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As an example, an early turbojet, the Bristol Olympus Mk. 101, had a momentum thrust of 9300 lb. and a pressure thrust of 1800 lb. giving a total of 11,100 lb. [1] Looking inside the "black box" shows that the thrust results from all the unbalanced momentum and pressure forces created within the engine itself. [2]
Engine power is the power that an engine can put out. It can be expressed in power units, most commonly kilowatt, pferdestärke (metric horsepower), or horsepower.In terms of internal combustion engines, the engine power usually describes the rated power, which is a power output that the engine can maintain over a long period of time according to a certain testing method, for example ISO 1585.
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.
TSFC or SFC for thrust engines (e.g. turbojets, turbofans, ramjets, rockets, etc.) is the mass of fuel needed to provide the net thrust for a given period e.g. lb/(h·lbf) (pounds of fuel per hour-pound of thrust) or g/(s·kN) (grams of fuel per second-kilonewton). Mass of fuel is used, rather than volume (gallons or litres) for the fuel ...
The expanding flow in the diverging section caused a forward thrust force on the exhaust nozzle: a 29% contribution to the overall propulsion system thrust at cruise. [16] During cruise at Mach 2.02 each Olympus 593 was producing around 10,000 lbf (44 kN) of thrust, equivalent to 36,000 hp (27,000 kW) per engine. [23]
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]
The bypass ratio (BPR) of a turbofan engine is the ratio between the mass flow rate of the bypass stream to the mass flow rate entering the core. [1] A 10:1 bypass ratio, for example, means that 10 kg of air passes through the bypass duct for every 1 kg of air passing through the core.
At take-off, the fan displaces up to 1.3 t (2,900 lb) of air per second, the jet nozzle velocity is almost 1,000 mph (450 m/s) and each high pressure turbine blade generates around 800 hp (600 kW), rotating at 12,500 rpm with their tips reaching 1,200 mph (540 m/s). [3] Rolls-Royce reports the engine is 10 dB quieter than the Trent 700. [15]