Hiram S. Maxim

“ All the early mathematicians, and some of those of the present day, imagine that the lift must be in proportion to the square of the sine of the angle. They reason it out as follows:—If an aeroplane is forced through the air at a given velocity, the aeroplane in which the sine of the angle is 2 inches will push the air down with twice as great a velocity as the one in which the sine of the angle is only 1 inch, and as the force of the wind blowing against a normal plane increases as the square of the velocity, the same law holds good in driving a normal plane through still air. ”

“ Since that time, notwithstanding that a great deal has appeared in the public prints about the efficiency and lightness of electric motors, I am unable to learn of any concern that is ready to furnish a complete motor, including a primary battery, which would supply the necessary current for two hours at a time, at a weight of less than 150 lbs. per horse-power, and as far as I have been able to ascertain from what I have myself seen, I cannot learn that there are any motors in practical use which do not weigh, including their storage batteries, at least 300 lbs. ”

“ I well remember how, as a child, when lying in a New England pasture, I watched a hawk soaring far up in the blue, and sailing for a long time without any motion of its wings, as though it needed no work to sustain it, but was kept up there by some miracle. ”

“ Nineteen years ago, when I commenced my own experiments, I was told that my reputation would be greatly injured, that mankind looked upon artificial flight as an ignis-fatuus, and that anyone who experimented in that direction was placed in the same category as those who sought to make perpetual-motion machines or to find the philosopher’s stone. ”

“ Nature has made her flying machine in the bird, which is nearly a thousand times as heavy as the air its bulk displaces, and only those who have tried to rival it know how inimitable her work is, for ‘the way of a bird in the air’ remains as wonderful to us as it was to Solomon, and the sight of the bird has constantly held this wonder before men’s eyes, and in some men’s minds, and kept the [12] flame of hope from utter extinction, in spite of long disappointment. ”

“ Inventors of, and experimenters with, flying machines are not at all agreed by any means in regard to the best position for the screw. It would appear that many, having noticed that a horse-propelled carriage always has the horse attached to the front, and that the carriage is drawn instead of pushed, have come to the conclusion that, in a flying machine, the screw ought, in the very nature of things, to be attached to the front of the machine, so as to draw it through the air. Railway trains have their propelling power in front, and why should it not be the same with flying machines? ”

“ Recently there has been a great deal of discussion in Engineering and other journals regarding the comparative merits of the aeroplane system and the hélicoptère. Some condemn both systems and pin their faith to flapping wings. It has been contended that the screw propeller is extremely wasteful in energy, and that in all Nature neither fish nor bird propels itself by means of a screw. As we do not find a screw in Nature, why then should we employ it in a machine for performing artificial flight? ”

“ While a machine is running, although there is a marked difference between water and air as far as skin friction is concerned, still the conditions are the same as far as the position of the screw is concerned. With a well-designed steamship, the efficiency of the screw is so great as to be almost unbelievable; in fact, if a steamship had never been made, and the design of one should be placed before the leading mathematicians of to-day, with the request that they should compute the efficiency of the screw, none of them would come anywhere near the mark. ”

“ There is no question but what a bird has a higher physical development, as far as the generation of power is concerned, than any other animal we know of. Nevertheless, I think that everyone who has made a study of the question will agree that some animals, such as hares and rabbits, exert quite as much power in running, in proportion to their weight, as a sea-gull or an eagle does in flying. ”

“ Remembering the effortless flight of the soaring bird, it seemed that the first thing to do was to discard rules which led to such results, and to commence new experiments, not to build a flying machine at once, but to find the principles upon which one should be built ”

“ I think, in fact I assert, that the time has now arrived, having regard to the advanced state of the art in building motors, when it will be quite a simple and safe affair to erect works and turn out successful flying machines at less cost than motor cars; in fact, there is nothing that stands in the way of success to-day. The value of a successful flying machine, when considered from a purely military standpoint, cannot be over-estimated. The flying machine has come, and come to stay, and whether we like it or not, it is a problem that must be taken into serious consideration. ”

