Aspect ratio (aeronautics)
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In aeronautics, the aspect ratio of a wing is the ratio of its span to its mean chord. It is equal to the square of the wingspan divided by the wing area. Thus, a long, narrow wing has a high aspect ratio, whereas a short, wide wing has a low aspect ratio.
An ASH 31 glider with very high aspect ratio (AR=33.5) and lift-to-drag ratio (L/D=56)
Extremely high aspect ratio wing (AR=51.33) of the Eta motor glider providing a L/D ratio of 70
High aspect ratio wing (AR=12.8) of the Bombardier Dash 8 Q400
Moderate aspect ratio wing (AR=5.6) of a Piper PA-28 Cherokee
Lift-to-drag ratio
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In aerodynamics, the lift-to-drag ratio is the lift generated by an aerodynamic body such as an aerofoil or aircraft, divided by the aerodynamic drag caused by moving through air. It describes the aerodynamic efficiency under given flight conditions. The L/D ratio for any given body will vary according to these flight conditions.
Drag vs Speed. L/DMAX occurs at minimum Total Drag (e.g. Parasite plus Induced)
Coefficients of drag CD and lift CL vs angle of attack.
The eta has the best glide ratio for a sailplane