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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] |
Stall (fluid Dynamics)
In fluid dynamics, a stall is a reduction in the lift coefficient generated by a foil as angle of attack increases.Crane, Dale: ''Dictionary of Aeronautical Terms, third edition'', p. 486. Aviation Supplies & Academics, 1997. This occurs when the critical angle of attack of the foil is exceeded. The critical angle of attack is typically about 15°, but it may vary significantly depending on the fluid, foil, and Reynolds number. Stalls in fixed-wing flight are often experienced as a sudden reduction in lift as the pilot increases the wing's angle of attack and exceeds its critical angle of attack (which may be due to slowing down below stall speed in level flight). A stall does not mean that the engine(s) have stopped working, or that the aircraft has stopped moving—the effect is the same even in an unpowered glider aircraft. Vectored thrust in aircraft is used to maintain altitude or controlled flight with wings stalled by replacing lost wing lift with engine or propeller ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pugachev's Cobra
In aerobatics, the cobra maneuver (or just the ''cobra''), also called ''dynamic deceleration'', among other names (see Etymology), is a dramatic and demanding maneuver in which an airplane flying at a moderate speed abruptly raises its nose momentarily to a vertical and slightly past vertical attitude, causing an extremely high angle of attack and momentarily stalling the plane, making a full-body air brake before dropping back to normal position, during which the aircraft does not change effective altitude. The maneuver relies on the ability of the plane to be able to quickly change angle of attack (alpha) without overloading the airframe, and sufficient engine thrust to maintain nearly constant altitude through the entire move, but also post-stall stability and aerodynamics that allows for the recovery to level flight. The maneuver demands accurate pitch control, alpha stability and engine-versus-inlet compatibility for the aircraft, as well as a high skill level on the part ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lift Curve
Lift or LIFT may refer to: Physical devices * Elevator, or lift, a device used for raising and lowering people or goods ** Paternoster lift, a type of lift using a continuous chain of cars which do not stop ** Patient lift, or Hoyer lift, mobile lift, ceiling lift, a lift to assist a caregiver for a disabled patient ** Rack lift, a type of elevator ** Ski lift, an aerial or surface lift for uphill transport ** Space elevator, a hypothetical structure for transporting material from a planet's surface into outer space ** Wheelchair lift or platform lift, a powered device to assist a person in a wheelchair * Forklift, a powered industrial truck used to lift and move materials short distances * Scissor lift, a type of aerial work platform * Body lift, an adaptation (of fixed height) to lift the automobile body from the frame * Suspension lift, a modification raising the suspension of the automobile * Stairlift, a mechanical device to help people with disabilities get up stairs Sp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Induced Drag
In aerodynamics, lift-induced drag, induced drag, vortex drag, or sometimes drag due to lift, is an aerodynamic drag force that occurs whenever a moving object redirects the airflow coming at it. This drag force occurs in airplanes due to wings or a lifting body redirecting air to cause lift and also in cars with airfoil wings that redirect air to cause a downforce. It is symbolized as D_\text, and the ''lift-induced drag coefficient'' as C_. For a constant amount of lift, induced drag can be reduced by increasing airspeed. A counter-intuitive effect of this is that, up to the speed-for-minimum-drag, aircraft need less power to fly faster. Induced drag is also reduced when the wingspan is higher, or for wings with wingtip devices. Explanation The total aerodynamic force acting on a body is usually thought of as having two components, lift and drag. By definition, the component of force parallel to the oncoming flow is called drag; and the component perpendicular to the oncomi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Su-35 (12509727094)
The Sukhoi Su-35 (russian: link=no, Сухой Су-35; NATO reporting name: Flanker-E) is the designation for two improved derivatives of the Su-27 air-defence fighter. They are single-seat, twin-engine, supermaneuverable aircraft, designed by the Sukhoi Design Bureau and built by Sukhoi. The type was originally developed by the Soviet Union from the Su-27 and was known as the Su-27M. It incorporated canards and a multi-function radar giving it multi-role capabilities. The first prototype made its maiden flight in June 1988. Following the dissolution of the Soviet Union Sukhoi re-designated it as the Su-35 to attract export orders. Fourteen aircraft were produced and used for tests and demonstrations; one example had thrust-vectoring engines and was in turn redesignated the Su-37. A sole Su-35UB two-seat trainer was also built in the late 1990s that resembled the Su-30MK family. In 2003, Sukhoi embarked on a second modernization of the Su-27 to serve as an interim aircraft ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Airspeed Indicator
