Airlock

“ In principle, the air-lock of a caisson in no way differs from the well-known lock on a canal. The air-lock is formed by a tube of larger diameter, which surrounds the upper end of the vertical tube leading to the air-chamber.
Having entered this outer chamber, the door is closed behind us, and our connection with the outer world severed. A cock is turned, and with a steady hiss, the compressed air enters, a fact of which we soon become painfully conscious by the pressure that is brought to bear upon the drum of the ear. ”

“ When a fellow goes down from the surface he can’t be seen and so he has to have a signal line and a rope for hauling him up. But down here I can come back to the sub whenever I please and just climb into the air-lock on the ladder, and if I want to signal I can do it without any line—just wave my hands—as you can see me all the time. The airhose runs from a connection in the air-lock and I carry a light line along just as a safeguard and have a man in the air-lock holding it. ”

“ Tassifer," remarked Bennie, "that is the air-lock. It has double doors. When the car is in a vacuum, or beyond the earth's atmosphere, the contained air would all rush out into space if there were any direct communication with the outside. You enter the air-lock from the inside, close and bolt the inner door behind you, open the other door and step out, just as the divers leave and enter a submarine on the bottom of the ocean." ”

“ An improved air-lock, by which access is given from the exterior to the working chamber at the part where the men work in an atmosphere sufficiently condensed to exclude water from the lower open end—like a tumbler inverted in water—is the principal addition which America has made to the device. ”

“ Pausing only to make sure of his surmise, Tom began to tap out on his wireless key the location of the hidden machine gun nest.
Most of the aeroplanes carry a wireless outfit. An aerial trails after them, and the electric impulses, dripping off this, so to speak, reach the battery headquarters. Owing to the noise caused by the motor of the airship, no message can be sent to the airman in return, and he has to depend on signs made on the ground, arrows or circles in white by day and lighted signals at night, to make sure that his messages are being received and understood. ”

“ A swift, boisterous wind shakes the wings of the plane which slopes to the right and to the left according to the movements of the pilot. At times the entire machine vibrates 156 and we feel ourselves so closely bound in its flight that often we believe its wings are attached to our very shoulders. As I look back at the oil guides I see the sparks from the exhaust tube escaping rapidly like a swarm of fireflies swept by the wind. The tube of the silencer which is fastened onto the motor, although the exhaust remains at present completely open, is red and incandescent. ”

“ The flying machine which will navigate successfully in a perfectly quiet atmosphere may be unseaworthy, or rather, unairworthy, when a wind springs up, or the shifting of the wind may spoil all the air pilot’s plans. To add to his troubles, the aviator must move among air currents which change and change again in a moment’s time. As we study the difficulties of air navigation we will appreciate, more than ever, the wonderful patience, skill, and daring of the successful aviators.
The action of the air currents had first to be carefully studied before flight became possible. ”

“ Whichever of these devices is used it is connected in between the aerial and an outside ground wire so that a direct circuit to the earth will be provided at all times except when you are sending or receiving. So your aerial instead of being a menace really acts during an electrical storm like a lightning rod and it is therefore a real protection. The air-gap and vacuum tube lightning arresters are little devices that can be used only where you are going to receive, while the lightning switch must be used where you are going to send ”

“ The airplane communicates with the battery largely by means of the radio telegraphy, but as it was not practicable to receive the radio signals in the plane from the ground, we used these panels. Among the signals formed by these white panels, which are quite clearly discernible from the air, are those meaning that the “Battery is ready to fire,” “Battery has fired,” “Fire by Salvo,” “Change target,” and many, many others including the signal “There is an Enemy Plane near you,” which is the most dreaded panel that can be displayed. ”

“ But at night,—on a cloudy night at that, when there are no lights on earth to guide him and no stars visible in the sky—the aviator faces some of his gravest perils. Strange as it may seem it is often very difficult for him to tell whether his machine is in a horizontal position, whether he is flying right-side-up or is toppling over at a perilous angle. ”

“ Of course there are “air pockets,” and when these are encountered even the best airship may take a sudden drop, which sensation is slightly felt. And if one exposes one’s face or hands or other part of the body to the rush of air, there is a most distinct sensation felt. But the cowl of the cockpit protects those in it from the terrific rush of wind, the pressure of which at two hundred and six miles an hour, is tremendous; and of course those housed in the car felt nothing. ”

“ Then against our aerostat, and with the wind driving them clean overhead of us, come the antagonistic flying-machines. I incline to imagine there will be a steel prow with a cutting edge at either end of the sort of aerostat I foresee, and conceivably this aerial ram will be the most important weapon of the affair. When operating against balloons, such a fighting-machine will rush up the air as swiftly as possible, and then, with a rapid contraction of its bladders, fling itself like a knife at the sinking war-balloon of the foe. ”

“ 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. ”

“ The credit of this sudden apparition belongs, in part at least, to the Royal Engineers, and to their child, the balloon school, which by a steady process of growth had been transformed into the airship squadron of the Royal Flying Corps.
The power of sending messages through space, in any direction, over great distances, is so enormous an addition to the utility of aircraft that a few words must here be said about wireless telegraphy. The discovery was made by the gradual researches of men of science. ”

