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Encyclopedia Britannica - Main :: PAI-PAS |
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PARACHUTE (from Ital. parare, to shield, protect; cf. " parasol," " parapet," and Fr. chute, a fall) , an instrument more or less resembling a large umbrella, which by the resistance it offers to the air enables an aeronaut attached to it to descend safely from a balloon or flying machine in the air. The principle of the parachute is so simple that the idea must have occurred to persons in all ages. Simon de la Loubere (16421729), in his History of Siam (Paris, 1691), tells of a person who frequently diverted the court by the prodigious leaps he used to take, having two parachutes or umbrellas fastened to his girdle. In 1783 Sebastien Lenormand practically demonstrated the efficiency of a' parachute by descending from the tower of Montpellier observatory; but he merely regarded it as a useful means whereby to escape from fire. To J. P. Blanchard (17531809) is due the idea of using it as an adjunct to the balloon. As early as 1785 he had constructed a parachute to which was attached a basket. In this he placed a dog, which descended safely to the ground when the parachute was released from a balloon at a considerable elevation
7eleased the parachute, which was attached to the balloon in place of a car; the balloon, relieved suddenly of so great a weight, rose very rapidly till it burst, while the parachute descended very fast, making violent oscillations all the way. Garnerin, however, reached the earth in safety. He repeated his parachute experiment in England on the 21st of September 1802. The parachute was dome -shaped, and bore a resemblance to a largeumbrella (fig. 1). The case or dome was made ofwhite canvas, and was 23 ft. in diameter . At the top was a truck or round piece of wood
diameter , with a hole in its centre, fastened to the canvas by 32 short pieces of tape. The parachute was suspended from a hoop attached to the netting of the balloon, and below it was placed a cylindrical basket, 4 ft.high and 24 ft. in diameter, which contained the aeronaut. The ascent took place at about six o'clock from North Audley Street, London; and at a height of about (it is believed) 8000 ft. Garnerin separated the parachute from the balloon. For a few seconds his fate seemed certain, as the parachute retained the collapsed state in which it had originally ascended and fell very rapidly. It suddenly, however, expanded, and the rapidity of its descent was at once checked, though oscillations were so violent that the car, which was suspended 20 ft. below, was sometimes on a level with the rest of the apparatus. Some accounts state that these oscillations increased, others that they decreased as the parachute descended; the latter seems the more probable. It came to the ground in a field at the back of St Pancras Church, the descent having occupied rather more than ten minutes. Garnerin was hurt a little by the violence with which the basket containing him struck the earth; but a few cuts and a slight nausea represented all the ill effects of his fall. A few years later, Jordaki Kuparento, a Polish aeronaut, made real use of a parachute. He ascended from Warsaw on the 24th of July 1808, in a fire-balloon, which, at a considerable elevation
The next experiment made with a parachute resulted in the death of Robert Cocking, who as early as 1814 had become interested in the subject. The great defect of Garnerin's umbrella-shaped parachute had been its violent oscillation during descent, and Cocking considered that if the parachute were made of a conical form (vertex downwards) the whole of this oscillation would be avoided; and if it were made of sufficient size there would be resistance enough to check too rapid a descent. He therefore constructed.a parachute on this principle (fig.2), the radius of which at its widest part was about 17 ft. It was stated in the public an- nouncements previous to the experiment that the whole weighed 223 lb; but from the evidence at the inquest it appeared that the weight must have been over 400 lb exclusive of Cocking'sweight,which was 177 lb. On the 24th of July 1837, the Nassau balloon, with Charles Green, the aeronaut, and Edward Spencer
tor, in the car, and having suspended below it the parachute, PARADISE 751 in the car of which was Cocking, rose from Vauxhall Gardens, London, at twenty-five minutes to eight in the evening. A good deal of difficulty was experienced in rising to a suitable height, partly in consequence of the resistance to the air offered by the expanded parachute, and partly owing to its weight. Cocking wished the height to be 8000 ft.; but when the balloon reached the height of 5000 ft., nearly over Greenwich, Green called out to Cocking that he should be unable to ascend to the requisite height if the parachute was to descend in daylight. Cocking accordingly let slip the catch which was to liberate him from the balloon. The parachute for a few seconds descended very rapidly, but still evenly, until suddenly the upper rim seemed to give way and the whole apparatus collapsed (taking a form resembling an umbrella turned inside out, and nearly closed), and the machine descended with great rapidity, oscillating very much. When about 200 or 300 ft. from the ground the basket became disengaged from the remnant of the parachute, and Cocking was found in a field at Lee, literally dashed to pieces. Many objections were made to the form of Cocking's parachute; but there is little doubt that had it been constructed of sufficient strength, and perhaps of somewhat larger size, it would have answered its purpose. John Wise (18081879), the American aeronaut, made some experiments on parachutes of both forms (Garnerin's and Cocking's), and found that the latter always were much more steady, descending generally in a spiral curve. A descending balloon half-full of gas either does rise, or can with a little management be made to rise, to the top of the netting and take the form of a parachute, thus materially lessening the rapidity of descent. Wise, in fact, having noticed this, once purposely exploded his balloon when at a considerable altitude, and the resistance offered to the air by the envelope of the balloon was sufficient to enable him to reach the ground without injury. In more recent
End of Article: PARACHUTE (from Ital. parare, to shield, protect; cf. " parasol," " parapet," and Fr. chute, a fall) If you wish, you can link directly to this article.
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