High speed

“ Tests of High-speed Engines.—High-speed engines present various difficulties which must be contended with in controlling their operation. Their high speed renders it impossible to take indicator records as in the case of most industrial engines. ”

“ A.--Yes; it increases very rapidly, partly from the undulation of the earth when a heavy train passes over it at a high velocity, but chiefly from the resistance of the atmosphere and blast pipe, which constitute the greatest of the impediments to motion at high speeds. At a speed of 30 miles an hour, the atmospheric resistance has been found in some cases to amount to about 12 lbs. ”

“ So that, in a properly constructed engine, the higher the speed the smoother and more uniform and more silent the running will be.”
After a page or more devoted to a demonstration of this action, Mr. Colburn sums up the advantage of high speed in the following illustration:
“Let us suppose that, in an engine making 75 revolutions per minute, the reciprocating parts are of such a weight that the force required at the commencement of the stroke to put them in motion is equal to a pressure of 20 pounds on the square inch of piston. ”

“ A high speed engine means one in which the speed of the piston back and forth is high, rather than the speed of rotation, there being sometimes a difference. High speed engines came into use because of the need of such to run dynamos for electric lighting. Without a high speed engine an intermediate gear would have to be used, so as to increase the speed of the operating shaft. ”

“ I believe we will be able to accelerate the car rapidly to a speed of several miles a second at very high altitudes, and as we will be able to use a perfectly enclosed streamlined car, we should get tremendous speeds. ”

“ The speed of 300 revolutions per minute had proved to be admirably suited for the machine. Familiarity with this speed in the running of the stone-dressing machine made me alive to the value of high rotative speeds in all cases to which they are adapted. ”

“ I have now started the motor, and after a moment or two I shall have obtained the right speed, and this I know by blowing through the holes, when a musical note will be produced, higher than the fork if the speed is too high, and lower than the fork if the speed is too low, and exactly the same as the fork if it is right. ”

“ The idea is that when this monster has all its tubes shooting out the burning, expanding gases and liquids from the nozzles, the high pressure exerted on the atmosphere makes the wheel revolve at enormous speed—speed probably greater than that attained by any other human machine! ”

“ Regarding density, the pilot should know that for a low density he should theoretically get a high speed. As density decreases, high up in the air, the speed tends to increase, and moreover he gets more speed for the same amount of gasoline. Unfortunately, at an altitude the motor power falls off, so that nowadays the speed is not faster high up than low down; but when the motor builders succeed in designing their motors to give the same horsepower at 20,000 ft. as they do on the ground, airplanes will be able to reach terrific speed by doing their work above the clouds. ”

“ A. The different speeds required to meet road conditions are obtained by opening or closing the throttle. Practically all the running speeds needed for ordinary travel are obtained on high gear, and it is seldom necessary to use the low gear except to give the car momentum in starting. The speed of the car may be temporarily slackened in driving through crowded traffic, turning corners, etc., by “slipping the clutch,” i. e., pressing the clutch pedal forward into neutral. ”

“ High rates of speed are generally combined with light loads, and heavy trains are required to move at the lower velocities.
Great speeds require the rapid production and consumption of a large bulk of steam of but little density; large wheels and short stroke, that the ratio of velocities of piston and wheel may be as great as possible. ”

“ Since high average speed on a line with frequent stops depends largely on rapidity of acceleration, the tendency in modern equipment is to secure as great an output of power as possible during the accelerating period, with corresponding increase in weight available for adhesion. ”

“ For instance, the deceleration of a ship does not follow the exponential, but at high velocities the decrease of speed is a greater fraction of the speed than during the same time interval at lower velocities, and the speed-time curves for different initial speeds are not proportional to each other, but are as shown in Fig. ”

“ Nature may reach the same result in many ways. Like a wave in the physical world, in the infinite ocean of the medium which pervades all, so in the world of organism:, in life, an impulse started proceeds onward, at times, may be, with the speed of light, at times, again, so slowly that for ages and ages it seems to stay; passing through processes of a complexity inconceivable to men, but in ;ill its forms, in all its stages, its energy. ever and ever integrally present. ”

“ In less time than it takes to write we saw that it was an enormous racing automobile, probably undergoing a test of speed. We were running at our own highest pace, perhaps forty-five miles an hour; the thing approaching us was coming at seventy or more. You may imagine the rush of air as we passed each other. One glimpse we had of a masked automobilist like a figure of death in an Albert Dürer cartoon, or the familiar of a Vehmgericht, and then we were gasping in the vortex of air caused by the speed of the gigantic car. ”

“ Air tight cars of special design are used, and only one car is allowed in the tube at one time.
You cannot imagine the frightful velocity of the ride, but the passenger is not as conscious of this as you might think. The first fifty miles of the descent is controlled by the exterior or surface engines. The speed is gradually increased until it reaches that of the falling body. ”

“ When a railway train has just begun to move, its velocity v is small; but it is rapidly gaining speed–it is being hurried up, or accelerated, by the effort of the engine. So its is large. When it has got up its top speed it is no longer being accelerated, so that then has fallen to zero. ”

“ A very good formula to follow in regard to changing speeds is to continue on the speed on which you are running until the engine cuts out or shows signs of extra vibration or noise, which will at once indicate to you that it is running faster than it ought, and that it is desirable to change on to the next speed. This will ensure there being a good run on the car, and that the next higher speed will take up the run and increase the pace. ”

“ Overrunning the Engine.—We will suppose that you are running down a steep hill with the speed lever set in the third speed—with the left pedal down and the motor consequently disconnected—and this third speed gives, say, a rate of twenty miles an hour. The car, however, from its own momentum and the force of gravity, may be running at twenty-five miles an hour, and to let the clutch in then throws a very unfair strain on the engine. ”

