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It is also useful to show the relationship between section lift coefficient and drag coefficient. The section lift coefficient is based on two-dimensional flow over a wing of infinite span and non-varying cross-section so the lift is independent of spanwise effects and is defined in terms of L ′ {\displaystyle L^{\prime }} , the lift force ...
In aerodynamics, the lift-to-drag ratio (or L/D ratio) is the 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.
XFOIL is an interactive program for the design and analysis of subsonic isolated airfoils.Given the coordinates specifying the shape of a 2D airfoil, Reynolds and Mach numbers, XFOIL can calculate the pressure distribution on the airfoil and hence lift and drag characteristics.
The significant aerodynamic properties of aircraft wings are summarised by two dimensionless quantities, the lift and drag coefficients C L and C D. Like other such aerodynamic quantities, they are functions only of the angle of attack α, the Reynolds number R e and the Mach number M. C L and C D can be plotted against α, or can be plotted ...
= (,,) drag coefficient equation. The aerodynamic efficiency has a maximum value, E max, respect to C L where the tangent line from the coordinate origin touches the drag coefficient equation plot. The drag coefficient, C D, can be decomposed in two ways. First typical decomposition separates pressure and friction effects:
However, while it does generate lift, it also generates a large amount of drag. [8] Since even a flat plate can generate lift, a significant factor in foil design is the minimization of drag. An example of this is the rudder of a boat or aircraft. When designing a rudder a key design factor is the minimization of drag in its neutral position ...
Lift is proportional to the density of the air and approximately proportional to the square of the flow speed. Lift also depends on the size of the wing, being generally proportional to the wing's area projected in the lift direction. In calculations it is convenient to quantify lift in terms of a lift coefficient based on these factors.
The first one is the thrust coefficient of the rotor, which is the one which should be corrected for high rotor loading (i.e., for high values of ), while the second one is the tangential aerodynamic coefficient of an individual blade element, which is given by the aerodynamic lift and drag coefficients.