On most engines, ram recovery occurs above how many knots?

The correct answer is 140 knots because ram recovery in jet engines refers to the phenomenon where the engine intake design facilitates the recovery of dynamic pressure, enhancing airflow into the engine at higher speeds. This process typically begins at around this speed, allowing for increased efficiency and performance of the engine as the aircraft accelerates.

When the aircraft reaches 140 knots, it is often at a point in its operational profile where the forces from the surrounding air can effectively overcome adverse effects on airflow into the engine, such as boundary layers or shock waves, which can occur at lower speeds. This speed is crucial for optimizing the engine's performance and maintaining thrust, particularly at takeoff and climb phases when aerodynamic efficiency becomes vital.

Understanding the dynamics of ram recovery is important for flight engineers, as it directly impacts engine performance and fuel efficiency during various phases of flight.