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Aviation History
1951
1951 - 0805.PDF
5oa V (Left) Drilling operations for stubbing attachment to the fuselage centre-section are here seen being performed with the special radial drills which can operate at compound angles. (Right) Protective clothing with fresh-air supply and intercom telephone is worn by operatives working in the integral fuel tanks as a protection against toxic fumes from the sealant. COMET CONSTRUCTION METHODS . . . static, but, when the components were withdrawn from them, subsequent operations were performed on the track, and all components were transported to the various stations on mobile jig trolleys. The stub-wing called for very special attention, in that, as this portion of the wing was an integral fuel tank, great accuracy was necessary in the manufacture of the mating components. The drilling operation of the stub- wing consisted in drilling and reaming 252 tight-limit holes for attachment of the wing to the centre-section. The method adopted involved the use of a large drilling jig controlling the drilling of the nests of holes in top and bottom boom attachments of the front and rear spars to the fuselage centre-section. These nests were also located in stria relation to each other about the centre-line of the fuselage longitudinally and laterally. Two special radial drilling machines were employed, the drill heads of which were arranged to revolve through 360 deg and to drill at any compound angle. With these machines, jig-drilling could be One of the main longitudinal portions of the cowling skin (20ft x 4ft) is here being pulled over a concrete tool by the Sheridan stretcher-p done vertically downwards through the top spar booms and centre-section fish-plates and, by dropping the drill-heads and rotating them through 180 deg, the operation could be repeated vertically upwards through the bottom spar booms. Before subsequent assembly the stub-wings were taken on the track to a position outside the shop where a fluid test was given. Each stub-wing was filled with 2,000 gall of paraffin, and any weeps which might occur were remedied. Although the actual sealing of the tank was made by an internal rubber seal, the tank interior was also given a thin coating of Bostik solution as an added protection. Because of the confined working space in the wing, and the fact that toxic fumes were given off by the Bostik solution, precautions had to be taken to safeguard operatives. Special clothing was provided which enabled the worker to be given a fresh-air supply during time inside the wing. The suit was provided with intercom telephone, and the operative was kept in constant touch with external personnel. After the fluid test, the wing was wheeled into several station positions on the track where the various elements were assembled. An interesting problem was the accurate and economic production of the large quantity of Hufford stretcher-press tools required for the manufacture of the cross-members in the engine cowling. It was decided to try, for the first time, the development of concrete tools for this job, and the experiment had proved most successful. The method was to cast direct on to the same master model which was used for making the longitudinal skin. All the cross-member tools were cast transversely on this model at whatever position they were located. This ensured accuracy of fit, and enabled 25 pairs of tools per week to be built by eight men. The total number of tools required for the top and bottom cowls, left- and right-hands, was 195. After all concrete stretcher-press and Hufford tools had been made from the master model, it was dismantled and the eight units were used for the manufacture of assembly jigs for the cowling doors. This was done simply by adding wooden facing strips to the Jin-thick metal loft-plates, and providing hinge locations and trim lines. The great advantage of this method was the accuracy provided by using the actual loft plates for the dual purposes of making the model from which all tools were cast, and afterwards transforming the matrix of the model into the assembly jig. The fact that the stretcher-press tools were all taken from the same mould formed by these plates meant that the skins and cross- members made by the tools all fitted accurately into the assembly jig without any adjustment whatsoever. The lecturer concluded by giving a brief account of the
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