Page:Aerial Flight - Volume 1 - Aerodynamics - Frederick Lanchester - 1906.djvu/276

§ 177 point, the tabulated figures,, where not considered reliable, have been entitled “plausible values,” and accompanied by a sign of interrogation (?).

It has been demonstrated in § 161 that, on the hypothesis of constant sweep, the constants $$C\ c$$ and $$\kappa$$ are related to one another according to the equation—

$$\frac{\alpha}{\beta} = \frac{c\ C}{\kappa} - 1 ,$$

or, employing as before, the symbol $$\epsilon$$ to denote $$\alpha / \beta ,$$ we have—

$$\epsilon = \frac{c\ C}{\kappa} - 1 ,$$

that is to say, theory supplies us with a link connecting the whole of the constants involved in the equations of best value of $$\beta$$ and least value of $$\gamma .$$

Of the above constants the value of $$C$$ is known for planes of different aspect ratio from the experiments of Dines, the results being given in the form of a curve in Fig. 89 (Chap. V.). These values tabulated are as follows:—

"$$C.$$" is defined by equation— $$P_{90} = C\ \rho\ V^2 .$$

The values of $$c$$ are less authentically known; they must be regarded at present merely as plausible values ; they have been