I didn't know how the fire was, said he, poking at the hot coals, and looking furtively at Mrs. Errington. 234 This is viewing the matter in a broad and general sense; there were firms, especially in France, but also in England and America, which looked confidently for the great days of flying to arrive, and regarded their sunk capital as investment which would eventually bring its due return. But when one looks back on those years, the firms in question stand out as exceptions to the general run of people, who regarded aeronautics as something extremely scientific, exceedingly dangerous, and very expensive. The very fame that was attained by such pilots as became casualties conduced to the advertisement of every death, and the dangers attendant on the use of heavier-than-air machines became greatly exaggerated; considering the matter as one of number of miles flown, even in the early days, flying exacted no more toll in human life than did railways or road motors in the early stages of their development. But to take one instance, when C. S. Rolls was killed at Bournemouth by reason of a faulty tail-plane, the fact was shouted to the whole world with almost as much vehemence as characterised the announcement of the Titanic sinking in mid-Atlantic. In this work is no claim to originality鈥攊t has been a matter mainly of compilation, and some stories, notably those of the Wright Brothers and of Santos Dumont, are better told in the words of the men themselves than any third party could tell them. The author claims, however, that this is the first attempt at recording the facts of development and stating, as fully as is possible in the compass of a single volume, how flight and aerostation have evolved. The time for a critical history of the subject is not yet. An engine of the rotary type, almost as well known as the Gnome, is the Clerget, in which both cylinders and crank case are made of steel, the former having the usual radial fins for cooling. In this type the inlet and exhaust valves are both located in the cylinder head, and mechanically operated by push-rods and rockers. Pipes are carried from the crank case to the inlet valve casings to convey the mixture to the cylinders, a carburettor of the central needle type being used. The carburetted mixture is taken into the crank case chamber in a manner similar to that of the Gnome engine. Pistons of aluminium alloy, with three cast-iron rings, are fitted, the top ring being of the obturator type. The large end of one of the nine connecting rods embraces the crank pin and the pressure is taken on two ball-bearings housed in the end of the rod. This carries eight pins,435 to which the other rods are attached, and the main rod being rigid between the crank pin and piston pin determines the position of the pistons. Hollow connecting-rods are used, and the lubricating oil for the piston pins passes from the crankshaft through the centres of the rods. Inlet and exhaust valves can be set quite independently of one another鈥攁 useful point, since the correct timing of the opening of these valves is of importance. The inlet valve opens 4 degrees from top centre and closes after the bottom dead centre of the piston; the exhaust valve opens 68 degrees before the bottom centre and closes 4 degrees after the top dead centre of the piston. The magnetos are set to give the spark in the cylinder at 25 degrees before the end of the compression stroke鈥攖wo high-tension magnetos are used; if desired, the second one can be436 adjusted to give a later spark for assisting the starting of the engine. The lubricating oil pump is of the valveless two-plunger type, so geared that it runs at seven revolutions to 100 revolutions of the engine; by counting the pulsations the speed of the engine can be quickly calculated by multiplying the pulsations by 100 and dividing by seven. In the 115 horse-power nine-cylinder Clerget the cylinders are 4鈥? bore with a 6鈥? inches stroke, and the rated power of the engine is obtained at 1,200 revolutions per minute. The petrol consumption is 0鈥?5 pint per horse-power per hour. 久久爱www免费人成_人人插大香蕉免费视频_久久黄色视 CHAPTER II That's a very kind feeling, Mr. Errington. But I shouldn't think an innocent person would mind being watched in such a case. For my own part, I hope we shall trace the matter out. It shan't be my fault if we don't. There is no doubt that the Germans had made study of aerial military needs just as thoroughly as they had perfected their ground organisation. Thus there were 21 illuminated aircraft stations in Germany before the War, the most powerful being at Weimar, where a revolving electric flash of over 27 million candle-power was located. Practically all German aeroplane tests in the period immediately preceding the War were of a military nature, and quite a number of reliability tests were carried out just on the other side of the French frontier. Night flying and landing were standardised items in the German pilot鈥檚 course of instruction while they were still experimental in other countries, and a system of signals was arranged which rendered the instructional course as perfect as might be. 148 Wilbur Wright has set down the beginnings of the practical experiments made by the two brothers very clearly. 鈥楾he difficulties,鈥?he says, 鈥榳hich obstruct the pathway to success in flying machine construction are of three general classes: (1) Those which relate to the construction of the sustaining wings; (2) those which relate to the generation and application of the power required to drive the machine through the air; (3) those relating to the balancing and steering of the machine after it is actually in flight. Of these difficulties two are already to a certain extent solved. Men already know how to construct wings, or aeroplanes, which, when driven through the air at sufficient speed, will not only sustain the weight of the wings themselves, but also that of the engine and the engineer as well. Men also know how to build engines and screws of sufficient lightness and power to drive these planes at sustaining speed. Inability to balance and steer still confronts students of the flying problem, although nearly ten years have passed (since Lilienthal鈥檚 success). When this one feature has been worked out, the age of flying machines will have arrived, for all other difficulties are of minor importance.