An aircraft brake generates heat during operation due to the conversion of kinetic energy into thermal energy. When the brakes are engaged, the friction between the brake pads and the rotating discs or drums slows down the aircraft by converting its forward motion into heat energy. This process is known as frictional heating.
Under normal operating conditions, the brakes are designed to dissipate this heat efficiently, using various cooling mechanisms such as airflow, heat sinks, or cooling channels. These systems prevent the brakes from overheating and ensure that they can continue to function effectively.
However, if the brakes are subjected to excessive or prolonged braking, such as during an emergency stop or heavy landing, the heat generated can exceed the brake's ability to dissipate it effectively. In such cases, the brake components may become extremely hot, and if the temperature rises significantly, they can even reach a point where they become red hot.
The change in color from normal operating temperatures to red hot is due to the phenomenon of incandescence. When a material is heated to high temperatures, it emits visible light as a result of its thermal radiation. As the temperature of the brake components increases, they can emit light in the visible spectrum, appearing red or even white-hot.
It's important to note that red-hot brakes are indicative of an extreme condition and can be dangerous. The excessive heat can degrade the brake's performance and potentially cause structural damage to the braking system. Therefore, proper maintenance, monitoring, and cooling systems are crucial to ensure the safe and efficient operation of aircraft brakes.