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Aviation History
1938
1938 - 1592.PDF
552 FLIGHT. JUNE 2, 1938. AIRCRAFT MATERIALS Professor H. J. Gough, M.B.E., D.Sc, M.I.M.E., F.R.S., Reviews Present Position and Calls Attention to Useful Fields for Research THE lecture hall of the Institution of MechanicalEngineers was filled to capacity last Thursday whenProf. H. J. Gough, of the National Physical Labora- tory, read the twenty-sixth Wilbur Wright lecture before the Royal Aeronautical Society. Mr. Handley Page was in the chair, and apologised to the lecturer for having to embarrass him by giving an outline of his career. The achievements enumerated by Mr. Handley Page were in- deed such that they might well embarrass the lecturer, but they did give the audience an indication of the very remarkable qualifications of the man to whom they were going to listen. Prof. Gough pointed out that a relatively few years had seen the relinquishment of the position held by steel as a structural material. The use of light alloys had become very general, and an improved form of wood was definitely in the field, so it might be that the entire structure of moulded plastics would become a practical proposition in the fairly near future. Development by the engine builder was retarded to some extent by the fact that a number of materials appeared to have reached the visible peak of their development, and new materials were urgently required. It might be that the airscrew of the future 2,000 to 4,000 h.p. engine would be made of materials other than metal, although the present aluminium- alloy propellers had given such good performance. Historical Review Prof. Gough divided his paper into five parts, of which the first dealt with the developments which had taken place in the period 1903 to 1938, that is, from the first flight of the Wright Brothers in 1903 to the present time. In part two he discussed briefly some of the typical features of representa- tive British aircraft of 1938. Part three was a summarised technical survey of the principal aircraft materials available— steels, light alloys, special alloys, wood, plastics and rubber. Part four was a discussion of the materials in their relation to the purpose for which they were used in aircraft and engines, and part five dealt with some specially interesting characteristics of metals. The paper, with illustrations, occu- pied 114 pages of the size of the Royal Aeronautical Society's journal, so that obviously we shall have room for only the briefest outline of the main points raised. The lecturer gave the best estimate he could of the materials nsed by the Wright Brothers in the engine used in the machine which made the first flight on December 17, 1903. He had been helped to a certain extent by Mr. Orville Wright, but most of the information had been obtained by referring to contemporary technical publications and discovering from them which materials were in current use at that time. The lecturer then assumed that, as the Wright Brothers had no special materials ordered for their engines, they were using those available at the time. He suggested, however, that as a matter of historical interest the engine should be dissembled and an exact determination made of the materials used. Using micro-chemical methods, the damage caused would be negligible. ' Part two of the lecture dealt with some typical aircraft and engines of 1938. As, however, it is to be assumed that these will be familiar to readers of Flight, we shall not devote space to this section of the paper beyond giving, in table II, a general analysis of the materials used in regard to broad classi- fication and principal sub-divisions within each class of engines. The lecturer pointed out that an analysis of this type had not previously been published, so far as he knew, and, taken in conjunction with the table of data for the Wright engines, the table showed in vivid contrast the de- velopment that has taken place in the nature and number of engine materials used during the last thirty-five years. Re- duced to an even broader type of classification, the materials of these engines on a weight basis showed the following per- centages : — Ferrous Metals Non-Fercous Alloys, Light Non-Ferrous Alloys, Heavy Non-Metallic Materials ... :-•-*• " •- 42%53.5% 4% 0.5% • ••• •-" -B 48% 47% 4-7% 0.3°;. c 48.1% 48.3% 3:4% 0.2% Crankshaft, connecting rods, valves and gears might, the lecturer stated, be used as typical illustrations of the constant efforts made to devise improved materials to meet increasing severity conditions. Table III indicates the changes that have taken place during the last thirty years in the materials used for these components. Noteworthy Component The supercharger impeller was a noteworthy component, as it might have to revolve at 24,000 r.p.m. Sometimes it was made of 55-ton nickel-chromium steel, while in other cases successful use had been made of a 27-ton high-grade wrought aluminium alloy. Part three of Prof. Gough's paper, which related to a survey of materials used at the present time, is of extraordinary interest to engineers, but this section of the lecture cannot usefully be summarised, and we must refer readers who wish to study it in detail to obtain a copy of the paper from the Secretary of the Royal Aeronautical Society. TABLE II. A GENERAL ANALYSIS OF THE MATERIALS USED IN THREE MODERN AERO ENGINES. GeneralClassi- fication. JHClalS. Non- Ferrous Metals. Non- Metallic. T<gt Cast Iron Carbon Steels Low Allov Steels— (a) Nickel (b) Nickel-Chromium 1 (c) Chromium (d) Chrom.-Molybdenum.. (e) Chrom.-Vanadium High Alloy Steels- fa) Chromium (b) Nickel-Chromium 'Aluminium Alloys— (a) Castings (b) Forgings, etc. . Magnesium Alloys— \ (a) Castings (b) Forgings, etc. .. Copper Brass ... , Bronze Rubber, Bakelite, etc. Totals ... ENGINE A (Radial Air-Cooled). Number of Materials. 2 U 1 5 1 __ 3 1 3 6 3 1 1 4 4 — 44 Weight, tb. 5 30 60 180 50 _ B 90 200 303 31 1 3 7 30 5 1,000 % of Total Weight of Engine. 0.5 8.0 I\ 29.0 1J 9.5 > »0,3 \ 3.2 0.3 0.7 3.0 0.5 100 ENGINE B (In-line, LK|uid-Cooled). Number of Materials. 3 3 2 \ 1 1 2 2 1 5 1 1 3 — 27 Weight, Hi. 114.5 185 123.5 9 02.5 13 24.5 440 114.5 — 9 4.r> 44 3 1,186 % of Total Weight of Engine. _ 9.6 1V 35.6 11 | 2.8 — 0.7 0.3 3.7. 0.3 100 ENGINE C (In-line, Air-Cooled). Number of Materials. 2 20 2 10 2 4 16 1 1 2 10 12 R Weight, Ib. 2 212 14 308 10 15 221 172 168 1 7 s 1,167 % of Total Weight of Engine. 0.1 18.2 27.6 2-2 ] 33.7 I 3.4 J 0.2 100
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