Old 26th Nov 2012, 14:34
  #117 (permalink)  
Join Date: Jul 2009
Location: France - mostly
Age: 80
Posts: 1,689
one might be able to derive some sort of formula
Equation (9) in the paper referenced in post#27 gives the minimum drag speed Vmd. It corresponds to a lift coefficient equal to √(Cd0/K).

If Vmd1 and Vmd2 are the minimum drag speeds at different weights, then the speed at which the airplane has the same L/D at both weights is given by:

V = √(Vmd1*Vmd2)

A pretty useless formula, isn't it? It took me a whole evening to work it out. Just for the fun of doing it. But the result is a beauty, for those open to it.

Last edited by HazelNuts39; 28th Nov 2012 at 07:16. Reason: to correct the misunderstanding OG points out in Post#118
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