1.
Space Shuttle Atlantis
–
Space Shuttle Atlantis is a Space Shuttle orbiter belonging to the National Aeronautics and Space Administration, the spaceflight and space exploration agency of the United States. Its maiden flight was STS-51-J from 3 to 7 October 1985, Atlantis embarked on its 33rd and final mission, also the final mission of a space shuttle, STS-135, on 8 July 2011. STS-134 by Endeavour was expected to be the flight before STS-135 was authorized in October 2010. STS-135 took advantage of the processing for the STS-335 Launch On Need mission that would have been necessary if STS-134s crew became stranded in orbit, Atlantis landed for the final time at the Kennedy Space Center on 21 July 2011. By the end of its mission, Atlantis had orbited the Earth a total of 4,848 times. Atlantis is named after RV Atlantis, a sailing ship that operated as the primary research vessel for the Woods Hole Oceanographic Institution from 1930 to 1966. Weight,151,315 pounds Length,122.17 feet Height,56.58 feet Wingspan,78.06 feet Atlantis was completed in half the time it took to build Space Shuttle Columbia. When it rolled out of the Palmdale assembly plant, weighing 151,315 lb, Atlantis is the lightest shuttle of the remaining fleet, weighing three pounds less than the Space Shuttle Endeavour. Space Shuttle Atlantis lifted off on its voyage on 3 October 1985, on mission STS-51-J. It flew one mission, STS-61-B, the second night launch in the shuttle program. Atlantis was then used for ten flights between 1988 and 1992, two of these, both flown in 1989, deployed the planetary probes Magellan to Venus and Galileo to Jupiter. With STS-30 Atlantis became the first shuttle to launch an interplanetary probe, during another mission, STS-37 flown in 1991, Atlantis deployed the Compton Gamma Ray Observatory. Beginning in 1995 with STS-71, Atlantis made seven flights to the former Russian space station Mir as part of the Shuttle-Mir Program. When linked, Atlantis and Mir together formed the largest spacecraft in orbit at the time, Shuttle Atlantis also delivered several vital components for the construction of the International Space Station. During the February 2001 mission STS-98 to the ISS, Atlantis delivered the Destiny Module, the five hour 25 minute third spacewalk performed by astronauts Robert Curbeam and Thomas Jones during STS-98 marked NASAs 100th extra vehicular activity in space. The Quest Joint Airlock, was flown and installed to the ISS by Atlantis during the mission STS-104 in July 2001. The successful installation of the airlock gave on-board space station crews the ability to stage repair, the first mission flown by Atlantis after the Space Shuttle Columbia disaster was STS-115, conducted during September 2006. The mission carried the P3/P4 truss segments and solar arrays to the ISS, on ISS assembly flight STS-122 in February 2008, Atlantis delivered the Columbus laboratory to the ISS
Space Shuttle Atlantis
–
Atlantis launching on the
STS-122 mission to dock with the
International Space Station in February 2008
Space Shuttle Atlantis
–
Space Shuttle Atlantis as it
transits the
Sun
Space Shuttle Atlantis
–
Atlantis docked to the International Space Station during STS-132 mission.
Space Shuttle Atlantis
–
Atlantis heads toward Earth orbit at the beginning of
STS-129.
2.
Kennedy Space Center
–
The John F. Kennedy Space Center is one of ten National Aeronautics and Space Administration field centers. Since December 1968, Kennedy Space Center has been NASAs primary launch center of human spaceflight, Launch operations for the Apollo, Skylab and Space Shuttle programs were carried out from Kennedy Space Center Launch Complex 39 and managed by KSC. Located on the east coast of Florida, KSC is adjacent to Cape Canaveral Air Force Station, the management of the two entities work very closely together, share resources, and even own facilities on each others property. Additionally, the center manages launch of robotic and commercial missions, researches food production and In-Situ Resource Utilization for off Earth exploration. Since 2010, the center has worked to become a multi-user spaceport through industry partnerships, there are about 700 facilities grouped across the centers 144,000 acres. There is also a Visitor Complex open to the public on site, the military had been performing launch operations since 1949 at what would become Cape Canaveral Air Force Station. In December 1959, the Department of Defense transferred 5,000 personnel, President John F. Kennedys 1961 goal of a manned lunar landing before 1970 required an expansion of launch operations. On July 1,1962, the Launch Operations Directorate was separated from MSFC to become the Launch Operations Center, therefore, the decision was made to build a new LOC site located adjacent to Cape Canaveral on Merritt Island. NASA began land acquisition in 1962, buying title to 131 square miles, the major buildings in KSCs Industrial Area were designed by architect Charles Luckman. Construction began in November 1962, and Kennedy visited the site twice in 1962, on November 29,1963, the facility was given its current name by President Lyndon B. Johnson under Executive Order 11129. Johnsons order joined both the civilian LOC and the military Cape Canaveral station under the designation John F. Kennedy Space Center, spawning some confusion joining the two in the public mind. Located on Merritt Island, Florida, the center is north-northwest of Cape Canaveral on the Atlantic Ocean and it is 34 miles long and roughly six miles wide, covering 219 square miles. KSC is a major central Florida tourist destination and is one hours drive from the Orlando area. The Kennedy Space Center Visitor Complex offers public tours of the center, Center workers can encounter bald eagles, American alligators, wild boars, eastern diamondback rattlesnakes, the endangered Florida panther and Florida manatees. From 1967 through 1973, there were 13 Saturn V launches, the first of two unmanned flights, Apollo 4 on November 9,1967, was also the first rocket launch from KSC. The Saturn Vs first manned launch on December 21,1968 was Apollo 8s lunar orbiting mission, the next two missions tested the Lunar Module, Apollo 9 and Apollo 10. Apollo 11, launched from Pad A on July 16,1969, Apollo 12 followed four months later. From 1970–1972, the Apollo program concluded at KSC with the launches of missions 13 through 17, on May 14,1973, the last Saturn V launch put the Skylab space station in orbit from Pad 39A
Kennedy Space Center
–
Aerial view of
KSC Headquarters looking south
Kennedy Space Center
–
KSC shown in white;
CCAFS in green
Kennedy Space Center
–
A Saturn V carrying
Apollo 15 rolls out to Pad 39A in 1971 on
Mobile Launch Platform 1.
Kennedy Space Center
–
Shuttle Discovery launching from Pad 39A on
STS-60, February 3, 1994
3.
Force (physics)
–
In physics, a force is any interaction that, when unopposed, will change the motion of an object. In other words, a force can cause an object with mass to change its velocity, force can also be described intuitively as a push or a pull. A force has both magnitude and direction, making it a vector quantity and it is measured in the SI unit of newtons and represented by the symbol F. The original form of Newtons second law states that the net force acting upon an object is equal to the rate at which its momentum changes with time. In an extended body, each part usually applies forces on the adjacent parts, such internal mechanical stresses cause no accelation of that body as the forces balance one another. Pressure, the distribution of small forces applied over an area of a body, is a simple type of stress that if unbalanced can cause the body to accelerate. Stress usually causes deformation of materials, or flow in fluids. In part this was due to an understanding of the sometimes non-obvious force of friction. A fundamental error was the belief that a force is required to maintain motion, most of the previous misunderstandings about motion and force were eventually corrected by Galileo Galilei and Sir Isaac Newton. With his mathematical insight, Sir Isaac Newton formulated laws of motion that were not improved-on for nearly three hundred years, the Standard Model predicts that exchanged particles called gauge bosons are the fundamental means by which forces are emitted and absorbed. Only four main interactions are known, in order of decreasing strength, they are, strong, electromagnetic, weak, high-energy particle physics observations made during the 1970s and 1980s confirmed that the weak and electromagnetic forces are expressions of a more fundamental electroweak interaction. Since antiquity the concept of force has been recognized as integral to the functioning of each of the simple machines. The mechanical advantage given by a machine allowed for less force to be used in exchange for that force acting over a greater distance for the same amount of work. Analysis of the characteristics of forces ultimately culminated in the work of Archimedes who was famous for formulating a treatment of buoyant forces inherent in fluids. Aristotle provided a discussion of the concept of a force as an integral part of Aristotelian cosmology. In Aristotles view, the sphere contained four elements that come to rest at different natural places therein. Aristotle believed that objects on Earth, those composed mostly of the elements earth and water, to be in their natural place on the ground. He distinguished between the tendency of objects to find their natural place, which led to natural motion, and unnatural or forced motion
Force (physics)
–
Aristotle famously described a force as anything that causes an object to undergo "unnatural motion"
Force (physics)
–
Forces are also described as a push or pull on an object. They can be due to phenomena such as
gravity,
magnetism, or anything that might cause a mass to accelerate.
Force (physics)
–
Though
Sir Isaac Newton 's most famous equation is, he actually wrote down a different form for his second law of motion that did not use
differential calculus.
Force (physics)
–
Galileo Galilei was the first to point out the inherent contradictions contained in Aristotle's description of forces.
4.
Isaac Newton
–
His book Philosophiæ Naturalis Principia Mathematica, first published in 1687, laid the foundations of classical mechanics. Newton also made contributions to optics, and he shares credit with Gottfried Wilhelm Leibniz for developing the infinitesimal calculus. Newtons Principia formulated the laws of motion and universal gravitation that dominated scientists view of the universe for the next three centuries. Newtons work on light was collected in his influential book Opticks. He also formulated a law of cooling, made the first theoretical calculation of the speed of sound. Newton was a fellow of Trinity College and the second Lucasian Professor of Mathematics at the University of Cambridge, politically and personally tied to the Whig party, Newton served two brief terms as Member of Parliament for the University of Cambridge, in 1689–90 and 1701–02. He was knighted by Queen Anne in 1705 and he spent the last three decades of his life in London, serving as Warden and Master of the Royal Mint and his father, also named Isaac Newton, had died three months before. Born prematurely, he was a child, his mother Hannah Ayscough reportedly said that he could have fit inside a quart mug. When Newton was three, his mother remarried and went to live with her new husband, the Reverend Barnabas Smith, leaving her son in the care of his maternal grandmother, Newtons mother had three children from her second marriage. From the age of twelve until he was seventeen, Newton was educated at The Kings School, Grantham which taught Latin and Greek. He was removed from school, and by October 1659, he was to be found at Woolsthorpe-by-Colsterworth, Henry Stokes, master at the Kings School, persuaded his mother to send him back to school so that he might complete his education. Motivated partly by a desire for revenge against a bully, he became the top-ranked student. In June 1661, he was admitted to Trinity College, Cambridge and he started as a subsizar—paying his way by performing valets duties—until he was awarded a scholarship in 1664, which guaranteed him four more years until he would get his M. A. He set down in his notebook a series of Quaestiones about mechanical philosophy as he found it, in 1665, he discovered the generalised binomial theorem and began to develop a mathematical theory that later became calculus. Soon after Newton had obtained his B. A. degree in August 1665, in April 1667, he returned to Cambridge and in October was elected as a fellow of Trinity. Fellows were required to become ordained priests, although this was not enforced in the restoration years, however, by 1675 the issue could not be avoided and by then his unconventional views stood in the way. Nevertheless, Newton managed to avoid it by means of a special permission from Charles II. A and he was elected a Fellow of the Royal Society in 1672. Newtons work has been said to distinctly advance every branch of mathematics then studied and his work on the subject usually referred to as fluxions or calculus, seen in a manuscript of October 1666, is now published among Newtons mathematical papers
Isaac Newton
–
Portrait of Isaac Newton in 1689 (age 46) by
Godfrey Kneller
Isaac Newton
–
Newton in a 1702 portrait by
Godfrey Kneller
Isaac Newton
–
Isaac Newton (Bolton, Sarah K. Famous Men of Science. NY: Thomas Y. Crowell & Co., 1889)
Isaac Newton
–
Replica of Newton's second
Reflecting telescope that he presented to the
Royal Society in 1672
5.
Acceleration
–
Acceleration, in physics, is the rate of change of velocity of an object with respect to time. An objects acceleration is the net result of any and all forces acting on the object, the SI unit for acceleration is metre per second squared. Accelerations are vector quantities and add according to the parallelogram law, as a vector, the calculated net force is equal to the product of the objects mass and its acceleration. For example, when a car starts from a standstill and travels in a line at increasing speeds. If the car turns, there is an acceleration toward the new direction, in this example, we can call the forward acceleration of the car a linear acceleration, which passengers in the car might experience as a force pushing them back into their seats. When changing direction, we call this non-linear acceleration, which passengers might experience as a sideways force. If the speed of the car decreases, this is an acceleration in the direction from the direction of the vehicle. Passengers may experience deceleration as a force lifting them forwards, mathematically, there is no separate formula for deceleration, both are changes in velocity. Each of these accelerations might be felt by passengers until their velocity matches that of the car, an objects average acceleration over a period of time is its change in velocity divided by the duration of the period. Mathematically, a ¯ = Δ v Δ t, instantaneous acceleration, meanwhile, is the limit of the average acceleration over an infinitesimal interval of time. The SI unit of acceleration is the metre per second squared, or metre per second per second, as the velocity in metres per second changes by the acceleration value, every second. An object moving in a circular motion—such as a satellite orbiting the Earth—is accelerating due to the change of direction of motion, in this case it is said to be undergoing centripetal acceleration. Proper acceleration, the acceleration of a relative to a free-fall condition, is measured by an instrument called an accelerometer. As speeds approach the speed of light, relativistic effects become increasingly large and these components are called the tangential acceleration and the normal or radial acceleration. Geometrical analysis of space curves, which explains tangent, normal and binormal, is described by the Frenet–Serret formulas. Uniform or constant acceleration is a type of motion in which the velocity of an object changes by an amount in every equal time period. A frequently cited example of uniform acceleration is that of an object in free fall in a gravitational field. The acceleration of a body in the absence of resistances to motion is dependent only on the gravitational field strength g
Acceleration
–
Components of acceleration for a curved motion. The tangential component a t is due to the change in speed of traversal, and points along the curve in the direction of the velocity vector (or in the opposite direction). The normal component (also called centripetal component for circular motion) a c is due to the change in direction of the velocity vector and is normal to the trajectory, pointing toward the center of curvature of the path.
