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Aviation History
1932
1932 - 0315.PDF
FLIGHT, APRIL 1, 1932 THE INDUSTRY AERIAL PHOTOGRAPHY s4: EKOFILMS, LTD., who have recently transferred their business to Bush House, Kingsway, London, W.C.2, have specialised in aerial photo graphy for many years, and during this time have accumulated a unique collection of some 50,000 views of all subjects taken all over the country. These are stored in new offices at Bush House in the form of a library where any particular plate can immediately be produced. The uses to which aerial photo graphs can be put are many and varied ; for example, there is a book produced by George Philip & Son, Ltd., which is a collection calculated to assist greatly in teaching children geography. It includes such varied features as town settlements, industrial areas, docks, and factories, thus show ing in a manner easily assimilated by the younger generation the chief topo graphical features of different parts of our country. For survey work, aerial photography makes its appeal to every conceivable kind of engineering and constructional contract. This will include road con struction, way-leads for power lines, drainage and sewerage schemes, town- planning schemes, railway construc tion, traffic congestion and control, dock and water port plans, estate de velopment, and, in fact, everything wherein maps are required. Thus Aerofilms undertake surveys for many people dealing in such undertakings, for whom they compile either mosaic maps built up from a series of vertical views, in which case these are pro duced in the usual standard scales, or as a series of oblique views which are an effective means of illustrating the existing conditions over a large area of ground. In this connection it is not too much to say that every town surveyor who w-ishes thoroughly to understand the problems raised by his work should undoubtedly make use of an aerial survey of his territory. Archaeological surveys are yet another application and an extremely interest ing one at that, of aerial photography. The ease with which the outlines of, for example, ancient Roman structures may be seen from the air cannot be realised until this method of investi gation has been tried. For purely industrial purposes Aero- films supply aerial photographs which may be used as pictorial envelopes, letter headings, posters and striking advertisements, as well as for every other purpose where distinctive effects are desired. It is not possible in the scope of a short article like this to enter into the methods whereby maps are made from such aerial photographs, but very roughly it may be said that the area to be mapped is covered by photo graphs taken from a pre-determined height and in such a manner that each photograph overlaps its neighbour by a considerable amount in order that the joining-up process may be done with great accuracy. This, when com plete, then produces the original mosaic map. A step further is to transfer all the details thus disclosed to a map drawn in the usual way. Yet another activity of this firm which is quite apart from aerial photo graphy, is the production of distinctive folders for new novels and covers for industrial publication. These are photographically produced in the Aero films' studio and many striking effects are obtained. THE MAKING OF PLYWOOD '"THE STANDARD of plywood *• manufactured in this country for aviation purposes is so much higher than the standard pertaining abroad that the foreign output of, for example, the Aeronautical & Panel Plywood Co., Ltd., is considerable. They supply plywood to Australia, South Africa, Canada, Italy, Greece, Belgium, the Argentine, Norway, Ger many and Turkey, while they have their own factory in Spain. Naturally, the demand is greatest from those countries which still manu facture their aircraft with wood. In our own country these manufacturers of plywood supply, we believe, about 80 per cent, or more of the plywood used in aircraft. The company's output is not, of course, confined to the aircraft world entirely. During a recent visit to their works in Kingsland Road, London, we were shown some very fine, solid panels with plywood veneers intended for the new Bank of England. For aircraft the plywood produced is " Mallite," which is waterproof and mostly of Canadian birch, so that the finished material is 100 per cent. British. The wood arrives from Canada in logs, is stripped and cut to size, and is supplied to the plywood manufacturers in this form. All the plies must have approxi mately the same moisture content be fore assembly, in order to prevent un equal shrinkage in drying. To ensure an even content of moisture, the sheets are first placed between the warm plates of a steam-heated machine, which is almost human in its selective power of drawing out excessive moisture in one sheet and placing it on an equal with the others. This machine also takes out any buckling, leaving the sheets flat. The process of then making up the plywood is as follows. Glueing, Pressing and Drying The plies are run through a glueing machine, which consists of two large rollers dripping with glue, and are then placed together and put into a cold hydraulic press. Next they are submitted to further compression in a massive hot hydraulic press, and the heat produces a certain chemical action on the glued plies, which contributes to the ultimate waterproofness of the plywood. From the polite but negative answer that we received to the re peated question as to the precise chemical effect of the heated pressure, we gathered that therein is contained a " secret of the trade," or perhaps a secret of this particular manufac turer. The pressure employed in the hydraulic presses, of which there are several, is from half-a-ton per sq. in. upwards. After this process comes drying in kilns. The best results by kiln drying are obtained with a temperature of 80 deg. F. (27 deg. C.) to 110 deg. F. (43 deg. C), and a relative humidity ranging from 40 to 60 per cent., de pending upon the thickness of the plywood and the number of plies. The moisture content of the condi tioned plywood must be not greater than 18 per cent, and not less than 8 per cent, when calculated on the oven dry weight. If the plywood has to have a polished finish, the veneers are placed in drum-sanding machines, which can treat them swiftly with the desired degree of light sanding. There is also a shaving • machine which will shave a surface to a very fine degree. An aerial view taken by Aerofilms, Ltd., of the Great West Road. It shows how industries congregate on our arterial roads. In the left foreground are the works of Telcalemit, Ltd., whose oil cleaner was described in " Flight," for January 15. 291
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