and [[SpaceShipOne]]) have used [[air-breathing engine]]s on their [[Multistage rocket|first stage]]. Most satellites have simple reliable chemical thrusters (often [[monopropellant rocket]]s) or [[resistojet rocket]]s for [[orbital station-keeping]] and some use [[momentum wheel]]s for [[Spacecraft attitude control|attitude control]]. Soviet bloc satellites have used [[Electrically powered spacecraft propulsion|electric propulsion]] for decades, and newer Western geo-orbiting spacecraft are starting to use them for north–south stationkeeping and orbit raising. Interplanetary vehicles mostly use chemical rockets as well, although a few have used [[ion thruster]]s and [[Hall-effect thruster]]s (two different types of electric propulsion) to great success. [53] => {{clear}} [54] => [55] => ===Cable=== [56] => {{main|Cable car (railway)}} [57] => A cable car is any of a variety of transportation systems relying on cables to pull vehicles along or lower them at a steady rate. The terminology also refers to the vehicles on these systems. The cable car vehicles are motor-less and engine-less and they are pulled by a cable that is rotated by a motor off-board. [58] => [59] => ==Animal== [60] => {{main|Animal locomotion}} [61] => [[Image:Beeinflightfromfront.jpg|thumb|upright=1.3|A [[bee]] in flight]] [62] => [63] => Animal locomotion, which is the act of self-propulsion by an animal, has many manifestations, including [[running]], [[aquatic locomotion|swimming]], [[jumping]] and [[Flying and gliding animals|flying]]. Animals move for a variety of reasons, such as to find food, a mate, or a suitable [[microhabitat]], and to escape predators. For many animals the ability to move is essential to survival and, as a result, selective pressures have shaped the locomotion methods and mechanisms employed by moving organisms. For example, migratory animals that travel vast distances (such as the [[Arctic tern]]) typically have a locomotion mechanism that costs very little energy per unit distance, whereas non-migratory animals that must frequently move quickly to escape predators (such as [[frog]]s) are likely to have costly but very fast locomotion. The study of animal locomotion is typically considered to be a sub-field of [[biomechanics]]. [64] => [65] => Locomotion requires [[energy]] to overcome [[friction]], [[drag (physics)|drag]], [[inertia]], and [[gravity]], though in many circumstances some of these factors are negligible. In [[Terrestrial planet|terrestrial]] environments gravity must be overcome, though the drag of air is much less of an issue. In aqueous environments however, friction (or drag) becomes the major challenge, with gravity being less of a concern. Although animals with natural [[buoyancy]] need not expend much energy maintaining vertical position, some will naturally sink and must expend energy to remain afloat. Drag may also present a problem in [[flight]], and the [[aerodynamic]]ally efficient body shapes of [[bird]]s highlight this point. Flight presents a different problem from movement in water however, as there is no way for a living organism to have lower [[density]] than air. Limbless organisms moving on land must often contend with surface friction, but do not usually need to expend significant energy to counteract gravity. [66] => [67] => [[Newton's laws of motion|Newton's third law of motion]] is widely used in the study of animal locomotion: if at rest, to move forward an animal must push something backward. Terrestrial animals must push the solid ground; swimming and flying animals must push against a [[fluid]] (either [[water]] or [[air]]).{{Cite book |last=Biewener |first=Andrew A. |url=https://books.google.com/books?id=yMaN9pk8QJAC&q=biomechanics+biewener |title=Animal Locomotion |date=2003-06-19 |publisher=OUP Oxford |isbn=978-0-19-850022-3 |language=en}} The effect of forces during locomotion on the design of the skeletal system is also important, as is the interaction between locomotion and muscle physiology, in determining how the structures and effectors of locomotion enable or limit animal movement. [68] => [69] => ==See also== [70] => * [[Jetpack]] [71] => * [[Transport]] [72] => [73] => ==References== [74] => {{reflist}} [75] => [76] => ==External links== [77] => *{{Commons category-inline|Propulsion}} [78] => {{wiktionary|propulsion}} [79] => * {{cite web|last=Pickering|first=Steve|title=Propulsion Efficiency|url=http://www.sixtysymbols.com/videos/propulsion.htm|work=Sixty Symbols|publisher=[[Brady Haran]] from the [[University of Nottingham]]|year=2009}} [80] => [81] => {{Authority control}} [82] => [83] => [[Category:Propulsion| ]] [84] => [[Category:Vehicle technology]] [] => )
good wiki

Propulsion

Propulsion is the generation of force by any combination of pushing or pulling to modify the translational motion of an object, which is typically a rigid body (or an articulated rigid body) but may also concern a fluid. The term is derived from two Latin words: pro, meaning before or forward; and pellere, meaning to drive.

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