Acceleration
–
Acceleration is the rate of change of velocity. At any point on a trajectory, the magnitude of the acceleration is given by the rate of change of velocity in both magnitude and direction at that point. The true acceleration at time t is found in the limit as
time interval Δt → 0 of Δ v / Δt
6.
Mass
–
In physics, mass is a property of a physical body. It is the measure of a resistance to acceleration when a net force is applied. It also determines the strength of its gravitational attraction to other bodies. The basic SI unit of mass is the kilogram, Mass is not the same as weight, even though mass is often determined by measuring the objects weight using a spring scale, rather than comparing it directly with known masses. An object on the Moon would weigh less than it does on Earth because of the lower gravity and this is because weight is a force, while mass is the property that determines the strength of this force. In Newtonian physics, mass can be generalized as the amount of matter in an object, however, at very high speeds, special relativity postulates that energy is an additional source of mass. Thus, any body having mass has an equivalent amount of energy. In addition, matter is a defined term in science. There are several distinct phenomena which can be used to measure mass, active gravitational mass measures the gravitational force exerted by an object. Passive gravitational mass measures the force exerted on an object in a known gravitational field. The mass of an object determines its acceleration in the presence of an applied force, according to Newtons second law of motion, if a body of fixed mass m is subjected to a single force F, its acceleration a is given by F/m. A bodys mass also determines the degree to which it generates or is affected by a gravitational field and this is sometimes referred to as gravitational mass. The standard International System of Units unit of mass is the kilogram, the kilogram is 1000 grams, first defined in 1795 as one cubic decimeter of water at the melting point of ice. Then in 1889, the kilogram was redefined as the mass of the prototype kilogram. As of January 2013, there are proposals for redefining the kilogram yet again. In this context, the mass has units of eV/c2, the electronvolt and its multiples, such as the MeV, are commonly used in particle physics. The atomic mass unit is 1/12 of the mass of a carbon-12 atom, the atomic mass unit is convenient for expressing the masses of atoms and molecules. Outside the SI system, other units of mass include, the slug is an Imperial unit of mass, the pound is a unit of both mass and force, used mainly in the United States
Mass
–
Depiction of early
balance scales in the
Papyrus of Hunefer (dated to the
19th dynasty, ca. 1285 BC). The scene shows
Anubis weighing the heart of Hunefer.
Mass
–
The kilogram is one of the seven
SI base units and one of three which is defined ad hoc (i.e. without reference to another base unit).
Mass
–
Galileo Galilei (1636)
Mass
–
Distance traveled by a freely falling ball is proportional to the square of the elapsed time
7.
Normal vector
–
In geometry, a normal is an object such as a line or vector that is perpendicular to a given object. For example, in the case, the normal line to a curve at a given point is the line perpendicular to the tangent line to the curve at the point. In the three-dimensional case a normal, or simply normal. The word normal is used as an adjective, a line normal to a plane, the normal component of a force. The concept of normality generalizes to orthogonality, the concept has been generalized to differentiable manifolds of arbitrary dimension embedded in a Euclidean space. The normal vector space or normal space of a manifold at a point P is the set of the vectors which are orthogonal to the tangent space at P, in the case of differential curves, the curvature vector is a normal vector of special interest. For a convex polygon, a surface normal can be calculated as the cross product of two edges of the polygon. For a plane given by the equation a x + b y + c z + d =0, the vector is a normal. For a hyperplane in n+1 dimensions, given by the equation r = a 0 + α1 a 1 + ⋯ + α n a n, where a0 is a point on the hyperplane and ai for i =1. N are non-parallel vectors lying on the hyperplane, a normal to the hyperplane is any vector in the space of A where A is given by A =. That is, any vector orthogonal to all in-plane vectors is by definition a surface normal. If a surface S is parameterized by a system of coordinates x, with s and t real variables. For a surface S given explicitly as a function f of the independent variables x, y, the first one is obtaining its implicit form F = z − f =0, from which the normal follows readily as the gradient ∇ F. The second way of obtaining the normal follows directly from the gradient of the form, ∇ f, by inspection, ∇ F = k ^ − ∇ f. Note that this is equal to ∇ F = k ^ − ∂ f ∂ x i ^ − ∂ f ∂ y j ^, if a surface does not have a tangent plane at a point, it does not have a normal at that point either. For example, a cone does not have a normal at its tip nor does it have a normal along the edge of its base, however, the normal to the cone is defined almost everywhere. In general, it is possible to define a normal almost everywhere for a surface that is Lipschitz continuous, a normal to a surface does not have a unique direction, the vector pointing in the opposite direction of a surface normal is also a surface normal. For an oriented surface, the normal is usually determined by the right-hand rule
Normal vector
–
A polygon and two of its normal vectors
8.
International System of Units
–
The International System of Units is the modern form of the metric system, and is the most widely used system of measurement. It comprises a coherent system of units of measurement built on seven base units, the system also establishes a set of twenty prefixes to the unit names and unit symbols that may be used when specifying multiples and fractions of the units. The system was published in 1960 as the result of an initiative began in 1948. It is based on the system of units rather than any variant of the centimetre-gram-second system. The motivation for the development of the SI was the diversity of units that had sprung up within the CGS systems, the International System of Units has been adopted by most developed countries, however, the adoption has not been universal in all English-speaking countries. The metric system was first implemented during the French Revolution with just the metre and kilogram as standards of length, in the 1830s Carl Friedrich Gauss laid the foundations for a coherent system based on length, mass, and time. In the 1860s a group working under the auspices of the British Association for the Advancement of Science formulated the requirement for a coherent system of units with base units and derived units. Meanwhile, in 1875, the Treaty of the Metre passed responsibility for verification of the kilogram, in 1921, the Treaty was extended to include all physical quantities including electrical units originally defined in 1893. The units associated with these quantities were the metre, kilogram, second, ampere, kelvin, in 1971, a seventh base quantity, amount of substance represented by the mole, was added to the definition of SI. On 11 July 1792, the proposed the names metre, are, litre and grave for the units of length, area, capacity. The committee also proposed that multiples and submultiples of these units were to be denoted by decimal-based prefixes such as centi for a hundredth, on 10 December 1799, the law by which the metric system was to be definitively adopted in France was passed. Prior to this, the strength of the magnetic field had only been described in relative terms. The technique used by Gauss was to equate the torque induced on a magnet of known mass by the earth’s magnetic field with the torque induced on an equivalent system under gravity. The resultant calculations enabled him to assign dimensions based on mass, length, a French-inspired initiative for international cooperation in metrology led to the signing in 1875 of the Metre Convention. Initially the convention only covered standards for the metre and the kilogram, one of each was selected at random to become the International prototype metre and International prototype kilogram that replaced the mètre des Archives and kilogramme des Archives respectively. Each member state was entitled to one of each of the prototypes to serve as the national prototype for that country. Initially its prime purpose was a periodic recalibration of national prototype metres. The official language of the Metre Convention is French and the version of all official documents published by or on behalf of the CGPM is the French-language version
International System of Units
–
Stone marking the
Austro-Hungarian /Italian border at
Pontebba displaying
myriametres, a unit of 10 km used in
Central Europe in the 19th century (but since
deprecated).
International System of Units
–
The seven base units in the International System of Units
International System of Units
–
Carl Friedrich Gauss
International System of Units
–
Thomson
9.
Newton (unit)
–
The newton is the International System of Units derived unit of force. It is named after Isaac Newton in recognition of his work on classical mechanics, see below for the conversion factors. One newton is the force needed to one kilogram of mass at the rate of one metre per second squared in direction of the applied force. In 1948, the 9th CGPM resolution 7 adopted the name newton for this force, the MKS system then became the blueprint for todays SI system of units. The newton thus became the unit of force in le Système International dUnités. This SI unit is named after Isaac Newton, as with every International System of Units unit named for a person, the first letter of its symbol is upper case. Note that degree Celsius conforms to this rule because the d is lowercase. — Based on The International System of Units, section 5.2. Newtons second law of motion states that F = ma, where F is the applied, m is the mass of the object receiving the force. The newton is therefore, where the symbols are used for the units, N for newton, kg for kilogram, m for metre. In dimensional analysis, F = M L T2 where F is force, M is mass, L is length, at average gravity on earth, a kilogram mass exerts a force of about 9.8 newtons. An average-sized apple exerts about one newton of force, which we measure as the apples weight, for example, the tractive effort of a Class Y steam train and the thrust of an F100 fighter jet engine are both around 130 kN. One kilonewton,1 kN, is 102.0 kgf,1 kN =102 kg ×9.81 m/s2 So for example, a platform rated at 321 kilonewtons will safely support a 32,100 kilograms load. Specifications in kilonewtons are common in safety specifications for, the values of fasteners, Earth anchors. Working loads in tension and in shear, thrust of rocket engines and launch vehicles clamping forces of the various moulds in injection moulding machines used to manufacture plastic parts
Newton (unit)
–
Base units
10.
Mechanical engineering
–
Mechanical engineering is the discipline that applies the principles of engineering, physics, and materials science for the design, analysis, manufacturing, and maintenance of mechanical systems. It is the branch of engineering that involves the design, production and it is one of the oldest and broadest of the engineering disciplines. The mechanical engineering field requires an understanding of areas including mechanics, kinematics, thermodynamics, materials science, structural analysis. Mechanical engineering emerged as a field during the Industrial Revolution in Europe in the 18th century, however, Mechanical engineering science emerged in the 19th century as a result of developments in the field of physics. The field has evolved to incorporate advancements in technology, and mechanical engineers today are pursuing developments in such fields as composites, mechatronics. Mechanical engineers may work in the field of biomedical engineering, specifically with biomechanics, transport phenomena, biomechatronics, bionanotechnology. Mechanical engineering finds its application in the archives of various ancient, in ancient Greece, the works of Archimedes deeply influenced mechanics in the Western tradition and Heron of Alexandria created the first steam engine. In China, Zhang Heng improved a water clock and invented a seismometer, during the 7th to 15th century, the era called the Islamic Golden Age, there were remarkable contributions from Muslim inventors in the field of mechanical technology. Al-Jazari, who was one of them, wrote his famous Book of Knowledge of Ingenious Mechanical Devices in 1206 and he is also considered to be the inventor of such mechanical devices which now form the very basic of mechanisms, such as the crankshaft and camshaft. Newton was reluctant to publish his methods and laws for years, gottfried Wilhelm Leibniz is also credited with creating Calculus during the same time frame. On the European continent, Johann von Zimmermann founded the first factory for grinding machines in Chemnitz, education in mechanical engineering has historically been based on a strong foundation in mathematics and science. Degrees in mechanical engineering are offered at universities worldwide. In Spain, Portugal and most of South America, where neither B. Sc. nor B. Tech, programs have been adopted, the formal name for the degree is Mechanical Engineer, and the course work is based on five or six years of training. In Italy the course work is based on five years of education, and training, in Greece, the coursework is based on a five-year curriculum and the requirement of a Diploma Thesis, which upon completion a Diploma is awarded rather than a B. Sc. In Australia, mechanical engineering degrees are awarded as Bachelor of Engineering or similar nomenclature although there are a number of specialisations. The degree takes four years of study to achieve. To ensure quality in engineering degrees, Engineers Australia accredits engineering degrees awarded by Australian universities in accordance with the global Washington Accord, before the degree can be awarded, the student must complete at least 3 months of on the job work experience in an engineering firm. Similar systems are present in South Africa and are overseen by the Engineering Council of South Africa
Mechanical engineering
–
Mechanical engineers design and build
engines,
power plants, other machines...
Mechanical engineering
–
...
structures, and
vehicles of all sizes.
Mechanical engineering
–
An oblique view of a four-cylinder inline crankshaft with pistons
Mechanical engineering
–
Training FMS with learning robot
SCORBOT-ER 4u, workbench CNC Mill and CNC Lathe
11.
Orthogonal
–
The concept of orthogonality has been broadly generalized in mathematics, as well as in areas such as chemistry, and engineering. The word comes from the Greek ὀρθός, meaning upright, and γωνία, the ancient Greek ὀρθογώνιον orthogōnion and classical Latin orthogonium originally denoted a rectangle. Later, they came to mean a right triangle, in the 12th century, the post-classical Latin word orthogonalis came to mean a right angle or something related to a right angle. In geometry, two Euclidean vectors are orthogonal if they are perpendicular, i. e. they form a right angle, two vectors, x and y, in an inner product space, V, are orthogonal if their inner product ⟨ x, y ⟩ is zero. This relationship is denoted x ⊥ y, two vector subspaces, A and B, of an inner product space, V, are called orthogonal subspaces if each vector in A is orthogonal to each vector in B. The largest subspace of V that is orthogonal to a subspace is its orthogonal complement. Given a module M and its dual M∗, an element m′ of M∗, two sets S′ ⊆ M∗ and S ⊆ M are orthogonal if each element of S′ is orthogonal to each element of S. A term rewriting system is said to be if it is left-linear and is non-ambiguous. Orthogonal term rewriting systems are confluent, a set of vectors in an inner product space is called pairwise orthogonal if each pairing of them is orthogonal. Such a set is called an orthogonal set, nonzero pairwise orthogonal vectors are always linearly independent. In certain cases, the normal is used to mean orthogonal. For example, the y-axis is normal to the curve y = x2 at the origin, however, normal may also refer to the magnitude of a vector. In particular, a set is called if it is an orthogonal set of unit vectors. As a result, use of the normal to mean orthogonal is often avoided. The word normal also has a different meaning in probability and statistics, a vector space with a bilinear form generalizes the case of an inner product. When the bilinear form applied to two results in zero, then they are orthogonal. The case of a pseudo-Euclidean plane uses the term hyperbolic orthogonality, in the diagram, axes x′ and t′ are hyperbolic-orthogonal for any given ϕ. In 2-D or higher-dimensional Euclidean space, two vectors are orthogonal if and only if their dot product is zero, i. e. they make an angle of 90°, hence orthogonality of vectors is an extension of the concept of perpendicular vectors into higher-dimensional spaces
Orthogonal
–
The line segments AB and CD are orthogonal to each other.
