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Aviation History
1947
1947 - 0339.PDF
MARCH 13TH, 1947 FLIGHT 215 HUNTING AEROSURVEYS Multi-purpose Air Photography : World-wide Organization : Extreme Accuracy Achieved PHOTOGRAPHY from the air, which played such a bigpart in the defeat of our enemies, is now the acceptedform of mapping. Huge areas all over the world are being accurately charted in a fraction of the time taken by the older and much more tedious ground methods. With special equipment, such as has been installed by Hunting Aerosurveys, Ltd., it is possible to produce plans up to a ^ of 1/1,250 and show accurate 5ft contours on these. Revision of existing Ordnance Survey maps is one of the most important undertakings, but town planning, estate and factory layout, traffic control, car parking, engineers' maps, land utilization, geological survey and forestry all have their particular applications. A considerable amount of air photography is also done for catchment boards for river control, and even seaweed surveys are made so as to ensure economical gathering. Seaweed beds can be identified in air photographs to a depth of 30ft. Aircraft Employed At the moment three types of aircraft are being employed. For low oblique photography, that is to say, for factories, estates and suchlike targets, Austers are used. The excel- lent view and slow speed make this type eminently suitable for this work. The roominess of the cabin in such an economical aircraft is also an advantage. Survey contracts in the United Kingdom are flown by a Percival Proctor which has a Williamson Eagle IX Vertical camera fitted, and for surveys abroad there is a D.H. Rapide employing one of the new Williamson O.S.C.-i cameras. This aircraft at the moment is engaged on a contract in Arabia. The O.S.C.-i incorporates almost every modern feature. It is enclosed in a transparent dome, and heat is led into this dome and also through the body of the camera, in order that an even temperature can be main- tained at all heights. The magazine contains sufficient film for 500 exposures without changing. (The O.S.C.-i camera was fully described in Flight of July 26th, 1945.) For covering the huge areas which have to be mapped abroad a very stable aircraft of long endurance is necessary, and as soon as the Percival Merganser becomes available, it is the intention of Hunting Aerosurveys to have one or more specially equipped for aerial photography, A genoral- arrangement drawing of the layout which appears on this page shows the adequate space available for all the neces- sary gear and equipment. Air mapping is no longer a simple business of plotting details from air photographs on to existing maps requiring revision. A lot o>4his work is still done, of course, but PERSPEX NOSE ^COURSE & DRIFT SIGHT OBSERVERS PRONE POSITION CAMERA CONTROLS -PILOT- TRI-METROCON CAMERA PORTS PILLAR MOUNTINGS FOR OBLIQUE CAMERAS REMOVABLE WINDOWS LONC RANCE FUEL TANK Cabin layout of the Percival Merganser for employment as an-.'.-•• air survey aircraft. for accurately contoured plans of hitherto unmapped terri- tory, complicated stereoplotting machines are employed. Pairs of photographs, with 60 per cent overlap, are put into the Wild A.5 stereoplotter in the relative positions they were in when taken and, starting from ground control points checked by theodolite, it is possible to put in the contours over the whole area. The system employed is one of optical triangulation, the angles altering according to Below is a portion of the existing map of Seaham with a 1 /5,oooair photograph superimposed over the lower half. On the left is a model of the same area made from the new photographs.It is so accurate that even the fence heights are to exact scale.
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