“ Sometime somebody is going to invent an instrument which will record an aeroplane's actual speed with relation to the distance covered above the ground; in other words, which will actually show a speed of only twenty-five miles an hour when a hundred-mile-an-hour engine speed is being reduced to twenty-five by a head-on seventy-five-mile-an-hour gale ”

“ An engine running thirty miles an hour, without once slacking speed, could go around our globe in thirty-five days. Start it off for a trip to the moon, and with the same speed it would reach there in eleven months. And then send it from the earth to the sun, at an equal rate of travel: year after year it must rush on, until three hundred and fifty-one years were passed before it could reach the sun. But so much faster does light travel than a railroad train, that light comes to us from the sun in eight minutes and nineteen seconds! ”

“ Seventy-five miles an hour!!" This is really exciting; one feels exhilarated by such rapid motion, the engine leaping along as though endowed with life. Oscillation increases with speed, and, in order to preserve my balance, I find a friendly hook near the weather-glass convenient to hold on by. Away, with a roar and a rattle! No sooner are distant signals seen than we are upon them; no sooner do we realise that an object half-a-mile away is a wayside cottage than we reach it, rush by, and leave it far behind. ”

“ Now a spring has a certain speed at which it naturally vibrates and other things being equal that speed depends upon its length. You can, of course, force any spring to vibrate at any speed if you care to take the trouble, but each one has its own natural speed at which it will vibrate under very slight provocation.
Every engine is, of course, made to run as smoothly as possible. ”

“ Two drivers A, A′, equally speeded in opposite directions, will drive the bevil gear at same velocity without revolving the spur wheel C′ which is loose on the shaft; but any alteration in the relative speeds of A and A′, causes the bevil pinion to travel round, carrying the spur wheel C′ at a speed equal to half the difference of the two velocities. ”

“ At higher speeds of rotation some light would reappear, and at lower speeds it would also reappear; by noticing, therefore, the precise speed at which there was constant eclipse the velocity of light could be determined. ”

“ And again,—“We have spoken of vehicles travelling at twenty miles an hour; but we see no reason for thinking that, in the progress of improvement, a much higher velocity might not be found practicable; and in twenty years hence a shopkeeper or mechanic, on the most ordinary occasion, may probably travel with a speed that would leave the fleetest courser behind.” ”

“ My dear boy, who knows what the human body can stand? When the locomotive was first invented learned scientists predicted that the limit of speed was thirty miles an hour, as the human body could not stand a higher speed. To-day the human body stands a speed of three hundred and sixty miles an hour without ill effects. At any rate, on my first trip I intend to take no chances. We know that the body can stand an acceleration of thirty-two feet per second without trouble. That is the rate of acceleration due to gravity and is the rate at which a body increases speed when it falls. ”

“ What is of yet more importance, the higher the speed the less the inclination required, and, if we leave out of consideration the friction of the air and the resistance arising from any object which the machine may carry, the less the horse-power expended in driving the plane. ”

“ If, however, we push it rapidly forward, the resistance greatly increases, for the air-molecules must have time to change their position, and we encounter them in their passage. If, now, we increase the velocity of the motion to the highest speed ever attained by a locomotive—say, one and one-fifth mile per minute—we should encounter still more particles, and find a resistance which no human muscle could overcome. Increase that velocity ten times, to twelve miles a minute, the velocity of sound, and the air would oppose such a resistance that our wooden board would be shivered into splinters. ”

“ From what has been explained, respecting the resistance of fluids, and from the relation which I have shown to subsist between the speed of horses and the performances which they are able to effect, it will be apparent that that rate of motion which renders the resistance of a fluid least injurious to the effect produced, is also that speed at which a horse can work with the greatest possible effect. This speed is from two and a half to three miles an hour ”

“ The tractive power, therefore, increases rapidly to a value far exceeding the frictional resistances, but this surplus energy serves to increase the velocity, and disappears as soon as a uniform velocity is reached.
The average speed, both with one and three cars, was 30 kilometers per hour.--Zeitsch. f. Elektrotechnik. ”

“ He paused a moment impressively. "No one has hitherto discovered any system which will accurately record the speed of a vehicle or of any rotary movement and register it at the lowest as at the highest speeds." ”

“ The success of a U-boat campaign does not depend solely on the number of the boats, but rather upon their quality and the skill of their navigators. U-boats of great speed and unlimited powers of remaining at sea, which could not be caught, would soon paralyse the sea traffic of an Island State like England. As such an ideal was not capable of full attainment, the greater number of boats had to make up for the lack of perfection. The results achieved fulfilled, and even surpassed, expectation, even though a criminally long time was allowed the enemy to organise his defence. ”

“ The velocity necessary to just sustain the load at a given angle of inclination is called the critical or soaring velocity. For a given machine, there is an angle of inclination (about half a right angle) at which the minimum speed is necessary. This speed is called the “least soaring velocity.” If the velocity is now increased, the angle of inclination may be reduced and the planes will soar through the air almost edgewise, apparently with diminished resistance and power consumption. ”

“ We determine the velocity of a railway train by the time it takes to pass from one mile-post to the next. We learn the speed [Pg 263] of a rifle bullet by an ingenious contrivance really founded on the same principle. The greater the velocity, the more desirable is it that the distance traversed during the experiment shall be as large as possible. In dealing with the measurement of the velocity of light, we therefore choose for our measured distance the greatest length that may be convenient. ”