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Trailing Edge
The trailing edge of an aerodynamic surface such as a wing is its rear edge, where the airflow separated by the leading edge meets.Crane, Dale: ''Dictionary of Aeronautical Terms, third edition'', page 521. Aviation Supplies & Academics, 1997. Essential flight control surfaces are attached here to control the direction of the departing air flow, and exert a controlling force on the aircraft. Such control surfaces include ailerons on the wings for roll control, elevator (aircraft), elevators on the tailplane controlling Aircraft principal axes, pitch, and the rudder on the fin controlling Aircraft principal axes, yaw. Elevators and ailerons may be combined as elevons on tailless aircraft. The shape of the trailing edge is of prime importance in the aerodynamic function of any aerodynamic surface. A sharp trailing edge is always employed in an airfoil. George Batchelor has written about: :“ ... the remarkable controlling influence exerted by the sharp trailing edge of an aerof ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
George Batchelor
George Keith Batchelor FRS (8 March 1920 – 30 March 2000) was an Australian applied mathematician and fluid dynamicist. He was for many years a professor of applied mathematics in the University of Cambridge, and was founding head of the Department of Applied Mathematics and Theoretical Physics (DAMTP). In 1956 he founded the influential ''Journal of Fluid Mechanics'' which he edited for some forty years. Prior to Cambridge he studied at Melbourne High School and University of Melbourne. As an applied mathematician (and for some years at Cambridge a co-worker with Sir Geoffrey Taylor in the field of turbulent flow), he was a keen advocate of the need for physical understanding and sound experimental basis. His ''An Introduction to Fluid Dynamics'' (CUP, 1967) is still considered a classic of the subject, and has been re-issued in the ''Cambridge Mathematical Library'' series, following strong current demand. Unusual for an 'elementary' textbook of that era, it presented ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aspect Ratio (aeronautics)
In aeronautics, the aspect ratio of a wing is the ratio of its span to its mean chord. It is equal to the square of the wingspan divided by the wing area. Thus, a long, narrow wing has a high aspect ratio, whereas a short, wide wing has a low aspect ratio.Kermode, A.C. (1972), ''Mechanics of Flight'', Chapter 3, (p.103, eighth edition), Pitman Publishing Limited, London Aspect ratio and other features of the planform are often used to predict the aerodynamic efficiency of a wing because the lift-to-drag ratio increases with aspect ratio, improving the fuel economy in powered airplanes and the gliding angle of sailplanes. Definition The aspect ratio \text is the ratio of the square of the wingspan b to the projected wing area S, which is equal to the ratio of the wingspan b to the standard mean chord \text: \text \equiv \frac = \frac Mechanism As a useful simplification, an airplane in flight can be imagined to affect a cylinder of air with a diameter equal to the wing ... [...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] |
Cusp (singularity)
In mathematics, a cusp, sometimes called spinode in old texts, is a point on a curve where a moving point must reverse direction. A typical example is given in the figure. A cusp is thus a type of singular point of a curve. For a plane curve defined by an analytic, parametric equation :\begin x &= f(t)\\ y &= g(t), \end a cusp is a point where both derivatives of and are zero, and the directional derivative, in the direction of the tangent, changes sign (the direction of the tangent is the direction of the slope \lim (g'(t)/f'(t))). Cusps are ''local singularities'' in the sense that they involve only one value of the parameter , in contrast to self-intersection points that involve more than one value. In some contexts, the condition on the directional derivative may be omitted, although, in this case, the singularity may look like a regular point. For a curve defined by an implicit equation :F(x,y) = 0, which is smooth, cusps are points where the terms of lowest degre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Static Wick
Static wicks, also called static dischargers or static discharge wicks, are devices used to remove static electricity from aircraft in flight. They take the form of small sticks pointing backwards from the wings, and are fitted on almost all civilian aircraft. Function Precipitation static is an electrical charge on an airplane caused by flying through rain, snow storms, ice, or dust particles. Charge also accumulates through friction between the aircraft hull and the air. When the aircraft charge is great enough, it discharges into the surrounding air. Without static dischargers, the charge discharges in large batches through pointed aircraft extremities, such as antennas, wing tips, vertical and horizontal stabilizers, and other protrusions. The discharge creates a broad-band radio frequency noise from DC to 1000 MHz, which can affect aircraft communication. To control this discharge, so as to allow the continuous operation of navigation and radio communication systems ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anti-shock Body
