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Aviation History
1952
1952 - 1911.PDF
FLIGHT, II July 1952 51 THE INDUSTRY O* Compact Tape-recorder kNE of the lightest self-contained tape-recording units is now ' marketed by Wirek Electronics Ltd., of Edgware, Middlesex. The complete equipment is supplied in a box 14m by 7m by 6£in and weighs but 11 lb. Although familiar refinements such as high-speed rewinding and automatic erasure of old recordings have been eliminated—largely to save weight and reduce battery drain—the performance is in no way inferior to that of much larger sets; for example, frequency response is ± 2db between 30 and 8,000 cyc/sec. The recorder—known as the "Reporter"—is operated by a single "off-playback-record" knob; drive is effected by a spring motor and electrical power is taken from dry batteries. With a tape speed of 7jin/sec the duration is 8 minutes per winding, or 16 minutes per spool. The apparatus is supplied complete with 600ft of plastic tape, take-up spool, H.T. and L.T. batteries, valves, motor, winding handle and hand microphone. New H.P. Pneumatic System BOTH in this country and in the U.S.A. high-pressure pneu matic systems are firmly established to meet the working demands of high-performance aircraft. A completely new high- capacity system has now been developed by the Aviation Division of the Dunlop Rubber Co., operating at a normal working pressure of 3,300 lb/sq in. Unusually, the system is designed for initial super charging from the main compressor of the aircraft's turbine power plant, the degree of such boost being variable up to 30 lb/sq in gauge pressure. From the gas turbine compressor the delivery passes through a filter with a glass-fabric element capable of operat ing at 250 deg C, before being pre-cooled in a light- alloy unit consisting of six gilled-tubes. The cooled air is then expanded through a pres sure-reducing valve so that delivery to the intake of the pneumatic compressor does not exceed atmospheric temperature and pressure by more than a few degrees centigrade and 30 lb/sq in. The compressor is shaft driven at 3,200 r.p.m. (overload limit 4,000 r.p.m. for 5 min) and consists of three reciprocating stages; at normal operating conditions the unit absorbs 2.5 h.p. and delivers 2.5 cu ft/min at 30 lb/sq in initial boost. The delivery temperature at 3,300 Ib/sq in is 150 deg C. The high-pressure delivery is led past a relief valve designed to operate if 3,750 lb/sq in—the delivery pressure at 4,000 r.p.m.— is exceeded; and from there passes through a pressure regulator which limits storage pressure to 3,000 lb/sq in and unloads the compressor when this value has been reached. The delivery is then led through an oil-water trap, non-return valve and de- hydrator and is thereafter stored in a spherical light-alloy bottle of a capacity suitable to the system. Delivery from the storage bottle is finally filtered before it is passed to the service system. For some applications, where a self-contained compressed-air generating plant is required, an electrically driven unit is available. A 3.5 h.p. motor, taking about 85 amp at 24 V, drives the compres sor through a 1.8 : 1 reduction gear box. This unit—which includes an oil pump and pre-cooler—is also designed for initial boosting at 30 lb/sq in, and delivery pressure is maintained between 3,000 and 3,300 lb/sq in by a pressure-operated switch. The electrically-driven unit weighs 49 lb, dry. Six-channel Recorder A PROFUSION of photographic recording units has appeared in recent years for facilitating the analysis of cathode ray tube readings. Without doubt one of the most useful of these is the_six- channel equipment developed by Boulton Paul Aircraft Ltd. Designated Type P.76, the unit contains six self-contained trays each accommodating reactive and resistive transducer balance con- ~^53^ The Dunlop Mk 1 3,000 Ib/sq in com pressor employs three air-cooled cylinder stages. Weighing 120 lb, and 15/n high, the type P.76 universal recorder has been designed by engineers familiar with the use of such equipment. trols, amplifier, C.R.T. display and camera lens. A standard film magazine attaches over the six lenses, film speed being variable up to 20in per second. Calibration and time-marking signals can be inserted auto matically, manually, or by external triggering. It is possible, for example, to integrate the continuous trace recorder with the opera tion of an auxiliary control or intermittent recorder, such as an automatic flight observer. Two commendable features of the photographed trace are the manner in which the shape of the modulated transducer carrier wave is faithfully reproduced and the use of brilliance modulation to determine the sign of the actuating force under examination. The recorder can be used for comparison and evaluation of almost all kinds of stresses, loads, pressures, flows, responses, relative movements and vibrations; additionally, these parameters can be measured and correlated with the readings of separate indicators, either by synchronizing with the automatic observer or by the use of special transducer elements. Full-scale deflection—equivalent to a trace width of 0.65m on the film—can be obtained for any input signal between 1 V and 1 mV; frequency response is very uniform over the range 50 to 20,000 cyc/sec, and the overall inaccuracy in the measurement of amplitude ordinates should not exceed z\ per cent. By adjustment of timing control and film speed, time intervals can be measured to almost any desired precision. The recorder is intended both for ground and airborne use and may be operated from any standard 50 cyc/sec mains supply or from 115 V, 400 cyc/sec 3-phase systems. The camera may be remotely controlled from a unit which is sufficiently small for it to be strapped to an observer's leg during flight trials. This remote- control unit contains camera controls, calibration and tuning con trols, note pad, indicator lights and main control switches. New Ekco Factory THE volume of electronic work undertaken by E. K. Cole, Ltd., of Southend-on-Sea, Essex, has steadily expanded to the point where a completely new factory has become necessary. A site in Kenway Road, Prittlewell—near the company's main plant—was selected and a new building with a total area of 17,000 sq ft has been erected here. The first Ekco engineers moved in while construction was still incomplete and production started at the new facility on July 1st. The site permits further building to double the capacity of the new factory, if this becomes necessary. Airliner Equipment ALTHOUGH Teddington Controls, Ltd., are renowned as - manufacturers of precision control equipment, the factory at Cefn Coed, near Merthyr Tydfil, S. Wales, is also producing— among other things—a servicing valve for airborne toilet systems and a new temperature controller for cabin atmosphere systems. The valve is designed for use in conjunction with the standard types of ground servicing truck and is stated to provide positive shut-off against loss from the aircraft toilet system and also against air-loss from the pressurized fuselage. A design requirement was that, when open, the valve should have an unrestricted bore. The valve—which is fitted to the B.O.A.C. Hermes, Comet and forth coming Bristol 175—has a diameter of 4m and is manually operated. The cabin-atmosphere temperature controller, known as the type FHR, is an electronic unit which takes alternating current at 115 V, and is stated to maintain cabin temperature to within ± 1J deg F. It is standard on the Ambassador and Comet, will be fitted to the Bristol 175, and, optionally, to the Viscount.
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