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51-495: Slats are high-lift devices typically used on aircraft intended to operate within a wide range of speeds. Trailing-edge flap systems running along the trailing edge of the wing are common on all aircraft. Types include: The chord of the slat is typically only a few percent of the wing chord. The slats may extend over the outer third of the wing, or they may cover the entire leading edge . Many early aerodynamicists, including Ludwig Prandtl , believed that slats work by inducing

102-522: A circle. Buridan's theory was followed up by his pupil Albert of Saxony (1316–1390) and the Oxford Calculators , who performed various experiments which further undermined the Aristotelian model. Their work in turn was elaborated by Nicole Oresme who pioneered the practice of illustrating the laws of motion with graphs. Shortly before Galileo's theory of inertia, Giambattista Benedetti modified

153-422: A fixed component, or a movable mechanism which is deployed when required. Common movable high-lift devices include wing flaps and slats . Fixed devices include leading-edge slots , leading edge root extensions , and boundary layer control systems. The size and lifting capacity of a fixed wing is chosen as a compromise between differing requirements. For example, a larger wing will provide more lift and reduce

204-421: A heavy body on a spherical surface concentric with the earth will maintain itself in that state in which it has been; if placed in a movement towards the west (for example), it will maintain itself in that movement." This notion, which is termed "circular inertia" or "horizontal circular inertia" by historians of science, is a precursor to, but is distinct from, Newton's notion of rectilinear inertia. For Galileo,

255-421: A high energy stream to the flow of the main airfoil , thus re-energizing its boundary layer and delaying stall. In reality, the slat does not give the air in the slot a high velocity (it actually reduces its velocity) and also it cannot be called high-energy air since all the air outside the actual boundary layers has the same total heat . The actual effects of the slat are: The slat has a counterpart found in

306-459: A leading edge extension (LEX). A LERX typically consist of a small triangular fillet attached to the wing leading edge root and to the fuselage. In normal flight the LERX generates little lift. At higher angles of attack, however, it generates a vortex that is positioned to lie on the upper surface of the main wing. The swirling action of the vortex increases the speed of airflow over the wing, so reducing

357-449: A mechanism that ejects air backwards over a specially designed airfoil to create lift through the Coandă effect . The Blackburn Buccaneer had a sophisticated boundary layer control (BLC) system which involved compressor air blown onto the wings and tailplane to reduce the stalling speed and facilitate operations from smaller aircraft carriers. Another approach is to use the airflow from

408-454: A motion is " horizontal " if it does not carry the moving body towards or away from the center of the Earth, and for him, "a ship, for instance, having once received some impetus through the tranquil sea, would move continually around our globe without ever stopping." It is also worth noting that Galileo later (in 1632) concluded that based on this initial premise of inertia, it is impossible to tell

459-438: A patent challenge, they reached an ownership agreement with Lachmann. That year, an Airco DH.9 was fitted with slats and test flown. Later, an Airco DH.9A was modified as a monoplane with a large wing fitted with full-span leading edge slats and trailing-edge ailerons (i.e. what would later be called trailing-edge flaps) that could be deployed in conjunction with the leading-edge slats to test improved low-speed performance. This

510-441: A physical consequence of Descartes ' geometrization of space-matter, combined with the immutability of God." The first physicist to completely break away from the Aristotelian model of motion was Isaac Beeckman in 1614. The term "inertia" was first introduced by Johannes Kepler in his Epitome Astronomiae Copernicanae (published in three parts from 1617 to 1621). However, the meaning of Kepler's term, which he derived from

561-435: A right line, except insofar as it is compelled to change that state by forces impressed thereon. In his 1687 work Philosophiæ Naturalis Principia Mathematica , Newton defined inertia as a property: DEFINITION III. The vis insita , or innate force of matter, is a power of resisting by which every body, as much as in it lies, endeavours to persevere in its present state, whether it be of rest or of moving uniformly forward in

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612-525: A right line, unless it is compelled to change that state by forces impressed thereon. Despite having defined the concept in his laws of motion, Newton did not actually use the term "inertia.” In fact, he originally viewed the respective phenomena as being caused by "innate forces" inherent in matter which resist any acceleration. Given this perspective, and borrowing from Kepler, Newton conceived of "inertia" as "the innate force possessed by an object which resists changes in motion", thus defining "inertia" to mean

663-590: A right line. Professor John H. Lienhard points out the Mozi – based on a Chinese text from the Warring States period (475–221 BCE) – as having given the first description of inertia. Before the European Renaissance , the prevailing theory of motion in western philosophy was that of Aristotle (384–322 BCE). On the surface of the Earth, the inertia property of physical objects is often masked by gravity and

