Page:Aerial Flight - Volume 1 - Aerodynamics - Frederick Lanchester - 1906.djvu/406

§ 245 the direct resistance of the ballast. Taking this as the equivalent of a normal plane area of .025 sq. in., or .000174 sq. ft., and multiplying by $$\frac{144}{16}$$ to bring up to a per sq. ft. basis, we have .00156, or resistance per sq. ft. due to ballast

Again,