Supersonic/Hypersonic Lift-to-Drag Ratio

Description

In aerodynamics, the lift-to-drag ratio, or L/D ratio, is the amount of lift generated by a wing or vehicle, divided by the drag it creates by moving through the air. A higher or more favorable L/D ratio is typically one of the major goals in aircraft design.

At very high speeds, lift to drag ratios tend to be lower. Concorde had a lift/drag ratio of around 7 at Mach 2, whereas a 747 is around 17 at about mach 0.85.
Dietrich Küchemann developed an empirical relationship for predicting L/D ratio for high Mach.Windtunnel tests have shown this to be roughly accurate.

Related formulas

Variables

Llift (N/m2)
Ddrag (N/m2)
MMach number (dimensionless)