What effect does high elevation have on engine thrust?

What effect does high elevation have on engine thrust?

• A. It increases thrust
• B. It reduces thrust
• C. It has no effect
• D. It increases engine wear

Answer: (B)

High elevation means thinner air, so the engine has to ingest fewer air molecules at a given throttle setting. In a jet engine, thrust comes from accelerating the air passing through the engine. With lower air density, the mass flow is reduced, which means less momentum is added to the airflow and less thrust is produced. The lower ambient pressure also lowers the compressor’s pressure ratio, limiting the energy available to accelerate the exhaust. All of this combines to reduce thrust as altitude increases. The option stating no effect or increased wear isn’t supported by how engines rely on air density to generate thrust, and the idea that thrust increases at high altitude is incorrect.

High elevation means thinner air, so the engine has to ingest fewer air molecules at a given throttle setting. In a jet engine, thrust comes from accelerating the air passing through the engine. With lower air density, the mass flow is reduced, which means less momentum is added to the airflow and less thrust is produced. The lower ambient pressure also lowers the compressor’s pressure ratio, limiting the energy available to accelerate the exhaust. All of this combines to reduce thrust as altitude increases. The option stating no effect or increased wear isn’t supported by how engines rely on air density to generate thrust, and the idea that thrust increases at high altitude is incorrect.