Shapes
Henry Giffard’s Dirigible
(The first with steam power)
The cylindrical Zeppelin balloon with approximately conical ends has already been shown (page [68]). Those balloons in which the shape is maintained by internal pressure of air are usually pisciform, that is, fish-shaped. Studies have actually been made of the contour lines of various fishes and equivalent symmetrical forms derived, the outline of the balloon being formed by a pair of approximately parabolic curves.
Dirigible of Dupuy de Lome
(Man Power)
The first flight in a power driven balloon was made by Giffard in 1852. This balloon had an independent speed of about ten feet per second, but was without appliances for steering. A ballonetted balloon of 120,000 cubic feet capacity was directed by man power in 1872: eight men turned a screw thirty feet in diameter which gave a speed of about seven miles per hour. Electric motors and storage batteries were used for dirigible balloons in 1883-’84: in the latter year, Renard and Krebs built the first fish-shaped balloon. The first dirigible driven by an internal combustion motor was used by Santos-Dumont in 1901.
Tissandier Brothers’ Dirigible Balloon
(Electric Motor)