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Aviation History
1946
1946 - 1503.PDF
AUGUST 1ST, T946 FLIGHT WILLIAMSON O.S.C-1 AIR CAMERA Heated "Bubble" Installation : Remote Control of Shutter Speeds IncorporatedT HE science of photogrammetry should receive muchstimulation following the announcement made at the annual general meeting of the Williamson Manufac-: Co., Ltd., by Mr. Colin Williamson, chairman of the j, that £5,000 had been voted to endow a Chair ofPhotogrammetry at the London University. Air survey, in consequence, receives a dignity of whichit is worthy, and a new field of scope and opportunity is open to our young technicians and scientists. The result of much scientific research and mechanicalengineering is exemplified in the Williamson O.S.C. Mk.l Photogrammetric Air Camera, which has been producedto meet the exacting demands of modern air survey. In light of the long experience which the WilliamsonCompany are in a position to apply to the problems con cerned with air photography, developments can be seenin the design of the new camera. For instance, advantage has been taken of the high degree of reliability which hasnow been attained in electrical services. This has re- sulted in an all-electric operation of the camera which isarranged in such a manner that the independent function- ing of each unit is provided. The shutter, film wind, pres-sure plate, and instrument exposing switch are each separately powered units, electrically interlocked to ensurea correct functioning sequence. The camera body itself is of solid aluminium, providingthe required degree of rigidity between the register glass and the lens, which in turn are seated on parallel machinedfaces accurately spaced and tested for flatness and parallelism Each camera unit is integral to its appropriate lens andcone, and in addition to containing the usual lens, shutter and shutter driving mechanism, it also contains the instrument recording equipment and electrical connections. Operated by a remote control giving accurate exposureintervals over a range of from 2 to 60 seconds. Remote control of the shutter speeds is also provided. The efficient < peration of the camera in view of theextremes in climatic conditions to which it may be subject in the course of normal routine is ensured by the installa-tion of a hot air system which takes the form of an air- heated enclosure within which the camera operates. Thisinnovation forms the subject of a patent taken out by Williamsons in 1937. Heat is obtained from the normalcabin heating supply. It ensures not only satisfactory pro- tection in the interests of the camera's mechanical effi-ciency, but it also plays an important part in maintaining constancy on all optically calibrated points and serves toregulate trie temperature variations which might otherwise create distortion effects. In effect, the camera operateswithin a bubble of warm air Heat Circulation The hot aii supply is not fed directly into the enclosure,but is led by a pipe into the camera body and thence to a no^6"<^hich projects the heated air over the back of thelens filter glass* to avoid any possibility of condensation. The air then freely circulates within the camera body, andfinally passes out to the enclosure through holes on the opposite side. A thermometer is fitted under the transparent cover adjacent to the spirit level and the supply of hot air may be suitably regulated to maintain stableconditions within the enclosure. When adequate exhai t heat is available this is the most convenient and efficientmethod of heating the enclosure, but an electrical blower and heater unit has been designed for use with the O.S.C.Mk.l. A consumption of 800 watts for blower and heater will cover a temperature rise of 30 degrees, and 1,000 wattsis required for 50 degrees. Petrol air heaters, now being STABILISING CONTROL HANDLE THERMOMETER LOCKINGLEVERS DRIFT ADJUSTMENT DRIFT SCALE The O.S.C. Mk. I camera shown in its completely enclosedmounting, which provides a balanced temperature both inside and outside the camera. The tilt and drift adjustment andthe control column used to enable the camera to be stabilised in verticality in conjunction with the spirit level is also s(hown ¥~4\C * t<~£-Wv*^-v\, p. b H"Hr t L employed tor aircraft heating can also be used for thatcamera heating system. An innovation in camera instru- ment installation is the provision of a Kollsman self- correcting altimeter, and this introduces for the first time a means of recording accurately indications of relative altitude. The complete camera enclosure is supported on twohorizontal tilting axes disposed at right angles. Each of these tilt axes can be separately locked by convenientlyarranged handles Apart from functioning as locks, the requisite amount of. friction may be applied by thesehandles to make operations by the stabilising control handle possible without excessive effort while ensuring atthe same time the camera will not shift. Messrs Williamsons have established an organization inCanada to deal with service and maintenance problems appertaining to their air survey equipment. This is a logicalstep in view of Canada's vast national development pro- gramme entailing the extensive application of photogrammetry, FORTHCOMING EVENTS Aug. 14th (provisional date).—Attempt on World's Air Speed Record by R.A.F. High Speed Flight. Aug. 22nd.—Model Engineer Exhibition opens at the New Horticultural Hall, Vincent Sq., Westminster, London. Sept. 9th.—Ministry of Civil Aviation demonstrations of technical radio equipment. More details pending.
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