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1879-1885
The LA FRANCE dirigible in 1885 |
EXPERIMENTS WITH DIRIGIBLE |
| "... the French War Department took up the problem. Renard
and Krebs, the officers in charge of the War Aeronautical Department
at Meudon, built and experimented with in 1884 and 1885 the fusiform balloon
" La France," in which the " master " or maximum section was about one-quarter
of the distance from the stem. The propelling screw was at the front of
the car and driven by an electric motor of unprecedented lightness.
Seven ascents were made on very calm days, a maximum speed of 14 M. an hour was obtained, and the balloon returned to its starting-point on five of the seven occasions. ... An airship constructed by Pierre and Paul Lebaudy in 1904 also made a number of successful trials in the vicinity of Paris; with a motor of 40 h.p., its speed was about 25 M. an hour, and it regularly carried three passengers. ... Dupuy de Lome was the first to estimate in detail the resistances to balloon propulsion, but experiment showed that in the aggregate they were greater than he calculated. Renard and Krebs also found that their computed resistances were largely exceeded, and after revising the results they gave the formula R=o•o1685 D2V2, R being the resistance in kilograms, D the diameter in metres and V the velocity in metres per second. Reduced to British measures, in pounds, feet and miles per hour, R= o•0006876 D2V2, which is somewhat in excess of the formula computed by Dr William Pole from Dupuy de Lome's experiments. The above coefficient applies only to the shape and rigging of the balloon " La France,” and combines all resistances into one equivalent, which is equal to that of a flat plane 18/0 of the " master section.” This coefficient may perhaps hereafter be reduced by one-half through a better form of hull and car, more like a fish than a spindle, by diminished sections of suspension lines and net, and by placing the propeller at the centre of resistance. To compute the results to be expected from new projects, it will be preferable to estimate the resistances in detail. The following table shows how this was done by Dupuy de Lome, and the probable corrections which should have been made by him: RESISTANCES—DUPUY DE LOME'S BALLOON Computed by Dupuy de Lome. ..." |
