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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] Drag may be expressed as actual drag or the coefficient of drag.
Cross-sectional area distribution along the complete airframe determines wave drag, largely independent of the actual shape. The blue and light green shapes are roughly equal in area. The Whitcomb area rule , named after NACA engineer Richard Whitcomb and also called the transonic area rule , is a design procedure used to reduce an aircraft 's ...
= (,,) 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:
As noted earlier, , =,. The total drag coefficient can be estimated as: = [()], where is the propulsive efficiency, P is engine power in horsepower, sea-level air density in slugs/cubic foot, is the atmospheric density ratio for an altitude other than sea level, S is the aircraft's wing area in square feet, and V is the aircraft's speed in miles per hour.
Aerodynamic spin diagram: lift and drag coefficients vs. angle of attack. Many types of airplanes spin only if the pilot simultaneously yaws and stalls the airplane (intentionally or unintentionally). [5] Under these circumstances, one wing stalls, or stalls more deeply than the other.
Lift and drag are the two components of the total aerodynamic force acting on an aerofoil or aircraft.. 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.
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Energy–maneuverability theory is a model of aircraft performance. It was developed by Col. John Boyd, a fighter pilot, and Thomas P. Christie, a mathematician with the United States Air Force, [1] and is useful in describing an aircraft's performance as the total of kinetic and potential energies or aircraft specific energy.