Page:Aerial Flight - Volume 1 - Aerodynamics - Frederick Lanchester - 1906.djvu/398

§ 244. Method of Total Surface.—Mica Aerodone. Series E., No. I. Fig. 155.

This aerodone was one of a series of models specially designed for the purpose of measuring $\xi$ by the method of total surface.
Fig. 155. The supporting member is an aeroplane whose angle to the line of flight is determined by a pair of tail planes whose sole function is directive. It may be noted that the tail planes are so placed as to be influenced equally by the downward and upward

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${\frac {20.25\times 2}{6\times 3}}$ $=2.25\ {\mbox{sq. in.}}=.0156\ {\mbox{sq. ft.}}$
or weight carried $={\frac {.6}{.0156}}\ {\mbox{grams per sq. ft.}}=38.5$ or ${\frac {38.5\times 32.2}{45.36}}=2.73\ {\mbox{poundals}}.$
Now $V=11.5$ or $V^{2}=132$ or $P/V^{2}={\frac {2.73}{1.32}}=.0214$ against $.0286$ given in Table IX.
This difference is not more than might be expected in view of the present state of knowledge.

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