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Aviation History
1910
1910 - 0770.PDF
THE "MORNING POST" „,Mink *T„«„¥« NATIONAL FUND AIRSHIP. As every Briton knows, and as every patriotic Briton fully appreciates, the Lebaudy military airship which we are now about to describe owes its existence—or at least its British proprietorship —to the extremely laudable enterprise of one of London's most justly respected leading morning newspapers—to wit, the Morning Post. That journal it was which, at a time when the science of aeronautics was being most sadly neglected by those in high authority in this country, as compared with the activity of foreign contemporaries, aroused the British public to the risks that were being incurred, and organised in its columns the National Fund with which this latest ship has been acquired. Now, therefore, the result of their action has materialised into a real war-type of dirigible, than which no more up-to-date model exists throughout the world. Built by MM. Paul and Pierre Lebaudy, at their works at La Villette and Moisson to the plans of their engineer, M. Julliot, this airship belongs to the type known as " semi-rigid"—that is to say, on the one hand, the rigidity of the exterior form of the gas-bag is obtained by the use of ballonets and ventilators ; on the other hand, the gas-bag carries immediately beneath it a combination of two kinds of planes, namely, horizontal and vertical planes, movable and fixed, which enable the balloon to be steered in any direction, and which ensure stability. The combination of fixed planes forms a rigid under-frame, which divides the suspension by which the car is hung from the gas-bag excessive. Further, they can be worked by hand. There is, in addition, a valve at the top of the gas-bag, which is usually closed by a diaphragm. This valve can only be worked by hand, and allows the balloon to be entirely emptied. The two lower valves are placed in the stern of the gas-bag to avoid all risk of ignition from the motors. In cases of emergency two long ripping panels, one fore, one aft, glued and only lightly sewn to the rest of the fabric, allow the balloon to be completely deflated in a few seconds. By means of four observation holes, each covered with glass and framed with aluminium, the condition of the interior of the balloon can be inspected visually when it is at rest in its shed. Water and metal manometers show the pressure of the gas in the envelope at any given moment. There are inside the gas-bag three ballonets that can be filled with air under pressure, so that when the gas contracts or is lost the pressure within the envelope, which preserves the shape and rigidity of the gas-bag, may be maintained. These ballonets have a capacity of over 2,500 cubic metres, or rather more than a quarter of the capacity of the balloon. Their size is an important factor in enabling the airship to travel at a height cf from 6,000 to 6,500 ft., an altitude far beyond the range of an enemy's fire. The ballonets fore and aft of the central one have an additional purpose. By forcing air into one or other of them the pilot can change or regulate the longitudinal equilibrium of the airship so as to make it fly point The " Morning Post" National Fund Airship. into two parts. The upper part between the under-frame and the gas-bag is short, and, if the gas-bag becomes limp and loses its shape, cannot break or tear the envelope through uneven and excessive tension; the lower part of the suspension between the under-frame and the car, that is to say, between two rigid bodies, can be of considerable length without risk of uneven and excessive strain, no matter what may be the variations in the pressure of the gas and in the shape of the gas-bag. The essential parts of the "dirigible" are:—(1) The gas-bag or envelope ; (2) the fixed and movable planes ; (3) the car ; (4) the suspension or hanging gear ; (5) the motors ; (6) the propellers ; (7) various accessories. The envelope is 103 metres (337 ft. 10ins.) in length, I2'02 metres (39 ft. 5\ ins.) in diameter, and has a cubic capacity of 10,000 metres (353,165-8 cubic feet). In the bows it tapers to a sharp point, and is egg-shaped at the stern. It is composed of panels of waterproof canvas, consisting of two tissues of cotton and two layers of vulcanised indiarubber, superposed alternately, these panels being glued and sewn together. The outer tissue is dyed an inactinic yellow to diminish the injurious effects of light on the rubber, while the interior layer of rubber makes the envelope more gas-proof, and preserves the cotton tissue from the injurious effects that might be caused by impurities in the gas. Thanks to the care with which It is constructed, it loses consider ably less than 1 per cent, of its volume in gas in every 24 hours. To be precise, the loss of hydrogen is only *6 per cent. The envelope is provided in its lower surface with two valves of large diameter, which allow for the escape of hydrogen, more particularly while the balloon is in flight. These valves are automatic ; that is to say, they open as soon as the pressure of the gas in the envelope becomes upwards or downwards at any angle he wishes. Each ballonet is provided with a safety-valve, which opens automatically and allows the air to escape at a pressure slightly inferior to that of the gas. When need arises these valves can be worked by hand. The air required for the ballonets is pumped into them by two powerful centrifugal fans which can work either separately or together, and are each of them driven by a separate motor, so that in case one engine breaks down it will still be possible to use the other fan. The air is forced into a collector, whence it is admitted into any of the three ballonets that the pilot desires. In the very exceptional case of all three ballonets being filled before the end of the flight—that is, if loss of gas and contraction should reduce the volume of the hydrogen in the gas-bag by more than a quarter—air can be pumped directly into the gas-bag, so that under no circumstances need it lose that rigidity which is indispensable to a dirigible balloon. The outside of the envelope is provided with flaps made of layers of canvas glued and sewn together. These flaps are known as "ralingues." In them are fitted short wooden pegs of the type used in spherical ballooning, set in a continuous and flexible line, and to them the extreme ends of the cordage for suspension are firmly attached. The movable planes, which are intended to steer the airship both horizontally and vertically, consist of— 1. A vertical plane articulated round an almost vertical axis. The word "almost" is used advisedly, since in case of accident the rudder falls into a neutral position in wholly automatic fashion. This is the rudder in the ordinary sense of the word. It is placed immediately below the gas-bag at the sterrr of the rigid under-frame, which transmits its action directly to the dirigible. 2. Two horizontal planes with rounded angles, articulated round 768
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