How does air cooling differ from liquid cooling in aircraft engines?

• A. Air cooling uses liquid circulated through engine passages.
• B. Liquid cooling relies on fins to transfer heat to the air.
• C. Air cooling uses airflow over fins to remove heat; liquid cooling uses coolant circulated through the engine.
• D. Both systems rely on electric fans only.

Answer: (C)

Air cooling relies on airflow moving over the engine’s fins to carry away heat. The fins dramatically increase the surface area, so as the aircraft moves, air flows past them and convection removes heat directly to the surrounding air.

Liquid cooling uses a closed loop where coolant is pumped through passages in the engine to absorb heat, and then the heated coolant goes to a radiator or heat exchanger where air removes the heat. This keeps the engine at a more uniform temperature and relies on the liquid’s ability to carry heat away to the cooling radiator.

So the main idea is the cooling medium and path: air-cooled engines shed heat with air flowing over fins, while liquid-cooled engines transport heat via coolant to a radiator. The other statements mix up where heat transfer happens or how cooling is achieved, and they don’t describe how each system actually removes heat.