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时间: 2019年12月07日 21:26

The pistons are built up from two pieces; a dropped forged steel piston head, from which depend the piston pin bosses, is combined with a cast-iron skirt, into which the steel head is screwed. Four rings are fitted, three at the upper and one at the lower end of the piston skirt, and two lubricating oil grooves are cut in the skirt, in addition to the ring grooves. Two small rivets462 retain the steel head on the piston skirt after it has been screwed into position, and it is also welded at two points. The coefficient of friction between the cast-iron and steel is considerably less than that which would exist between two steel parts, and there is less tendency for the skirt to score the cylinder walls than would be the case if all steel were used鈥攕o noticeable is this that many makers, after giving steel pistons a trial, discarded them in favour of cast-iron; the Gnome is an example of this, being originally fitted with a steel piston carrying a brass ring, discarded in favour of a cast-iron piston with a percentage of steel in the metal mixture. In the Le Rhone engine the difficulty is overcome by a cast-iron liner to the cylinders. While these trials were in progress Audemars accomplished the first flight between Paris and Berlin, setting out from Issy early in the morning of August 18th, landing at Rheims to refill his tanks within an hour and a half, and then coming into bad weather which forced him to land successively at Mezieres, Laroche, Bochum, and finally nearly Gersenkirchen, where, owing to a leaky petrol tank, the attempt to win the prize offered for the first flight between the two capitals had to be abandoned after 300 miles had been covered, as the time limit was definitely exceeded.238 Audemars determined to get through to Berlin, and set off at 5 in the morning of the 19th, only to be brought down by fog; starting off again at 9.15 he landed at Hanover, was off again at 1.35, and reached the Johannisthal aerodrome in the suburbs of Berlin at 6.48 that evening. Algernon laughed quite genuinely. "Oh yes it is!" he cried. "A proof of the direst malignity. What worse can they do?" Must I? she answered gloomily. Beyond the 1901 experiments in gliding, the record grows more scrappy, less detailed. It appears that once power-driven flight had been achieved, the brothers were not so willing to talk as before; considering the amount of work that they put in, there could have been little time for verbal description of that work鈥攁s already remarked, their tables still stand for the designer and experimenter. The end of the 1901 experiments left both brothers somewhat discouraged, though they had accomplished more than any others. 鈥楬aving set out167 with absolute faith in the existing scientific data, we were driven to doubt one thing after another, till finally, after two years of experiment, we cast it all aside, and decided to rely entirely on our own investigations. Truth and error were everywhere so intimately mixed as to be indistinguishable.... We had taken up aeronautics as a sport. We reluctantly entered upon the scientific side of it.鈥? Borelli was a versatile genius. Born in 1608, he was practically contemporary with Francesco Lana, and there is evidence that he either knew or was in correspondence with many prominent members of the Royal Society of Great Britain, more especially with John Collins, Dr Wallis, and Henry Oldenburgh, the then Secretary of the Society. He was author of a long list of scientific essays, two of which only are responsible for his fame, viz., Theorice Medic?arum Planetarum, published in Florence, and the better known posthumous De Motu Animalium. The first of these two is an astronomical study in which Borelli gives evidence of an instinctive knowledge of gravitation, though no definite expression is given of this. The second work, De Motu Animalium, deals with the mechanical action of the limbs of birds and animals and with a theory of the action of the internal organs. A section of the first part of this work, called De Volatu, is a study of bird flight; it is quite independent of Da Vinci鈥檚 earlier22 work, which had been forgotten and remained unnoticed until near on the beginning of practical flight. 韩国三级电影网站 免费韩国成人影片 韩国三级片大全在线观看 To hover ever round thy bed, During 1907 and 1908 a new type of machine, in the monoplane, began to appear from the workshops of Louis Bl茅riot, Robert Esnault-Pelterie, and others, which was destined to give rise to long and bitter controversies on the relative advantages of the two types, into which it is not proposed to enter here; though the rumblings of the conflict are still to be heard by discerning ears. Bl茅riot鈥檚 early monoplanes had certain new features, such as the location of the pilot, and in some cases the engine, below the wing; but in general his monoplanes, particularly the famous No. XI on which the first Channel crossing was made on July 25th, 1909, embodied the main principles of the Wright and Voisin types, except that the propeller was in front of instead of behind the supporting surfaces, and was, therefore, what is called a 鈥榯ractor鈥?in place of the then more conventional 鈥榩usher.鈥?Bl茅riot aimed at lateral balance290 by having the tip of each wing pivoted, though he soon fell into line with the Wrights and adopted the warping system. The main features of the design of Esnault-Pelterie鈥檚 monoplane was the inverted dihedral (or kathedral as this was called in Mr S. F. Cody鈥檚 British Army Biplane of 1907) on the wings, whereby the tips were considerably lower than the roots at the body. This was designed to give automatic lateral stability, but, here again, conventional practice was soon adopted and the R.E.P. monoplanes, which became well-known in this country through their adoption in the early days by Messrs Vickers, were of the ordinary monoplane design, consisting of a tractor propeller with wire-stayed wings, the pilot being in an enclosed fuselage containing the engine in front and carrying at its rear extremity fixed horizontal and vertical surfaces combined with movable elevators and rudder. Constructionally, the R.E.P. monoplane was of extreme interest as the body was constructed of steel. The Antoinette monoplane, so ably flown by Latham, was another very famous machine of the 1909-1910 period, though its performance were frequently marred by engine failure; which was indeed the bugbear of all these early experimenters, and it is difficult to say, after this lapse of time, how far in many cases the failures which occurred, both in performances and even in the actual ability to rise from the ground, were due to defects in design or merely faults in the primitive engines available. The Antoinette aroused admiration chiefly through its graceful, bird-like lines, which have probably never been equalled; but its chief interest for our present purpose lies in the novel method of wing-staying which was employed. Contemporary monoplanes practically all had their291 wings stayed by wires to a post in the centre above the fuselage, and, usually, to the undercarriage below. In the Antoinette, however, a king post was introduced half-way along the wing, from which wires were carried to the ends of the wings and the body. This was intended to give increased strength and permitted of a greater wing-spread and consequently improved aspect ratio. The same system of construction was adopted in the British Martinsyde monoplanes of two or three years later. In Manly鈥檚 engine the cylinders were of steel, machined outside and inside to 1/16 of an inch thickness; on the side of the cylinder, at the top end, the valve chamber was brazed, being machined from a solid forging. The casing which formed the water-jacket was of sheet steel, 1/50 of an inch in thickness, and this also was brazed on the cylinder and to the valve chamber. Automatic inlet valves were fitted, and the exhaust valves were operated by a cam which had two points, 180 degrees apart; the cam was rotated in the opposite direction to the engine at one-quarter engine speed.419 Ignition was obtained by using a one-spark coil and vibrator for all cylinders, with a distributor to select the right cylinder for each spark鈥攖his was before the days of the high-tension magneto and the almost perfect ignition systems that makers now employ. The scheme of ignition for this engine was originated by Manly himself, and he also designed the sparking plugs fitted in the tops of the cylinders. Through fear of trouble resulting if the steel pistons worked on the steel cylinders, cast-iron liners were introduced in the latter, 1/16 of an inch thick. Latham鈥檚 Antoinette 29. Horatia. Go, dear Aunt, precious Aunt, do go.