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

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:—

Table I.

Aspect Ratio "$n.$"	Constant "$C.$"
3 4 5 6 7 8 — 10 — 12	.685 .70 .71 .72 .725 .73 — .74 — .75

"$C.$" 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^[1]; they have been

1. See footnote on § 172 as to $c$ values.

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