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Aviation History
1944
1944 - 1864.PDF
268 FLIGHT SEPTEMBER 7TH, 1944 Like the L type, the G type is speed about 63 m.p.h. All U.S. NAVAL AIRSHIPS remembered that an airship's crew work under more com fortable conditions, and can therefore keep a better look out. Also, it is easier to pick out small objects from the slow-moving airship, which has no wing to spoil the vision of the crew, than from a fast-moving heavier-than- air craft. When the present war broke out, Lakehurst, com manded for a long period by Captain Mills, got busy, and the airships mentioned at the 1 icginning of this article, to which should be added the Ki, of 320,000 cu. ft., imme diately began carrying out experimental patrols off the western seaboard. By this means, a large amount of data were accumulated, and-. valuable experiments were carried out with U.S. sub marines. Month after month, this work went on, and the airships proved themselves to be very nearly all-weather flying craft. Facts began to speak for themselves, and by 1 '941 it was decreed that 200 airships should be put in com mission and stations built on both seaboards. Thus was the efficiency and enthusiasm of the naval airship officers at last rewarded, and it was -decided to concentrate on a slightly enlarged K-class for operation purposes, with the L and G class airships mainly for use as school ships. The '.' K " ships, successlul as they have been, however, have re-emphasised one important fact. That is, that with a medium-sized airship it is not possible to make full use of its powers of endurance, as the smallish crew of ten cannot keep an efficient look-out foi more than a certain number of hours. Also, of course, there is the fact that when employed in hot climates, the lift falls, Thus a larger type was called for, and so the "M" class was born. As can be seen from the photographs, all the previous ships had short cars slung right under the envelope, the ideal position, in fact, for head resistance is reduced to a minimum. This arrangement, by keeping the ship low, makes very high sheds unnecessary, ground handling easier, and raises the centre of thrust. Thus high speeds and excel lent handling qualities have been gained, without a great increase of engine power, which, of course, means increased endurance. Need for a Longer Car When, however, the time came to produce the "M" type, it was not possible to perpetuate this design, for with a longer ship a short car would have put a big com pression load on the envelope, unless such a car was slung at a very great distance below it, or an inordinately heavy envelope employed to allow a much higher internal pres sure with concurrent loss of lift. Provision also had to be made for a larger crew, to work in watches; and for increased crew space to provide greater all-round comfort, so allowing longer patrols to be carried out. The car itself is actually in three sections, joined together by flexible gangways. The M-i, which is of 625,000 cu. ft., with twin engines, went through her trials with flying colours, and now it can be taken that this class will be adopted and put into commission. It is, unfortunately, impossible to give any details of present-day American airships or of their work, but a few indications can be given as to how some of the technical problems are being tackled. Americans employ helium, which is very much more 4\i&S^ a training ship. The capacity is 178,000 cu. ft. and the maximum American airship stations are now equipped with transporter masts. expensive than hydrogen, and it is, therefore, important to avoid useless loss of gas. Every hour an airship flies, it burns up so many pounds of fuel. In fact, a large non- rigid, at full throttle, might burn anything up to 200-300 lb. of fuel per hour. This means, then, that the airship will be lighter by this amount for every hour flown, and so a requisite amount of gas has to be exhausted to atmosphere when ballasting before landing. Ballast from Water Recovery In the case of the large rigid airship, this difficulty would be overcome by the employment of water-recovery appara tus, by means of which water is manufactured from the engine exhaust gases, soiifat the ship makes ballast as she flies along. This appaj^tus, however, is too heavy for use on non-rigids, and indeed it is estimated that the old Macon could have extended her flying range by some 1,500 miles, had it not been necessary to carry the water recovery -gear; this would have given her a range of 11,000 miles at 50 m.p.h. carrying four aircraft and lull crew. A very useful asset for the war against Japan. For non-rigids, however, the problem has been largttfy solved when flying over the sea by lowering a hose fittec with an electric pump. By this method water is pumped up into the ship's ballast tanks while under way, and the loss of fuel compensated. In passing, it may be mentioned that -the same type of gear co'uld also be carried on rigid airships. Modern airships can, if need be, fly overloaded by taking qft like an air craft, and gas can be saved by starting and landing when the sun is down. It is also possible to change crews and refuel when flying. The other big problem was the old one of mooring and handling on the ground. In the past, due to narrow sheds, many an airship has been shed-bound when, if safely launched, she could nave flown perfectly well. It is pro bably forgotten by now that' thanks to our notorious weather the British Airship Service was the pioneer at this game, and the Americans began where we left off. Each American airship station is now equipped with transporter masts, to which the ship is moored after landing, and then taken into the shed, thus greatly reducing the size of the handling party and making it possible to take the airship in and out of its shed whilst on its mast, even in a con siderable cross wind. *: So successful have these masts been that the 420,000 cu. ft. "K" airships have, on occasions, been moored out i.ooo miles from a shed for weeks at a time. This is a big step forward, for in the past the largest ships to be so
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