714-410: A wing surface can change shape in flight to deflect air flow. The X-53 Active Aeroelastic Wing is a NASA effort. The adaptive compliant wing is a military and commercial effort. High-lift device In aircraft design and aerospace engineering , a high-lift device is a component or mechanism on an aircraft's wing that increases the amount of lift produced by the wing. The device may be

765-413: Is rotational inertia (→ moment of inertia ), the property that a rotating rigid body maintains its state of uniform rotational motion. Its angular momentum remains unchanged unless an external torque is applied; this is called conservation of angular momentum. Rotational inertia is often considered in relation to a rigid body. For example, a gyroscope uses the property that it resists any change in

816-491: Is any movement of a body that is not affected by forces of electrical, magnetic, or other origin, but that is only under the influence of gravitational masses. Physically speaking, this happens to be exactly what a properly functioning three-axis accelerometer is indicating when it does not detect any proper acceleration . The term inertia comes from the Latin word iners , meaning idle or sluggish. A quantity related to inertia

867-414: Is the gap between the slat and the wing. The slat may be fixed in position, with a slot permanently in place behind it, or it may be retractable so that the slot is closed when not required. If it is fixed, then it may appear as a normal part of the leading edge of a wing, with the slot buried in the wing surface immediately behind it. A slat or slot may be either full-span, or may be placed on only part of

918-418: Is today. The principle of inertia, as formulated by Aristotle for "motions in a void", includes that a mundane object tends to resist a change in motion. The Aristotelian division of motion into mundane and celestial became increasingly problematic in the face of the conclusions of Nicolaus Copernicus in the 16th century, who argued that the Earth is never at rest, but is actually in constant motion around

969-508: The University of Miami . For a hybrid-electric regional aircraft based on the ATR 72 with the same wing area, size and weight, CFJ improves its cruise lift coefficient for a higher wing loading , allowing more fuel and batteries for longer range. Inertia Inertia is the natural tendency of objects in motion to stay in motion and objects at rest to stay at rest, unless a force causes

1020-413: The cause of the phenomenon, rather than the phenomenon itself. However, Newton's original ideas of "innate resistive force" were ultimately problematic for a variety of reasons, and thus most physicists no longer think in these terms. As no alternate mechanism has been readily accepted, and it is now generally accepted that there may not be one that we can know, the term "inertia" has come to mean simply

1071-493: The principle of relativity could only apply to inertial reference frames. To address this limitation, Einstein developed his general theory of relativity ("The Foundation of the General Theory of Relativity", 1916), which provided a theory including noninertial (accelerated) reference frames. In general relativity, the concept of inertial motion got a broader meaning. Taking into account general relativity, inertial motion

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1122-429: The "default state" of the matter was motion, not stasis (stagnation). In the 6th century, John Philoponus criticized the inconsistency between Aristotle's discussion of projectiles, where the medium keeps projectiles going, and his discussion of the void, where the medium would hinder a body's motion. Philoponus proposed that motion was not maintained by the action of a surrounding medium, but by some property imparted to

1173-520: The 11th century, Persian polymath Ibn Sina (Avicenna) claimed that a projectile in a vacuum would not stop unless acted upon. In the 14th century, Jean Buridan rejected the notion that a motion-generating property, which he named impetus , dissipated spontaneously. Buridan's position was that a moving object would be arrested by the resistance of the air and the weight of the body which would oppose its impetus. Buridan also maintained that impetus increased with speed; thus, his initial idea of impetus

1224-546: The 1930s automatic slats had been developed, which opened or closed as needed according to the flight conditions. Typically they were operated by airflow pressure against the slat to close it, and small springs to open it at slower speeds when the dynamic pressure reduced, for example when the speed fell or the airflow reached a predetermined angle-of-attack on the wing. Modern systems, like modern flaps, can be more complex and are typically deployed hydraulically or with servos. Powered high-lift systems generally use airflow from

1275-511: The German patent office at first rejected it, as the office did not believe the possibility of postponing the stall by dividing the wing. Independently of Lachmann, Handley Page Ltd in Great Britain also developed the slotted wing as a way to postpone the stall by delaying separation of the flow from the upper surface of the wing at high angles of attack, and applied for a patent in 1919; to avoid

1326-434: The Latin word for "idleness" or "laziness", was not quite the same as its modern interpretation. Kepler defined inertia only in terms of resistance to movement, once again based on the axiomatic assumption that rest was a natural state which did not need explanation. It was not until the later work of Galileo and Newton unified rest and motion in one principle that the term "inertia" could be applied to those concepts as it

