What defines detonation in an aircraft engine?

Detonation in an aircraft engine is defined as the uncontrolled firing of the fuel-air mixture. This occurs when the pressure and temperature in the combustion chamber rise to a point where the fuel ignites spontaneously rather than burning in a controlled manner. This phenomenon is often characterized by a rapid increase in pressure and temperature, which can lead to engine knocking or pinging.

In a properly functioning engine, the fuel-air mixture should ignite in a controlled way, allowing for smooth and efficient combustion. When detonation occurs, it can result in severe engine damage due to the shock waves produced by the rapid pressure changes. Recognizing the signs of detonation is crucial for pilots to maintain engine performance and avoid catastrophic failure.

While controlled ignition and delayed ignition pertain to the timing and manner of combustion, they do not encompass the chaotic nature of detonation. Excessive fuel burn refers more to the efficiency and fuel consumption of the engine rather than the characteristics of the combustion process.