Define "lift-to-drag ratio".

The lift-to-drag ratio is a critical concept in aerodynamics that specifically focuses on the efficiency of an aircraft's wing. It quantifies how effectively the wing can generate lift in relation to the drag it experiences during flight. A higher lift-to-drag ratio indicates that an aircraft is more aerodynamically efficient, requiring less power to maintain flight and able to achieve longer distances for a given amount of energy. This ratio is particularly significant during different phases of flight, such as gliding or climbing, where maximizing lift while minimizing drag is essential for optimal performance.

Understanding this concept is vital for pilots and engineers as it helps them make informed decisions regarding aircraft design, fuel efficiency, and overall flight planning.