needs and who didn't build strong organizationsall those promotersstarted to fall apart and, eventually,fall out. During 1913 the (at one time almost universal) practice originated by the Wright Brothers, of warping the wings for lateral stability, began to die out and the bulk of aeroplanes began to be fitted with flaps (or 鈥榓ilerons鈥? instead. This was a distinct change for the better, as continually warping the wings by bending down the extremities of the rear spars was bound in time to produce 鈥榝atigue鈥?in that member and lead to breakage; and the practice became completely obsolete during the next two or three years. Often. Every day. Every hour. 鈥楾he act of flying requires less exertion than from the appearance is supposed. Not having sufficient data to ascertain the exact degree of propelling power exerted by birds in the act of flying, it is uncertain what degree of energy may be required in this respect for vessels of aerial navigation; yet when we consider the many hundreds of miles of continued flight exerted by birds of passage, the idea of its being only a small effort is greatly corroborated. To apply the power of the first mover to the greatest advantage in producing this effect is a very material point. The mode universally adopted by Nature is the oblique waft of the wing. We have only to choose between the direct beat overtaking the velocity of the current, like the oar of a boat, or one applied like the wing, in some assigned degree of obliquity to it. Suppose 35 feet per second to be the velocity of an aerial vehicle, the oar must be moved with this speed previous to its being able to receive any resistance; then if it be only required to obtain a pressure of one-tenth of a lb. upon each square foot it must exceed the velocity of the current 7.3 feet per second. Hence its whole velocity must be 42.5 feet per second. Should the same surface be wafted downward like a wing with the hinder edge inclined upward in an angle of about 50 deg. 40 feet to the current it will overtake it at a velocity of 3.5 feet per second; and as a slight unknown angle of resistance generates a lb. pressure per square foot at this velocity, probably a waft of a little more than 4 feet per second would produce this effect, one-tenth part of which would be the propelling power. The advantage of this mode of48 application compared with the former is rather more than ten to one. After a dissertation upon the history and strength of the condor, and on the differences between the weights of birds, he says: 鈥楾he following observations upon the wonderful difference in the weight of some birds, with their apparent means of supporting it in their flight, may tend to remove some prejudices against my plan from the minds of some of my readers. The weight of the humming-bird is one drachm, that of the condor not less than four stone. Now, if we reduce four stone into drachms we shall find the condor is 14,336 times as heavy as the humming-bird. What an amazing disproportion of weight! Yet by the same mechanical use of its wings the condor can overcome the specific gravity of its body with as much ease as the little humming-bird. But this is not all. We are informed that this enormous bird possesses a power in its wings, so far exceeding what is necessary for its own conveyance through the air, that it can take up and fly away with a whole sheep in its talons, with as much51 ease as an eagle would carry off, in the same manner, a hare or a rabbit. This we may readily give credit to, from the known fact of our little kestrel and the sparrowhawk frequently flying off with a partridge, which is nearly three times the weight of these rapacious little birds.鈥? 日本强奷片/日本在线/日本高清a/一级日本100集a BUD WALTON: Probably wakened to realisation of the possibilities of the aeroplane by the Rheims Meeting, Germany turned out its first plane late in 1909. It was known as the Grade monoplane, and was a blend of the Bleriot and Santos-Dumont machines, with a tail suggestive of the Antoinette type. The main frame took the form of a single steel tube, at the forward end of which was rigged a triangular arrangement carrying the pilot鈥檚 seat and the landing wheels underneath, with the wing warping wires and stays above. The sweep of the wings was rather similar to the later Taube design, though the sweep back was not so pronounced, and the machine was driven by a four-cylinder, 20 horse-power, air-cooled engine which drove a two-bladed tractor propeller. In spite of Lilienthal鈥檚 pioneer work years before, this was the first power-driven German plane which actually flew.