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Aviation History
1928
1928 - 0345.PDF
MAY 3| 1928 FLYING-BOATS Famous German Designer's Lecture to R.Ae.S. & I.Ae.E. THE theatre of the Royal Society of Arts was packed on Thursday of last week, April 26, when the paper on " Flying- Boats " (the original German title was " Mitteilungen "iiber cine Familie ahnlicher Flugboote "—Ed.) by Herr C Dormer was read before the R.Ae.E. and I.Ae.E. Col. the Master of Sempill was in the chair, and explained that they were indebted to Major Low for the English translation'of the paper. The lecturer spoke English very well, but was rather modest about it, and they had persuaded Mr. Bramson to read the paper for Herr Dornier, who, however, read the introduction himself. Mr. Bramson then read the paper and explained the lantern slides thrown on.the screen. It is quite impossible for us to give Herr Dornier's paper in full, and in particular because of the numerous diagrams and tables which accompanied it. These will be published in due course in the Society's Journal, and we must refer those of our readers who wish to study the paper in detail to that publication. In the meantime, by the courtesy of Mr. Pritchard, we have been permitted to" examine the" original tables, and wre have extracted from these a certain amount of data, which we give in the tables published below. These tables, it should be pointed out, have been somewhat changed from the original ones. For instance, we have converted the metric units used in the original into the more familiar ft.,lb. and miles units, hoping that therebv it would be simpler for our readers to see at a. glance the main features of the family of flying-boats to which Herr Dornier's paper referred. Moreover, in our converted Table I we have taken the liberty of adding four columns, of which three were taken from Table VIII, while the fourth, that giving the power loading, was compiled by us in order to be able to compare the five machines on a basis of power loading also. The first part of Heir Dornier's paper deals with the flight for comparison. In Table VI the basis taken is 1 -8 litres per h.p. installed (i.e., 3-17 pint). The manner of carrying out this reduction is shown in Tables V and VI. The tank weight falls off with size, from 0-07 kg./litre (0-7 lb./gallon) for type A, to 0-036 kg. litre (0-36 1b.'gallon) for type E, as the tank capacity increases from 50 litres to 16,000 litres. A similar drop is found in the case of the oil tanks. The last part of the paper deals with performance, i.e., with : 1, the variation of the ratio a -•• load/tare weight, that is, the disposable load per kg. of tare weight, or the reciprocal 1/af , that is the tare weight per kg. ofdisposable load. 2, the variation of the radius of action, or range, with size ; and 3, the variation of the paying load with the range. The dis- posable load is defined as : total permissible gross weight — (tare weight -f crew), and figures will be found in Table VIII. A few figures relating to speed, range and fuel consumption are given in Table IX, but this side of the problem was illustrated chiefly by graphs, which unfortunately are not available. For a range of 1,000 km. (erroneously given in the printed copy as 10,000 km.), type B has a disposable load of 332 kg., type C 1,351 kg., type D 2,411 kg., and type E 19,738 kg. In passing from type B to type E, the area is increased nine times, and the disposable load sixty times. With a range of 2,000 km. type C has a disposable load of 218 kg,, type D 1,881 kg., and type E 13,378 kg. With an increase in area of 4 -8 times, there is an increase in disposable load of 61 times. (Another and. perhaps, more illuminating, way of looking at this is to take the disposable load per h.p. of the engines. If that is done for a range of 1,000 km., it is found that the disposable load per h.p. is, for type B, 0 • 75 kg. ; for type C 1-5 kg. ; for type D 1-2 kg., and for type E 3-3 kg.—Ed.). The remaining portion of the paper requires the use of the ype. A Bc D E No. of Engines. 1 1 2 4 12 Total power b.h.p. 80 450 900 2,000 6,000 Total Wing Area Sq. ft. 166-8 570-0 1,024 1,547 5,032 Wing Span Ft. 32-1 57-5 73-8 94-0 — Length O.A. Ft. 24-5 42-2 57 • 5 80 • 8 131 0 TABLE I. Height of Propeller above W.L.Ft. 2-36 4 • 58 5-93 7-35 21 -2 Tare Wt. Lb. 1,122 3,823 7,460 16,200 54,900 Loaded Wt. Lb. 1,473 6,280 13,270 31,000 113,300 Wing Loading. Lb./sq.ft 8-78 11 -0 12-95 20-0 22 • 5 Power Loading. Lb./h.p. 18-4 13-95 14-75 15-5 18-8 Type Name. Li belle Do.E. Wai. Superwal. Do. X. Type A has Siemens engine ; the other types have Gnome-Rhone " Jupiters." The columns giving tare weight, loaded weight, wing loading, and power loading, have been added by us.—ED. general design and construction of the five Dornier flying- boats which form the basis of the paper. Most of the essential •data are contained in our Table I, but it might be pointed out that type A had folding wings, a feature not possessed by any of the other four boats. Table II contains a detailed statement of item weights of the five boats, the items being divided into three groups : aircraft, power plant, and instruments and equipment, which three together give the tare weights of the five boats. In each group details are given of the various items composing the group, and the item weights are given, as well as the per- centage weight which each item forms of the total group weight. This table is most informative, and we regret that we are not able to reproduce it. Tables III, IV, V, VI and VII give data for the five machines of the boat structure weights, wing item weights, petrol and oil installation weights, and tail surface weights, etc. 1-rom Table III it is seen that with increase in size the percentage weight of frames and longitudinals increases, while the percentage weight of the skin decreases. The weight per cubic metre of the hulls drops from 29-85 kg./cub.m. (1-83 lb./ cub. ft ) for the small boat, type A, to 18-83 kg./CUD. m. (1 • 168 lb./cub. ft.) for the very large machine, type E, now under •construction. . TV ,, For the wings similar figures are given m Table IV, tne specific weight rising from 6-97 kg./sq. m. (1-43 lb./sq.lt.) for type A to 15-97 kg./sq. m. (3-27 lb. /sq. ft.) for type E. Tables V and VI contain detailed data about fue and o installation weights. It is pointed out that the fuel and oil tanks actually installed in the different boats were not en a common basis, and had to be reduced to a standard time of 309 graphs thrown on the screen, and without them cannot use- fully be summarised. At the end of the lecture a series of lantern slides and cine- matograph films were shown, illustrating the various types of Dornier flying-boats. The little " Libelle " caused much amusement by coming out of a harbour with its wings folded, the pilot then spreading the wings, opening up his engine and flying off.. Some slow-motion films were most instruc- tive, and certainly appeared to indicate that the Dornier boats are comparatively " clean " on the water. A tilt of the cine-camera caused the horizon to be tilted, and the sight of a large flying-boat slowly crawling up a hill of water caused a good deal of merriment. The manner of hoisting these big boats into their sheds by a simple tackle was impressive and very different from the usual business with slipways, beaching trolleys, and what not. The Discussion Col. the Master of Sempill, in opening the discussion, saidit was a very great tribute to the Royal Aeronautical Society, and one not shared, as far as he knew, by any other in theworld, that a designer of such importance as Herr Dornier should have agreed to come over here personally to givethis very important paper. He reflected on the fact th at the British Empire, much more than Germany, was in need ofdeveloping the flying-boat, and yet Germany, and in par- ticular Herr Dornier, had shown them what very greatdevelopments had been made there, a fact which gave one much to think about. He would call on Lieut.-Col. O'Gorm anto open the discussion. Col. O'Gorman recalled the enthusiasm with which, in
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