Aërodynamically considered, this tiny motor balloon was by far the best in design of any that appeared during the first century of aëronautics. It may be regarded as the harbinger of the swiftest modern French balloons. It was also an inspiration to Henri Giffard who assisted Jullien in constructing his clever model, and shortly afterwards built the first dirigible ever driven by a heat engine.
The illustrious Henri Giffard was perhaps the first aëronautical engineer adequately endowed and circumstanced to realize, on a practical scale, General Meusnier’s well pondered and truly scientific plans for a motor balloon. He had studied in the college of Bourbon, and had worked in the railroad shops of the Paris and St. Germain railway. He had further equipped himself by making free balloon ascensions, under the auspices of Eugene Godard, for the purpose of studying the atmosphere; and by building light engines, one of which weighed 100 pounds, and developed three horse power. Finally in 1851 he patented an air ship, consisting of an elongated bag and car, propelled by a screw driven by a steam engine. He had not the means to build such a vessel, but he had the genius and training necessary to construct it, and at the same time enough enthusiasm and persuasive power to induce his friends, David and Sciama, to loan him the requisite funds.
Fig. 18.—Giffard’s Steam Dirigible, 1852.
Giffard’s first dirigible was successful in both design and operation. It consisted of a spindle-shaped bag covered with a net whose cords were drawn down and attached to a horizontal pole, from which the car and motor were suspended, and at the end of which was a triangular sail serving as a rudder. To guard against fire, the furnace of the vertical coke-burning boiler was shielded by wire gauze, like a miner’s lamp, and the draft, taken from its top through a downward pointing smoke pipe, was ejected below the car by force of exhaust steam, from the engine, thus obviating, as Giffard asserted, all danger from the use of fire near an inflammable gas. The car hung twenty feet below the suspension pole, and carried a three horse-power engine driving a three-blade propeller 11 feet in diameter, making 110 turns a minute. The motor complete, including the engine and boiler without supplies, weighed 110 pounds per horse power. The bag measured 143 feet long, 39 feet in diameter, and 75,000 cubic feet in volume. Giffard reports of his first voyage, made from the Hippodrome in Paris at five fifteen o’clock, September 23, 1852, that although he could not sail directly against the strong wind then blowing, he could attain a speed of six to ten feet per second relatively to the air, and he could easily guide the vessel by turning her rudder. He continued his journey till nightfall, then made a good landing, near Trappes, and by ten o’clock was back in Paris.
This vessel was but a prelude to mightier projects. After some further experience with dirigibles of moderate size, Giffard designed a colossal air ship calculated for a speed of forty-four miles an hour. Its hull was to be of torpedo shape, measuring 2,000 feet in length, 100 feet in diameter, and 7,000,000 cubic feet in volume. It was a most audacious project, one worthy of the genius and energy of that illustrious engineer, the most original and daring inventor known in the aëronautical world during the nineteenth century.
Stimulated by this huge enterprise, Giffard’s first step was to pay his debts and make a fortune. He soon acquired a hundred thousand francs from the sale of small high-speed engines of his own construction, and with this, settled his account with David and Sciama. Next he realized several million francs from his world-famous injector, a device by which steam flowing from a boiler is made to drive in feed-water against the same pressure.
He now made definite plans to build a motor balloon of one and a half million cubic feet capacity, driven by a condensing engine drawing steam from two boilers, one fired with oil, the other with gas from the balloon, so as to keep the vessel from rising with loss of weight. His designs were complete, and everything was provided for. He had deposited a million francs in the Bank of Paris to defray the estimated cost. But, in the words of Tissandier,[10] “above the human will and foresight are the fatal laws of destiny to which the strongest must submit.” The great inventor was visited with a painful affliction of the eyes; his sight waned, unfitting him for work; he became disconsolate, pined away with pain and grief, and in 1882 ended his life by taking chloroform.
Giffard was succeeded in France, first by Dupuy de Lome; then by Gaston Tissandier, well-meaning projectors of steerable balloons, but too cautious to effect an important advance in the art. The first of these gentlemen, an eminent marine engineer, in 1872, completed a gas balloon for the French government, resembling the one designed by General Meusnier in 1784, and like that also driven by muscular power actuating a screw, and kept rigidly inflated by use of an internal balloon, or ballonet. The car was suspended from the bag by a close fitting cover instead of a net, in order to lessen the resistance, and it was kept in alignment by use of crossed suspension cords. A speed of but six miles an hour was attained by the industrious work of eight men operating an ample screw propeller. A decade later Tissandier, with a balloon of like design, but driven by the power of an electric motor and bichromate of potash battery, attained a speed of six to eight miles an hour.
