Lift-to-Drag Ratios
Summary
On Table 1 we have a summary of aerodynamic efficiency L/D (for
high speed flows, transonic as well as supersonic, the efficiency is M L/D, with M =
free stream Mach number). Some data are estimated. The L/D quantity is important because
it also appears in the Breguet range equation.
The ratio L/D is sometimes called glide number, or glide ratio, or
finesse.
Table 1: Summary of Lift-to-Drag Ratios
Wings for Racing Cars, Re >  | 2.5-3.5 |
| Hypersonic Waverider , M=8-10 [*] | 3 ÷ 4 |
| Supersonic Jet Transport (Concorde) | 8 |
| Tilt-rotor aircraft | 9÷10 |
| New Supersonic Transport [*] | 15 |
| Oblique Flying Wing [*] | 16÷17 |
| Subsonic Jet Transport | 16÷18 |
| Bomber B-52 | 20 |
| Airfoil Eppler E 193 , Re=0.1 | 50 |
| Airfoil Liebeck L 1003, Re= | 220 |
[*] Estimated data
Table 2: L/D of Subsonic Jet Aircraft
| Aircraft (year) | (L/D)max |
| Boeing B707-320 | 19.4 |
| Douglas DC-8 | 17.9 |
| Airbus A320 | 17. |
| Boeing 767-200 | 19. |
| Boeing 747-100 | 17.7 |
| Douglas DC-10 | 17.7 |
| Lockeed Tristar L1011 | 17.0 |
| Douglas DC-9 (1966) | 16.5 |
| Boeing B727-200 | 16.4 |
| Fokker 50 (1966) | 16 |
| Douglas DC-3 (1935) | 14.7 |
| Ford Trimotor (1927) | 12. |
| Wright Flyer I (1903) | 8.3 |
Table 3: L/D of Some Birds
| Bird | L/D |
|---|
| House Sparrow (passer domesticus) | 4. |
| Herring Gull (larus argentatus ) | 10. |
| Common Tern (sterna hirundo ) | 12. |
| Albatross (diomeda exulans ) | 20. |
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