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Aviation History
1936
1936 - 0026.PDF
*4 FLIGHT. JANUARY 2, 1936. THE L.Z.129's POWER UNITS Details of the New Mercedes-Benz Oil En gines : 750 h.p. at 1,750 r.p.m. : 3.8 lb. h.p. A S reported elsewhere in this issue, it is /\ now practically certain that the new J. V Zeppelin, L.Z.129 (which was de scribed in Flight of October 3), will be launched within the next three months. Thus there is particular interest in the details of a new Mercedes-Benz Diesel engine of the type which is presumably to be fitted to the airship. Known as the O.F.2, it is a water-cooled 60 deg. vee-twelve, in which, following the practice successfully applied in their heavy- oil commercial vehicle engines, the Daimler- Benz works have employed the four-stroke in conjunction with pre-combustion. The crank case, of three sections, is cast in Elektron, and single-row roller bearings carry the six-throw crankshaft, at the rear end of which is a vibration damper. The cylinders, which are cast separately and have non-detachable heads; each have two inlet and two exhaust valves. The pre- combustion chamber lies in the centre of the head, midway between the four valves, and the oil is injected into it by a Bosch nozzle. The water jackets are of sheet steel, welded to the cylinders. Each of the alloy pistons carries four rings and two scrapers. Of the floating type, the gudgeon pins are laterally located by pegs. The master connecting-rods are of I section and the auxiliary rods of circular section. The former have three- row roller big ends and the latter are attached to the main rods by the medium of needle roller bearings. Two overhead camshafts are employed, located in Elektron housings and driven by shafts and bevel gearing. To- facilitate starting, heater plugs are employed in the pre- combustion chamber. Starting is effected by means of com pressed air. Two centrifugal pumps, one foi each cylinder bank, attend to the cooling water circulation, and are accessibly arranged In these days of monobloc cylinder castings, the separate water-cooled cylinders of the new Mercedes-Benz engines strike an unfamiliar note. at the rear end of the crank case, while a gear-type oil pump is situated in the lower portion of the crank case. The reduc tion gear is of the spur wheel type, and has a ratio of 1.73 : 1. The principal data are as follows:— Bore, 165 mm', stroke, 210 mm; total cylinder capacitv, 53,88 Hires; cruising power, 720 h.p. at 1.720 r.p.m.; full- throttle power, 750 h.p. at 1,750 r.p.m., short-period output, 800 h.p. at 1,790 r.p.m.: weight dry, 935 kg (3,061 lb.); weight per h.p., 1.17 kg (3.8 lb.) (at 800 h.p.) ; compression pressure, 532-560 Ib./sq. in.; max. pressure, 840 lb./sq. in.; injection pressure, 1,330 lb./sq. in.; length overall (without airscrew hub), 1 S80 mm (74m.); width overall, 980 mm (38.2m.) ; height overall, 1080 mm (42.5m.). The Book of the Day THE welcome given by the public to Flight's book Squadrons of (he Royal Air Force has not in any way surprised us, but it has been most gratifying. The interest taken by every body in the Air Force, which is now being so vigorously expanded, is both wide and deep, and before this book was published there was no ready means, other than the pages of Flight, of learning about the organisation of that Force, the work of its various squadrons, and the elaborate training organisation. A member of the staff has seen a reader looking through the numerous illustrations and interspersing exclama tions of admiration with the repeated confession, ' How little we know about the R.A.F. ! " For the future there will be no excuse for any person to make that admission, and the process of filling up gaps in knowledge will, we feel sure, be made by this book not a drudgery but a pleasure. R.Ae.S. Southampton Branch IT has long been felt, that a branch of the Royal Aeronautical Society should be formed at Southampton in visw of the concentration of aeronautical activity in that neighbourhood. In the summer ol this year a ballot was taken by the Society to see what response would be forthcoming. The result was very encouraging, and in the autumn a committee was formed to , start the new oianch under the chairmanship of Wing Cdr. Cave-Browne-Cave, who is Professor of Engineering at Uni versity Ccllege, Southampton. The inaugural address was given at the end of October before some 250 people by the president of the society, Lt. Col. Moore-Brabazon, and since then several lectures have been given, while a programme for the future has been drawn up. The honorary secretary of the branch, which has now nearly 200 members, is Mr S. Scott-Hall, to whom enquiries may be addressed at the Supermarine Aviation Works (Vickersj, Ltd., Wcolsion, Southampton. Towards the Gliding Subsidy THE Federation of British Gliding Clubs has now prepared a scheme for the registration of gliding clubs as of limited liability for the modest fee of ^3. The scheme is available to all clubs joining the Federation. Incidentally, clubs with less than twenty-five members are eligible for enrolment. The address of the hon secretary is Lady Place, Sutton Courtenay, Berks. Aviation Paper Discontinued THE monthly publication, Aero and Airways, it is an nounced by Bernard Jones Publications, Ltd., is to be discontinued. The publishers state that " no paper can exist nowadays without a reasonable number of advertisements, and whilst we have had loyal support from our readers", we have not had the support we expected from aircraft manufacturers."
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