Airfoil

“ There is magic in salt water which transmogrifies all things it touches. The aeroplane with its cubist outline undergoes a sea change on reaching the coast and becomes a flying-boat, a thing of beauty, a Viking dragon ship, a shape born of the sea and air with pleasant and easy lines, and in the sun, the dull war-paint stripped from the natural mahogany, a flashing golden craft of enchantment. ”

“ However that may be, what may be termed the mathematising of aeronautics has rendered the type itself evanescent; your pilot of to-day knows his craft, once he is trained, much in the manner that a driver of a motor-lorry knows his vehicle; design has been systematised, capabilities have been tabulated; camber, dihedral angle, aspect ratio, engine power, and plane surface, are business items of drawing office and machine shop; there is room for enterprise, for genius, and for skill; once and again there is room for daring, as in the first Atlantic flight. ”

“ When all is ready to leave the masthead for flight, the pulling of a lever in the automatic coupling releases the ship. The latter then draws astern and upward, under the influence of the prevailing wind, until it is well clear of the landing station and can proceed on its course.
The design of this apparatus is such that the landing of an airship is as easy in a wind as in complete calm. With its help an airship can land in any speed of wind in which it is safe to fly. ”

“ The sea-plane, when a flight is made, is launched upon the water down a slipway; then the pilot and his passenger embark, the motor is started, and the propeller draws the machine across the water at a rapidly increasing pace. The floats raise themselves higher and higher upon the water, as the air-planes exercise a growing lift, until they only just skim the surface. And now comes the moment when the airman, drawing back his elevating lever, seeks to raise his craft from the water into the air. ”

“ HOW does it feel to travel in an air-ship? My first impression of aerial navigation was surprise to feel the air-ship going straight ahead. It was astonishing to feel the wind in my face. In spherical balloons we go with the wind and do not feel it. True, in rising and descending, the spherical balloonist feels the friction of the atmosphere, and vertical oscillation often makes the flag flutter; but in all its horizontal movements the ordinary balloon seems to stand still while the earth flies past under it. ”

“ Just as the navigator must know the sea, so the aviator must have a knowledge of the heavens and the basic principles of aerodynamics in order to become a successful pilot. Although the air is volatile like the water, the aviator flies through it as a fish moves through water. Therefore the aerial navigator must know enough about the medium through which he travels to know what to do in an emergency. ”

“ We are about to consider man’s efforts to rise from the bottom of this ocean and wing his flight a little way through the atmosphere above him. His excursions upward are limited, for he could not live near the surface heights of this ocean, vast and deep and boundless. The art and science of his flight through the air, because of its relation to the flight of birds, we call aviation. ”

“ Now the wings and fuselage of our airplane are ready, and the rudder, the elevating surfaces and the ailerons are in course of production. They are made in the same manner as the wings, with a wooden framework over which fabric is stretched and “doped.” We begin to think our big bird is almost ready to be put together, but we have forgotten two important items: the engine and the propeller.
The airplane manufacturer usually does not attempt to build his own engines or propellers. ”

“ I have always kept a cool head. Alone in the air-ship I am always busy, for there is more than enough work for one man. Like the captain of a yacht, I must not let go the rudder for an instant. Like its chief engineer, I must watch the motor. The balloon's rigidity of form must be preserved. And with this capital detail is connected the whole complex problem of the air-ship's altitude, the manœuvring of guide rope and shifting weights, the economising of ballast, and the surveillance of the air pump attached to the motor. ”

“ In a flying machine, the combination, with an aeroplane, and means for simultaneously moving the lateral portions thereof into different angular relations to the normal plane of the body of the aeroplane and to each other, so as to present to the atmosphere different angles of incidence, of a vertical rudder, and means whereby said rudder is caused to present to the wind that side thereof nearest the side of the aeroplane having the smaller angle of incidence and offering the least resistance to the atmosphere, substantially as described. ”

“ On the other hand, the airship, being provided with engines to propel it through the air, and with rudders and elevators to control it for direction and height, can be steered in whatever direction is desired, and voyages can be made from one place to another--always provided that the force of the wind is not sufficiently strong to overcome the power of the engines. ”

“ Of course, when an aviator is lost in the fog or above the clouds he needs to use all the instruments on board to find his position. For that purpose drift instruments are mounted on aircraft; those tell how much the air-currents, which have the same effect on aircraft as the tide has on a boat, have driven him off his course. A compass indicates the direction in which he is travelling, and other instruments show him whether his machine is climbing, diving, or “banking”; the aneroid barometer indicates the altitude. ”

“ OF THE NEW YORK HERALD.
“Three sets of follow or tandem planes project, with slight dihedral angles, for from eighty to forty feet on each side of the body of the craft, a wing width never before attained. Yet, in flight, the enormous craft is readily held aloft, with all its load, by wings that are no more than seven and one-half feet in chord—from front to trailing edge. Although it will be incomprehensible to many how such small lifting surface can elevate such a heavy structure, this becomes apparent when the airship is seen at rest. ”

“ I’ve finally worked out the complete tetrahedral aeroplane, following some plans of Alexander Graham Bell—the man who invented the telephone. You see, boys, with all these little planes put together, the air can get hold of lots more surface than it can on the ordinary aeroplane. It doesn’t make any difference which way the aeroplane is turned, there’s always planes for the air to get under and hold the machine. An ordinary aeroplane is like the sides of a wooden box that honey comes in, and mine is like the honey itself, with all the hundreds of little walls of wax. ”