12.
Helical gear
–
A gear or cogwheel is a rotating machine part having cut teeth, or cogs, which mesh with another toothed part to transmit torque. Geared devices can change the speed, torque, and direction of a power source, Gears almost always produce a change in torque, creating a mechanical advantage, through their gear ratio, and thus may be considered a simple machine. The teeth on the two meshing gears all have the same shape, two or more meshing gears, working in a sequence, are called a gear train or a transmission. A gear can mesh with a linear toothed part, called a rack, the gears in a transmission are analogous to the wheels in a crossed, belt pulley system. An advantage of gears is that the teeth of a gear prevent slippage, in transmissions with multiple gear ratios—such as bicycles, motorcycles, and cars—the term gear as in first gear refers to a gear ratio rather than an actual physical gear. The term describes similar devices, even when the ratio is continuous rather than discrete, or when the device does not actually contain gears. Early examples of gears date from the 4th century BC in China, examples of further development include, Ma Jun used gears as part of a south-pointing chariot. The Antikythera mechanism is an example of an early and intricate geared device. Its time of construction is now estimated between 150 and 100 BC, the water-powered grain-mill, the water-powered saw mill, fulling mill, and other applications of watermill often used gears. The first mechanical clocks were built in AD725, the 1386 Salisbury cathedral clock may be the worlds oldest working mechanical clock. The definite ratio that teeth give gears provides an advantage over other drives in precision machines such as watches that depend upon an exact velocity ratio, an external gear is one with the teeth formed on the outer surface of a cylinder or cone. Conversely, a gear is one with the teeth formed on the inner surface of a cylinder or cone. For bevel gears, a gear is one with the pitch angle exceeding 90 degrees. Internal gears do not cause output shaft direction reversal, spur gears or straight-cut gears are the simplest type of gear. They consist of a cylinder or disk with teeth projecting radially, though the teeth are not straight-sided, the edge of each tooth is straight and aligned parallel to the axis of rotation. These gears mesh together correctly only if fitted to parallel shafts, No axial thrust is created by the tooth loads. Spur gears are excellent at moderate speeds but tend to be noisy at high speeds, helical or dry fixed gears offer a refinement over spur gears. The leading edges of the teeth are not parallel to the axis of rotation, since the gear is curved, this angling makes the tooth shape a segment of a helix
Helical gear
–
Multiple reducer gears in microwave oven (ruler for scale)
Helical gear
–
Helical gears Top: parallel configuration Bottom: crossed configuration
Helical gear
–
Herringbone Gears
Helical gear
–
Bevel Gear
13.
Aerofoil
–
An airfoil or aerofoil is the shape of a wing, blade, or sail. An airfoil-shaped body moved through a fluid produces an aerodynamic force, the component of this force perpendicular to the direction of motion is called lift. The component parallel to the direction of motion is called drag, subsonic flight airfoils have a characteristic shape with a rounded leading edge, followed by a sharp trailing edge, often with a symmetric curvature of upper and lower surfaces. Foils of similar function designed with water as the fluid are called hydrofoils. The lift on an airfoil is primarily the result of its angle of attack, when oriented at a suitable angle, the airfoil deflects the oncoming air, resulting in a force on the airfoil in the direction opposite to the deflection. This force is known as force and can be resolved into two components, lift and drag. Most foil shapes require an angle of attack to generate lift. This turning of the air in the vicinity of the airfoil creates curved streamlines, resulting in pressure on one side. The lift force can be related directly to the average top/bottom velocity difference without computing the pressure by using the concept of circulation, a fixed-wing aircrafts wings, horizontal, and vertical stabilizers are built with airfoil-shaped cross sections, as are helicopter rotor blades. Airfoils are also found in propellers, fans, compressors and turbines, sails are also airfoils, and the underwater surfaces of sailboats, such as the centerboard and keel, are similar in cross-section and operate on the same principles as airfoils. Swimming and flying creatures and even many plants and sessile organisms employ airfoils/hydrofoils, common examples being bird wings, the bodies of fish, an airfoil-shaped wing can create downforce on an automobile or other motor vehicle, improving traction. Any object with an angle of attack in a fluid, such as a flat plate. Airfoils are more efficient lifting shapes, able to more lift. A lift and drag curve obtained in wind tunnel testing is shown on the right, the curve represents an airfoil with a positive camber so some lift is produced at zero angle of attack. With increased angle of attack, lift increases in a linear relation. At about 18 degrees this airfoil stalls, and lift falls off quickly beyond that, the drop in lift can be explained by the action of the upper-surface boundary layer, which separates and greatly thickens over the upper surface at and past the stall angle. The thicker boundary layer also causes an increase in pressure drag, so that the overall drag increases sharply near. Airfoil design is a facet of aerodynamics
Aerofoil
–
Lift and Drag curves for a typical airfoil
Aerofoil
–
Examples of airfoils in nature and within various vehicles. Though not strictly an airfoil, the dolphin flipper obeys the same principles in a different fluid medium.
Aerofoil
–
An airfoil section is displayed at the tip of this
Denney Kitfox aircraft, built in 1991.
Aerofoil
–
Airfoil of Kamov Ka-26 helicopters
14.
Fixed-wing aircraft
–
A fixed-wing aircraft is an aircraft, such as an aeroplane, which is capable of flight using wings that generate lift caused by the vehicles forward airspeed and the shape of the wings. Fixed-wing aircraft are distinct from rotary-wing aircraft, in which the form a rotor mounted on a spinning shaft. Glider fixed-wing aircraft, including free-flying gliders of various kinds and tethered kites, powered fixed-wing aircraft that gain forward thrust from an engine include powered paragliders, powered hang gliders and some ground effect vehicles. The wings of an aircraft are not necessarily rigid, kites, hang-gliders, variable-sweep wing aircraft. Most fixed-wing aircraft are flown by a pilot on board the aircraft, kites were used approximately 2,800 years ago in China, where materials ideal for kite building were readily available. Some authors hold that leaf kites were being flown much earlier in what is now Indonesia, by at least 549 AD paper kites were being flown, as it was recorded in that year a paper kite was used as a message for a rescue mission. Ancient and medieval Chinese sources list other uses of kites for measuring distances, testing the wind, lifting men, signaling, and communication for military operations. Stories of kites were brought to Europe by Marco Polo towards the end of the 13th century, although they were initially regarded as mere curiosities, by the 18th and 19th centuries kites were being used as vehicles for scientific research. This machine may have been suspended for its flight, some of the earliest recorded attempts with gliders were those by the 9th-century poet Abbas Ibn Firnas and the 11th-century monk Eilmer of Malmesbury, both experiments injured their pilots. In 1799, Sir George Cayley set forth the concept of the aeroplane as a fixed-wing flying machine with separate systems for lift, propulsion. Cayley was building and flying models of fixed-wing aircraft as early as 1803, in 1856, Frenchman Jean-Marie Le Bris made the first powered flight, by having his glider LAlbatros artificiel pulled by a horse on a beach. In 1884, the American John J. Montgomery made controlled flights in a glider as a part of a series of gliders built between 1883-1886, other aviators who made similar flights at that time were Otto Lilienthal, Percy Pilcher, and Octave Chanute. In the 1890s, Lawrence Hargrave conducted research on wing structures and his box kite designs were widely adopted. Although he also developed a type of aircraft engine, he did not create. Sir Hiram Maxim built a craft that weighed 3.5 tons, in 1894, his machine was tested with overhead rails to prevent it from rising. The test showed that it had enough lift to take off, the craft was uncontrollable, which Maxim, it is presumed, realized, because he subsequently abandoned work on it. By 1905, the Wright Flyer III was capable of fully controllable, stable flight for substantial periods, the flight was certified by the FAI. This was the first controlled flight, to be officially recognised, the Bleriot VIII design of 1908 was an early aircraft design that had the modern monoplane tractor configuration
Fixed-wing aircraft
–
A
Boeing 737 aeroplane - an example of a fixed-wing aircraft
Fixed-wing aircraft
–
A
delta -shaped
kite
Fixed-wing aircraft
–
Boys flying a kite in 1828 Germany, by
Johann Michael Voltz
Fixed-wing aircraft
–
Le Bris and his glider, Albatros II, photographed by
Nadar, 1868
15.
Propeller (aircraft)
–
An aircraft propeller or airscrew converts rotary motion from an engine or other mechanical power source, to provide propulsive force. It comprises a rotating hub, to which are attached several radial airfoil-section blades such that the whole assembly rotates about a longitudinal axis. The blade pitch may be fixed, manually variable to a few set positions, the propeller attaches to the power sources driveshaft either directly or, especially on larger designs, through reduction gearing. Most early aircraft propellers were carved by hand from solid or laminated wood, more recently, composite materials are becoming increasingly used. The earliest references for vertical flight came from China, since around 400 BC, Chinese children have played with bamboo flying toys. This bamboo-copter is spun by rolling a stick attached to a rotor between ones hands, the spinning creates lift, and the toy flies when released. The 4th-century AD Daoist book Baopuzi by Ge Hong reportedly describes some of the ideas inherent to rotary wing aircraft, designs similar to the Chinese helicopter toy appeared in Renaissance paintings and other works. It was not until the early 1480s, when Leonardo da Vinci created a design for a machine that could be described as an aerial screw, that any recorded advancement was made towards vertical flight. His notes suggested that he built flying models, but there were no indications for any provision to stop the rotor from making the craft rotate. As scientific knowledge increased and became accepted, men continued to pursue the idea of vertical flight. Many of these models and machines would more closely resemble the ancient bamboo flying top with spinning wings. In July 1754, Russian Mikhail Lomonosov had developed a small coaxial modeled after the Chinese top but powered by a spring device. It was powered by a spring, and was suggested as a method to lift meteorological instruments, a dirigible airship was described by Jean Baptiste Marie Meusnier presented in 1783. The drawings depict a 260-foot-long streamlined envelope with internal ballonnets that could be used for regulating lift, the airship was designed to be driven by three propellers. In 1784 Jean-Pierre Blanchard fitted a hand-powered propeller to a balloon, sir George Cayley, influenced by a childhood fascination with the Chinese flying top, developed a model of feathers, similar to that of Launoy and Bienvenu, but powered by rubber bands. By the end of the century, he had progressed to using sheets of tin for rotor blades and his writings on his experiments and models would become influential on future aviation pioneers. William Bland sent designs for his Atmotic Airship to the Great Exhibition held in London in 1851 and this was an elongated balloon with a steam engine driving twin propellers suspended underneath. Alphonse Pénaud developed coaxial rotor model helicopter toys in 1870, also powered by rubber bands, in 1872 Dupuy de Lome launched a large navigable balloon, which was driven by a large propeller turned by eight men
Propeller (aircraft)
–
The feathered propellers of an
RAF Hercules C.4
Propeller (aircraft)
–
The three-bladed propeller of a light aircraft: the
Vans RV-7A
Propeller (aircraft)
–
Cut-away view of a
Hamilton Standard propeller. This type of propeller was used on many American fighters, bombers and transport aircraft of
World War II
Propeller (aircraft)
–
Feathered propeller on the outboard
TP400 turboprop of an
Airbus A400M
16.
Mechanical fan
–
A fan is a machine used to create flow within a fluid, typically a gas such as air. The fan consists of an arrangement of vanes or blades which act on the fluid. The rotating assembly of blades and hub is known as an impeller, usually, it is contained within some form of housing or case. This may direct the airflow or increase safety by preventing objects from contacting the fan blades, most fans are powered by electric motors, but other sources of power may be used, including hydraulic motors and internal combustion engines. Fans produce flows with high volume and low pressure, as opposed to compressors which produce high pressures at a low volume. A fan blade will often rotate when exposed to a fluid stream, thus, fans may become ineffective at cooling the body if the surrounding air is near body temperature and contains high humidity. During periods of high heat and humidity, governments actually advise against the use of fans. The word fan comes from Middle English, winnowing fan, from Old English fann, the punkah fan was used in India about 500 BCE. It was a fan made from bamboo strips or other plant fibre. During British rule, the word came to be used by Anglo-Indians to mean a large swinging flat fan, fixed to the ceiling, and pulled by a servant, called the punkawallah. In the 17th century, the experiments of scientists like Otto von Guericke, Robert Hooke and Robert Boyle, established the principles of vacuum. The English architect Sir Christopher Wren applied an early system in the Houses of Parliament that used bellows to circulate air. Wrens design would be the catalyst for much improvement and innovation. The first rotary fan used in Europe was for mine ventilation during the 16th century, good ventilation was particularly important in coal mines to reduce casualties from asphyxiation. The civil engineer John Smeaton, and later John Buddle installed reciprocating air pumps in the mines in the North of England, however, this arrangement was not ideal as the machinery was liable to breaking down. With the advent of steam power, fans could finally be used for ventilation. In 1837 William Fourness of England installed a fan at Leeds. In 1849 a 6 m radius steam driven fan, designed by William Brunton, was operational in the Gelly Gaer Colliery of South Wales
Mechanical fan
–
Household electric "box" fan with a propeller style blade
Mechanical fan
–
A household electric floor fan
Mechanical fan
–
A 6 blade
HVLS fan.
Mechanical fan
–
Two c. 1980 box fans
17.
