Which statement correctly describes a turbofan compared to a turboprop?

Which statement correctly describes a turbofan compared to a turboprop?

• A. The fan is outside the nacelle
• B. The fan replaces the propeller and is inside a cowling
• C. Airflow is highly affected by aircraft speed
• D. They perform poorly at high altitude

Answer: (B)

The main idea is how the vehicle gets its thrust and where the moving air device sits. In a turbofan, the large front fan is housed inside the engine’s nacelle (the cowling) and is driven by the turbine. This fan moves a large amount of air, most of which bypasses the core, providing most of the thrust. In a turboprop, the propeller sits on the outside of the engine and is driven through a reduction gearbox by the turbine, so the propeller itself provides the primary thrust. So the statement that best fits a turbofan compared to a turboprop is that the fan replaces the propeller in function and is inside a cowling. The other options describe the fan being outside the nacelle, or make general claims about airflow or high-altitude performance that aren’t defining features of turbofan versus turboprop.

The main idea is how the vehicle gets its thrust and where the moving air device sits. In a turbofan, the large front fan is housed inside the engine’s nacelle (the cowling) and is driven by the turbine. This fan moves a large amount of air, most of which bypasses the core, providing most of the thrust. In a turboprop, the propeller sits on the outside of the engine and is driven through a reduction gearbox by the turbine, so the propeller itself provides the primary thrust.

So the statement that best fits a turbofan compared to a turboprop is that the fan replaces the propeller in function and is inside a cowling. The other options describe the fan being outside the nacelle, or make general claims about airflow or high-altitude performance that aren’t defining features of turbofan versus turboprop.