Lift-to-drag ratio in the context of "Hang gliding"

A wing is a type of fin that produces both lift and drag while moving through air. Wings are defined by two shape characteristics, an airfoil section and a planform. Wing efficiency is expressed as lift-to-drag ratio, which compares the benefit of lift with the air resistance of a given wing shape, as it flies. Aerodynamics includes the study of wing performance in air.

Equivalent foils that move through water are found on hydrofoil power vessels and foiling sailboats that lift out of the water at speed and on submarines that use diving planes to point the boat upwards or downwards, while running submerged. The study of foil performance in water is a subfield of Hydrodynamics.

A short takeoff and landing (STOL) aircraft is a fixed-wing aircraft that can take off and land on runways that are much shorter than the typical ones needed for conventional take-off and landing. STOL-capable aircraft are usually light aircraft (mostly propeller-driven utility aircraft, sporters or motor gliders) with a high lift-to-drag ratio and typically also a high aspect ratio, allowing them to achieve minimum takeoff speed (i.e. liftoff speed or V_LOF) much more quickly and thus requiring a shorter accelerating run before taking off (takeoff roll); and perform landing at a lower minimum steady flight speed (V_S0) and thus also a shorter decelerating run (rollout).

Gyrocopters, despite being rotary-wing aircraft, need a forward motion to drive air flow past autorotating rotor blades to generate lift and thus still mandate runways (albeit a very short one) for takeoff and landing. They are therefore also considered STOL aircraft, as they cannot perform vertical takeoff and landing like helicopters.

A wingsail, twin-skin sail or double skin sail is a variable-camber aerodynamic structure that is fitted to a marine vessel in place of conventional sails. Wingsails are analogous to airplane wings, except that they are designed to provide lift on either side to accommodate being on either tack. Whereas wings adjust camber with flaps, wingsails adjust camber with a flexible or jointed structure (for hard wingsails). Wingsails are typically mounted on an unstayed spar—often made of carbon fiber for lightness and strength. The geometry of wingsails provides more lift, and a better lift-to-drag ratio, than traditional sails. Wingsails are more complex and expensive than conventional sails.