Jet engine
–
A jet engine is a reaction engine discharging a fast-moving jet that generates thrust by jet propulsion. This broad definition includes airbreathing jet engines and non-airbreathing jet engines, in general, jet engines are combustion engines. In common parlance, the jet engine loosely refers to an internal combustion airbreathing jet engine. These typically feature an air compressor powered by a turbine. Jet aircraft use such engines for long-distance travel, early jet aircraft used turbojet engines which were relatively inefficient for subsonic flight. Modern subsonic jet aircraft usually use more complex high-bypass turbofan engines and these engines offer high speed and greater fuel efficiency than piston and propeller aeroengines over long distances. Jet engines date back to the invention of the aeolipile before the first century AD and this device directed steam power through two nozzles to cause a sphere to spin rapidly on its axis. So far as is known, it did not supply mechanical power, instead, it was seen as a curiosity. However, although powerful, at reasonable flight speeds rockets are very inefficient. The earliest attempts at airbreathing jet engines were hybrid designs in which a power source first compressed air. In one such system, called a thermojet by Secondo Campini but more commonly, motorjet, examples of this type of design were the Caproni Campini N.1, and the Japanese Tsu-11 engine intended to power Ohka kamikaze planes towards the end of World War II. None were entirely successful and the N.1 ended up being slower than the design with a traditional engine. If aircraft performance were ever to increase beyond such a barrier and this was the motivation behind the development of the gas turbine engine, commonly called a jet engine. The key to a jet engine was the gas turbine. The gas turbine was not an idea developed in the 1930s, the first gas turbine to successfully run self-sustaining was built in 1903 by Norwegian engineer Ægidius Elling. Limitations in design and practical engineering and metallurgy prevented such engines reaching manufacture, the main problems were safety, reliability, weight and, especially, sustained operation. The first patent for using a gas turbine to power an aircraft was filed in 1921 by Frenchman Maxime Guillaume and his engine was an axial-flow turbojet. Alan Arnold Griffith published An Aerodynamic Theory of Turbine Design in 1926 leading to work at the RAE
Jet engine
–
A
Pratt & Whitney F100 turbofan engine for the
F-15 Eagle being tested in the
hush house at
Florida Air National Guard base. The tunnel behind the engine muffles noise and allows exhaust to escape
Jet engine
–
U.S. Air Force
F-15E Strike Eagles
Jet engine
–
Simulation of a low-bypass turbofan's airflow.
Jet engine
–
Jet engine airflow during take-off.
18.
Rocket engine
–
A rocket engine is a type of jet engine that uses only stored rocket propellant mass for forming its high speed propulsive jet. Rocket engines are reaction engines, obtaining thrust in accordance with Newtons third law, most rocket engines are internal combustion engines, although non-combusting forms also exist. Vehicles propelled by rocket engines are commonly called rockets, since they need no external material to form their jet, rocket engines can perform in a vacuum and thus can be used to propel spacecraft and ballistic missiles. Compared to other types of jet engines, rocket engines have the highest thrust, are by far the lightest, the ideal exhaust is hydrogen, the lightest of all gases, but chemical rockets produce a mix of heavier species, reducing the exhaust velocity. Rocket engines become more efficient at high velocities, since they do not require an atmosphere, they are well suited for uses at very high altitude and in space. Here, rocket is used as an abbreviation for rocket engine, chemical rockets are powered by exothermic chemical reactions of the propellant. Thermal rockets use a propellant, heated by a power source such as electric or nuclear power. Solid-fuel rockets are chemical rockets which use propellant in a solid state, liquid-propellant rockets use one or more liquid propellants fed from tanks. Hybrid rockets use a propellant in the combustion chamber, to which a second liquid or gas oxidiser or propellant is added to permit combustion. Monopropellant rockets use a single propellant decomposed by a catalyst, the most common monopropellants are hydrazine and hydrogen peroxide. Rocket engines produce thrust by the expulsion of an exhaust fluid which has accelerated to a high speed through a propelling nozzle. The fluid is usually a gas created by high pressure combustion of solid or liquid propellants, consisting of fuel and oxidiser components, within a combustion chamber. The nozzle uses the energy released by expansion of the gas to accelerate the exhaust to very high speed. An alternative to combustion is the rocket, which uses water pressurised by compressed air, carbon dioxide, nitrogen, or manual pumping. Chemical rocket propellants are most commonly used, which undergo exothermic chemical reactions which produce hot gas which is used by a rocket for propulsive purposes. Alternatively, a chemically inert reaction mass can be heated using a power source via a heat exchanger. Solid rocket propellants are prepared as a mixture of fuel and oxidising components called grain, liquid-fuelled rockets force separate fuel and oxidiser components into the combustion chamber, where they mix and burn. Hybrid rocket engines use a combination of solid and liquid or gaseous propellants, both liquid and hybrid rockets use injectors to introduce the propellant into the chamber
Rocket engine
–
RS-68 being tested at NASA's Stennis Space Center. The nearly transparent exhaust is due to this engine's exhaust being mostly
superheated steam (water vapour from its propellants, hydrogen and oxygen)
Rocket engine
–
Viking 5C rocket engine
Rocket engine
–
Armadillo aerospace's quad vehicle showing visible banding (shock diamonds) in the exhaust plume
19.
Velocity
–
The velocity of an object is the rate of change of its position with respect to a frame of reference, and is a function of time. Velocity is equivalent to a specification of its speed and direction of motion, Velocity is an important concept in kinematics, the branch of classical mechanics that describes the motion of bodies. Velocity is a vector quantity, both magnitude and direction are needed to define it. The scalar absolute value of velocity is called speed, being a coherent derived unit whose quantity is measured in the SI system as metres per second or as the SI base unit of. For example,5 metres per second is a scalar, whereas 5 metres per second east is a vector, if there is a change in speed, direction or both, then the object has a changing velocity and is said to be undergoing an acceleration. To have a constant velocity, an object must have a constant speed in a constant direction, constant direction constrains the object to motion in a straight path thus, a constant velocity means motion in a straight line at a constant speed. For example, a car moving at a constant 20 kilometres per hour in a path has a constant speed. Hence, the car is considered to be undergoing an acceleration, Speed describes only how fast an object is moving, whereas velocity gives both how fast and in what direction the object is moving. If a car is said to travel at 60 km/h, its speed has been specified, however, if the car is said to move at 60 km/h to the north, its velocity has now been specified. The big difference can be noticed when we consider movement around a circle and this is because the average velocity is calculated by only considering the displacement between the starting and the end points while the average speed considers only the total distance traveled. Velocity is defined as the rate of change of position with respect to time, average velocity can be calculated as, v ¯ = Δ x Δ t. The average velocity is less than or equal to the average speed of an object. This can be seen by realizing that while distance is always strictly increasing, from this derivative equation, in the one-dimensional case it can be seen that the area under a velocity vs. time is the displacement, x. In calculus terms, the integral of the velocity v is the displacement function x. In the figure, this corresponds to the area under the curve labeled s. Since the derivative of the position with respect to time gives the change in position divided by the change in time, although velocity is defined as the rate of change of position, it is often common to start with an expression for an objects acceleration. As seen by the three green tangent lines in the figure, an objects instantaneous acceleration at a point in time is the slope of the tangent to the curve of a v graph at that point. In other words, acceleration is defined as the derivative of velocity with respect to time, from there, we can obtain an expression for velocity as the area under an a acceleration vs. time graph
Velocity
–
As a change of direction occurs while the cars turn on the curved track, their velocity is not constant.
20.
Thrust reversal
–
Thrust reversal, also called reverse thrust, is the temporary diversion of an aircraft engines thrust so that it is directed forward, rather than backwards. Reverse thrust acts against the travel of the aircraft, providing deceleration. Thrust reverser systems are featured on many jet aircraft to help slow down just after touch-down, reducing wear on the brakes, such devices affect the aircraft significantly and are considered important for safe operations by airlines. There have been accidents involving thrust reversal systems such as Lauda Air Flight 004, reverse thrust is also available on many propeller-driven aircraft through reversing the controllable-pitch propellers to a negative angle. The equivalent concept for a ship is called astern propulsion, a landing roll consists of touchdown, bringing the aircraft to taxi speed, and eventually to a complete stop. However, most commercial jet engines continue to produce thrust in the direction, even when idle. In scenarios involving bad weather, where factors like snow or rain on the runway reduce the effectiveness of the brakes, and in emergencies like rejected takeoffs, this need is more pronounced. A simple and effective method is to reverse the direction of the exhaust stream of the jet engine, ideally, the reversed exhaust stream would be directed straight forward. However, for reasons, this is not possible. Thrust reversal can also be used in flight to reduce airspeed, there are three common types of thrust reversing systems used on jet engines, the target, clam-shell, and cold stream systems. Some propeller-driven aircraft equipped with variable-pitch propellers can reverse thrust by changing the pitch of their propeller blades, most commercial jetliners have such devices, and it also has applications in military aviation. Small aircraft typically do not have thrust reversal systems, except in specialized applications, on the other hand, large aircraft almost always have the ability to reverse thrust. Reciprocating engine, turboprop and jet aircraft can all be designed to include thrust reversal systems, propeller-driven aircraft generate reverse thrust by changing the angle of their controllable-pitch propellers so that the propellers direct their thrust forward. Single-engine aircraft tend not to have reverse thrust, however, single-engine turboprop aircraft such as the PAC P-750 XSTOL, Cessna 208 Caravan, and Pilatus PC-6 Porter do have this feature available. One special application of reverse thrust comes in its use on multi-engine seaplanes and these aircraft, when landing on water, have no conventional braking method and must rely on slaloming and/or reverse thrust, as well as the drag of the water in order to slow or stop. On aircraft using jet engines, thrust reversal is accomplished by causing the jet blast to flow forward, the engine does not run or rotate in reverse, instead, thrust reversing devices are used to block the blast and redirect it forward. High bypass ratio engines usually reverse thrust by changing the direction of only the fan airflow, since the majority of thrust is generated by this section, as opposed to the core. There are three jet engine thrust reversal systems in use, The target thrust reverser uses a pair of hydraulically-operated bucket type doors to reverse the hot gas stream
Thrust reversal
–
Thrust reversers deployed on the
CFM56 engine of an
Airbus A320
Thrust reversal
–
Half-deployed target-type reverser of a
RB.199 engine for the
Panavia Tornado. One of very few fighter aircraft with thrust reversal.
Thrust reversal
–
Variable-pitch propellers of an
E-2C Hawkeye
Thrust reversal
–
Target 'bucket' thrust reverser deployed on the
Tay engines of a
Fokker 100
21.
Rotary wing aircraft
–
A rotorcraft or rotary-wing aircraft is a heavier-than-air flying machine that uses lift generated by wings, called rotary wings or rotor blades, that revolve around a mast. Several rotor blades mounted on a single mast are referred to as a rotor, the International Civil Aviation Organization defines a rotorcraft as supported in flight by the reactions of the air on one or more rotors. Rotorcraft generally include those aircraft where one or more rotors are required to provide lift throughout the flight, such as helicopters, cyclocopters, autogyros. Compound rotorcraft may also include additional thrust engines or propellers and static lifting surfaces, helicopters have several different configurations of one or more main rotors. A cyclocopter is a rotorcraft whose rotors are driven by the engine throughout the flight. At the present time flying model prototypes have been built in China, US, S. Korea, while similar to a helicopter rotor in appearance, the autogyros rotor must have air flowing up and through the rotor disk in order to generate rotation. Early autogyros resembled the fixed-wing aircraft of the day, with wings, late-model autogyros feature a rear-mounted engine and propeller in a pusher configuration. The autogyro was invented in 1920 by Juan de la Cierva, the autogyro with pusher propeller was first tested by Etienne Dormoy with his Buhl A-1 Autogyro. As power is increased to the propeller, less power is required by the rotor to provide forward thrust resulting in reduced pitch angles and rotor blade flapping. At cruise speeds with most or all of the thrust being provided by the propellers, a rotor kite or gyroglider is an unpowered rotary-wing aircraft. Like an autogyro or helicopter, it relies on lift created by one or more sets of rotors in order to fly, a rotary wing is characterised by the number of blades. Typically this is two and six per driveshaft. A rotorcraft may have one or more rotors, various rotor configurations have been used, One rotor. Powered rotors require compensation for the reaction causing yaw, except in the case of tipjet drive. These typically rotate in opposite directions cancelling the torque reaction so that no tail rotor or other yaw stabiliser is needed and these rotors can be laid out as Tandem – One in front of the other. Coaxial – One rotor disc above the other, with drive shafts. An uncommon configuration, the 1948 Cierva Air Horse had three rotors as it was not believed a single rotor of sufficient strength could be built for its size. All three rotors turned in the direction and yaw compensation was provided by inclining each rotor axis to generate rotor thrust components that opposed torque
Rotary wing aircraft
–
An
AS332 helicopter from the Hong Kong Government Flying Service conducts a water bomb demonstration
Rotary wing aircraft
–
A German-registered autogyro
Rotary wing aircraft
–
Fairey Rotodyne prototype.
Rotary wing aircraft
–
Helicopters
22.
