|
Wing Shape Optimization
Wing-shape optimization is a software implementation of shape optimization primarily used for aircraft design. This allows for engineers to produce more efficient and cheaper aircraft designs. History Shape optimization, as a software process and tool, first appeared as an algorithm in 1995 and as commercial software for the automotive industry by 1998, as noted by F. Muyl. Relative to the age of the automotive and aeronautical companies, this software is very new. The difficulty was not with the science behind the process, but rather the capabilities of computer hardware. In 1998, F. Muyl developed a compromise between exact accuracy and computational time to reduce drag of an automotive. GA phases are the standard genetic algorithm iterations and the BFGS phases are the approximated calculations designed to save time. However, he acknowledged that the computational time required on existing hardware, nearly two weeks for a moderate improvement on an oversimplified proof of co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shape Optimization
Shape optimization is part of the field of optimal control theory. The typical problem is to find the shape which is optimal in that it minimizes a certain cost functional while satisfying given constraints. In many cases, the functional being solved depends on the solution of a given partial differential equation defined on the variable domain. Topology optimization is, in addition, concerned with the number of connected components/boundaries belonging to the domain. Such methods are needed since typically shape optimization methods work in a subset of allowable shapes which have fixed topological properties, such as having a fixed number of holes in them. Topological optimization techniques can then help work around the limitations of pure shape optimization. Definition Mathematically, shape optimization can be posed as the problem of finding a bounded set \Omega, minimizing a functional :\mathcal(\Omega), possibly subject to a constraint of the form :\mathcal(\Omega)=0. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Angle Of Attack
In fluid dynamics, angle of attack (AOA, α, or \alpha) is the angle between a reference line on a body (often the chord line of an airfoil) and the vector representing the relative motion between the body and the fluid through which it is moving. Angle of attack is the angle between the body's reference line and the oncoming flow. This article focuses on the most common application, the angle of attack of a wing or airfoil moving through air. In aerodynamics, angle of attack specifies the angle between the chord line of the wing of a fixed-wing aircraft and the vector representing the relative motion between the aircraft and the atmosphere. Since a wing can have twist, a chord line of the whole wing may not be definable, so an alternate reference line is simply defined. Often, the chord line of the root of the wing is chosen as the reference line. Another choice is to use a horizontal line on the fuselage as the reference line (and also as the longitudinal axis). Some aut ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Moore’s Law
Moore's law is the observation that the number of transistors in a dense integrated circuit (IC) doubles about every two years. Moore's law is an observation and projection of a historical trend. Rather than a law of physics, it is an empirical relationship linked to gains from experience in production. The observation is named after Gordon Moore, the co-founder of Fairchild Semiconductor and Intel (and former CEO of the latter), who in 1965 posited a doubling every year in the number of components per integrated circuit, and projected this rate of growth would continue for at least another decade. In 1975, looking forward to the next decade, he revised the forecast to doubling every two years, a compound annual growth rate (CAGR) of 41%. While Moore did not use empirical evidence in forecasting that the historical trend would continue, his prediction held since 1975 and has since become known as a "law". Moore's prediction has been used in the semiconductor industry to gu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CRYSTAL BALL
A crystal ball, also known as an orbuculum or crystal sphere, is a crystal or glass ball and common fortune-telling object. It is generally associated with the performance of clairvoyance and scrying in particular. In more recent times, the crystal ball has been used for creative photography with the term lensball commonly used to describe a crystal ball used as a photography prop. History In the first century CE, Pliny the Elder describes use of crystal balls by soothsayers (''"crystallum orbis"'', later written in Medieval Latin by scribes as ''orbuculum''). By the fifth century CE, scrying was widespread within the Roman Empire and was condemned by the early medieval Christian Church as heretical. Dr. John Dee was a noted British mathematician, astronomer, astrologer, geographer, and consultant to Queen Elizabeth I. He devoted much of his life to alchemy, divination, and Hermetic philosophy, of which the use of crystal balls was often included. Crystal gazing was a popu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Boeing 747-200
The Boeing 747 is a large, long-range wide-body airliner designed and manufactured by Boeing Commercial Airplanes in the United States between 1968 and 2022. After introducing the 707 in October 1958, Pan Am wanted a jet times its size, to reduce its seat cost by 30%. In 1965, Joe Sutter left the 737 development program to design the 747, the first twin-aisle airliner. In April 1966, Pan Am ordered 25 Boeing 747-100 aircraft and in late 1966, Pratt & Whitney agreed to develop the JT9D engine, a high-bypass turbofan. On September 30, 1968, the first 747 was rolled out of the custom-built Everett Plant, the world's largest building by volume. The first flight took place on February 9, 1969, and the 747 was certified in December of that year. It entered service with Pan Am on January 22, 1970. The 747 was the first airplane dubbed "Jumbo Jet", the first wide-body airliner. The 747 is a four-engined jet aircraft, initially powered by Pratt & Whitney JT9D turbofan engines ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lift Coefficient
