Engineering Wonders of the World
Volume III

DIRIGIBLE BALLOONS. 51 During the siege of Paris (1870) Dupuy de Lome built for the French Government a dirigible shaped somewhat similarly to that of Giffard. In place of an ^^Löme^e engine the muscles of eight men were employed to turn a large screw, nearly 30 feet in diameter, about twenty-eight times per minute. The airship moved itself at a low speed, but ap- parently the inventor and the Government did not consider its behaviour sufficiently satisfactory to justify sending it over the beleaguering German army. an hour. The dirigible overcame winds of con- siderable strength, and on five of the seven trials returned to its starting-point. It is somewhat strange that the Government did not continue experiments with so efficient an airship, which, in the words of Renard, had “ furnished the first proof of the possibility of manoeuvring a spindle-shaped balloon in the air ocean by means analogous to those which allow ships to perform evolutions in the ocean of water.” During the years 1898 to 1905 the young Brazilian, It Fig. 2-—RENARD AND KREBS’ AIRSHIP (1884). The first really successful navigable balloon. Propelled by electric motors, made several considerable voyages at a good speed. Highest velocity attained, about fourteen miles an hour. Santos Dumont. to any one Renard and Krebs’ Dirigible. Passing over the experiments of Haenlein and Tissandier, we come to the famous air- ship constructed by Captains Renard and Krebs of th© French army in 1884 and 1885. This balloon (Fig. 2) was of more scientific design than its predecessors, having its largest diameter near the prow, and tapering gradually aft. The volume was comparatively small, only 1,864 cubic metres. As motive power the inventors selected elec- tricity, stored in a battery of thirty-two cells of special construction, and used in an 8’5 horse- power motor, which revolved a 23-foot pro- peller thirty to forty times Successful minute. Several successful Trials. trials were carried out in August, September, and November 1884, and in August and September of the following year, the highest speed attained being 14 miles metres m diameter, ^eutsch , r . Prize won. volume ot 630 cubic An internal air ballonet, fed by a maintained the tautness of the en- From the bag was suspended a long Alberto Santos Dumont, designed a series of dirigibles. Henri Deutsch, a wealthy member of the French Aero Club, of- fered in 1900 a prize of £4,000 who should start from the Aero Club park near Long- champs, sail to and round the Eiffel Tower, and return to the starting-point—a distance of about seven miles—in less than half an hour. After several unsuccessful attempts to capture the prize, M. Santos Dumont succeeded, on October 19, 1901, in covering the stipulated course in a minute less than the limit. The airship used, his No. VI., had a gas bag 33 metres long and 6 with a metres, pump, velope. truss carrying a basket-work car for the aero- naut, a 16 horse-power Buchet four-cylinder motor, and at the rear end a propeller four metres long, made of silk stretched tightly over a rigid frame. Steering was effected by a vertical rudder operated from a wheel at the front of the car. Santos Dumont’s bal- loons, though not a great advance on that of Renard and Krebs, proved the suitability of DANMARKS TEKNISKE BIBLIOTEK