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Aviation History
1932
1932 - 0041.PDF
FLIGHT, JANUARY 8, 1932 and it should be noted that without screening, satisfactory results cannot be expected. Agents of this firm also exist at Brooklands, Stag Lane and Hatfield, where orders can be expe ditiously handled. Standard Tele phones are also catering for any work in connection with aviation radio, and are always ready to provide equipment outside the standard ones. The advice of their experts will gladly be given without any obligation. COMFORTABLE GOGGLES /"• OGGLES round which the wind *J can leak, thus causing draughts between the glass and the eye, are always extremely uncomfortable. A recent type of Meyrowitz goggle has been produced to obviate this trouble. These goggles were designed in colla boration with the late Sir Henry Segrave, and besides the flat sorbo cushions, which, as may be seen from the illustration, fit the face in an admirable manner, they also have the Meyrowitz adjustable bridge, triplex glass lenses, with controlled ventilation and fiat very wide angle lens. In the Meyrowitz Showroom at 1A, Old Bond Street, London, W.l, both this new pattern and many other patterns of goggles will be found. Goggles are one of the things over which no pilot should stint himself, for an uncomfortable pair, or the lack of them due to blowing off at a criti cal moment, has been known to be the cause of losing more than one impor tant race. KE 965 SPECIAL VALVE STEEL \/ALVE steel has necessarily de manded special attention with the high temperatures now obtained in internal-combustion engines, and that it has met the severe conditions im posed by high-performance aero en gines is apparent in the air records of recent years. Up to a certain temperature, say, 750 deg. C, many types of valve steel give satisfaction, but when that tem perature is exceeded the number becomes restricted. Physical proper ties, such as scaling and erosion, which are not particularly noticeable at low temperatures, become prominent when valves are required to work in high temperatures. At temperatures up to 600 deg. C, the resistance to oxida tion is not a cause of trouble in the usual steels, but when a temperature of 900 deg. C. is approached then scaling is pronounced in many in stances. With increasing temperature all steels exhibit a falling off in ten sile strength, and it is a question of which kind of steel will give the greatest strength at the higher tem peratures, and how long will the strength be maintained under those temperatures. When a steel is under load during the time of heating its strength will gradually decrease, and steels giving a good tensile figure when tested for a short period at a given temperature will often prove comparatively weak after a much longer test in the same temperature. A valve steel which has proved its efficiency when working in high temperatures for long periods, is the KE 965 special steel, developed by Kavser, Ellison & Co., Ltd., Carlisle Steel Works, Sheffield. KE 965 is an Austenitic nickel- chrome steel which does not air-harden under any conditions, and, therefore, does not become brittle. It retains a high-tensile figure at the highest temperatures found in practice. From the chart KE 965's maximum stress at 900 deg. C, is seen to be 17.2 tons per sq. in. tensile, the figure being obtained while the test-pieces were actually being pulled hot in the furnace. A five-hour heating test at 1,000 deg. C, showed the resistance of KE 965 to the erosive action of exhaust gases, as there was no apparent loss of weight. KE 965, assists in overcoming one of the root causes of engine trouble, by eliminating valve dis tortion, and, incidentally, distortion of the seating. Oxidation does not occur with this steel, and it forges and machines quite well. The heat- treatment is very simple, the valve forgings usually being supplied in the ready heat-treated conditions; the treatment consisting of normalising by heating to 900 deg. C. and cooling on the floor. K.E. SPECIAL STE ELS POM VALVES For ordinary purposes the valves require no further heat-treatment after 41 machining, but if they are for use in an engine which will be highly stressed, the manufacturers recommend a second normalising at the same tem perature and cooling on the floor after rough machining and before final grinding and polishing. Turning or milling is not a difficulty with this high alloy if the tool angle is kept acute, and a trifling difficulty with drilling has been surmounted by the use of a short stubby drill, with a good backing off or cutting clearance at the cutting edge. INDICATING CALIPERS P\IRECT reading calipers are of the •^ greatest value in any branch of engineering, and those such as shown above, which are marketed by James W. Carr & Co., of 35, Queen Victoria Street, London, E.C.4, should prove a great time-saver. They have an open ing capacity of 3 in., and the scale is marked either in £ mm. or 64ths. With ground gears, ball bearings, glass-hard ends, a spring to take up back-lash and stop for repetition work, these calipers are undoubtedly a first- class precision tool. They are of ex ceptional value when the thickness of the part which it is desired to measure lies inside another part where it is impossible to use an ordinary micro meter. A good example of this is the centre of a saucer, and the aircraft constructor will find that there are thousands of such places in an aircraft. THE MENASCO B-4 -'PIRATE" AN extremely well got-up handbook, ** compiled on the loose-leaf prin ciple, has recently come to hand from Menasco Motors Inc., 6, 7 and 8, McKinley Avenue, Los Angeles, Cali fornia. This is by way of being a service manual for the model B-4 95- h.p. four-cylinder inverted, in-line, air-cooled engine, and copies of this will be sent by the publishers on re ceipt of $2.50. There are at present, as far as we are aware, no engines of this make in actual service in England, but no one who wishes to be thoroughly conversant with the work ings and construction of this engine can afford to be without this book. A series of appendices describe the magneto, carburettors and starters in very great detail, while the profuse illustrative matter in the principal part should make it an easy matter to follow the text.
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