“ The arrangements made for handling airships on the ground and while landing, and also for moving them in the open, provide scope for great ingenuity. An airship when about to land is brought over the aerodrome and is "ballasted up" so that she becomes considerably lighter than the air which she displaces. ”

“ According to this plan, although both names stand for an aerial vessel88 capable of travelling in the sky by its own motion, an airship is a machine supported in the air by reason of its buoyancy, while a flying machine is kept aloft only by virtue of its onward movement.
In other words, part of the construction of an airship consists of a bag or balloon, filled with gas or hot air, which causes the whole to rise and maintain its position in the air. ”

“ They spread their wings to the wind, and sail by the hour, with no perceptible exertion beyond that required to balance and steer themselves. What sustains them is not definitely known, though it is almost certain that it is a rising current of air. ”

“ The airship is, therefore, nothing else than a dirigible balloon, for the engines and other weights connected with the structure are supported in the air by an envelope or balloon, or a series of such chambers, according to design, filled with hydrogen or gas of some other nature. ”

“ No one who has considered rigid airship design and studied rapid strides which aeroplanes have made in the last three and a half years can doubt for a moment that an airship could be built in the course of the next two years which would have a disposal lift—or, [224] in aeroplane parlance, a ‘useful load’—of over two hundred tons, giving it an endurance of anything up to three weeks at a speed of forty to forty-five miles an hour. ”

“ Each young aviator winds up his craft, adjusts the power with his own hands, and sets the rudder for the flight.
The miniature air-craft must act in flight exactly the same as the great working air-craft which carry men aloft. A toy air-ship must make its flight in a horizontal position, and if it turns over in flight, even though it flies farther and faster than any other, it is disqualified. ”

“ Within a comparatively short time, then, we ought to see many companies organized in this country for aerial transnavigation of the globe by helium airship! Before the year 1919 has come to a close we ought to see aeroplanes and dirigibles jumping the Atlantic from shore to shore. Who knows, it may even come to pass that man shall become as much a creature of the air as the birds! As a world of exploration and travel the heavens offer him many adventures. ”

“ Just as the curve of a clam shell helps it to mount upward, so the curve of the elevating or depressing rudder on an airship helps it to go up or down. If the rudder is inclined upward the aeroplane shoots toward the clouds. When the rudder is parallel to the plane of the earth's surface, the airship flies in a straight line. When the rudder is tilted downward, down goes the craft. ”

“ On a clear night, however, with flambeaux, search-light flares, etc., a pilot has little trouble in landing, for [152] the straightaway can be as illuminated as it is in broad daylight. Nevertheless, when the aircraft is high in the sky, owing to the vast distances of infinite space, the speed at which an aeroplane moves, and the drift out of its regular course, due to the wind, it is often difficult for the flier to keep his bearings. ”

“ Most aeroplanes have little planes called “ailerons,” which swing up and help to [Pg 30] balance the aeroplane when it tips. They are worked by the aviator, and if anything happens to him, or to them, very quick trouble follows. But with the tetrahedral’s many little planes, facing every way, the machine caught the air and righted itself no matter which way it leaned.
To all of this, Lieutenant Adeler listened without saying much. ”

“ The aeroplane is eminently adapted for certain purposes, and the greatest bigot in favour of the airship can hardly dispute the claims of this machine to remain predominant for short-distance travel, where high speed is essential and the load to be carried is light. For long distance voyages over the oceans or broken or unpopulated country, where large loads are to be carried, the airship should be found to be the more suitable. ”

“ Support of an Airplane by Its Wings.—An airplane is supported just as definitely as though on top of a post, and by the same law, namely reaction. If you try to sweep the air downward with a wing held at a slight angle, the air just before it consents to be pushed downward, delivers a momentary reaction which is upward. ”

“ We shall not need to traverse long distances in a wrong direction to find a bridge by which we may cross a river, nor zigzag for toilsome miles up the steep slopes of a mountain-side to the pass where we may cross the divide. The course of the airship is the proverbial bee-line—the most economical in time as well as in distance. 37
Chapter III.
LAWS OF FLIGHT.
The bird—Nature’s models—Man’s methods—Gravity—The balloon—The airship—Resistance of the air—Winds—The kite—Laws of motion and force—Application to kite-flying—Aeroplanes. ”

“ He who wishes to navigate an air-ship should first practice landing in an ordinary balloon, that is, if he wishes to land without breaking motor and propeller. The wind being rather strong, it was necessary to profit by a moment of comparative calm, and seek a shelter. ”

“ For light loads, great speed, and quick manœuvering, the airplane is supreme. For heavy loads, long distance, ability to remain in the air for great periods of time, the dirigible is the only air craft that can fulfill the requirements. ”

“ The Control Cables of twisted wire, a bit tight before, have slightly lengthened by perhaps the eighth of an inch, and, the Controls instantly responding to the delicate touch of the Pilot, the Aeroplane, at the will of its Master, darts this way and that way, dives, loops, spirals, and at last, in one long, magnificent glide, lands gently in front of its shed. ”

“ Experience, the researches of science, and the growing skill with which aircraft are built, stand between the airman and many of his previous dangers. The aeroplane to-day, one of the structural triumphs of the world in its lightness and its strength, has a factor of safety which is sufficient to meet, and to withstand, not merely ordinary strains, but any such abnormal stresses as it may encounter—and which may be many times greater than the strains of normal flight. ”

“ Efficiency of Airplane Wings.—I said at the beginning of this chapter that the airplane was a device for pushing down an enormous quantity of air. A certain amount of force has to be furnished in order to keep the airplane moving, and this force is furnished by the engine and propeller. ”