Page:Aerial Flight - Volume 1 - Aerodynamics - Frederick Lanchester - 1906.djvu/403

Rh Whence, $$V = 36\ \mbox{ft./sec.} \tan \gamma = .246$$ or $$\gamma = 13^\circ - 50'$$ or $$\sin \gamma = .239 .$$

or in poundals per sq. ft.

But normal plane reaction at 36 ft./sec. (poundals),

If we make an allowance in respect of the aeroplane in accordance with §§ 182, 183, and 184, deducting half the area, we have, 72.65 – 22 = 50.65 sq. in. = .351 sq. ft. in lieu of .504 as above. Or skin resistance in poundals per sq. ft.

In the case of an aerodone having a natural velocity as high as 36 ft./sec, it is impossible to be sure, in so short a flight as 65 feet, that the true natural velocity and gliding angle are recorded; in a short flight the launching velocity and angle have a serious influence on the flight path.

If the altitude of discharge could be increased to 50 feet or thereabouts, with a flight path of some 200 feet length, this difficulty would be overcome, or at least its importance would be reduced to a negligible quantity.