“ During the last 50 years a great deal has been said and written in regard to the flight of birds; no other natural phenomenon has excited so much interest and been so imperfectly understood. Learned treatises have been written to prove that a bird is able to develop from ten to twenty times as much power for its weight as other animals, while other equally learned works have shown most conclusively that no greater amount of energy is exerted by a bird in flying than by land animals in running or jumping. ”

“ For many years scientific mechanicians and mathematicians have told us that the navigation of the air was quite possible. They have said it is only a question of motive power; “Give us a motor that is sufficiently light and strong, and we will very soon give you a practical flying machine.” A domestic goose weighs about 12 lbs., and it has been estimated that it only exerts about one-twelfth part of a horse-power in flying—that is, it is able to exert one man-power with a weight of only 12 lbs., which seems to be a very good showing for the goose. ”

“ What is required by experimenters in flying machines—and there will soon be a great number of them—is a treatise which they can understand, and which requires no more delicate instruments than a carpenter’s 2-foot rule and a grocer’s scales. The calculations relating to the lift, drift, and the skin friction of an aeroplane are extremely simple, and it is quite possible to so place this matter that it can be understood by anyone who has the least smattering of mathematical knowledge. ”

“ The movement of a bird’s wings, from long years of development, has without doubt attained a great degree of perfection. Birds are able to scull themselves through the air with very little loss of energy. To imitate by mechanical means, the exact and delicate motion of their wings would certainly be a very difficult task, and I do not believe that we should attempt it in constructing an artificial flying machine. In Nature it is necessary that an animal should be made all in one piece. ”

“ It is then only a question as to whether an oil engine can be made so light as to keep its weight within that of a steam motor; that is, an oil engine in order to be available for the purpose must be as light, including its water supply, as a complete steam motor, which includes not only the engine, but also the boiler, the feed pumps, the water supply, the burner, the gas generator, and six-sevenths of the condenser. It requires a very perfect steam engine and boiler, not using a vacuum, to develop a horse-power with a consumption of 11⁄2 lbs. ”

“ The movement of the air is the resultant of more than one force. The air is not only rising in some places and descending in others, but at the same time, the whole mass is moving forward with more or less rapidity from one part of the earth to another, so we must consider that, instead of the air ascending directly from the relatively hot surface of the earth and descending vertically in other places, in reality the whole mass of rotating air is moving horizontally at the same time. ”

“ If the length was infinitely great the tendency to pitch would be infinitely small. I have shown a steering gear consisting of a lever with a handle n, arranged in such a manner that it moves both the vertical rudder c, and the horizontal rudder d, so that the man who steers the machine has nothing to think of except to point the lever n, p, in the direction that he wishes the machine to go. This lever is mounted on a universal joint at h, and is connected with suitable wires to the two rudders. ”

“ In all Nature, we do not find any bird or insect that does not fly by dynamic energy alone, and I do not believe that the time is far distant when those now advocating machines lighter than the air, will join the party advocating machines heavier than the air, and, eventually, balloons will be abandoned altogether. No matter from what standpoint we examine the subject, the balloon is unsuitable for the service, and it is not susceptible of much improvement. On the other hand, the flying machine is susceptible of a good deal of improvement ”

“ We should not lose sight of the fact that weight tells very seriously against the success of a flying machine, and that no expense should be spared to reduce the weight, providing that it is possible to do so without reducing the factor of safety. Suppose, for example, that we use an ordinary hub secured to a solid shaft by a common key. All the parts have to be made heavy in order to be sufficiently strong to withstand the strain. In the drawing (Fig. 20) I have shown a hub which I think is quite as light and strong as it is possible to make it. ”

“ But, as a matter of fact, the air in which a bird flies is never stationary, as I propose to show; it is always moving either up or down, and soaring birds, by a very delicate sense of feeling, always take advantage of a rising column. If a bird finds itself in a column of air which is descending, it is necessary for it to work its wings very rapidly in order to prevent a descent to the earth.
I have often observed the flight of hawks and eagles. They seem to glide through the air with hardly any movement of their wings. ”

