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Lift-to-drag Ratio
In aerodynamics, the lift-to-drag ratio (or L/D ratio) is the Lift (force), lift generated by an aerodynamic body such as an aerofoil or aircraft, divided by the aerodynamic drag caused by moving through air. It describes the aerodynamic efficiency under given flight conditions. The L/D ratio for any given body will vary according to these flight conditions. For an aerofoil wing or powered aircraft, the L/D is specified when in straight and level flight. For a glider it determines the Lift-to-drag ratio#Glide ratio, glide ratio, of distance travelled against loss of height. The term is calculated for any particular airspeed by measuring the lift generated, then dividing by the drag at that speed. These vary with speed, so the results are typically plotted on a 2-dimensional graph. In almost all cases the graph forms a U-shape, due to the two main components of drag. The L/D may be calculated using computational fluid dynamics or computer simulation. It is measured empirically by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Airfoil Lift And Drag
An airfoil (American English) or aerofoil (British English) is a streamlined body that is capable of generating significantly more Lift (force), lift than Drag (physics), drag. Wings, sails and propeller blades are examples of airfoils. Foil (fluid mechanics), Foils of similar function designed with water as the working fluid are called hydrofoils. When oriented at a suitable angle, a solid body moving through a fluid deflects the oncoming fluid (for fixed-wing aircraft, a downward force), resulting in a force on the airfoil in the direction opposite to the deflection. This force is known as aerodynamic force and can be resolved into two components: lift (perpendicular to the remote freestream velocity) and drag (Parallel (geometry), parallel to the freestream velocity). The lift on an airfoil is primarily the result of its angle of attack. Most foil shapes require a positive angle of attack to generate lift, but Camber (aerodynamics), cambered airfoils can generate lift at zero ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polar Curve 2
Polar may refer to: Geography * Geographical pole, either of the two points on Earth where its axis of rotation intersects its surface ** Polar climate, the climate common in polar regions ** Polar regions of Earth, locations within the polar circles, referred to as the Arctic and Antarctic Places * Polar, Wisconsin, town in Langlade County, Wisconsin, United States ** Polar (community), Wisconsin, unincorporated community in Langlade County, Wisconsin, United States Arts, entertainment and media * ''Polar'' (webcomic), a webcomic and series of graphic novels by Víctor Santos * ''Polar'' (film), a 2019 Netflix film adaption of the above comic series * ''Polar'', a 2002 novel by T. R. Pearson Music * Polar Music, a record label * Polar Studios, music studio of ABBA in Sweden * ''Polar'' (album), second album by the High Water Marks * ''Polars'' (album), an album by the Dutch metal band, Textures Brands and enterprises * Polar Air Cargo, an American airline * Polar Airl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aeronautical Engineering
Aerospace engineering is the primary field of engineering concerned with the development of aircraft and spacecraft. It has two major and overlapping branches: aeronautical engineering and astronautical engineering. Avionics engineering is similar, but deals with the electronics side of aerospace engineering. "Aeronautical engineering" was the original term for the field. As flight technology advanced to include vehicles operating in outer space, the broader term "aerospace engineering" has come into use. Aerospace engineering, particularly the astronautics branch, is often colloquially referred to as "rocket science". Overview Flight vehicles are subjected to demanding conditions such as those caused by changes in atmospheric pressure and temperature, with structural loads applied upon vehicle components. Consequently, they are usually the products of various technological and engineering disciplines including aerodynamics, air propulsion, avionics, materials science, st ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cruising Speed
Cruise is the phase of aircraft flight from when the aircraft levels off after a climb until it begins to descend for landing. Cruising usually comprises the majority of a flight, and may include small changes in heading (direction of flight), airspeed, and altitude. Airliner cruise Commercial or passenger aircraft are usually designed for optimum performance around their cruise speed ( VC) and cruise altitude. Factors affecting optimum cruise speed and altitude include payload, center of gravity, air temperature, and humidity. Cruise altitude is usually where the higher ground speed is balanced against the decrease in engine thrust and efficiency at higher altitudes. Common narrowbodies like the Airbus A320 and Boeing 737NG cruise at , while modern widebodies like the Airbus A350 and Boeing 787 cruise at . The typical cruising altitude for commercial airliners is . The speed which covers the greatest distance for a given amount of fuel is known as the maximum range spee ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drag Curve
