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Aviation History
1918
1918 - 0029.PDF
Mm.0.794 1.5881.984 2.381 2.7783-175 3-5723-969 4-7635.556 6.35o 7.9388.731 9-535 Mm. 305 406 406 406 406 406 610 610 610 610 813 813 813 813 1.524 Mm. 102 102 178 178 254 254 254 254 254 254457 457 508 508 METIC UNITS. metres. Mm.203 254 305 305 203 203 =54 254=54 254 406 406 406 406 Mm.28.58 28.58 28.5828.58 28.5828.s8 38.5828. <8 53.9853-98 53.98 53-9879.38 79.38 Mm.40 £ 406 4O6 4O6 457 6io 610 610 610 813 9*4 9M1,2 70 1,270 3,048Mm. 102 178 254 254 254 254 40 f> 406 406 508 560 560 406 406 metres. Mm. 254 3O5 203 203 203 2 54 254 254 254 406 457 457 660 660 JANUARY 3, 191S. Mm.28.58 28.5828.58 28.5828.58 28.5853-98 53-9853.98 79-3879-38 79-3879-38 79.38 In making racks for the above reels allow a 4-in. or 102-mm., greater width than the traverse specified, below. 27^1.—Specifications for Ingot Aluminium. GENERAL.—The general specifications, 1G1, shall form, according to their applicability, a part of these specifications. MATERIAL.—2. (a) Three grades of ingot aluminum are recognized : Per cent.Standard No. i, aluminium . . . . . . .. not less than 99.0 Standard No. 2, aluminium . . .. . . . . ,, 98.0Special, aluminium .. .. .. .. .. ,, 99-5 Analysis.—(b) One sample ingot of each heat shall b? taken for analysis, and in any case not less than one sample ingot from each 500 lb. (226.8 kg.) of metal. (c) Samples shall be obtained by drilling completely through the ingot or half through from top to bottom. The weight of the samples obtained by drilling the ingot or ingots should not be less than 120 grams. MANUFACTURE.—3. No scrap shall be used except such as shall accumulate at the manufacturer's plant from material of the same composition and of their own make. 3S14.—Specification for 7 x 7 Flexible Steel-Wire Cable. GENERAL.—I. (a) This specification covers the finish, material, and construction of high-strength steel-wire cable composed of steel wires twisted concentrically around a steel- wire centre, thus forming a strand, and such strands twisted concentrically around a central strand of the same construction, forming a cable. (b) The general specifications, 1G1, shall form, according to their applicability, a part of these specifications. MATERIAL.—2. The wire shall be manufactured of either I.A.S.B. standard steel, No. 1065, No. 1070, or No. 1080, the compositions of which are listed below. MANUFACTURE.—3. (a) The steel wires composing the individual strands of the cable shall be laid concentrically around the centre wire in one layer of six wires with a left- hand (counter-clockwise) pitch or lay. The cable itself shall be constructed by twisting six of these strands composed of seven wires each around a seventh strand of the same con- struction and material with a right-hand (clockwise) pitch and with a length of lay of six to eight times the diameter of the whole. (b) The steel from which the wires composing the cable are drawn shall be manufactured by the acid open-hearth process. (c) Wires composing the cable shall be uniformly coated with pure tin to solder readily. (d) Joints in wires in cable having a diameter of 0.156 (&) inch (3.969 mm.) and larger shall be brazed in a gas fire. In cable having a diameter of 0.125 (J) inch (3.175 mm.) or less, wires may be joined either by brazing or twisting, at the manufacturer's convenience. Tucked-in or welded joints are not permitted. No two joints in individual wires shall be closer to one another in the completed cable than 3c) ft. (9.14 m.). All brazed joints shall be tinned. Exposed brass at joints shall not constitute cause for rejection. WORKMANSHIP AND FINISH.—4. Each length of cable is to be evenly laid, and free from kinks, loose wires, or other irregularities. The cable shall remain in this condition when unwound from the reel or bent around a standard thimble, proper precautions being taken to secure the ends. PHYSICAL PROPERTIES AND TESTS.—Tensile test.—5 (a) A tensile test shall be made upon each individual reel of cable purchased of a size. (b) Samples of cable for testing for tensile strength shall be no less than 24 ins. (610 mm.) in length. In making tests the distance between jaws of testing machine with sample in place and before test shall be not less than 10 ins. (254 mm.). (c) Samples for tensile test may be clamped in the jaws of the testing machine in the usual manner to facilitate testing ; but in case of failure or dispute on individual tests and at the request of the manufacturer check tests shall be made by socketing the samples with pure zinc. (d) Cable for use in the construction of aircraft shall meet the required breaking strength specified in the table. Bend Test.