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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"). [ 1 ]
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 testing in a wind tunnel or in free flight test. [1] [2] [3]
The expectation that it would reach design speed had been based on optimistic wind-tunnel drag predictions. [15] [16] Modifications which included indenting the fuselage beside the wings and adding more volume to the rear of the aircraft, reduced the transonic drag significantly and the Mach 1.2 design speed was reached. The reason for using ...
The drag characteristics of a wing with infinite span can be simulated using an airfoil segment the width of a wind tunnel. [12] An increase in wingspan or a solution with a similar effect is one way to reduce induced drag. [6]: 4.10 The Wright brothers used curved trailing edges on their rectangular wings. [13]
[23] [24] When the flow separates there is a large increase in drag. If the aircraft overrotates on take-off at too low a speed the increased drag can prevent the aircraft from leaving the ground. Two de Havilland Comets overran the end of the runway after overrotating. [25] [26] Loss of control may occur if one wing tip stalls in ground effect.
The information in a graph of this kind is gathered using a model of the airfoil in a wind tunnel. Because aircraft models are normally used, rather than full-size machines, special care is needed to make sure that data is taken in the same Reynolds number regime (or scale speed) as in free flight.
QBlade is especially adequate for teaching, as it provides a ’hands-on’ feeling for Horizontal-axis wind turbine (HAWT) rotor design and shows all the fundamental relationships between blade twist, blade chord, section airfoil performance, turbine control, power and load curves in an easy and intuitive way. QBlade also includes post ...
The G7 drag curve model prediction method (recommended by some manufacturers for very-low-drag shaped rifle bullets) when using a G7 ballistic coefficient (BC) of 0.377 yields very similar results in the supersonic flight regime compared to the Doppler radar test derived drag coefficients (C d) prediction method. At 1,500 m (1,640 yd) range the ...