The airspeed indicator (ASI) or airspeed gauge is a flight instrument indicating the airspeed of an aircraft in kilometers per hour (km/h), knots (kn), miles per hour (MPH) and/or meters per second (m/s). The recommendation by ICAO is to use km/h, however knots is currently the most used unit. The ASI measures the pressure differential between static pressure from the static port, and total pressure from the pitot tube. This difference in pressure is registered with the ASI pointer on the face of the instrument. Color-coded speeds and ranges The ASI has standard color-coded markings to indicate safe operation within the limitations of the aircraft. At a glance, the pilot can determine a recommended speed (V speeds) or if speed adjustments are needed. Single and multi-engine aircraft have common markings. For instance, the green arc indicates the normal operating range of the aircraft, from ''V''S1 to ''V''NO. The white arc indicates the flap operating range, ''V''SO ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
STOL
A short takeoff and landing (STOL) aircraft is a conventional fixed-wing aircraft that has short runway requirements for takeoff and landing. Many STOL-designed aircraft also feature various arrangements for use on airstrips with harsh conditions (such as high altitude or ice). STOL aircraft, including those used in scheduled passenger airline operations, have also been operated from STOLport airfields which feature short runways. Design considerations Many fixed-wing STOL aircraft are bush planes, though some, like the de Havilland Canada Dash-7, are designed for use on prepared airstrips; likewise, many STOL aircraft are taildraggers, though there are exceptions like the PAC P-750 XSTOL, the Quest Kodiak, the de Havilland Canada DHC-6 Twin Otter and the Peterson 260SE. Autogyros also have STOL capability, needing a short ground roll to get airborne, but capable of a near-zero ground roll when landing. Runway length requirement is a function of the square of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Load Factor (aeronautics)
In aeronautics, the load factor is the ratio of the lift of an aircraft to its weightHurt, page 37 and represents a global measure of the stress ("load") to which the structure of the aircraft is subjected: : n = \frac, where : n is the load factor, : L is the lift : W is the weight. Since the load factor is the ratio of two forces, it is dimensionless. However, its units are traditionally referred to as g, because of the relation between load factor and apparent acceleration of gravity felt on board the aircraft. A load factor of one, or 1 g, represents conditions in straight and level flight, where the lift is equal to the weight. Load factors greater or less than one (or even negative) are the result of maneuvers or wind gusts. Load factor and g The fact that the load factor is commonly expressed in ''g'' units does not mean that it is dimensionally the same as the acceleration of gravity, also indicated with ''g''. The load factor is strictly non-dimensional. The use of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Airspeed
In aviation, airspeed is the speed of an aircraft relative to the air. Among the common conventions for qualifying airspeed are: * Indicated airspeed ("IAS"), what is read on an airspeed gauge connected to a Pitot-static system; * Calibrated airspeed ("CAS"), indicated airspeed adjusted for pitot system position and installation error; * Equivalent airspeed ("EAS"), calibrated airspeed adjusted for compressibility effects; * True airspeed ("TAS"), equivalent airspeed adjusted for air density, and is also the speed of the aircraft through the air in which it is flying. Calibrated airspeed is typically within a few knots of indicated airspeed, while equivalent airspeed decreases slightly from CAS as aircraft altitude increases or at high speeds. With EAS constant, true airspeed increases as aircraft altitude increases. This is because air density decreases with higher altitude. The measurement and indication of airspeed is ordinarily accomplished on board an aircraft by an ai ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Swept Wing
A swept wing is a wing that angles either backward or occasionally forward from its root rather than in a straight sideways direction. Swept wings have been flown since the pioneer days of aviation. Wing sweep at high speeds was first investigated in Germany as early as 1935 by Albert Betz and Adolph Busemann, finding application just before the end of the Second World War. It has the effect of delaying the shock waves and accompanying aerodynamic drag rise caused by fluid compressibility near the speed of sound, improving performance. Swept wings are therefore almost always used on jet aircraft designed to fly at these speeds. The term "swept wing" is normally used to mean "swept back", but variants include forward sweep, variable sweep wings and oblique wings in which one side sweeps forward and the other back. The delta wing is also aerodynamically a form of swept wing. Reasons for sweep There are three main reasons for sweeping a wing: 1. to arrange the center of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Planform (aeronautics)
The wing configuration of a fixed-wing aircraft (including both gliders and powered aeroplanes) is its arrangement of lifting and related surfaces. Aircraft designs are often classified by their wing configuration. For example, the Supermarine Spitfire is a conventional low wing cantilever monoplane of straight elliptical planform with moderate aspect ratio and slight dihedral. Many variations have been tried. Sometimes the distinction between them is blurred, for example the wings of many modern combat aircraft may be described either as cropped compound deltas with (forwards or backwards) swept trailing edge, or as sharply tapered swept wings with large leading edge root extensions (or LERX). Some are therefore duplicated here under more than one heading. This is particularly so for variable geometry and combined (closed) wing types. Most of the configurations described here have flown (if only very briefly) on full-size aircraft. A few theoretical designs are also notab ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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