1377-544: The Sun. Galileo , in his further development of the Copernican model , recognized these problems with the then-accepted nature of motion and, at least partially, as a result, included a restatement of Aristotle's description of motion in a void as a basic physical principle: A body moving on a level surface will continue in the same direction at a constant speed unless disturbed. Galileo writes that "all external impediments removed,

1428-449: The aerodynamic purpose with the advantages of less: mass, cost, drag, inertia (for faster, stronger control response), complexity (mechanically simpler, fewer moving parts or surfaces, less maintenance), and radar cross-section for stealth . These may be used in many unmanned aerial vehicles (UAVs) and 6th generation fighter aircraft . One promising approach that could rival slats are flexible wings. In flexible wings, much or all of

1479-515: The aircraft to takeoff into a light wind in less than 45 m (150 ft), and land in 18 m (60 ft). Aircraft designed by the Messerschmitt company employed automatic, spring-loaded leading-edge slats as a general rule, except for the Alexander Lippisch -designed Messerschmitt Me 163B Komet rocket fighter, which instead used fixed slots built integrally with, and just behind,

1530-401: The continued motion of projectiles, after being separated from their projector, as an (itself unexplained) action of the surrounding medium continuing to move the projectile. Despite its general acceptance, Aristotle's concept of motion was disputed on several occasions by notable philosophers over nearly two millennia . For example, Lucretius (following, presumably, Epicurus ) stated that

1581-651: The difference between a moving object and a stationary one without some outside reference to compare it against. This observation ultimately came to be the basis for Albert Einstein to develop the theory of special relativity . Concepts of inertia in Galileo's writings would later come to be refined, modified, and codified by Isaac Newton as the first of his laws of motion (first published in Newton's work, Philosophiæ Naturalis Principia Mathematica , in 1687): Every body perseveres in its state of rest, or of uniform motion in

Leading-edge slat - Misplaced Pages Continue

1632-438: The distance and speeds required for takeoff and landing, but will increase drag, which reduces performance during the cruising portion of flight. Modern passenger jet wing designs are optimized for speed and efficiency during the cruise portion of flight, since this is where the aircraft spends the vast majority of its flight time. High-lift devices compensate for this design trade-off by adding lift at takeoff and landing, reducing

1683-411: The effects of friction and air resistance , both of which tend to decrease the speed of moving objects (commonly to the point of rest). This misled the philosopher Aristotle to believe that objects would move only as long as force was applied to them. Aristotle said that all moving objects (on Earth) eventually come to rest unless an external power (force) continued to move them. Aristotle explained

1734-430: The engine to shape the flow of air over the wing, replacing or modifying the action of the flaps. Blown flaps take " bleed air " from the jet engine 's compressor or engine exhaust and blow it over the rear upper surface of the wing and flap, re-energising the boundary layer and allowing the airflow to remain attached at higher angles of attack. A more advanced version of the blown flap is the circulation control wing ,

1785-507: The engines directly, by placing a flap so that it deploys into the path of the exhaust. Such flaps require greater strength due to the power of modern engines and also greater heat resistance to the hot exhaust, but the effect on lift can be significant. Examples include the C-17 Globemaster III . More common on modern fighter aircraft but also seen on some civil types, is the leading-edge root extension (LERX), sometimes called just

1836-486: The growing theory of impetus to involve linear motion alone: [Any] portion of corporeal matter which moves by itself when an impetus has been impressed on it by any external motive force has a natural tendency to move on a rectilinear, not a curved, path. Benedetti cites the motion of a rock in a sling as an example of the inherent linear motion of objects, forced into circular motion. According to science historian Charles Coulston Gillispie , inertia "entered science as

1887-424: The massive lift required during takeoff. Another common high-lift device is the slat, a small aerofoil shaped device attached just in front of the wing leading edge. The slat re-directs the airflow at the front of the wing, allowing it to flow more smoothly over the upper surface when at a high angle of attack . This allows the wing to be operated effectively at the higher angles required to produce more lift. A slot

1938-509: The object when it was set in motion. Although this was not the modern concept of inertia, for there was still the need for a power to keep a body in motion, it proved a fundamental step in that direction. This view was strongly opposed by Averroes and by many scholastic philosophers who supported Aristotle. However, this view did not go unchallenged in the Islamic world , where Philoponus had several supporters who further developed his ideas. In

1989-460: The phenomenon itself, rather than any inherent mechanism. Thus, ultimately, "inertia" in modern classical physics has come to be a name for the same phenomenon as described by Newton's first law of motion, and the two concepts are now considered to be equivalent. Albert Einstein 's theory of special relativity , as proposed in his 1905 paper entitled " On the Electrodynamics of Moving Bodies ",

