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The Lanchester-Prandtl lifting-line theory [1] is a mathematical model in aerodynamics that predicts lift distribution over a three-dimensional wing from the wing's geometry. [2] The theory was expressed independently [ 3 ] by Frederick W. Lanchester in 1907, [ 4 ] and by Ludwig Prandtl in 1918–1919 [ 5 ] after working with Albert Betz and ...
For symmetrical airfoils =, so the aerodynamic center is at 25% of chord measured from the leading edge. But for cambered airfoils the aerodynamic center can be slightly less than 25% of the chord from the leading edge, which depends on the slope of the moment coefficient, . These results obtained are calculated using the thin airfoil theory so ...
Years of research and experience with the unusual conditions of supersonic flow have led to some interesting conclusions about airfoil design. Considering a rectangular wing, the pressure at a point P with coordinates (x,y) on the wing is defined only by the pressure disturbances originated at points within the upstream Mach cone emanating from point P. [3] As result, the wing tips modify the ...
For example, the NACA 2412 airfoil has a maximum camber of 2% located 40% (0.4 chords) from the leading edge with a maximum thickness of 12% of the chord. The NACA 0015 airfoil is symmetrical, the 00 indicating that it has no camber. The 15 indicates that the airfoil has a 15% thickness to chord length ratio: it is 15% as thick as it is long.
Supersonic interceptor: Profile of an F-104 wing at root, drawn over own photo of a wing section exhibited in the Deutsches Museum; Blackbird : as shown in Alexander 2002 [2] (very approximate drawing on original, chord completely estimated) Dragonfly: loosely interpreted from data, photo and diagram in Hertel 1966 [3]. Section roughly mid-wing.
Supercritical airfoils feature four main benefits: they have a higher drag-divergence Mach number, [21] they develop shock waves farther aft than traditional airfoils, [22] they greatly reduce shock-induced boundary layer separation, and their geometry allows more efficient wing design (e.g., a thicker wing and/or reduced wing sweep, each of which may allow a lighter wing).
Schemes have been devised to define airfoils – an example is the NACA system. Various airfoil generation systems are also used. An example of a general purpose airfoil that finds wide application, and pre–dates the NACA system, is the Clark-Y. Today, airfoils can be designed for specific functions by the use of computer programs.
An example of a wing without protuberances compared to a wing with protuberances is shown. The geometry of tubercles must also be considered, as the amplitude and wavelength of tubercles have an effect on flow control. Tubercles can be thought of as small delta wings with a curved apex, since they create a vortex on the upper edge of the tubercle.