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Aviation History
1921
1921 - 0084.PDF
FEBRUARY 3, 1921 Some examples of the various forms of girder construction employed throughout " L. 64 "and"L.71On the extreme right is shown that mainly employed in the rear and side cars of " L.71." from that of " L.64," shown in one of the accompanying illustrations. The petrol tanks, in the catwalk, are arranged in groups of four or six in the locality of their respective engine cars, and some of each group are provided with a slip-gear by means of which a portion of the total petrol carried may be dropped overboard in case of emergency. The forward car is practically the same as that—which is located below the second and third gas compartments— on "L.64," and differs only in minor details. There is, for instance, a small gangway communicating with the engine compartment, whilst a neat and, we should think, very efficient arrangement of mounting the radiator is em- ployed. The radiator is supported on two lattice girders inside and at the forward end of the engine compartment. The forward face of the radiator is enclosed by a " bag " leading to a hinged scoop or hood mounted in the roof of the car. The mouth of this scoop, which faces forward, may be raised or lowered, thus allowing more or less air to pass in, and thence through the radiator. The engine in this car is a 260 h.p. 6-cyIindered Maybach (the same make and power is employed in the other five cars), and it is fitted with a reverse as well as a clutch. The overall length of the front car is about 40 ft. The wing or side cars are very much smaller than those on the "L.64," and are well streamlined. The first two are located below the sixth and seventh gas compartments from the nose, and are mounted fairly high up and far out. The main framework, mostly of channel-section members, is in the lower half, the upper half consisting of a pair of inverted V struts, to which the suspension cables are attached, and a light fabric-covered framework with side windows. The petrol pipes from the tanks and the engine telegraph cables are led through the streamline struts. The second pair of cars are very similar to the first, but these are located— below the ninth and tenth gas compartments—a little lower down and closer together. In all four side cars, as well as the rear car, the radiator is mounted within the car in the nose. Two sliding shutters in the latter, and operated from within, regulate the volume of air passing through the radiator. • The rear car is comparatively small, though larger than the side cars, and is provided with a second set of controls, the second-in-command being located in this car. It is located below the eleventh and twelfth gas compartments, and is built up mainly of T-section—or strictly speaking two L's placed back to back—transverse hoops with channel-section longitudinals, the whole framework being covered with fabric and sheet aluminium. The engine is fitted with a clutch only, and no reverse. Both front and rear cars are "fitted with bumping and floatation bags. All six cars have the folding ladder arrangement previously described. HOWARD LECTURES—ROYAL SOCIETY OF ARTS THE Howard Lectures, 167th Session, 1920-21, were given by Mr. Alan E. L. Chorlton, C.B.E., of Messrs. Beardmore and Co., Ltd. The subject chosen by Mr. Chorlton was " Aero Engines," and the first paper was read on January 17. Mr. Chorlton then dealt with the early attempts to produce motive power for flight, and mentioned the' external and internal combustion methods. Hje also dealt with possible fuels, materials of construction, steam reciprocating and turbine engines, and internal-combustion engines and the development of the latter as regards thermal efficiency, power and weight. Reference was m ade to the first successful engines in flight, and an outline was given of aero engines existing in 1910 and the developments which took place before 1914. The lecturer also pointed out the relative importance of weight and fuel economy. The second lecture took place on January 24, when the subjects treated by Mr. Chorlton may be summarised as follows -.—British and German aero engines at the beginning of the War—development of the six main types during the War—comparison of British and German practice—special ^experimental types—limiting conditions in different types— supercharging—and examples of different types. The third lecture was given on Monday last, January 31, when Mr. Chorlton dealt with engines in use after the War and with future possibilities of development. With the object of presenting the possibilities of development of the engine in a ready manner, a comparative table of all types was shown and each type analysed separately and compared, in its fundamental details, with the others. The radial type as one coming into favour was shown to have a limitation in increase of speed due to the crank-pin load, and the possibility of the increase of speed, and therefore reduction in weight, in the simple vertical type appeared to be much greater than had been supposed. The general difference in weight between types does not come out to as much as had been thought, and therefore the considerations of simplicity and ease of examination as being of first-class importance can be more readily attained, as the restriction to type on account of weight is not so essential for the foregoing reasons. The engine was examined thermo- dynatnically, mechanically and metallurgically. As a final result of the examination it seems possible to look forward in the future to engines of even less than 1 lb. weight per b.h.p. Special engines with the exceptionally high economy in airship work were also dealt with. On the practical side, tables of alternative engines for a standard service, like the Paris service, were given. Figures were also given of upkeep and overhauling for both military and commercial service. The supreme importance at a period like this, when economy is in every mouth, of not cutting down experi- mental work on the aero engine as the absolute heart of all mechanical flight, was emphasised, and it was suggested that what has already been done can, with advantage, be increased. 84
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