Thrust vectoring
–
In rocketry and ballistic missiles that fly outside the atmosphere, aerodynamic control surfaces are ineffective, so thrust vectoring is the primary means of attitude control. For aircraft, the method was originally envisaged to provide vertical thrust as a means to give aircraft vertical or short takeoff. Subsequently, it was realized that using vectored thrust in combat situations enabled aircraft to perform various maneuvers not available to conventional-engined planes, in missile literature originating from Russian sources, thrust vectoring is often referred as gas-dynamic steering or gas-dynamic control. Thrust vector control is used when the system is creating thrust. At other stages of flight, separate mechanisms are required for attitude and it is possible to generate pitch and yaw moments by deflecting the main rocket thrust vector so that it does not pass through the mass center. Thrust vectoring for many liquid rockets is achieved by gimbaling the rocket engine, the Saturn V and the Space Shuttle used gimballed engines. If the liquid is injected on only one side of the missile, it modifies that side of the exhaust plume, resulting in different thrust on that side and this was the control system used on the Minuteman II and the early SLBMs of the United States Navy. A later method developed for solid propellant ballistic missiles achieves thrust vectoring by deflecting the rocket nozzle using electric servomechanisms or hydraulic cylinders, the Trident C4 and D5 systems are controlled via hydraulically actuated nozzle. The Apollo Lunar Module had an engine in the ascent stage. Attitude control was achieved by using 16 auxiliary reaction control system engines in 4 clusters mounted on the ascent stage, the descent stage engine gimbaled, but this was computer-controlled to keep the thrust vector aligned with the center of mass and attitude control was by the ascent stage RCS. The V-2 used exhaust vanes and aerodynamic vanes, as did the Redstone, some smaller sized atmospheric tactical missiles, such as the AIM-9X Sidewinder, eschew flight control surfaces and instead use mechanical vanes to deflect motor exhaust to one side. Thrust vectoring is a way to reduce a missiles minimum range, for example, anti-tank missiles such as the ERYX and the PARS3 LR use thrust vectoring for this reason. 9M96E uses a control system enables maneuver at altitudes of up to 35 km at forces of over 20g. 9K720 Iskander is controlled during the flight with gas-dynamic and aerodynamic control surfaces. Most currently operational vectored thrust aircraft use turbofans with rotating nozzles or vanes to deflect the exhaust stream and this method can successfully deflect thrust through as much as 90 degrees, relative to the aircraft centerline. However, the engine must be sized for vertical lift, rather than normal flight, afterburning is difficult to incorporate and is impractical for take-off and landing thrust vectoring, because the very hot exhaust can damage runway surfaces. Without afterburning it is hard to reach flight speeds. A PCB engine, the Bristol Siddeley BS100, was cancelled in 1965, tiltrotor aircraft vector thrust via rotating turboprop engine nacelles
Thrust vectoring
–
Thrust vectoring nozzle on a
Sukhoi Su-35S
Thrust vectoring
–
The
F-18 HARV,
X-31, and
F-16 MATV in flight
Thrust vectoring
–
Graphite exhaust vanes on a V-2 rocket motor's nozzle
Thrust vectoring
–
The pre-World War 1, British Army airship Delta, fitted with swiveling propellers
23.
V/STOL
–
A vertical and/or short take-off and landing aircraft is an airplane able to take-off or land vertically or on short runways. Vertical takeoff and landing aircraft are a subset of V/STOL craft that do not require runways at all, generally, a V/STOL aircraft needs to be able to hover. Most V/STOL aircraft types were experiments or outright failures from the 1950s to 1970s, V/STOL aircraft types that have been produced in large numbers include the Harrier, Yak-38 Forger and V-22 Osprey. A rolling takeoff, sometimes with a ramp, reduces the amount of thrust required to lift an aircraft from the ground, for instance, the Harrier is incapable of taking off vertically with full weapons and fuel load. Hence V/STOL aircraft generally use a runway if it is available, I. e. short takeoff and vertical landing or conventional takeoff and landing operation is preferred to VTOL operation. The main advantage of V/STOL aircraft is closer basing to the enemy, in the case of the Falklands War, it also permitted high-performance fighter air cover and ground attack without a large aircraft carrier equipped with aircraft catapult. The latest V/STOL aircraft is the F-35B, which is expected to service in 2016. This is a partial list, there have been designs for V/STOL aircraft. Hawker P. 1127/Kestrel/Harrier, four rotating nozzles for vectored thrust of fan, Bell XF-109 Bell 65 EWR VJ101 AgustaWestland Project Zero technology demonstrator Bell XV-3 Bell XV-15 Bell 609 Bell-Boeing V-22 Osprey Curtiss-Wright X-19 - four rotating propellers, tilt-wing. Canadair CL-84 Dynavert, two turboprop tilt-wing in RCAF service from 1960 LTV XC-142 four-engine tilt-wing cross-shafted turboprop Bell X-22 rotating ducted propellers, fans in wings driven by engine exhaust gas. VFW VAK 191B Attack fighter similar to Harrier but supersonic dash speed, smaller wings, first aircraft capable of demonstrating transition from short take-off to supersonic flight to vertical landing on the same sortie
V/STOL
–
RAF Harrier GR9 arrives at
RIAT 2008
V/STOL
–
A U.S. Marine Corps
MV-22 Osprey prepares to land aboard a ship
24.
Motorboat
–
A motorboat, speedboat, or powerboat is a boat which is powered by an engine. Some motorboats are fitted with engines, others have an outboard motor installed on the rear, containing the internal combustion engine, the gearbox. An inboard-outboard contains a hybrid of a powerplant and an outboard, where the combustion engine is installed inside the boat. There are two configurations of an inboard, V-drive and direct drive, the V-drive has become increasingly popular due to wakeboarding and wakesurfing. Motorboats vary greatly in size and configuration, from the four-meter, the earliest boat to be powered by a petrol engine was tested on the Neckar River by Gottlieb Daimler and Wilhelm Maybach in 1886, when they tested their new longcase clock engine. It had been constructed in the greenhouse in Daimlers back yard. The first public display took place on the Waldsee in Cannstatt, today a suburb of Stuttgart, the engine of this boat had a single cylinder of 1 horse power. Daimlers second launch in 1887 had a second cylinder positioned at an angle of 15 degrees to the first one, the first successful motor boat was designed by the Priestman Brothers in Hull, England, under the direction of William Dent Priestman. The company began trials of their first motorboat in 1888, the engine was powered with kerosene and used an innovative high-tension ignition system. The company was the first to large scale production of the motor boat. Working in the garden of their home in Olton, Warwickshire, they designed, in 1897, he produced a second engine similar in design to his previous one but running on benzene at 800 r. p. m. The engine drove a reversible propeller, an important part of his new engine was the revolutionary carburettor, for mixing the fuel and air correctly. His invention was known as a carburetor, because fuel was drawn into a series of wicks. He patented this invention in 1905, the Daimler Company began production of motor boats in 1897 from its manufacturing base in Coventry. The engines had two cylinders and the charge of petroleum and air was ignited by compression into a heated platinum tube. The engine gave about six horse-power, the petrol was fed by air pressure to a large surface carburettor and also an auxiliary tank which supplied the burners for heating the ignition tubes. It was not until 1901 that a safer apparatus for igniting the fuel with a spark was used in motor boats. Interest in fast motorboats grew rapidly in the years of the 20th century
Motorboat
–
Lazzara 80 Sky Lounge enclosed bridge
Motorboat
–
A motorboat with an
outboard motor
Motorboat
–
Model of the first motor boat constructed by
Gottlieb Daimler and
Wilhelm Maybach in 1886.
Motorboat
–
Dorothy Levitt won the first
Harmsworth Cup, driving the
Napier motor yacht in 1903.
25.
Momentum
–
In classical mechanics, linear momentum, translational momentum, or simply momentum is the product of the mass and velocity of an object, quantified in kilogram-meters per second. It is dimensionally equivalent to impulse, the product of force and time, Newtons second law of motion states that the change in linear momentum of a body is equal to the net impulse acting on it. If the truck were lighter, or moving slowly, then it would have less momentum. Linear momentum is also a quantity, meaning that if a closed system is not affected by external forces. In classical mechanics, conservation of momentum is implied by Newtons laws. It also holds in special relativity and, with definitions, a linear momentum conservation law holds in electrodynamics, quantum mechanics, quantum field theory. It is ultimately an expression of one of the symmetries of space and time. Linear momentum depends on frame of reference, observers in different frames would find different values of linear momentum of a system. But each would observe that the value of linear momentum does not change with time, momentum has a direction as well as magnitude. Quantities that have both a magnitude and a direction are known as vector quantities, because momentum has a direction, it can be used to predict the resulting direction of objects after they collide, as well as their speeds. Below, the properties of momentum are described in one dimension. The vector equations are almost identical to the scalar equations, the momentum of a particle is traditionally represented by the letter p. It is the product of two quantities, the mass and velocity, p = m v, the units of momentum are the product of the units of mass and velocity. In SI units, if the mass is in kilograms and the velocity in meters per second then the momentum is in kilogram meters/second, in cgs units, if the mass is in grams and the velocity in centimeters per second, then the momentum is in gram centimeters/second. Being a vector, momentum has magnitude and direction, for example, a 1 kg model airplane, traveling due north at 1 m/s in straight and level flight, has a momentum of 1 kg m/s due north measured from the ground. The momentum of a system of particles is the sum of their momenta, if two particles have masses m1 and m2, and velocities v1 and v2, the total momentum is p = p 1 + p 2 = m 1 v 1 + m 2 v 2. If all the particles are moving, the center of mass will generally be moving as well, if the center of mass is moving at velocity vcm, the momentum is, p = m v cm. This is known as Eulers first law, if a force F is applied to a particle for a time interval Δt, the momentum of the particle changes by an amount Δ p = F Δ t
Momentum
–
In a game of
pool, momentum is conserved; that is, if one ball stops dead after the collision, the other ball will continue away with all the momentum. If the moving ball continues or is deflected then both balls will carry a portion of the momentum from the collision.
26.
Rocket
–
A rocket is a missile, spacecraft, aircraft or other vehicle that obtains thrust from a rocket engine. Rocket engine exhaust is formed entirely from propellant carried within the rocket before use, Rocket engines work by action and reaction and push rockets forward simply by expelling their exhaust in the opposite direction at high speed, and can therefore work in the vacuum of space. In fact, rockets work more efficiently in space than in an atmosphere, multistage rockets are capable of attaining escape velocity from Earth and therefore can achieve unlimited maximum altitude. Compared with airbreathing engines, rockets are lightweight and powerful and capable of generating large accelerations. To control their flight, rockets rely on momentum, airfoils, auxiliary engines, gimballed thrust, momentum wheels, deflection of the exhaust stream, propellant flow, spin. Rockets for military and recreational uses date back to at least 13th century China, significant scientific, interplanetary and industrial use did not occur until the 20th century, when rocketry was the enabling technology for the Space Age, including setting foot on the Earths moon. Rockets are now used for fireworks, weaponry, ejection seats, launch vehicles for satellites, human spaceflight. Chemical rockets are the most common type of high power rocket, chemical rockets store a large amount of energy in an easily released form, and can be very dangerous. However, careful design, testing, construction and use minimizes risks, the first gunpowder-powered rockets were developed in Song China, by the 13th century. The Chinese rocket technology was adopted by the Mongols and the invention was spread via the Mongol invasions to the Near East, medieval and early modern rockets were used militarily as incendiary weapons in sieges. An early Chinese text to mention the use of rockets was the Huolongjing, between 1270 and 1280, Hasan al-Rammah wrote al-furusiyyah wa al-manasib al-harbiyya, which included 107 gunpowder recipes,22 of which are for rockets. In Europe, Konrad Kyeser described rockets in his military treatise Bellifortis around 1405. The name Rocket comes from the Italian rocchetta, meaning bobbin or little spindle, the Italian term was adopted into German in the mid 16th century by Leonhard Fronsperger and Conrad Haas, and by the early 17th century into English. Artis Magnae Artilleriae pars prima, an important early work on rocket artillery. The first iron-cased rockets were developed in the late 18th century in the Kingdom of Mysore, in 1814, Francis Scott Key wrote the line rockets red glare while held captive on a British ship that was laying siege to Fort McHenry. The first mathematical treatment of the dynamics of rocket propulsion is due to William Moore, in 1815, Alexander Dmitrievich Zasyadko constructed rocket-launching platforms, which allowed rockets to be fired in salvos, and gun-laying devices. William Hale in 1844 greatly increased the accuracy of rocket artillery, the Congreve rocket was further improved by Edward Mounier Boxer in 1865. Konstantin Tsiolkovsky first speculated on the possibility of manned spaceflight with rocket technology, robert Goddard in 1920 published proposed improvements to rocket technology in A Method of Reaching Extreme Altitudes
Rocket
–
A
Soyuz-U, at
Baikonur cosmodrome 's
Site 1/5 in
Kazakhstan
Rocket
–
A depiction of the "long serpent" rocket launcher from the 11th century book
Wujing Zongyao. The holes in the frame are designed to keep the fire arrows separate.
Rocket
–
Ryusei Festival at
Yoshida town,
Chichibu city,
Saitama, Japan
Rocket
–
Kyeser was infatuated with the
legend of Alexander the Great: here Alexander holds a rocket, the first depiction of one
27.
Exhaust velocity
–
Specific impulse is a measure of the efficiency of rocket and jet engines. By definition, it is the total impulse delivered per unit of propellant consumed and is equivalent to the generated thrust divided by the propellant flow rate. If mass is used as the unit of propellant, then specific impulse has units of velocity, if weight is used instead, then specific impulse has units of time. Multiplying flow rate by the gravity before dividing it into the thrust. In rockets, this means the engine is more efficient at gaining altitude, distance and this is much less of a consideration in jet engines that employ wings and outside air for combustion to carry payloads that are much heavier than the propellant. Specific impulse includes the contribution to impulse provided by air that has been used for combustion and is exhausted with the spent propellant. Jet engines use air, and therefore have a much higher specific impulse than rocket engines. The specific impulse in terms of propellant mass spent is in units of distance per time and this is higher than the actual exhaust velocity because the mass of the combustion air is not being accounted for. Actual and effective exhaust velocity are the same in rocket engines not utilizing air, Specific impulse is inversely proportional to specific fuel consumption by the relationship Isp = 1/ for SFC in kg/ and Isp = 3600/SFC for SFC in lb/lbf-hr. The amount of propellant is normally measured either in units of mass or weight, however, if propellant weight is used, an impulse divided by a force turns out to be a unit of time, and so specific impulses are measured in seconds. These two formulations are both used and differ from each other by a factor of g0, the dimensioned constant of gravitational acceleration at the surface of the Earth. Note that the rate of change of momentum of a rocket per unit time is equal to the thrust, the higher the specific impulse, the less propellant is needed to produce a given thrust during a given time. In this regard a propellant is more efficient the greater its specific impulse and this should not be confused with energy efficiency, which can decrease as specific impulse increases, since propulsion systems that give high specific impulse require high energy to do so. It is important that thrust and specific impulse not be confused, the specific impulse is a measure of the impulse produced per unit of propellant expended, while thrust is a measure of the momentary or peak force supplied by a particular engine. In many cases, propulsion systems with high specific impulses—some ion thrusters reach 10,000 seconds—produce low thrusts. When calculating specific impulse, only propellant that is carried with the vehicle use is counted. Air resistance and the inability to keep a high specific impulse at a fast burn rate are why all the propellant is not used as fast as possible. If an engine weighs more in order to gain a specific impulse, it may not be as efficient in gaining altitude, distance
Exhaust velocity
–
The specific impulse of various jet engines
28.
