Ram effect due to forward speed will cause engine efficiency to

• A. Decrease
• B. No effect
• C. Increase
• D. Fluctuate

Answer: (C)

The effect being tested is how forward speed changes the air entering the engine and what that does to efficiency. As an aircraft moves, the air hitting the intake has higher total pressure and density than stationary air—that’s the ram effect. This boosts the compressor inlet conditions, so for the same compressor speed you can achieve a higher pressure at the compressor face or, equivalently, you can move the same amount of air with less compressor work.

That means for a given thrust or fuel flow, less energy is required to compress the incoming air, which improves the overall efficiency of the engine. In practical terms, the ram effect allows more of the energy to go into producing thrust rather than wasting work on compressing air, so engine efficiency increases with forward speed (at typical subsonic conditions).

The other options don’t fit because the ram effect does not reduce efficiency, leave it unchanged, or cause random fluctuations in this context; it tends to improve the inlet conditions and thus the efficiency.