Anti-shock body is the name given by Richard T. Whitcomb to a pod positioned on the upper surface of a wing. Its purpose is to reduce wave drag while travelling at transonic speeds (Mach 0.8–1.0), which includes the typical cruising range of conventional jet airliners. The Cambridge Aerospace Dictionary defines shock body (also known as Whitcomb body, Küchemann carrot or speed bump) as a streamlined volume added to improve area rule distribution. The anti-shock, or shock, body was one of a number of ways of implementing what was then the recently developed area rule. Another was fuselage shaping. Theory The theory behind the anti-shock body was independently developed during the early 1950s, by two aerodynamists, Richard Whitcomb at NASA and Dietrich Küchemann at the British Royal Aircraft Establishment.Barnard and Philpott 2010, p. 254. The anti-shock body is closely associated with the area rule, a recent innovation of the era to minimise wave drag by having a cross ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flap (aircraft)
A flap is a high-lift device used to reduce the stall (flight), stalling speed of an aircraft wing at a given weight. Flaps are usually mounted on the wing trailing edges of a fixed-wing aircraft. Flaps are used to reduce the take-off distance and the landing distance. Flaps also cause an increase in Drag (physics), drag so they are retracted when not needed. The flaps installed on most aircraft are partial-span flaps; spanwise from near the wing root to the inboard end of the ailerons. When partial-span flaps are extended they alter the spanwise lift distribution on the wing by causing the inboard half of the wing to supply an increased proportion of the lift, and the outboard half to supply a reduced proportion of the lift. Reducing the proportion of the lift supplied by the outboard half of the wing is accompanied by a reduction in the angle of attack on the outboard half. This is beneficial because it increases the margin above the Stall (fluid dynamics), stall of the outbo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Servo Tab
A servo tab is a small hinged device installed on an aircraft control surface to assist the movement of the Flight control surfaces, control surfaces. Introduced by the German firm Flettner, servo tabs were formerly known as Flettner tabs. Servo tabs are not true servomechanisms, as they do not employ negative feedback to keep the control surfaces in a desired position; they only provide a mechanical advantage to the pilot. Servo tabs A servo tab, or balance tab, moves in the direction opposite to the desired movement of the control surface. It deflects airflow, generating force on the whole control surface in the desired direction. The tab has a leverage advantage, being located well aft of the control surface hinge line, and thus its airflow deflection moves the control surface in the opposite direction, overcoming the resistance generated by the airflow deflection of the control surface. This has the effect of reducing the control force required from the pilot to move the c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trim Tabs
Trim tabs are small surfaces connected to the trailing edge of a larger control surface on a boat or aircraft, used to control the trim of the controls, i.e. to counteract hydro- or aerodynamic forces and stabilise the boat or aircraft in a particular desired attitude without the need for the operator to constantly apply a control force. This is done by adjusting the angle of the tab relative to the larger surface. Changing the setting of a trim tab adjusts the neutral or resting position of a control surface (such as an elevator or rudder). As the desired position of a control surface changes (corresponding mainly to different speeds), an adjustable trim tab will allow the operator to reduce the manual force required to maintain that position—to zero, if desired. Thus the trim tab acts as a servo tab. Because the center of pressure of the trim tab is farther away from the axis of rotation of the control surface than the center of pressure of the control surface, the moment ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Circulation (fluid Dynamics)
In physics, circulation is the line integral of a vector field around a closed curve embedded in the field. In fluid dynamics, the field is the fluid velocity field. In electrodynamics, it can be the electric or the magnetic field. In aerodynamics, it finds applications in the calculation of lift, for which circulation was first used independently by Frederick Lanchester, Ludwig Prandtl, Martin Kutta and Nikolay Zhukovsky. It is usually denoted (uppercase gamma). Definition and properties If is a vector field and is a vector representing the differential length of a small element of a defined curve, the contribution of that differential length to circulation is : \mathrm\Gamma = \mathbf \cdot \mathrm\mathbf = \left, \mathbf\ \left, \mathrm\mathbf\ \cos \theta. Here, is the angle between the vectors and . The circulation of a vector field around a closed curve is the line integral: \Gamma = \oint_\mathbf \cdot \mathrm d \mathbf. In a conservative vector field ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