Space Shuttle
–
The Space Shuttle was a partially reusable low Earth orbital spacecraft system operated by the U. S. National Aeronautics and Space Administration, as part of the Space Shuttle program. Its official program name was Space Transportation System, taken from a 1969 plan for a system of reusable spacecraft of which it was the only item funded for development, the first of four orbital test flights occurred in 1981, leading to operational flights beginning in 1982. Five complete Shuttle systems were built and used on a total of 135 missions from 1981 to 2011, the Shuttle fleets total mission time was 1322 days,19 hours,21 minutes and 23 seconds. Shuttle components included the Orbiter Vehicle, a pair of solid rocket boosters. The Shuttle was launched vertically, like a rocket, with the two SRBs operating in parallel with the OVs three main engines, which were fueled from the ET. The SRBs were jettisoned before the vehicle reached orbit, and the ET was jettisoned just before orbit insertion, at the conclusion of the mission, the orbiter fired its OMS to de-orbit and re-enter the atmosphere. The orbiter then glided as a spaceplane to a landing, usually at the Shuttle Landing Facility of KSC or Rogers Dry Lake in Edwards Air Force Base. After landing at Edwards, the orbiter was back to the KSC on the Shuttle Carrier Aircraft. The first orbiter, Enterprise, was built in 1976, used in Approach, four fully operational orbiters were initially built, Columbia, Challenger, Discovery, and Atlantis. Of these, two were lost in accidents, Challenger in 1986 and Columbia in 2003, with a total of fourteen astronauts killed. A fifth operational orbiter, Endeavour, was built in 1991 to replace Challenger, the Space Shuttle was retired from service upon the conclusion of Atlantiss final flight on July 21,2011. Nixons post-Apollo NASA budgeting withdrew support of all components except the Shuttle. The vehicle consisted of a spaceplane for orbit and re-entry, fueled by liquid hydrogen and liquid oxygen tanks. The first of four orbital test flights occurred in 1981, leading to operational flights beginning in 1982, all launched from the Kennedy Space Center, Florida. The system was retired from service in 2011 after 135 missions, the program ended after Atlantis landed at the Kennedy Space Center on July 21,2011. Major missions included launching numerous satellites and interplanetary probes, conducting space science experiments, the first orbiter vehicle, named Enterprise, was built for the initial Approach and Landing Tests phase and lacked engines, heat shielding, and other equipment necessary for orbital flight. A total of five operational orbiters were built, and of these and it was used for orbital space missions by NASA, the US Department of Defense, the European Space Agency, Japan, and Germany. The United States funded Shuttle development and operations except for the Spacelab modules used on D1, sL-J was partially funded by Japan
Space Shuttle
–
Discovery lifts off at the start of
STS-120.
Space Shuttle
–
STS-129 ready for launch
Space Shuttle
–
President Nixon (right) with
NASA Administrator Fletcher in January 1972, three months before Congress approved funding for the Shuttle program
Space Shuttle
–
STS-1 on the launch pad, December 1980
29.
Space Shuttle Main Engine
–
Built in the United States by Rocketdyne, the RS-25 burns cryogenic liquid hydrogen and liquid oxygen propellants, with each engine producing 1,859 kN of thrust at liftoff. Although the RS-25 can trace its heritage back to the 1960s, concerted development of the began in the 1970s, with the first flight, STS-1. The RS-25 has undergone several upgrades over its history to improve the engines reliability, safety. The RS-25 operates at temperatures ranging from −253 °C to 3300 °C, the Space Shuttle used a cluster of three RS-25 engines mounted in the aft structure of the orbiter, with fuel being drawn from the external tank. Following each flight, the engines were removed from the orbiter, the RS-25 engine consists of various pumps, valves and other components which work in concert to produce thrust. Once in the MPS lines, the fuel and oxidizer each branch out into separate paths to each engine, in each branch, prevalves then allow the propellants to enter the engine. Once in the engine, the flow through low-pressure fuel and oxidizer turbopumps. From these HPTPs the propellants take different routes through the engine, meanwhile, fuel flows through the main fuel valve into regenerative cooling systems for the nozzle and MCC, or through the chamber coolant valve. Fuel passing through the MCC cooling system then passes back through the LPFTP turbine before being routed either to the tank pressurization system or to the hot gas manifold cooling system. Once in the injectors, the propellants are mixed and injected into the combustion chamber where they are ignited. The burning propellant mixture is ejected through the throat and bell of the engines nozzle. It boosts the liquid oxygens pressure from 0.7 to 2.9 MPa, during engine operation, the pressure boost permits the high-pressure oxidizer turbine to operate at high speeds without cavitating. The LPOTP, which measures approximately 450 by 450 mm, is connected to the vehicle propellant ducting, the HPOTP consists of two single-stage centrifugal pumps mounted on a common shaft and driven by a two-stage, hot-gas turbine. The main pump boosts the liquid oxygens pressure from 2.9 to 30 MPa while operating at approximately 28,120 rpm, the HPOTP discharge flow splits into several paths, one of which drives the LPOTP turbine. Another path is to, and through, the oxidizer valve. Another small flow path is tapped off and sent to the heat exchanger. The gas is sent to a manifold and then routed to pressurize the liquid oxygen tank, another path enters the HPOTP second-stage preburner pump to boost the liquid oxygens pressure from 30 to 51 MPa. It passes through the oxidizer preburner oxidizer valve into the oxidizer preburner, the HPOTP measures approximately 600 by 900 mm
Space Shuttle Main Engine
–
Space Shuttle Main Engine test firing. (The bright area at the bottom of the picture is a
Mach disk.)
Space Shuttle Main Engine
–
The nozzles of
Space Shuttle Columbia 's three RS-25s following the landing of
STS-93.
Space Shuttle Main Engine
–
A Block II RS-25D Main Engine Controller.
Space Shuttle Main Engine
–
Space Shuttle Atlantis 's three RS-25D main engines at liftoff during
STS-110.
30.
Meganewton
–
The newton is the International System of Units derived unit of force. It is named after Isaac Newton in recognition of his work on classical mechanics, see below for the conversion factors. One newton is the force needed to one kilogram of mass at the rate of one metre per second squared in direction of the applied force. In 1948, the 9th CGPM resolution 7 adopted the name newton for this force, the MKS system then became the blueprint for todays SI system of units. The newton thus became the unit of force in le Système International dUnités. This SI unit is named after Isaac Newton, as with every International System of Units unit named for a person, the first letter of its symbol is upper case. Note that degree Celsius conforms to this rule because the d is lowercase. — Based on The International System of Units, section 5.2. Newtons second law of motion states that F = ma, where F is the applied, m is the mass of the object receiving the force. The newton is therefore, where the symbols are used for the units, N for newton, kg for kilogram, m for metre. In dimensional analysis, F = M L T2 where F is force, M is mass, L is length, at average gravity on earth, a kilogram mass exerts a force of about 9.8 newtons. An average-sized apple exerts about one newton of force, which we measure as the apples weight, for example, the tractive effort of a Class Y steam train and the thrust of an F100 fighter jet engine are both around 130 kN. One kilonewton,1 kN, is 102.0 kgf,1 kN =102 kg ×9.81 m/s2 So for example, a platform rated at 321 kilonewtons will safely support a 32,100 kilograms load. Specifications in kilonewtons are common in safety specifications for, the values of fasteners, Earth anchors. Working loads in tension and in shear, thrust of rocket engines and launch vehicles clamping forces of the various moulds in injection moulding machines used to manufacture plastic parts
Meganewton
–
Base units
31.
Space Shuttle Solid Rocket Booster
–
After burnout, they were jettisoned and parachuted into the Atlantic Ocean where they were recovered, examined, refurbished, and reused. The SRBs were the most powerful rocket motors ever flown, each provided a maximum 13,800 kN thrust, roughly double the most powerful single-combustion chamber liquid-propellant rocket engine ever flown, the Rocketdyne F-1. With a combined mass of about 1,180,000 kg, the motor segments of the SRBs were manufactured by Thiokol of Brigham City, Utah, which was later purchased by ATK. The prime contractor for most other components of the SRBs, as well as for the integration of all the components and retrieval of the spent SRBs, was USBI, a subsidiary of Pratt and Whitney. This contract was subsequently transitioned to United Space Alliance, a liability company joint venture of Boeing. Out of 270 SRBs launched over the Shuttle program, all but four were recovered – those from STS-4, over 5,000 parts were refurbished for reuse after each flight. The final set of SRBs that launched STS-135 included parts that flew on 59 previous missions, recovery also allowed post-flight examination of the boosters, identification of anomalies, and incremental design improvements. The two reusable SRBs provided the main thrust to lift the shuttle off the pad and up to an altitude of about 150,000 ft. While on the pad, the two SRBs carried the weight of the external tank and orbiter and transmitted the weight load through their structure to the mobile launch platform. Each booster had a liftoff thrust of approximately 2,800,000 pounds-force at sea level and they were ignited after the three Space Shuttle Main Engines thrust level was verified. Each is 149.16 ft long and 12.17 ft in diameter, only then could any conceivable set of launch or post-liftoff abort procedures be contemplated. In addition, failure of an individual SRBs thrust output or ability to adhere to the designed performance profile was not survivable, each SRB weighed approximately 1,300,000 lb at launch. The two SRBs constituted about 69% of the total lift-off mass, the propellant for each solid rocket motor weighed approximately 1,100,000 lb. The inert weight of each SRB was approximately 200,000 pounds, while the terms solid rocket motor and solid rocket booster are often used interchangeably, in technical use they have specific meanings. The term solid rocket motor applied to the propellant, case, igniter, each booster was attached to the external tank at the SRBs aft frame by two lateral sway braces and a diagonal attachment. The forward end of each SRB was attached to the tank at the forward end of the SRBs forward skirt. On the launch pad, each booster also was attached to the launcher platform at the aft skirt by four frangible nuts that were severed at lift-off. The boosters were composed of seven individually manufactured steel segments and these were assembled in pairs by the manufacturer, and then shipped to Kennedy Space Center by rail for final assembly
Space Shuttle Solid Rocket Booster
–
Solid Rocket Booster
Space Shuttle Solid Rocket Booster
–
Solid Rocket Booster (SRB) separation
Space Shuttle Solid Rocket Booster
–
Splashdown of the right hand SRB from the launch of
STS-124.
Space Shuttle Solid Rocket Booster
–
The solid rocket boosters, jettisoned from the
Space Shuttle Discovery following the launch of
STS-116, floating in the Atlantic Ocean about 150 miles northeast of
Cape Canaveral.
32.
Simplified Aid For EVA Rescue
–
Simplified Aid For EVA Rescue is a small, self-contained, propulsive backpack system worn during spacewalks, to be used in case of emergency only. If an untethered astronaut were to lose contact with the vessel. It is worn on spacewalks outside the International Space Station, and was worn on spacewalks outside the Space Shuttle, so far, there has not been an emergency in which it was needed. SAFER is a small, simplified version of the Manned Maneuvering Unit, SAFER is worn by every ISS crewmember using an Extravehicular Mobility Unit. SAFER was co invented by former astronaut Joseph Kerwin, Paul Cottingham and it was later sponsored by the Space Shuttle Program and developed by Lockheed and NASA personnel. Ralph Anderson was the Shuttle Program Offices Project Manager for the SAFER Development Test Objective, cliff Hess was the NASA Project Engineer. The device was developed by the Robotics Division of NASA at the Johnson Space Center, the SAFER was the design solution to the Shuttle Programs requirement to provide a means of self rescue should an EVA crewmember become untethered during an EVA. SAFER was first flown on STS-64 September 9,1994, where a flight test was performed first by astronaut Mark Lee. Both astronauts flew the SAFER up and around the Shuttles Robotic Arm along with a demonstration test of the SAFERs automatic attitude hold feature and this feature arrests uncontrolled rotation of a detached crewmember expected in an accidental separation. SAFER has a mass of approximately 83 lb and can provide a change in velocity of at least 10 ft/s. It was also tested during flight STS-92 when astronauts Wisoff and Lopez-Alegria performed test maneuvers, the left side latch on the SAFER unit became unlatched during an EVA by astronaut Piers Sellers on STS-121 while testing shuttle repair techniques. The latch had been inadvertently bumped and moved to the unlatch position, as a precaution, Mike Fossum tethered it to him and the spacewalk continued. In subsequent spacewalks, the latches were secured with Kapton tape, a hard cover is being designed for future missions. Suited for spacewalking - NASA Video of SAFER being attached
Simplified Aid For EVA Rescue
–
Astronaut
Rick Mastracchio working with a SAFER system attached.
Simplified Aid For EVA Rescue
–
SAFER
33.
