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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.
2.1 Airplane/aeroplane. ... Download as PDF; Printable version; In other projects ... The highest lift-to-drag ratio is 70:1, though 50:1 is common. After take-off ...
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 perpendicular to the direction of flight. The Sopwith Camel has a drag area of 8.73 sq ft (0.811 m 2 ), compared to 3.80 sq ft (0.353 m 2 ) for the P-51 Mustang.
An aircraft is streamlined from nose to tail to reduce drag making it advantageous to keep the sideslip angle near zero, though an aircraft may be deliberately "sideslipped" to increase drag and descent rate during landing, to keep aircraft heading same as runway heading during cross-wind landings and during flight with asymmetric power. [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]
In flight a powered aircraft can be considered as being acted on by four forces: lift, weight, thrust, and drag. [1] Thrust is the force generated by the engine (whether that engine be a jet engine, a propeller, or -- in exotic cases such as the X-15-- a rocket) and acts in a forward direction for the purpose of overcoming drag. [2]
In the diagram at right, the green line represents, 2-g, the blue line 3-g, and so on. The F-16 Fighting Falcon has a very small area just below Mach 1 and close to sea level where it can maintain a 9-g turn. Flying outside the envelope is possible, since it represents the straight-and-level condition only.
There are two causes of aerodynamic force: [1]: §4.10 [2] [3]: 29 the normal force due to the pressure on the surface of the body; the shear force due to the viscosity of the gas, also known as skin friction. Pressure acts normal to the surface, and shear force acts parallel to the surface. Both forces act locally.