Page:Aerial Flight - Volume 1 - Aerodynamics - Frederick Lanchester - 1906.djvu/399

Rh components of the terminal vortices, so that no error shall be introduced by an allowance for the “downthrow current,” as would be necessary were the tail plane situated in the ordinary position (Fig. 151).

Flight Data.

Whence,

And area $$= 2.645$$ sq. in. or skin resistance per sq. ft. area— $$\frac{.063 \times 144}{2.645} = 3.43\ (\mbox{grams}).$$

$$\frac{3.43 \times 32.2}{453.6} = .243\ (\mbox{poundals}).$$

But normal plane reaction at $$15.5\ \mbox{ft./sec.}$$ $$= .7 \times .078 \times 15.5 \times 15.5 = 13.1$$ $$\quad \xi = \frac{.243}{13.1} = .0185$$