Radio-controlled aircraft
–
A radio-controlled aircraft is a small flying machine that is controlled remotely by an operator on the ground using a hand-held radio transmitter. The transmitter communicates with a receiver within the craft that sends signals to servomechanisms which move the control based on the position of joysticks on the transmitter. The control surfaces, in turn, affect the orientation of the plane, flying RC aircraft as a hobby grew substantially from the 2000s with improvements in the cost, weight, performance and capabilities of motors, batteries and electronics. A wide variety of models and styles is available, the earliest examples of electronically guided model aircraft were hydrogen-filled model airships of the late 19th century. They were flown as a music hall act around theater auditoriums using a form of spark-emitted radio signal. During World War II, the U. S. Army, there are many types of radio-controlled aircraft. For beginning hobbyists, there are park flyers and trainers, for more experienced pilots there are glow plug engine, electric powered and sailplane aircraft. For expert flyers, jets, pylon racers, helicopters, autogyros, 3D aircraft, some models are made to look and operate like a bird instead. Full-scale aircraft designs from every era of aviation, from the Pioneer Era and World War Is start, if the full-sized aircraft possessed such features as part of its design. Gliders are planes that do not typically have any type of propulsion, unpowered glider flight must be sustained through exploitation of the natural lift produced from thermals or wind hitting a slope. Dynamic soaring is another way of providing energy to gliders that is becoming more and more common. However, even conventional slope soaring gliders are capable of achieving speeds comparable with similar sized powered craft, gliders are typically partial to slow flying and have high aspect ratio, as well as very low wing loading. Powered gliders have recently seen an increase in popularity, a common method of maximising flight duration is to quickly fly a powered glider upwards to a chosen altitude and descending in an unpowered glide. Folding propellers which reduce drag are standard, powered gliders built with stability in mind and capable of aerobatics, high speed flight and sustained vertical flight are classified as Hot-liners. Warm-liners are powered craft with similar abilities but less extreme thrust capability, jets tend to be very expensive and commonly use a micro turbine or ducted fan to power them. Most airframes are constructed from glass and carbon fiber. For electric powered flight which are powered by electric ducted fans. Inside the aircraft, wooden spars reinforce the body to make a rigid airframe and they also have kevlar fuel tanks for the Jet A fuel that they run on
Radio-controlled aircraft
–
A radio control flyer (holding a transmitter) guides his aircraft in for a landing
Radio-controlled aircraft
–
This
Kyosho "Phantom 70" biplane is a semi-scale replica of a class winner and record holder from the 2007
Reno Air Races. In this example, the fuselage with its complex curves as well as the engine cowl, wheel pants and wing struts are rendered in fiberglass. The wings and horizontal stabilizer are traditional balsa/plywood construction
Radio-controlled aircraft
–
A large (~40 inch wingspan) scale remote control P-51 Mustang.
Radio-controlled aircraft
–
F3A Pattern Ship – ZNline Alliance by CPLR
34.
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 81,000 to 115,000 lbf. It entered service with British Airways in November 1995 and it is one of three options for the 777-200, -200ER, and -300 versions, and the exclusive engine of the -200LR, -300ER, and 777F. Developed from the NASA 1970s Energy Efficient Engine, the 10-stage high-pressure compressor develops an industry record pressure ratio of 23,1 and is driven by a 2-stage, air-cooled, a 3-stage low-pressure compressor, situated directly behind the fan, supercharges the core. The fan/LPC is driven by a 6-stage low-pressure turbine, the GE90 series are physically the largest engines in aviation history, the fan diameter of the original series being 123 in, and the largest variant GE90-115B has a fan diameter of 128 in. The GE90 engine was launched in 1990, GE Aviation teamed with Snecma, IHI and Avio for the program. It is the worlds largest and the most powerful jet engine, for Boeings next-generation 777 long-range versions, greater thrust was needed to meet the specifications. General Electric and Pratt & Whitney insisted on a contract due to the $500 million investment in engine modifications needed to meet the requirements. GE received sole engine supplier status for the higher-thrust engine variants for the 777-200LR, -300ER, a net increase in core flow was achieved. General Electric performed a similar re-staging exercise when they upgraded the CF6 from the -6 to the higher-thrust -50, however, this thrust growth route is expensive, since all the downstream components must be larger for flow capacity. The fan is an advanced, larger diameter unit made from composite materials and is the first production engine to feature swept rotor blades, the GE90-115B is powerful enough to fully operate GEs Boeing 747 testbed on its own power, an attribute demonstrated during a flight test. The first General Electric-powered Boeing 777 was delivered to British Airways on November 12,1995, initial service was affected by gearbox bearing wear concerns, which caused the airline to temporarily withdraw its 777 fleet from transatlantic service in 1997. British Airways aircraft returned to service later that year. Problems with GE90 development and testing caused delays in Federal Aviation Administration certification, in addition the GE90s increased output was not yet put to use by airlines and it was also the heaviest engine option, making it the least popular choice while Rolls-Royce held the top spot. British Airways soon replaced the GE90 with Rolls-Royce engines on their 777s, if the fan is removed from the core, then the engines may be shipped on a 747 Freighter. The GE90-equipped Boeing 777s have been the best-selling long-range large wide-body aircraft in the 2000s, the -94B for the -200ER is being retrofitted with some of the first FAA-approved 3D-printed components. It has an in-flight shutdown rate of one per million engine flight-hours and it accumulated more than 8 million cycles and 50 million flight hours in 20 years. According to the Guinness Book of Records, at 127,900 lbf and this thrust record was accomplished inadvertently as part of a one-hour, triple-red-line engine stress test. To accommodate the increase in torsional stresses, a new alloy, GE1014 was created
GE90
–
GE90
GE90
–
A 1998
CFD simulation of airflow through the engine
GE90
–
The higher-thrust GE90-115B mounted on GE's Boeing 747 aircraft during a flight test campaign.
GE90
–
A GE90-110B1 mounted on an
Air Canada Boeing 777-200LR inflight over
Siberia
35.
Boeing 777
–
The Boeing 777 is a family of long-range wide-body twin-engine jet airliners developed and manufactured by Boeing Commercial Airplanes. It is the worlds largest twinjet and has a seating capacity of 314 to 396 passengers. Developed in consultation with eight major airlines, the 777 was designed to replace older wide-body airliners, as Boeings first fly-by-wire airliner, it has computer-mediated controls. It was also the first commercial aircraft to be designed entirely with computer-aided design, the 777 is produced in two fuselage lengths as of 2017. The original 777-200 variant entered service in 1995, followed by the extended-range 777-200ER in 1997. The stretched 777-300, which is 33.25 ft longer, the initial 777-200, -200ER and -300 versions are equipped with General Electric GE90, Pratt & Whitney PW4000, or Rolls-Royce Trent 800 engines. The 777-200LR is the worlds longest-range airliner, able to fly more than halfway around the globe, the 777 first entered commercial service with United Airlines on June 7,1995. It has received more orders than any other wide-body airliner, as of March 2017,60 customers had placed orders for 1,911 aircraft of all variants, with 1,481 delivered. The most common and successful variant is the 777-300ER with 722 delivered and 815 orders, Emirates operates the largest 777 fleet, with 157 passenger and freighter aircraft as of July 2016. The 777 has been involved in six hull losses as of October 2016, the 777 ranks as one of Boeings best-selling models. Airlines have acquired the type as a comparatively fuel-efficient alternative to other wide-body jets and have deployed the aircraft on long-haul transoceanic routes. Direct market competitors include the Airbus A330-300, newly launched Airbus A350 XWB, the 787 Dreamliner, which entered service in 2011, shares design features and a common type rating for pilots with the 777. The new 777X series is planned to service by 2020. In the early 1970s, the Boeing 747, McDonnell Douglas DC-10, the mid-size 757 and 767 launched to market success, due in part to 1980s extended-range twin-engine operational performance standards regulations governing transoceanic twinjet operations. These regulations allowed twin-engine airliners to make ocean crossings at up to three hours distance from emergency diversionary airports, under ETOPS rules, airlines began operating the 767 on long-distance overseas routes that did not require the capacity of larger airliners. The trijet 777 was later dropped, following marketing studies that favored the 757 and 767 variants, Boeing was left with a size and range gap in its product line between the 767-300ER and the 747-400. By the late 1980s, DC-10 and L-1011 models were approaching retirement age, McDonnell Douglas was working on the MD-11, a stretched and upgraded successor of the DC-10, while Airbus was developing its A330 and A340. The initial proposal featured a fuselage and larger wings than the existing 767
Boeing 777
–
Boeing 777
Boeing 777
–
Glass cockpit of a
Transaero Airlines 777-200ER
Boeing 777
–
An
Air India Boeing 777-200LR is rolled out at the
Boeing Everett Factory
Boeing 777
–
The first Boeing 777-200 in commercial service,
United Airlines ' N777UA, taking off from
Amsterdam Airport Schiphol in 2005.
36.
Guinness Book of World Records
–
The book itself holds a world record, as the best-selling copyrighted book of all time. As of the 2017 edition, it is now in its 63rd year of publication, the international franchise has extended beyond print to include television series and museums. On 10 November 1951, Sir Hugh Beaver, then the director of the Guinness Breweries, went on a shooting party in the North Slob, by the River Slaney in County Wexford. After missing a shot at a golden plover, he involved in an argument over which was the fastest game bird in Europe. That evening at Castlebridge House, he realised that it was impossible to confirm in reference books whether or not the golden plover was Europes fastest game bird. Beaver knew that there must be numerous other questions debated nightly in pubs throughout Ireland and abroad and he realised then that a book supplying the answers to this sort of question might prove successful. Beavers idea became reality when Guinness employee Christopher Chataway recommended University friends Norris and Ross McWhirter, the twin brothers were commissioned to compile what became The Guinness Book of Records in August 1954. A thousand copies were printed and given away, after the founding of The Guinness Book of Records at 107 Fleet Street, the first 198-page edition was bound on 27 August 1955 and went to the top of the British best seller lists by Christmas. The following year, it launched in the US, and sold 70,000 copies, since then, Guinness World Records has become a household name and the global leader in world records. Because the book became a hit, many further editions were printed, eventually settling into a pattern of one revision a year, published in September/October. The McWhirters continued to compile it for many years, Ross McWhirter was assassinated by the Provisional Irish Republican Army in 1975. Following Ross assassination, the feature in the show where questions about records posed by children were answered was called Norris on the Spot, Guinness Superlatives Limited was formed in 1954 to publish the first book. Sterling Publishing owned the rights to the Guinness book in the US for decades, and, under their management, the group was owned by Guinness PLC and subsequently Diageo until 2001, when it was purchased by Gullane Entertainment. Gullane was itself purchased by HIT Entertainment in 2002, with offices in New York City and Tokyo, Guinness World Records global headquarters remain in London, while its museum attractions are based at Ripley headquarters in Orlando, Florida, US. Recent editions have focused on record feats by person competitors, many records also relate to the youngest person who achieved something, such as the youngest person to visit all nations of the world, being Maurizio Giuliano. Each edition contains a selection of the records from the Guinness database, as well as new records. The majority of records are no longer listed in the book or on the website. For those unable to wait the 4–6 weeks for a reply, the Guinness Book of Records is the worlds most sold copyrighted book, earning it an entry within its own pages
Guinness Book of World Records
–
Guinness World Records certificate
Guinness Book of World Records
–
The Guinness World Records logo
Guinness Book of World Records
–
Lucky Diamond Rich is "the world's most tattooed person", and has tattoos covering his entire body. He holds the Guinness world record as of 2006, being 100 percent tattooed.
Guinness Book of World Records
–
Sultan Kösen (Turkey) is the tallest living person since 17 September 2009, as verified by Guinness World Records. Turkey has 80 records in the book.
37.
Non-linear
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In mathematics and physical sciences, a nonlinear system is a system in which the change of the output is not proportional to the change of the input. Nonlinear problems are of interest to engineers, physicists and mathematicians, nonlinear systems may appear chaotic, unpredictable or counterintuitive, contrasting with the much simpler linear systems. In other words, in a system of equations, the equation to be solved cannot be written as a linear combination of the unknown variables or functions that appear in them. Systems can be defined as non-linear, regardless of whether or not known linear functions appear in the equations. In particular, an equation is linear if it is linear in terms of the unknown function and its derivatives. As nonlinear equations are difficult to solve, nonlinear systems are approximated by linear equations. This works well up to some accuracy and some range for the input values and it follows that some aspects of the behavior of a nonlinear system appear commonly to be counterintuitive, unpredictable or even chaotic. Although such chaotic behavior may resemble random behavior, it is not random. For example, some aspects of the weather are seen to be chaotic and this nonlinearity is one of the reasons why accurate long-term forecasts are impossible with current technology. Some authors use the term nonlinear science for the study of nonlinear systems and this is disputed by others, Using a term like nonlinear science is like referring to the bulk of zoology as the study of non-elephant animals. In mathematics, a function f is one which satisfies both of the following properties, Additivity or superposition, f = f + f, Homogeneity. Additivity implies homogeneity for any rational α, and, for continuous functions, for a complex α, homogeneity does not follow from additivity. For example, a map is additive but not homogeneous. The equation is called homogeneous if C =0, if f contains differentiation with respect to x, the result will be a differential equation. Nonlinear algebraic equations, which are also called polynomial equations, are defined by equating polynomials to zero, for example, x 2 + x −1 =0. For a single equation, root-finding algorithms can be used to find solutions to the equation. However, systems of equations are more complicated, their study is one motivation for the field of algebraic geometry. It is even difficult to decide whether a given system has complex solutions
Non-linear
–
Illustration of a pendulum
38.
Piston engine
–
A reciprocating engine, also often known as a piston engine, is typically a heat engine that uses one or more reciprocating pistons to convert pressure into a rotating motion. This article describes the features of all types. The main types are, the combustion engine, used extensively in motor vehicles, the steam engine, the mainstay of the Industrial Revolution. There may be one or more pistons, the hot gases expand, pushing the piston to the bottom of the cylinder. This position is known as the Bottom Dead Center, or where the piston forms the largest volume in the cylinder. The piston is returned to the top by a flywheel. This is where the forms the smallest volume in the cylinder. In most types the expanded or exhausted gases are removed from the cylinder by this stroke, the exception is the Stirling engine, which repeatedly heats and cools the same sealed quantity of gas. The stroke is simply the distance between the TDC and the BDC, or the greatest distance that the piston can travel in one direction, in some designs the piston may be powered in both directions in the cylinder, in which case it is said to be double-acting. In most types, the movement of the piston is converted to a rotating movement via a connecting rod. A flywheel is used to ensure smooth rotation or to store energy to carry the engine through an un-powered part of the cycle. The more cylinders an engine has, generally, the more vibration-free it can operate. The power of an engine is proportional to the volume of the combined pistons displacement. A seal must be made between the piston and the walls of the cylinder so that the high pressure gas above the piston does not leak past it. This seal is provided by one or more piston rings. These are rings made of a metal, and are sprung into a circular groove in the piston head. The rings fit tightly in the groove and press against the wall to form a seal. Cylinder capacities may range from 10 cm³ or less in model engines up to several thousand cubic centimetres in ships engines, the compression ratio affects the performance in most types of reciprocating engine
Piston engine
–
Internal combustion piston engine Components of a typical,
four stroke cycle, internal combustion piston engine. E - Exhaust
camshaft I - Intake camshaft S -
Spark plug V -
Valves P -
Piston R -
Connecting rod C -
Crankshaft W - Water jacket for coolant flow
39.