In fluid dynamics, the lift coefficient () is a dimensionless quantity that relates the lift generated by a lifting body to the fluid density around the body, the fluid velocity and an associated reference area. A lifting body is a foil or a complete foil-bearing body such as a fixed-wing aircraft. is a function of the angle of the body to the flow, its Reynolds number and its Mach number. The section lift coefficient refers to the dynamic lift characteristics of a two-dimensional foil section, with the reference area replaced by the foil chord. Abbott, Ira H., and Doenhoff, Albert E. von: ''Theory of Wing Sections''. Section 1.2 Definitions The lift coefficient ''C''L is defined by :C_\mathrm L \equiv \frac = = , where L\, is the lift force, S\, is the relevant surface area and q\, is the fluid dynamic pressure, in turn linked to the fluid density \rho\,, and to the flow speed u\,. The choice of the reference surface should be specified since it is arbitrary. For examp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Propeller (aircraft)
An aircraft propeller, also called an airscrew,Beaumont, R.A.; ''Aeronautical Engineering'', Odhams, 1942, Chapter 13, "Airscrews". converts rotary motion from an engine or other power source into a swirling slipstream which pushes the propeller forwards or backwards. It comprises a rotating power-driven 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, or of the automatically variable "constant-speed" type. The propeller attaches to the power source's driveshaft either directly or through reduction gearing. Propellers can be made from wood, metal or composite materials. Propellers are most suitable for use at subsonic airspeeds generally below about , although supersonic speeds were achieved in the McDonnell XF-88B experimental propeller-equipped aircraft. Supersonic tip-speeds are used in some aircraft like the Tupolev Tu-95, w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reno Air Race
The Reno Air Races, officially known as the STIHL National Championship Air Races from 2016, is a multi-day event tailored to the aviation community that takes place each September at the Reno Stead Airport a few miles north of Reno, Nevada. Air racing is billed as "the world's fastest motor sport" and Reno is one of the few remaining venues. The event includes races in six classes and demonstrations by airshow pilots. History Begun in 1964, the Reno Air Races feature multi-lap, multi-aircraft races among extremely high performance aircraft on closed ovoid courses which range between about (Biplanes and Formula One) and about (Jet, Unlimited) in length per lap. The chief organizer is the Reno Air Racing Association (RARA). The first Reno air races, in 1964 and 1965, were organized by World War II veteran Bill Stead. They took place at Sky Ranch airfield, a dirt strip barely long, which was located in present-day Spanish Springs. After Stead Air Force Base (20 miles t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
P-51 Mustang
The North American Aviation P-51 Mustang is an American long-range, single-seat fighter and fighter-bomber used during World War II and the Korean War, among other conflicts. The Mustang was designed in April 1940 by a team headed by James H. Kindelberger of North American Aviation (NAA) in response to a requirement of the British Purchasing Commission. The Purchasing Commission approached North American Aviation to build Curtiss P-40 fighters under license for the Royal Air Force (RAF). Rather than build an old design from another company, North American Aviation proposed the design and production of a more modern fighter. The prototype NA-73X airframe was rolled out on 9 September 1940, 102 days after the contract was signed, and first flew on 26 October. The Mustang was designed to use the Allison V-1710 engine, which had limited high-altitude performance in its earlier variants. The aircraft was first flown operationally by the RAF as a tactical-reconnaissance aircraf ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Process Optimization
Process optimization is the discipline of adjusting a process so as to optimize (make the best or most effective use of) some specified set of parameters without violating some constraint. The most common goals are minimizing cost and maximizing throughput and/or efficiency. This is one of the major quantitative tools in industrial decision making. When optimizing a process, the goal is to maximize one or more of the process specifications, while keeping all others within their constraints. This can be done by using a process mining tool, discovering the critical activities and bottlenecks, and acting only on them. Areas Fundamentally, there are three parameters that can be adjusted to affect optimal performance. They are: * Equipment optimization The first step is to verify that the existing equipment is being used to its fullest advantage by examining operating data to identify equipment bottlenecks. * Operating procedures Operating procedures may vary widely from person-t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shock Wave
In physics, a shock wave (also spelled shockwave), or shock, is a type of propagating disturbance that moves faster than the local speed of sound in the medium. Like an ordinary wave, a shock wave carries energy and can propagate through a medium but is characterized by an abrupt, nearly discontinuous, change in pressure, temperature, and density of the medium. For the purpose of comparison, in supersonic flows, additional increased expansion may be achieved through an expansion fan, also known as a Prandtl–Meyer expansion fan. The accompanying expansion wave may approach and eventually collide and recombine with the shock wave, creating a process of destructive interference. The sonic boom associated with the passage of a supersonic aircraft is a type of sound wave produced by constructive interference. Unlike solitons (another kind of nonlinear wave), the energy and speed of a shock wave alone dissipates relatively quickly with distance. When a shock wave passes through ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cabin (aircraft)
An aircraft cabin is the section of an aircraft in which passengers travel. Most modern commercial aircraft are pressurized, as cruising altitudes are high enough such that the surrounding atmosphere is too thin for passengers and crew to breathe. In commercial air travel, particularly in airliners, cabins may be divided into several parts. These can include travel class sections in medium and large aircraft, areas for flight attendants, the galley, and storage for in-flight service. Seats are mostly arranged in rows and aisles. The higher the travel class, the more space is provided. Cabins of the different travel classes are often divided by curtains, sometimes called class dividers. Passengers are not usually allowed to visit higher travel class cabins in commercial flights. Some aircraft cabins contain passenger entertainment systems. Short and medium haul cabins tend to have no or shared screens whereas long and ultra-long haul flights often contain personal screens. Ev ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