2040-408: The pressure and providing greater lift. LERX systems are notable for the potentially large angles in which they are effective. A Co-Flow Jet (CFJ) wing has an upper surface with an injection slot after the leading edge and a suction slot before the trailing edge, to augment lift, increase the stall margin and reduce drag. CFJ is promoted by the mechanical and aerospace engineering department of

2091-455: The speed and distance required to safely land the aircraft, and allowing the use of a more efficient wing in flight. The high-lift devices on the Boeing 747-400 , for example, increase the wing area by 21% and increase the lift generated by 90%. The most common high-lift device is the flap, a movable portion of the wing that can be lowered to produce extra lift. When a flap is lowered this re-shapes

Leading-edge slat - Misplaced Pages Continue

2142-621: The upper surface remains either fixed to the wing or moves independently. Travelling flaps also extend backwards, to increase the wing chord when deployed, increasing the wing area to help produce yet more lift. These began to appear just before World War II due to the efforts of many different individuals and organizations in the 1920s and 30s. Slotted flaps comprise several separate small airfoils which separate apart, hinge and even slide past each other when deployed. Such complex flap arrangements are found on many modern aircraft. Large modern airliners make use of triple-slotted flaps to produce

2193-404: The velocity to change. It is one of the fundamental principles in classical physics , and described by Isaac Newton in his first law of motion (also known as The Principle of Inertia). It is one of the primary manifestations of mass , one of the core quantitative properties of physical systems . Newton writes: LAW I. Every object perseveres in its state of rest, or of uniform motion in

2244-409: The wing (usually outboard), depending on how the lift characteristics need to be modified for good low speed control. Slots and slats are sometimes used just for the section in front of the ailerons, ensuring that when the rest of the wing stalls, the ailerons remain usable. The first slats were developed by Gustav Lachmann in 1918 and simultaneously by Handley-Page who received a patent in 1919. By

2295-456: The wing panel's outer leading edges. Post-World War II, slats have also been used on larger aircraft and generally operated by hydraulics or electricity . The A-4 Skyhawk slats were spring loaded and deployed by the air load below certain speeds. Several technology research and development efforts exist to integrate the functions of flight control systems such as ailerons , elevators , elevons , flaps , and flaperons into wings to perform

2346-430: The wing section to give it more camber . Flaps are usually located on the trailing edge of a wing, while leading edge flaps are used occasionally. There are many kinds of trailing-edge flap. Simple hinged flaps came into common use in the 1930s, along with the arrival of the modern fast monoplane which had higher landing and takeoff speeds than the old biplanes. In the split flap, the lower surface hinges downwards while

2397-580: The wing, a design that was used on a number of STOL aircraft. During World War II, German aircraft commonly fitted a more advanced version of the slat that reduced drag by being pushed back flush against the leading edge of the wing by air pressure , popping out when the angle of attack increased to a critical angle. Notable slats of that time belonged to the German Fieseler Fi 156 Storch . These were similar in design to retractable slats, but were fixed and non-retractable. This design feature allowed

2448-523: The wings of some birds, the alula , a feather or group of feathers which the bird can extend under control of its "thumb". Slats were first developed by Gustav Lachmann in 1918. The stall-related crash in August 1917 of a Rumpler C aeroplane prompted Lachmann to develop the idea, and a small wooden model was built in 1917 in Cologne . In Germany in 1918 Lachmann presented a patent for leading-edge slats. However,

2499-404: Was built on the understanding of inertial reference frames developed by Galileo, Huygens and Newton. While this revolutionary theory did significantly change the meaning of many Newtonian concepts such as mass , energy , and distance , Einstein's concept of inertia remained at first unchanged from Newton's original meaning. However, this resulted in a limitation inherent in special relativity:

2550-576: Was later known as the Handley Page H.P.20 Several years later, having subsequently taken employment at the Handley-Page aircraft company, Lachmann was responsible for a number of aircraft designs, including the Handley Page Hampden . Licensing the design became one of the company's major sources of income in the 1920s. The original designs were in the form of a fixed slot near the leading edge of

2601-509: Was similar in many ways to the modern concept of momentum. Despite the obvious similarities to more modern ideas of inertia, Buridan saw his theory as only a modification to Aristotle's basic philosophy, maintaining many other peripatetic views, including the belief that there was still a fundamental difference between an object in motion and an object at rest. Buridan also believed that impetus could be not only linear but also circular in nature, causing objects (such as celestial bodies) to move in

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