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All objects experience parasitic drag, regardless of whether they generate lift. Parasitic drag comprises all types of drag except lift-induced drag, and the total drag on an aircraft or other object which generates lift is the sum of parasitic drag and lift-induced drag. [5]
In aeronautics the parasitic drag and lift-induced drag are often given separately. For an aircraft at low speed, induced drag tends to be relatively greater than parasitic drag because a high angle of attack is required to maintain lift, increasing induced drag. As speed increases, the angle of attack is reduced and the induced drag decreases ...
Induced drag must be added to the parasitic drag to find the total drag. Since induced drag is inversely proportional to the square of the airspeed (at a given lift) whereas parasitic drag is proportional to the square of the airspeed, the combined overall drag curve shows a minimum at some airspeed - the minimum drag speed (V MD). An aircraft ...
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] Drag may be expressed as actual drag or the coefficient of drag.
The drag at zero-lift can be more easily conceptualized as the drag area which is simply the product of zero-lift drag coefficient and aircraft's wing area (, where is the wing area). Parasitic drag experienced by an aircraft with a given drag area is approximately equal to the drag of a flat square disk with the same area which is held ...
Parasitic drag: While high aspect wings create less induced drag, they have greater parasitic drag (drag due to shape, frontal area, and surface friction). This is because, for an equal wing area , the average chord (length in the direction of wind travel over the wing) is smaller.
One method for estimating the zero-lift drag coefficient of an aircraft is the equivalent skin-friction method. For a well designed aircraft, zero-lift drag (or parasite drag) is mostly made up of skin friction drag plus a small percentage of pressure drag caused by flow separation. The method uses the equation [7]
A 1974 NASA study found that for subsonic aircraft, skin friction drag is the largest component of drag, causing about 45% of the total drag. For supersonic and hypersonic aircraft, the figures are 35% and 25% respectively. [9] A 1992 NATO study found that for a typical civil transport aircraft, skin friction drag accounted for almost 48% of ...