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Aviation History
1933
1933 - 0467.PDF
FLIGHT, AUGUST 31, 1933 mixtures of petrol and air, the effect of supercharging is to narrow the practical range of mixture strength. Apart from the loss of economy to be expected in a supercharged engine by reason of the necessary lowering of compres sion ratio, and from having to drive its own supercharger, it appears that definite limitations to the degree of super charging in practice may be imposed by difficulties of combustion rather than by mechanical considerations. When compression-ignition engines are supercharged, the indicated power does not increase in proportion with the initial pressure. This difficulty is not likely to be over come by improvements in design, and it is not, therefore, considered that the production of light compression- ignition engines will be facilitated by heavy supercharg ing. A moderate degree of supercharge has, however, many advantages. The Committee holds the view that the development of the two-stroke compression-ignition engine holds out the greatest promise of success in the production of a satisfactory power unit sufficiently light to compete with the petrol engine. During recent years a satisfactory form of flame trap has been developed at the R.A.E. to prevent back-fires from the engine sending flames down the induction pipes. These flame traps are made of thin sheet metal which divides the pipe into a large number of passages suffi ciently small to cool and damp out any flame travelling along the pipe. In view of successful tests over many hours on the test bench and in the air, the Accidents Sub- Committee has amended its recommendation, made some years ago, that air intakes should preferably be placed outside the fuselage of an aeroplane. It is now suggested that with a satisfactory flame trap the air intakes may safely be placed inside the fuselage. Noise The Keport is not very encouraging on the subject of aircraft noise. Reference is made to a paper by Dr. A. H. Davis in which figures of noise levels are given for exhaust, engine clatter, and airscrews. It is also men tioned that Rolls-Royce, Ltd., have made experiments on exhaust silencers, but the general conclusion is reached that unless airscrew noise can be substantially reduced, it is not of importance to proceed to extremes in silencing the engine exhaust. S3 S 3 §5 33 S3 LARGE AUSTRALIAN AIR SURVEY CONTRACT T HE name of Maj. H. Hemming is well known to our readers in connection with air-survey enter prise's in many parts of the world. He is defi nitely one of the pioneers of air-survey work. Together with Maj. Cochran-Patrick he was responsible, many years ago, for surveying the Orinoco Delta. Later on, with the Air Operating Co., of which Mr. Alan Butler is the Chairman, he carried through large survey contracts in Brazil, Rhodesia and other parts Of the world, but so far he has not had the opportunity of working on Australian development. A large contract which he recently secured will, how ever, remedy that defect, as Austral Development, Ltd., acting on behalf of the Western Mining Corporation, Ltd.. have appointed H. Hemming and Partners as Managing Contractors for the survey of a very large area in the gold- mining districts of Western Australia. This application of aerial photography to geological pro specting will enable the work to be carried out at far greater speed than could be done with ground survey only. A further point which will help the work to be done quickly and accurately is the method by which the survey aircraft will be controlled from ground wireless stations. The area under survey extends over 1,200 miles of country, and the total area to be photographed may well be in the «gion of 88.000 sq. miles. The contract, relating to the rights for this survey obtained from the Government of Western Australia, calls for the use of the most modern methods, and in this con nection it is interesting to find that the aeroplanes will D.H. " Dragons " (two " Gipsy Majors "), and the cameras will be those well-known " Eagle " type, made by the Williamson Manufacturing Co. For a geological survey to use aerial methods satisfac torily, it must be carried out with the co-operation of a ground staff, and can only be the basis upon which the geologists on the ground can work. It does, however, save them an enormous amount of time, and shows up faults, outcrops, and other features upon which they can base their ground operations. The ground work will be done by the geologists and surveyors of the Western Mining Corporation, who will also provide the wireless operators and crews of the ground stations which will work with the aeroplanes during survey flights. Wing Com. F. V. Laws, at present Commandant of the School of Photography, who is retiring from the R.A.F., will be manager of the expedition; and Admiral Sir Percy Douglas, who has until recently been hydrographer of the Navy, will advise on the ground survey part of the opera tions. H. Hemming and Partners will also train local staff in air-survey methods, as it is the Mining Corpora tion's wish that, eventually, the entire staff should be Australian. Capt. C. W. Snook, whom, as we were able to announce not long ago, has been on a visit to this country in con nection with the flying equipment of the company, will be chief pilot, and he will have as one of his assistants Fit. Lt. S. C. Campbell, who piloted the seaplane used on the Sir Douglas Mawson expedition to the Antarctic. Flying operations are expected to start early next year. The Directors of the Western Mining Corporation, Ltd., are Messrs. Colin Fraser, W. S. Robinson, M. L. Baillieu, and Lindesav Clark, and its Share Capital is owned largely by North Broken Hill, Ltd., South Broken Hill, Ltd.. Zinc Corporation, Ltd., Electrolytic Zinc Co. of Austra lasia, Imperial Smelting Corporation, Central Mining & Investment Corporation, Case, Pomeroy & Co.. Union Corporation, and New Consolidated Goldfields. Chosen as the most suitable machine, a D.H. " Dragon " of the type to be used on air survey in Australia. Its clear outlook forward makes it ideal for the purpose. This particular machine is run on private charter work by Wrighton 8c Pearse at Heston, and was recently hired by the Prince of Wales. (FLIGHT Photo.) 877
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