For many systems, it is possible to define a lift-to-drag ratio.

For information about the forces in gliding flight, see lift-to-drag ratio.

Daggerboards are often long and thin, thus providing a better lift-to-drag ratio.

A wing's aerodynamic quality is expressed as its lift-to-drag ratio.

A blended wing body has lift-to-drag ratio 50% greater than a conventional airplane.

Such shapes offered much better lift-to-drag ratio than the broader wings the brothers had tried so far.

By opening the speed brakes, the lift-to-drag ratio of the aircraft could be reduced to less than 3:1.

As pilots began to understand how to use rising air, gliders were developed with a high lift-to-drag ratio.

Like all things in aeronautical engineering, the lift-to-drag ratio is not the only consideration for wing design.

Mathematically, the maximum lift-to-drag ratio can be estimated as:

A high lift-to-drag ratio requires a significantly smaller thrust to propel the wings through the air at sufficient lift.

Many aircraft are now made with wingtip devices to reduce such turbulence (which also improves both the lift-to-drag ratio and fuel economy).

Lift-to-drag ratios can be determined by flight test, by calculation or by testing in a wind tunnel.

Thrust power, is the speed multiplied by the drag, is obtained from the lift-to-drag ratio:

To improve the wing's lift-to-drag ratio and the aircraft's maximum speed the wing was given a very high aspect ratio of 12.

Like in the design of an airplane wing, a high lift-to-drag ratio is essential in designing an efficient turbine blade.

The tunnel fin has a large amount of horizontal lift utilizing the hydrofoil principle providing better lift-to-drag ratio.

At hypersonic speeds, during re-entry, the craft had a lift-to-drag ratio of 1.8 to 1, giving it ample maneuvering capability.

ZRay has a 35 to 1 lift-to-drag ratio, and has water jets for fine attitude control, as well as propulsion on the surface.

The Bermuda rig is the (nearly) undisputed champion of windward performance in soft sails, due to its very low drag and high lift-to-drag ratio.

Most importantly, the maximum lift-to-drag ratio is independent of the weight of the aircraft, the area of the wing, or the wing loading.

If the thrust-to-weight ratio times the lift-to-drag ratio is greater than local gravity then takeoff using aerodynamic lift is possible.

Poor lift-to-drag ratio performance in wind tunnel testing has meant that to date the KF airfoil has not been used on any full size aircraft.

Their experiments showed that high aspect ratio wings-long and narrow-had a better lift-to-drag ratio than short stubby wings with the same lifting area.

The primary purpose of flaps is to change the camber of the wing and so change the lift-to-drag ratio of the wing.