Which statement is true about jet engine thrust as engine speed increases?

Which statement is true about jet engine thrust as engine speed increases?

• A. At high speeds, thrust decreases with RPM
• B. Thrust is independent of RPM
• C. At the higher engine speeds, thrust increases rapidly with small increases in RPM
• D. Thrust is determined solely by nozzle area

Answer: (C)

As engine speed rises, the compressor draws in more air and compresses it to higher pressure, and the turbine adds more energy to that flow. This increases both the mass flow through the engine and the velocity of the exhaust. The result is a larger momentum change of the jet stream, which translates to greater thrust. At higher speeds, these effects compound, so small increases in RPM produce noticeably larger gains in thrust. Thrust isn’t independent of RPM—changing engine speed directly alters the amount of air being processed and the energy added to it. It isn’t determined only by nozzle area; while nozzle size affects how the exhaust expands, thrust depends mainly on how much air is being accelerated and how fast it’s expelled.

As engine speed rises, the compressor draws in more air and compresses it to higher pressure, and the turbine adds more energy to that flow. This increases both the mass flow through the engine and the velocity of the exhaust. The result is a larger momentum change of the jet stream, which translates to greater thrust. At higher speeds, these effects compound, so small increases in RPM produce noticeably larger gains in thrust.

Thrust isn’t independent of RPM—changing engine speed directly alters the amount of air being processed and the energy added to it. It isn’t determined only by nozzle area; while nozzle size affects how the exhaust expands, thrust depends mainly on how much air is being accelerated and how fast it’s expelled.