“ What is true of ships is true of flying machines. Good results can never be obtained by placing the screw in front instead of in the rear of the machine. If the screw is in front, the backwash strikes the machine and certainly has a decidedly retarding action. The framework, motor, etc., offer a good deal of resistance to the passage of the air, and if the air has already had imparted to it a backward motion, the resistance is greatly increased. ”

“ Experiments have shown that only a few hundred feet above the surface of the earth, the air is nearly always moving at a velocity of at least 15 miles an hour, and more than two-thirds of the time at a velocity considerably greater than this. In order to give a balloon sufficient lifting power to carry two men and a powerful engine, it is necessary that [121] it should be of enormous bulk. Considered as a whole, including men and engine, it must have a mean density less than the surrounding air, otherwise it will not rise. ”

“ Water may be considered as 2,400 times as efficient as air, volume for volume, in condensing steam. When a condenser is made for the purpose of using water as a cooling agent, a large number of small tubes may be grouped together in a box, and the water may be pumped in at one end of the box and discharged at the other end through relatively small openings; but when air is employed, the tubes or condensing surface must be widely distributed, so that a very large amount of air is encountered, and the air which has struck one tube and become heated must never strike a second tube. ”

“ Every flying machine must have what we will [8] call “a length of entering edge”—that is, the sum of entering edges of all the aeroplanes must bear a fixed relation to the load carried. If a machine is to have its lifting effect doubled, it is necessary to have the length of entering edge twice as long. This additional length may, of course, be obtained by superposed planes, but as we may assume that a large aeroplane will travel faster than a small one, increased velocity will compensate in some degree for the greater width of larger aeroplanes. ”

“ The advantages of a large screw will, therefore, be obvious. I have been unable to obtain correct data regarding the experiments which have taken place with the various machines on the Continent. I have, however, seen these machines, and I should say when they are in flight, providing that the engine develops 40 horse-power, that fully 28 horse-power is lost in screw slip, and the remainder in forcing the machine through the air. These machines weigh 1,000 lbs. each, and their engines are said to be 50 horse-power. The lifting effect, therefore, per horse-power is 20 lbs. ”

“ In a steam steering apparatus, such as is used on shipboard, it is not sufficient to apply steam-power to move the rudders, unless some means are provided whereby the movement of the rudder closes off the steam, otherwise the rudder might continue to travel after the effect had been produced, and ultimately be broken; and so it is with steering a flying machine in a vertical direction. Whenever the fore and aft rudders respond to the action of the gyroscope and are set in motion, they must at once commence to shut off the power that works them, otherwise they would continue to travel. ”

“ This we are quite unable to do with any artificial machine, but birds, for the most part, have to content themselves with food which is not very rich in carbon. It is quite true that a bird may develop from ten to fifteen times as much power from the carbon consumed as can be developed by the best steam engine, but, as an off-set against this, a steam engine is able to consume petroleum, which has at least twenty times as many thermal units per pound as the ordinary food of birds. ”

“ Steam at a very high pressure enters the high-pressure cylinder, expands and escapes at a lower pressure into a larger cylinder where it again expands and does more work. A compound engine is more economical in steam than a simple engine, and therefore requires a smaller boiler to develop the same horse-power, so that when we consider the weight of water and fuel for a given time, together with the weight of the boiler and the engine, the engine motor with a compound engine is lighter than a simple engine. ”

“ He admitted that there was no motor in existence light enough, but thought one might be invented, and that an engine might be worked by a series of explosions in the cylinder, that is, what is known to-day as internal combustion; but he was not clear how such an engine could be produced. He, however, said that a flying machine would be so valuable in time of war, that it mattered little how expensive the explosive might be, even if fulminate of mercury had to be used. ”

“ The ascending column of air is, of course, always very much warmer than the descending column, and this is taking place in a greater or lesser degree everywhere and at all times. A decided upward trend of air is often encountered by those who are experimenting with kites, the kite often mounting higher than can be accounted for on the hypothesis that the wind is moving in a horizontal direction. I have heard this discussed at considerable length. When a kite is flown in an upward current, it behaves in many respects like a soaring bird. ”

“ Many unscientific observers of the flight of birds have imagined that a wind or a horizontal movement of the air is all that is necessary to sustain the weight of a bird in the air after the manner of a kite. ”