Engineering Wonders of the World
Volume III

DIRIGIBLE BALLOONS. THE MALECOT = SEMI-RIGID AIRSHIP. (PAo/o, Bolak.) To the balloon arc attached a number of planes, which can be set at an angle to the horizontal to give vertical motion. In case of the collapse of the gas-holder, they would also have some of the effect of a parachute. prow and a conical tail give the best results as regards minimizing resistance. It is much less important to avoid a Prows and Sterns blunt prow than to keep tne lines of the after-part fine, since the resistance of the air to being pushed aside is small as compared with the “ suck ” of a badly-shaped stern. The ideal form has been adopted for a recently built Italian air- ship, and, with modification, for most other dirigibles. German examples—the Zeppelins excluded—have the hemispherical prow and conical tail, but these are separated by a cylindrical body. Some French airships have a conical prow. The Zeppelins are distin- guished by a very long cylindrical body, ter- minated at both ends by what may be termed a spherical cone. In this type the head re- sistance is said to be about one-fifth of that of a circular plane of the samo area as the cross-section of the body. In practice the shape of the envelope is governed by several factors other than that of mere resistance, and is more or less of a compromise. In a paper on military aeronautics, Major G. 0. Squier, of the United States Army Signal Corps, laid it down that the power consumed in propelling a displacement vessel supported by air or water at any con- , . • , , Resistances. st ant speed is considered as being two-thirds consumed by skin-resistance or surface resistance, and one-third by head resistance ; and that a dirigible balloon carry- ing the same weight, other things being equal, may be made to travel about twice as fast as a boat for the same power, or to be made to