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The optimum axial induction factor was then used to find the maximum coefficient of power. This maximum coefficient is the Betz limit. Betz was able to show that the maximum coefficient of power of a wind turbine is 16/27. Airflow operating at higher thrust will cause the axial induction factor to rise above the optimum value.
Diameter of the propeller. The propeller advance ratio or coefficient is a dimensionless number used in aeronautics and marine hydrodynamics to describe the relationship between the speed at which a vehicle (like an airplane or a boat) is moving forward and the speed at which its propeller is turning.
The thrust-to-weight ratio is usually calculated from initial gross weight at sea level on earth [6] and is sometimes called thrust-to-Earth-weight ratio. [7] The thrust-to-Earth-weight ratio of a rocket or rocket-propelled vehicle is an indicator of its acceleration expressed in multiples of earth's gravitational acceleration, g 0. [5]
For example, when rotor thrust coefficient is assumed to be constant, the weighing function comes out to be: = and the corresponding weighted solidity ratio is known as the thrust-weighted solidity ratio. [2] When rotor power or torque coefficient is assumed constant, the weighing function is:
The overall propulsive efficiency (an extension of effective power ()) is developed from the propulsive coefficient (), which is derived from the installed shaft power modified by the effective power for the hull with appendages (′), the propeller's thrust power (), and the relative rotative efficiency.
If a powered aircraft is generating thrust T and experiencing drag D, the difference between the two, T − D, is termed the excess thrust. The instantaneous performance of the aircraft is mostly dependent on the excess thrust. Excess thrust is a vector and is determined as the vector difference between the thrust vector and the drag vector.
Thrust is the force supplied by the engine and depends on the propellant mass flow through the engine. Specific impulse measures the thrust per propellant mass flow. Thrust and specific impulse are related by the design and propellants of the engine in question, but this relationship is tenuous: in most cases, high thrust and high specific ...
Characteristic velocity or , or C-star is a measure of the combustion performance of a rocket engine independent of nozzle performance, and is used to compare different propellants and propulsion systems. c* should not be confused with c, which is the effective exhaust velocity related to the specific impulse by: =.