What is the difference between disc brakes and drum brakes in typical aircraft usage?

• A. Drum brakes provide higher heat capacity.
• B. Disc brakes lose heat capacity.
• C. Disc brakes with calipers are common on modern jets for higher heat capacity and better performance; drum brakes are less common on large aircraft but used on some light aircraft.
• D. Disc brakes and drum brakes are identical in function.

Answer: (C)

The main idea here is how brake design affects heat management and where each type is used in aircraft. Disc brakes, with a rotor and calipers, expose a large, thin surface area to airflow. This lets heat escape more efficiently, so they can absorb more braking energy and maintain performance during repeated stops without fading. That high heat capacity and reliable performance are especially important for modern jets that require strong, repeatable braking at high speeds and loads.

Drums brake systems enclose the braking surfaces inside a drum and use shoes pressing outward against the interior. Heat builds up inside the enclosed drum, and cooling is limited, which makes fade more likely during heavy or repeated braking. Because of this, drum brakes are less common on large aircraft but are still seen on some light aircraft where the braking demands are lower and the simpler, cheaper drum design can be advantageous.

So the best answer states that disc brakes with calipers are common on modern jets for higher heat capacity and better performance, while drum brakes are less common on large aircraft but used on some light aircraft. The idea that disc brakes lose heat capacity or that both types are identical in function isn’t accurate.