Final answer:
Autorotation is a condition in rotorcraft flight that allows the helicopter's blades to rotate due to the upward flow of air when engine power is not available, allowing a controlled landing.
Step-by-step explanation:
Autorotation refers to a condition in rotorcraft flight where the helicopter's blades are driven not by engine power, but by the upward flow of air through the rotor system. This can happen either intentionally, such as in an engine-off landing scenario, or accidentally, in an engine failure. The concept of autorotation is critically important for the safety of helicopter operation, as it can potentially allow a controlled landing in the event of engine power loss.
Helicopters store large amounts of rotational kinetic energy in their blades, which can be conceptualized with the equation KE rot = 11², indicating the kinetic energy stored in the rotation. The engines provide the necessary thrust to maintain this energy, but once airborne, they may not have sufficient surplus power to significantly increase the rotational energy of the blades. Thus, the initial energy imparted to the blades must be preserved. In the event of an engine failure, the pilot must manage this stored kinetic energy to safely bring the helicopter to the ground using autorotation techniques.