— (e) One bend test is to be made on a sample cut from each reel of cable of a given size. Each sample must be bent once around its own diameter and straightened again at least 20 times in succession in the same direction of bending without any of the wires breaking. Torsion Test.—(f) A torsion test is to be made on one wire from each sample of cable for tensile test. The wire is to be gripped by two vices 8 ins. (203 mm.) apart. One vice shall be turned uniformly at as high a rate of speed as possible without perceptibly heating the wire. One vice shall have- free axial movement in either direction. (g) The number of complete turns which the wire shall stand is determined by the formula : Number of turns ~ ^ei£rln~iHch£ = _55:9 diameter in millimetres. (h) Failure of one piece of wire to show full number of turns specified in the above torsion test shall not be considered cause for rejection, but in such case two additional tests shall be made on two more wires from the same sample of cable, and if both samples meet the requirements of the specifications the cable shall be accepted in this respect. DIMENSIONS AND TOLERANCES.-—6. There shall be no permissible variation in gauge below size. Cable having a diameter of TV to ^ ins. (1.59 to 2.38 mm.), inclusive, shall have a permissible variation of 12 per cent, above size ; cable having a diameter of J to •& in. (3.18 to 4.76 mm.), inclusive, shall have a permissible variation of 10 per cent, above size ; and cable having a diameter of /„- to -»- in. (5.56 to 9.53 mm.), inclusive, shall have a permissible variation of 7 per cent, above size. DELIVERY, PACKING, AND SHIPPING.—7. (a) All cable shall be shipped on reels in lengths as specified on orders. (fe) The dimensions of reels for different lengths and sizes of cable shall conform to the table attached to this specification. (c) A tinned or galvanised steel seal wire of approved design shall pass around no less than three convolutions of the cable on the reel and shall pass through a linen tag showing the name of the manufacturer, the size and length of cable on the reel, the order number or other distinguishing marks, and a record of the test for tensile strength. A lead seal impressed with the official stamp of the representative of the Government making the inspection shall secure the ends of this seal wire and furnish evidence of inspection and acceptance. d) The outer layer of cable on a reel ready for shipment shall be protected from mechanical injury in handling and transporting by an efficient covering of burlap. (To be continued.) Aircraft Precision Tools. L,ORD IENTERDEN drew attention in the House of Lords the other day to the matter of the supply of precision tools to firms engaged in the production of aircraft. Lord Elphinstone, replying for the Minister of Munitions, was officially vague, and practically contented himself with asserting that the posi- tion of the " small tool " trade was quite satisfactory and that the machine tool trade was in exactly the same condition. All we can say about it is that if these trades are, as the noble lord says, in a perfectly satisfactory state and able to supply existing demands, there must be something very wrong between the works in which tools of precision are made and the works in which they are designed to be used. If Lord Elphin- stone is right, then some enquiries ought to be set on foot with a view to t'he discovery of what becomes of the tools after they have been made and have left the makers' works. One thing is certain : that they do not appear with any marked celerity in the places in which they are designed to be used. On the contrary, we hear, from time to time, harrowing stories of work delayed in a heartbreaking manner by the failure of the Ministry of Munitions, or its nominees, to deliver the necessary tools. Moreover these cases are not isolated. They are quite usual—at any rate usual enough to give us to wonder who has been pulling Lord Elphinstone's leg !
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