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Aviation History
1939
1939 - 1027.PDF
354 FLIGHT. APRIL 6, 1939 SAFEGUARDING A REPUTATION How Aero Engine Mate rials are Tested in the Recently Completed Rolls- Royce Research Labora tory By A. G. DOUGLAS CLEASE.B.Sc. Illustrated with " Flight " photographs. IN the attainment of the vital quality of reliability in aero engines there are many factors to be considered. In the first place, the design must be correct, and it must then be trans lated into concrete form with the utmost precision which modern manu facturing methods can give. Even so, granted that design and production are of the highest possible order, reliability cannot be achieved unless a con stant check is kept upon the specifications of the materials employed. It is not difficult, therefore, to understand why Rolls- Royce, Ltd., should maintain three laboratories at their Derby works. One is primarily concerned with the testing of materials as received from suppliers. Another watches over what may be described as ordinary production problems. The third is, perhaps, the most important of all, since it bears the title of research laboratory. In it is conducted development work on new alloys and materials, and solutions are also sought for the more complex problems which come to light during production. The research laboratory has only recently been com pleted, and it is a light, airy building of two storeys with each floor divided up into various departments, each deal ing with different sets of problems. The laboratory has been laid out and equipped with two ends in view: (1) To assist the foundry and to deal generally with light metal problems as they are encountered in the works ; and (2) to develop new, and improve existing, light alloys for future use as they are proved to be suitable for the purposes for which they are intended. On the ground floor there are a chemical laboratory, a furnace room, a mechanical test room, an X-ray room, a micro room and a macro room, as well as a very necessary machine room and a dark-room. Chemical analysis in such a laboratory is con cerned with a wide range of problems. In the first place, there is the routine checking of all materials employed, to ensure that they reach the high standard imposed. Indeed, the analytical chemist plays an important part in controlling the products of the foundry, alongside which the research laboratory stands. Another essential activity is the development of new methods of analysis to deal with the con stantly increasing diversity of the materials used. It is, for example, necessary to carry out chemical analysis on lubricating oils, corrosion products, inclusions in castines, refractory materials, sands, fluxes and gases. In view of the varied nature of the problems there are actually two chemical laboratories in the research building, the one on Determining damping capacity of a test-piece clamped in a machine designed for the purpose by the Cambridge Instrument Co. The imposing exterior of the new building. the ground floor dealing principally with the analysis of light alloys and sand, and the other on the upper floor being more intimately concerned with development and research work. Actually, the chemical and physical qualities of sand for casting are important. If, for example, when the sand is rammed into a moulding box, the particles are of a rounded nature, then obviously they could not be expected to adhere with such strength and tenacity as would be obtained if the particles were of an irregular shape. Accordingly, various sands are subjected to chemical analysis ; their water content is tested, the amount of clay they may contain is determined and the size and shape of the grains is examined. The hardness and strength of test- pieces moulded out of the sands are noted, these test-pieces being subjected to both compression and tensile tests. The permeability of the sand is also tested. In the furnace room there are provided gas, electric and high-frequency melting furnaces in order that the melting and casting of alloys may be studied under different con ditions. Investigations can also be carried out on heat
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