“ In his graceful air diving, looping the loop, and flying upside down, he gave the world a great object-lesson of the materiality of air. He showed the air can give the aviator as much support as the water can to a fancy swimmer. He showed that if the aëroplane is an unstable thing, the human brain can supply the stability; that in human flight, like the bird and its wings, the machine and individual can be in closest touch. No one has stripped the air of its terrors as has M. Pégoud. In the yielding air there is indeed safety! It is the ground the aviator has to fear! ”

“ Altogether, it was not until the nineteenth century that any real progress toward flight in a heavier-than-air machine was made. It came when experimenters began to investigate the definite laws of air resistance and air pressure which control the action of a bird just as they do the action of a kite. As a matter of fact, a bird, or an airplane, is nothing more than a complicated kite, controlled by an intelligence within itself, rather than by an operator standing on the ground and guiding it by means of a cord. ”

“ After the heading door is closed, with the workmen in the air-lock, a valve is opened which permits the air in the lock to exhaust into the normal air, until the pressure within the lock reduces to the same as that outside, when the outer door can be opened and persons inside the lock pass out. ”

“ Because of the comments that the crew had made regarding the operational status as you saw during the course of the animation, the discussion that they had regarding the operational status of the glide slope, we became concerned what may have caused them to have this discussion.
One of the aspects that we're looking at is what we call spurious signals or radio signals that may have influenced the navigation equipment on the airplane. That is an aspect that our aircraft systems group is currently looking into. ”

“ A part of the aërodrome should be given over to aëroplanes, used for the bringing of mails and urgent freight from places distant from the terminal. Heavier-than-air machines, in fact, will be the veins leading to the great arteries of the world's air routes, operated by dirigibles. A strong searchlight, for the guidance of aëroplane pilots flying in fog, might be necessary. Given improved landing facilities, means might be found for them to coast down the searchlight, if the ground away from it were invisible. ”

“ The Master laid one hand easily on the rim of the big steering-wheel, flung his cap upon a locker, pulled down the telephone headpiece and snapped it on.
He touched a button. The light died in the pilot-house, leaving only the hooded glows of the dials, switches, and small levers. Night seemed suddenly to close in about the vast machine. Till now it had been forgotten, ignored. But as darkness fingered at the panes, something of the vastness of sky and air made itself realized; something of the illimitable scope of this adventuring. ”

“ I refer to the soaring flight, by which the machine is permanently sustained in the air by the same means that are employed by soaring birds. 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. But whether it be a rising current or something else, it is as well able to support a flying machine as a bird, if man once learns the art of utilizing it. ”

“ A machine such as is described in the Signal Corps’ specifications would record the solution of all the difficulties in210 the way of the heavier-than-air airship, and, in fact, finally give mankind almost as complete control of the air as it now has of the land and the water. ”

“ Every wire and strut had been carefully examined and proved, for men's lives depended upon the testing, and oiling, and straining. And now the silent, filmy thing was waiting only for the pilot and observer.
A sound of footsteps upon the soft turf of the aerodrome was heard, and voices carried lightly down the soft morning air.
"Halt! Who goes there?" called the sentry, standing near by, and at the same instant a hand lamp was flashed in the direction of the newcomers. ”

“ Until you have hit upon the proper position, fasten them to the backbone with rubber bands. These permit you to slide the planes back and forth without the trouble of nailing.
Aëroplanes, unlike kites, fly best in a perfectly quiet atmosphere. If you make your trial flights out of doors, select a quiet day. A room, a barn, or any large interior will be found better. In launching your glider, hold it from beneath, so that it balances, and throw it forward with a swift, steady movement of the arm. A little practice will make you very expert. ”

“ Engine troubles are much fewer than they used to be, and a more dependable form of motor relieves the mind of the aviator from such mental disturbance. Some device in the line of a wind-shield would be a real boon, for even in the best weather there is the ceaseless rush of air into one’s face at 45 to 50 miles an hour. The endurance of this for hours is of itself a tax upon the most vigorous physique. 173
With the passing of the present spectacular stage of the art of flying there will doubtless come a more reliable form of machine, with corresponding relief to the operator. ”

“ On single-seater machines it is sometimes necessary for the pilot to have both hands free of the controls, so that it becomes necessary to install some form of locking device for the elevator control, there being many simple ways of accomplishing this. The locking of the control lever fixes the flight path of the machine, but, of course, lateral equilibrium can be maintained by movements of the lever sideways, and steering by the rudder bar. The German machines of the Fokker and Albatross types are both fitted with the single lever control with a locking arrangement. ”

“ This gliding by means of gravity without the motor working in times of peace may have been thought to be a foolhardy practice, merely done for the sake of sensation. But the sensation of a few years back is the necessity of to-day! The vol-plané has become one of the most useful features of aëroplaning. A machine that is fitted with wireless telegraphy equipment undoubtedly possesses a great advantage for reconnoitring. It is especially useful when a heavy attack on an enemy is in progress. ”

“ 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. ”