Anglický jazyk

Flying Machines

Na objednávku

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O knihe

Excerpt: ... miles an hour, and the machine is traveling 40 or more, there will be little trouble as regards equilibrium so far as wind disturbance goes, provided the wind blows evenly and does not come in gusts or eddying currents. But when conditions are reversed-when the machine travels only 30 miles an hour and the wind blows at the rate of 50, look out for loss of equilibrium. One of the main reasons for this is that high winds are rarely steady; they seldom blow for any length of time at the same speed. They are usually "gusty," the gusts being a momentary movement at a higher speed. Tornadic gusts are also formed by the meeting of two opposing currents, causing a whirling motion, which makes stability uncertain. Besides, it is not unusual for wind of high speed to suddenly change its direction without warning. Trouble With Vertical Columns. Vertical currents-columns of ascending air-are frequently encountered in unexpected places and have more or less tendency, according to their strength, to make it difficult to keep the machine within a reasonable distance from the ground. These vertical currents are most generally noticeable in the vicinity of steep cliffs, or deep ravines. In such instances they are usually of considerable strength, being caused by the deflection of strong winds blowing against the face of the cliffs. This deflection exerts a back pressure which is felt quite a distance away from the point of origin, so that the vertical current exerts an influence in forcing the machine upward long before the cliff is reached. CHAPTER XV. THE ELEMENT OF DANGER. That there is an element of danger in aviation is undeniable, but it is nowhere so great as the public imagines. Men are killed and injured in the operation of flying machines just as they are killed and injured in the operation of railways. Considering the character of aviation the percentage of casualties is surprisingly small. This is because the results following a...