Supersonic/hypersonic Lift To Drag Ratios
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:
where M is the Mach number. Windtunnel tests have shown this to be roughly accurate.
Read more about this topic: Lift-to-drag Ratio
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