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Aviation History
1932
1932 - 0084.PDF
FLIGHT, JANUARY 22, 1932 A typical Hiduminium casting for the blower casing of the Rolls-Royce " R " engine. HIDUMINIUM R.R. ALLOYS |N THE ACHIEVEMENT of the * Rolls-Royce " R " engine at the Schneider Contest of last year, tech nical interest in the design did not pass over the fact that all the aluminium parts, including the supercharger casing, cylinder blocks and crankcase, were manufactured of " Hiduminium " R.R. 50 aluminium alloy. The perfect reliability of these parts under gruel ling stresses probably lies in the fact that detail design throughout is delibe rately and exactly adapted to the peculiar properties, and the limitations, of aluminium alloy in the cast state. The successful production of high- quality alloys depends entirely on ob taining a close-grained structure in the ingot form. R.R. alloys have a fine close-grained crystal structure which indicates an ideally homogeneous material ensuring consistently high- quality results. R.R. alloys have been developed by Rolls-Royce, Ltd., and are manufac tured by High Duty Alloys, Ltd., Buckingham Avenue, Trading Estate, Slough, who are meeting with a con siderable demand for their work from many foreign countries, including Poland, France, Czechoslovakia, Sweden and Italy. They are produced in the form of ingot, castings, forgings or stampings. R.R. 50 alloy has among its other constituents, copper, silicon, nickel and titanium, and in the cast form it has an ultimate strength of not less than 12 tons with an elongation of 3 to 8 per cent. When sand-cast with a low temperature heat treatment it has a strength of not less than 14 tons and elongation of 3 per cent. It retains its strength at high temperatures and is consistent as a production material. R.R. 50 has been divided into four categories, namely : — R.R. 50 ... Sand and chill castings for general purposes. R.R. 53 ... Die cast piston alloy. R.R. 56 ... Forging alloy for general purposes. R.R. 59 ... Forged piston alloy. For cylinder heads, pistons and con necting rods, which are subjected to excessive temperatures and where light ness is desirable, R.R. 59, 56 and "Y" alloys are the recommended materials, the former being particularly suitable for forged cylinder heads on account of their strength and high conduc tivity. For parts not possible for forg ing, R.R. 53 casting material is avail able. High Duty Alloys, Ltd., issue valuable data sheets to assist the de signer and constructor of engines. Data Sheet No. 13 gives the physical properties of R.R. alloys compared with other wrought alloys at high temperatures, and No. 16 shows the physical properties of the alloys after annealing or taking up to various tem peratures and allowing to cool down again to normal temperature before testing. The tests from which the data were obtained demonstrate the suit ability of the R.R. wrought alloys for uses at high temperatures and their property of retaining strength on cool ing again to normal temperature. A comparison of steel and aluminium alloy Hiduminium R.R. 56 beams is given on Sheet No. 12, and No. 13 dis courses on the alloys for elevated tem peratures and gives charts revealing a comparative effect of temperature on the hardness of R.R. 56 and 59 forged heat-treated bar, and also a compara tive effect of temperature on the tensile strength of the two. Load extension curves of the Hiduminium R.R. Alloys compared with Mild Steel 0.27% C, 0.6% Mn., Brinell 220 and other light Alloys. SAN0 CAST ALLCS '«u>iu. / /mi e« r* cm i <> I PO -ion 0 \toTM4. ") 5 10 15 2u 5 10 irJ 20 S 10 If. 20 5 (0 fi 30 * O ft 0 5 O 5 O 5 O 2 < PERCENTAGE EXTENSION. A MARCONI APPOINTMENT A IR COMMODORE L. F. BLANDY, C.B., D.S.O., formerly head of the Signals Branch of the Air Ministry, has been appointed Deputy General Manager of Marconi's Wireless Telegraph Co., Ltd. Air Comm. Blandy joined the Mar coni Company in 1928, and during the last three years has been engaged on important missions abroad on be half of the company, for which his previous experience particularly fitted him. He was responsible for building up the wireless organisation of the post-war Air Force, and also the ground wireless organisation for British Civil Aviation. JOHN HAMILTON'S ADDRESS JOHN HAMILTON, LTD., the pub- J lishers of so many flying books, have recently moved to more commo dious premises. Their new address is 32, Bloomsbury Street, W.C.I, and their telephone number remains as before, Museum 4537. SELF-TAPPING SCREWS DUCK & HICKMAN, LTD., of 2, " Whitechapel Road, E.l, are the distributors in England for Parker- Kalon hardened self-tapping screws. These are offered as a quick and cheap method of joining sheet metal and making fastenings on to it from any gauge between 28 and 6. They cut a thread in the metal as they are screwed in, thus eliminating the cost of tapping, and are also satisfactory when the metal is too light to tap in the normal way. Due to the fact that they cut their own thread, they are also said to be much securer under vibration than a normal screw. For assembling small aluminium castings or articles made of Bakelite, hard rubber, fibre, and similar materials, these screws are equally useful.
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