The drag curve or drag polar is the relationship between the drag on an aircraft and other variables, such as lift, the coefficient of lift, angle-of-attack or speed. It may be described by an equation or displayed as a graph (sometimes called a "polar plot"). Drag may be expressed as actual drag or the coefficient of drag. Drag curves are closely related to other curves which do not show drag, such as the power required/speed curve, or the sink rate/speed curve. The drag curve The significant aerodynamic properties of aircraft wings are summarised by two dimensionless quantities, the lift and drag coefficients and . Like other such aerodynamic quantities, they are functions only of the angle of attack , the Reynolds number and the Mach number . and can be plotted against , or can be plotted against each other. The lift and the drag forces, and , are scaled by the same factor to get and , so = . and are at right angles, with parallel to the free stream velo ... [...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 e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drag (aerodynamics)
In fluid dynamics, drag, sometimes referred to as fluid resistance, is a force acting opposite to the direction of motion of any object moving with respect to a surrounding fluid. This can exist between two fluid layers, two solid surfaces, or between a fluid and a solid surface. Drag forces tend to decrease fluid velocity relative to the solid object in the fluid's path. Unlike other resistive forces, drag force depends on velocity. Drag force is proportional to the relative velocity for low-speed flow and is proportional to the velocity squared for high-speed flow. This distinction between low and high-speed flow is measured by the Reynolds number. Drag is instantaneously related to vorticity dynamics through the Josephson-Anderson relation. Examples Examples of drag include: * Net aerodynamic or hydrodynamic force: Drag acting opposite to the direction of movement of a solid object such as cars, aircraft, and boat hulls. * Viscous drag of fluid in a pipe: Drag force on the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drag Equation
In fluid dynamics, the drag equation is a formula used to calculate the force of drag (physics), drag experienced by an object due to movement through a fully enclosing fluid. The equation is: F_\, =\, \tfrac12\, \rho\, u^2\, c_\, A where *F_ is the drag force, which is by definition the force component in the direction of the flow velocity, *\rho is the mass density of the fluid, *u is the flow velocity relative to the object, *A is the reference area, and *c_ is the drag coefficient – a dimensionless number, dimensionless physical coefficient, coefficient related to the object's geometry and taking into account both skin friction and form drag. If the fluid is a liquid, c_ depends on the Reynolds number; if the fluid is a gas, c_ depends on both the Reynolds number and the Mach number. The equation is attributed to Lord Rayleigh, who originally used ''L''2 in place of ''A'' (with ''L'' being some linear dimension). The reference area ''A'' is typically defined as the area of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Profile Drag
Profile or profiles may refer to: Art, entertainment and media Music * Profile (Jan Akkerman album), ''Profile'' (Jan Akkerman album), 1973 * Profile (Githead album), ''Profile'' (Githead album), 2005 * Profile (Pat Donohue album), ''Profile'' (Pat Donohue album), 2005 * Profile (Duke Pearson album), ''Profile'' (Duke Pearson album), 1959 * ''Profiles (Nick Mason and Rick Fenn album), ''Profiles'' (Nick Mason and Rick Fenn album)'', a 1985 album by Nick Mason and Rick Fenn * Profiles (Gary McFarland album), ''Profiles'' (Gary McFarland album), a 1966 live album by Gary McFarland * Profile (Misako Odani album), ''Profile'' (Misako Odani album), 1997 * Profile (Wolfe Tones album), ''Profile'' (Wolfe Tones album) Film and television * Profile (2018 film), ''Profile'' (2018 film), a film directed by Timur Bekmambetov * Profile (1954 film), British thriller film * Profile (1955 TV series), ''Profile'' (1955 TV series) (1955–1957), a Canadian biographical television series * Profil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Air Resistance
In fluid dynamics, drag, sometimes referred to as fluid resistance, is a force acting opposite to the direction of motion of any object moving with respect to a surrounding fluid. This can exist between two fluid layers, two solid surfaces, or between a fluid and a solid surface. Drag forces tend to decrease fluid velocity relative to the solid object in the fluid's path. Unlike other resistive forces, drag force depends on velocity. Drag force is proportional to the relative velocity for low-speed flow and is proportional to the velocity squared for high-speed flow. This distinction between low and high-speed flow is measured by the Reynolds number. Drag is instantaneously related to vorticity dynamics through the Josephson-Anderson relation. Examples Examples of drag include: * Net force, Net Aerodynamic force, aerodynamic or Fluid dynamics, hydrodynamic force: Drag acting opposite to the direction of movement of a solid object such as cars, aircraft, and boat hulls. * Viscou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Form Drag
Parasitic drag, also known as profile drag, is a type of aerodynamic drag that acts on any object when the object is moving through a fluid. Parasitic drag is defined as the combination of '' form drag'' and ''skin friction drag''. It is named as such because it is not useful, in contrast with lift-induced drag which is created when an airfoil generates lift. All objects experience parasitic drag, regardless of whether they generate lift. Parasitic drag comprises all types of drag except lift-induced drag, and the total drag on an aircraft or other object which generates lift is the sum of parasitic drag and lift-induced drag. Form drag Form drag arises because of the shape of the object. The general size and shape of the body are the most important factors in form drag; bodies with a larger presented cross-section will have a higher drag than thinner bodies; sleek ("streamlined") objects have lower form drag. Form drag follows the drag equation, meaning that it increases with t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
