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The load factor, and in particular its sign, depends not only on the forces acting on the aircraft, but also on the orientation of its vertical axis. During straight and level flight, the load factor is +1 if the aircraft is flown "the right way up", [ 2 ] : 90 whereas it becomes −1 if the aircraft is flown "upside-down" (inverted).
Graphs of C L and C D vs. speed are referred to as drag curves. Speed is shown increasing from left to right. The lift/drag ratio is given by the slope from the origin to some point on the curve and so the maximum L/D ratio does not occur at the point of least drag coefficient, the leftmost point. Instead, it occurs at a slightly greater speed.
The low speed region of flight is known as the "back of the power curve" or "behind the power curve" [7] [8] (sometimes "back of the drag curve") where more thrust is required to sustain flight at lower speeds. It is an inefficient region of flight because a decrease in speed requires increased thrust and a resultant increase in fuel consumption.
These two properties determine the speed of sound in the gas at its given temperature. The Buckingham pi theorem then leads to a third dimensionless group, the ratio of the relative velocity to the speed of sound, which is known as the Mach number. Consequently when a body is moving relative to a gas, the drag coefficient varies with the Mach ...
Drag coefficients in fluids with Reynolds number approximately 10 4 [1] [2] Shapes are depicted with the same projected frontal area. In fluid dynamics, the drag coefficient (commonly denoted as: , or ) is a dimensionless quantity that is used to quantify the drag or resistance of an object in a fluid environment, such as air or water.
A plane can take off even if the thrust is less than its weight as, unlike a rocket, the lifting force is produced by lift from the wings, not directly by thrust from the engine. As long as the aircraft can produce enough thrust to travel at a horizontal speed above its stall speed, the wings will produce enough lift to counter the weight of ...
At low , is asymptotically proportional to , which means that the drag is linearly proportional to the speed, i.e. the drag force on a small sphere moving through a viscous fluid is given by the Stokes Law: = At high , is more or less constant, but drag will vary as the square of the speed varies. The graph to the right shows how varies with ...
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]