Early Dirigeables - Santos-Dumont
The term "dirigeable" soon replaced "ballon dirigeable" more or less completely in French. In English the first instances of dirigible after one isolated instance 1885 are in writings on or by Santos-Dumont. In 1901, M. Alberto Santos-Dumont, a Brazilian gentleman resident in Paris, excited widespread interest through his experiments with a dirigible balloon. This aeronaut built his first balloon in 1898. It was in the form of a cylinder, terminated at each end by a cone, and was 82 feet long and nearly 6 feet in diameter, with a capacity of 6,400 cubic feet. A basket suspended from the balloon carried a 1-1/2 horse-power gasoline motor, which operated a screw propeller. To provide the necessary fore and aft trim for ascent and descent when under way, the inventor made use of bags of ballast which could be attached or removed at will from ropes suspended from the forward and after part of the balloon and accessible from the basket or car.
With this balloon M. Santos-Dumont made an ascent in the autumn of 1898 which nearly resulted fatally to himself; the failure of an air-pump to work resulted in a partial collapse of the balloon, which fell 1300 feet to the ground. Aside from the air-pump accident, the success of this trip was unusually encouraging; the balloon proved perfectly dirigible in the light winds prevailing at the time of the trip. A second balloon, built exactly like the first, but larger, was never used by M. Santos-Dumont, owing to the fact that in some experiments made with his first balloon when captive the conclusion had been forced upon him that the model was incorrect.
A third balloon, shorter and very much thicker, was completed in the summer of 1899. This balloon was 66 feet long, 11% feet greatest diameter, and 17,600 cubic feet capacity, and into the construction was introduced the novelty of what the inventor termed a keel. This keel was nothing more or less than a bamboo pole, 30 feet long, fixed lengthwise to suspender cords just beneath the balloon, which supported the basket and other apparatus. M. Santos-Dumont was able to circle around the Eiffel Tower in this balloon but found that it was too clumsy and the motor too weak. He built a fourth, 95 feet long and 9 feet in diameter, elliptical in shape, with a capacity of 14,800 cubic feet. In this balloon the keel was a long framework of bamboo and wire, which carried directly - there being no suspended car - a 7 horse-power motor with its propeller and other mechanism. The operator managed his machine seated on a bicycle saddle attached to the keel. With this balloon M. Santos-Dumont made numerous short trips during the Paris Exposition of 1900.
Balloon No. 5 was made by cutting balloon No. 4 in half and inserting a cylindrical piece sufficient to increase its length to 109 feet. A 16 horse-power motor was adopted. The keel was a 60 foot framework of pine and piano wire, and into it, 20 feet from the stern, was fixed the motor, while the operator occupied a hasket 23 feet from the front end or stem. On August 18, 1901, M. Santos-Dumont navigated this balloon from St. Cloud to and around the Eiffel Tower, and was approaching the starting point when the balloon collapsed, and the whole structure, with its operator, was precipitated upon the roof of the Trocadero Hotel, where it hung, the keel spanning the space between the two roofs.
The sixth balloon of M. Santos-Dumont was like the previous one, except that it was longer, thicker, and more nearly ellipsoidal in shape. In October 1901, this balloon succeeded in making a trip from St. Cloud to and around the Eiffel Tower, and then back to the starting point, in 30 minutes 40 seconds. The trip was undertaken as the result of a prize of 100.000 francs offered to the inventor should he succeed in making the journey in 30 minutes.
In rapid succession the Brazilian aeronaut constructed balloons, each embodying some new feature, and in the main marking an advance over its predecessors. In some instances, notably in his No. 9, there was a return to the egg-shaped balloon of Krebs and Renard of 1885, with the larger end first, to give greater resistance to the air. In some cases speed was aimed at, in others, carrying capacity, while the control in each instance was made more complete.
In 1905 the Santos-Dumont XIV was finished, a balloon designed for speed. It was 41 meters (l:!4.5 feet) in length and was inflated with pure hydrogen. Its motor consisted of a 14 horse-power Pengot motor, weighing 27 kilograms (59.5 Ibs.) and connected with a propeller placed well forward near the motor, so that the airship is drawn rather than propelled. This dirigible balloon was tested at Trowville over the sea and was found to be readily guided and controlled.
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