Gas turbine engine thrust

<p>The familiar study of <a href="/facts/Jet_aircraft/esXNnbbg">jet aircraft</a> treats jet thrust with a "black box" description which only looks at what goes into the <a href="/facts/Jet_engine/CJjFpeqt">jet engine</a>, air and fuel, and what comes out, exhaust gas and an unbalanced force. This force, called thrust, is the sum of the momentum difference between entry and exit and any unbalanced pressure force between entry and exit, as explained in "Thrust calculation". 
</p><p>As an example, an early turbojet, the <a href="/facts/Bristol_Olympus/4FA2bzMq">Bristol Olympus</a> Mk. 101, had a momentum thrust of 9300 lb. and a pressure thrust of 1800 lb. giving a total of 11,100 lb. Looking inside the "black box" shows that the thrust results from all the unbalanced momentum and pressure forces created within the engine itself. These forces, some forwards and some rearwards, are across all the internal parts, both stationary and rotating, such as ducts, compressors, etc., which are in the primary gas flow which flows through the engine from front to rear. The algebraic sum of all these forces is delivered to the airframe for propulsion. "Flight" gives examples of these internal forces for two early jet engines, the <a href="/facts/Rolls-Royce_Avon/4c93bpXJ">Rolls-Royce Avon</a> Ra.14 and the <a href="/facts/De_Havilland_Goblin/mxzCfnLo">de Havilland Goblin</a>.
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Gas turbine engine thrust open-in-new

Gas turbine engine thrust