Aerodynamic drag
–
In aerodynamics, aerodynamic drag is the fluid drag force that acts on any moving solid body in the direction of the fluid freestream flow. Alternatively, calculated from the perspective, the drag force results from three natural phenomena, shock waves, vortex sheet, and viscosity. The pressure distribution acting on a surface exerts normal forces on the body. Those forces can be summed and the component of force that acts downstream represents the drag force, D p r. The nature of these normal forces combines shock wave effects, vortex system generation effects, the viscosity of the fluid has a major effect on drag. That is to say, the work the body does on the airflow, is reversible and is recovered as there are no effects to convert the flow energy into heat. Pressure recovery acts even in the case of viscous flow, viscosity, however results in pressure drag and it is the dominant component of drag in the case of vehicles with regions of separated flow, in which the pressure recovery is fairly ineffective. The friction drag force, which is a force on the aircraft surface, depends substantially on boundary layer configuration. The net friction drag, D f, is calculated as the projection of the viscous forces evaluated over the bodys surface. The sum of friction drag and pressure drag is called viscous drag and this drag component is due to viscosity. In a thermodynamic perspective, viscous effects represent irreversible phenomena and, therefore, the calculated viscous drag D v use entropy changes to accurately predict the drag force. When the airplane produces lift, another drag component results, induced drag, symbolized D i, is due to a modification of the pressure distribution due to the trailing vortex system that accompanies the lift production. An alternative perspective on lift and drag is gained from considering the change of momentum of the airflow, the wing intercepts the airflow and forces the flow to move downward. This results in an equal and opposite force acting upward on the wing which is the lift force, induced drag tends to be the most important component for airplanes during take-off or landing flight. Another drag component, namely wave drag, D w, results from shock waves in transonic and supersonic flight speeds, the shock waves induce changes in the boundary layer and pressure distribution over the body surface. The idea that a moving body passing through air or another fluid encounters resistance had been known since the time of Aristotle, louis Charles Breguets paper of 1922 began efforts to reduce drag by streamlining. Breguet went on to put his ideas into practice by designing several record-breaking aircraft in 1920s and 1930s, ludwig Prandtls boundary layer theory in the 1920s provided the impetus to minimise skin friction. A further major call for streamlining was made by Sir Melvill Jones who provided the concepts to demonstrate emphatically the importance of streamlining in aircraft design
Aerodynamic drag
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This article has multiple issues. Please help improve it or discuss these issues on the
talk page.
Aerodynamic drag
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Surfaces described in the integral equation.
40.
Euclidean vector
–
In mathematics, physics, and engineering, a Euclidean vector is a geometric object that has magnitude and direction. Vectors can be added to other vectors according to vector algebra, a Euclidean vector is frequently represented by a line segment with a definite direction, or graphically as an arrow, connecting an initial point A with a terminal point B, and denoted by A B →. A vector is what is needed to carry the point A to the point B and it was first used by 18th century astronomers investigating planet rotation around the Sun. The magnitude of the vector is the distance between the two points and the direction refers to the direction of displacement from A to B. These operations and associated laws qualify Euclidean vectors as an example of the more generalized concept of vectors defined simply as elements of a vector space. Vectors play an important role in physics, the velocity and acceleration of a moving object, many other physical quantities can be usefully thought of as vectors. Although most of them do not represent distances, their magnitude and direction can still be represented by the length, the mathematical representation of a physical vector depends on the coordinate system used to describe it. Other vector-like objects that describe physical quantities and transform in a similar way under changes of the system include pseudovectors and tensors. The concept of vector, as we know it today, evolved gradually over a period of more than 200 years, about a dozen people made significant contributions. Giusto Bellavitis abstracted the basic idea in 1835 when he established the concept of equipollence, working in a Euclidean plane, he made equipollent any pair of line segments of the same length and orientation. Essentially he realized an equivalence relation on the pairs of points in the plane, the term vector was introduced by William Rowan Hamilton as part of a quaternion, which is a sum q = s + v of a Real number s and a 3-dimensional vector. Like Bellavitis, Hamilton viewed vectors as representative of classes of equipollent directed segments, grassmanns work was largely neglected until the 1870s. Peter Guthrie Tait carried the standard after Hamilton. His 1867 Elementary Treatise of Quaternions included extensive treatment of the nabla or del operator ∇, in 1878 Elements of Dynamic was published by William Kingdon Clifford. Clifford simplified the quaternion study by isolating the dot product and cross product of two vectors from the complete quaternion product and this approach made vector calculations available to engineers and others working in three dimensions and skeptical of the fourth. Josiah Willard Gibbs, who was exposed to quaternions through James Clerk Maxwells Treatise on Electricity and Magnetism, the first half of Gibbss Elements of Vector Analysis, published in 1881, presents what is essentially the modern system of vector analysis. In 1901 Edwin Bidwell Wilson published Vector Analysis, adapted from Gibbs lectures, in physics and engineering, a vector is typically regarded as a geometric entity characterized by a magnitude and a direction. It is formally defined as a line segment, or arrow
Euclidean vector
41.
Centre of gravity
–
The distribution of mass is balanced around the center of mass and the average of the weighted position coordinates of the distributed mass defines its coordinates. Calculations in mechanics are simplified when formulated with respect to the center of mass. It is a point where entire mass of an object may be assumed to be concentrated to visualise its motion. In other words, the center of mass is the equivalent of a given object for application of Newtons laws of motion. In the case of a rigid body, the center of mass is fixed in relation to the body. The center of mass may be located outside the body, as is sometimes the case for hollow or open-shaped objects. In the case of a distribution of separate bodies, such as the planets of the Solar System, in orbital mechanics, the equations of motion of planets are formulated as point masses located at the centers of mass. The center of mass frame is a frame in which the center of mass of a system is at rest with respect to the origin of the coordinate system. The concept of center of mass in the form of the center of gravity was first introduced by the ancient Greek physicist, mathematician, and engineer Archimedes of Syracuse. He worked with simplified assumptions about gravity that amount to a uniform field, in work on floating bodies he demonstrated that the orientation of a floating object is the one that makes its center of mass as low as possible. He developed mathematical techniques for finding the centers of mass of objects of uniform density of various well-defined shapes, Newtons second law is reformulated with respect to the center of mass in Eulers first law. The center of mass is the point at the center of a distribution of mass in space that has the property that the weighted position vectors relative to this point sum to zero. In analogy to statistics, the center of mass is the location of a distribution of mass in space. Solving this equation for R yields the formula R =1 M ∑ i =1 n m i r i, solve this equation for the coordinates R to obtain R =1 M ∭ Q ρ r d V, where M is the total mass in the volume. If a continuous mass distribution has density, which means ρ is constant. The center of mass is not generally the point at which a plane separates the distribution of mass into two equal halves, in analogy with statistics, the median is not the same as the mean. The coordinates R of the center of mass of a system, P1 and P2, with masses m1. The percentages of mass at each point can be viewed as projective coordinates of the point R on this line, another way of interpreting the process here is the mechanical balancing of moments about an arbitrary point
Centre of gravity
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This child's toy uses the principles of center of mass to keep balance on a finger.
Centre of gravity
–
Estimated center of mass/gravity (blue sphere) of a gymnast at the end of performing a cartwheel. Notice center is outside the body in this position.
42.
Aerodynamic force
–
Aerodynamic force is exerted on a body by the air in which the body is immersed, and is due to the relative motion between the body and the gas. Aerodynamic force arises from two causes, the force due to the pressure on the surface of the body the shear force due to the viscosity of the gas. Pressure acts locally, normal to the surface, and shear force acts locally, the net aerodynamic force over the body is due to the pressure and shear forces integrated over the total exposed area of the body. When an airfoil is moving relative to the air it generates an aerodynamic force, in addition to these two forces, the body may experience an aerodynamic moment also, the value of which depends on the point chosen for calculation. The force created by a propeller or a jet engine is called thrust, the aerodynamic force on a powered airplane is commonly represented by three vectors, thrust, lift and drag. The other force acting on an aircraft during flight is its weight, weight is a body force and is not an aerodynamic force. A National Flightshop Reprint, Clearwater, Florida Clancy, L. J. Aerodynamics, london Library of Congress Catalog Card No
Aerodynamic force
–
Forces on an aerofoil.
43.
Astern propulsion
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Astern propulsion is a maneuver in which a ships propelling mechanism is used to develop thrust in a retrograde direction. Astern propulsion does not necessarily imply the ship is moving astern, astern propulsion is used to slow a ship by applying a force in the direction of the stern of the ship, the equivalent concept for an airplane is reverse thrust. In a sailing ship astern propulsion can be achieved by the manipulation of the sails. In square-rigged ships backing the sails, that is, aligning the sails so that the wind impinged on the bow surface and this maneuver had to be carried out with care as the rigging of masts and yards was principally designed to accept and transmit thrust in the forward direction. In a ship with a gas engine and a variable-pitch propeller. Most other propeller-driven ships will reverse the direction the prop spins, for a paddle wheel ship, reversing the direction of the paddle will provide astern propulsion. Redirecting the thrust of a water jet driven craft, changing the pitch of a Voith-Schneider propulsor, or rotating an azimuth thruster 180 degrees has the same effect. A marine vessel is required to signal that she is operating astern propulsion by either blowing three short, easily audible blasts or by flying the Sierra signal flag, some aircraft are also able to develop astern propulsion. Airships such as the R-100 could reverse the direction of rotation of some engines and this facility was used to slow down or stop the airship when mooring. Some propeller-driven aircraft using controllable pitch propellers can change the blade pitch sufficiently to provide astern propulsion and this facility is sometimes used to control aircraft speed in steep descents, or to taxi backwards when on the ground. Most jet airliners and some transport aircraft use astern propulsion to slow down after landing, reducing the load on the wheel brakes, helicopters can develop thrust in any direction, including astern. Most mechanically driven land vehicles can develop astern propulsion, although in case the ability is more usually termed reverse. In land vehicles reverse propulsion is achieved through various transmission arrangements
Astern propulsion
–
The Sierra
signal flag used to convey, "I am operating astern propulsion."
44.
Gimballed thrust
–
Gimbaled thrust is the system of thrust vectoring used in most modern rockets, including the Space Shuttle and the Saturn V lunar rockets. In a gimbaled thrust system, the exhaust nozzle of the rocket can be swiveled from side to side, as the nozzle is moved, the direction of the thrust is changed relative to the center of gravity of the rocket. The middle rocket shows the flight configuration in which the direction of thrust is along the center line of the rocket. On the rocket at the left, the nozzle has been deflected to the left, since the thrust no longer passes through the center of gravity, a torque is generated about the center of gravity and the nose of the rocket turns to the left. If the nozzle is gimballed back along the line, the rocket will move to the left. On the rocket at the right, the nozzle has been deflected to the right and the nose is moved to the right
Gimballed thrust
–
Gimballed thrust for different gimbal angles
45.
Thrust-to-weight ratio
–
The instantaneous thrust-to-weight ratio of a vehicle varies continually during operation due to progressive consumption of fuel or propellant and in some cases a gravity gradient. The thrust-to-weight ratio based on initial thrust and weight is often published and used as a figure of merit for quantitative comparison of the performance of vehicles. The thrust-to-weight ratio can be calculated by dividing the thrust by the weight of the engine or vehicle, note that the thrust can also be measured in pound-force provided the weight is measured in pounds, the division of these two values still gives the numerically correct thrust-to-weight ratio. For valid comparison of the initial ratio of two or more engines or vehicles, thrust must be measured under controlled conditions. The thrust-to-weight ratio and wing loading are the two most important parameters in determining the performance of an aircraft, for example, the thrust-to-weight ratio of a combat aircraft is a good indicator of the maneuverability of the aircraft. The thrust-to-weight ratio varies continually during a flight, thrust varies with throttle setting, airspeed, altitude and air temperature. Weight varies with fuel burn and changes of payload, for aircraft, the quoted thrust-to-weight ratio is often the maximum static thrust at sea-level divided by the maximum takeoff weight. In cruising flight, the ratio of an aircraft is the inverse of the lift-to-drag ratio because thrust is the inverse of drag. Rockets and rocket-propelled vehicles operate in a range of gravitational environments. The thrust-to-weight ratio is calculated from initial gross weight at sea-level on earth and is sometimes called Thrust-to-Earth-weight ratio. The thrust-to-Earth-weight ratio of a rocket or rocket-propelled vehicle is an indicator of its acceleration expressed in multiples of earth’s gravitational acceleration, the thrust-to-weight ratio for a rocket varies as the propellant is burned. If the thrust is constant, then the ratio is achieved just before the propellant is fully consumed. Each rocket has a characteristic thrust-to-weight curve or acceleration curve, not just a scalar quantity, for a takeoff from the surface of the earth using thrust and no aerodynamic lift, the thrust-to-weight ratio for the whole vehicle must be more than one. In general, the ratio is numerically equal to the g-force that the vehicle can generate. Take-off can occur when the vehicles g-force exceeds local gravity, many factors affect a thrust-to-weight ratio. The instantaneous value typically varies over the flight with the variations of thrust due to speed and altitude along with the due to the remaining propellant. The main factors include air temperature, pressure, density. Depending on the engine or vehicle under consideration, the performance will often be affected by buoyancy
Thrust-to-weight ratio
–
Rocket vehicle Thrust-to-weight ratio vs Isp for different propellant technologies
