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Aviation History
1959
1959 - 2377.PDF
264 FLIGHT, 18 September 1959 Engine condition analysers for gas turbines. (Above) Ultra Electric's unit shows temperature indications in the upper cathode-ray tube and vibration in the lower. A separate unit, the scanner, which is fixed in the equipment bay, is not shown. (Right) The two units of the EHiott- Bendix monitor. Temperature and vibration safety limits are indicated by red and green points on the oscilloscopes Round the Stands . . . to the fact that it incorporates major portions of the earlier Juniors.Flight development of the 10R is to be conducted by units mounted in a Javelin, the conversion having been effected byNapier's Flight Development Establishment at Luton. But for certain mechanical snags, particularly in the cockpit/powerplantlinkage, this aircraft would already be in the air. (So great is the thrust of its new engines that full reheat will be permissible onlyduring a steep climb.) The 10R has been selected to power the Bristol T.188 research aircraft. This will be the fastest, andhighest-flying, British aeroplane, and D.H. Engines are having to clear this type of Junior over an extreme range of ambient con-ditions. The actual engine exhibited at Farnborough is about to undertake reheat running in a high-altitude tunnel of theN.G.T.E. at Pyestock. Powerplant Accessories This year, for the first time, anumber of gas turbine engine analysers were on show. These are the gas turbine counterpart of ignition (and hence performance)analysers with which many recent piston-engine powered aircraft have been equipped. Sperry showed a pair of vibration sensers—transducers for mounting at suitable locations on the engine—to measure vibration and pass information back to a cockpit re-corder. A Bendix-Scintilla Engine Monitor was shown by Elliott Brothers, whose Engine Accessory Division are constructing itunder licence, and a further unit was shown by Ultra. Both vibration and front and rear bearing temperature arerecorded by the Elliott Monitor and presentation of this informa- tion is on a pair of rectangular-faced cathode-ray oscilloscopes.A rotary switch constantly sweeps sensors on the engine, and information is passed to the scopes in the form of a trace.Temperature information is presented in a similar fashion and the actual temperatures in any particular engine can be deter-mined by setting the zero on a scale on the oscilloscope face over Illustrated diagrammatically is de Havilland Propeller's automatic synchrophasing system. It consists of three actuators connected to the slave propellers and the computer seen at the bottom of the picture the electronic trace. This is done by first selecting the enginewhich is to be examined and then turning the scale setting knob; this has a veeder counter immediately above it and the figureswhich appear give a direct reading of temperature. Broadly similar in principle is the Engine Condition Analysershown by Ultra. Temperature information is obtained from up to 40 thermocouples situated in the combustion system. These cangive warning of hot or cold spots due to faulty burners or other causes, and the same information can be used to indicate con-sistency of combustion both during the starting cycle and normal running. Information on vibration is given to the first order ofamplitude. Two cathode-ray tubes again form the basis of the display; the upper one shows temperature and by actuating acontrol switch the full width of the screen can be used to show the ten temperature points of an individual engine. Two horizontallines across the screen are a temperature base Sne and a calibration line; the former is fixed in any one of four positions (selected bya switch) which, when the engine is functioning correctly, should pass through the mean of the engine temperature indications.The four positions are calibrated for the particular engine and represent take-off, climb, cruise and decent temperatures. Two units, a scanner and display, comprise the analyser andthey weigh respectively 8 lb and 5 lb without cables. About two years ago British Thomson-Houston and Hobson putup proposals for aircraft starting, using an A.C. alternator and constant-speed drive as the starting unit, and B.T-H. have con-tinued development of an electrical machine—a 50 kVA starter- alternator with a constant-running speed of 8,000 r.p.m.—for thispurpose. It is shortly to be run on the bench with a Hobson drive as a preliminary to further trials. There is admittedly someprejudice on the grounds of possible unreliability against elec- trical starting, but where a self-contained start is required thealternator-starter system operating from an auxiliary generator power unit is competitive with air starting systems and it maywell have advantages in weight and space. Since the proposal was first made, the Hobson unit has been redesigned on adifferent operating principle, but the new drive can now be offered with alternator starting facility. Meanwhile, B.T-H., who manu-facture a range of D.C. electric, iso-propyl nitrate and cartridge starters, are giving design attention to air starting. Quite a large number of fuel flowmeters are now on offer to theindustry. Some of the firms engaged are Negretti & Zambra. Integral, Firth Cleveland, Armstrong Whitworth Equipment andElliott Brothers. Integral's flowmeter has now been in production for some while, and like Firth Cleveland's design utilizes a flowtransmitter and electronic integrator. Both the Armstrong Whit- worth (Gloster Technical Developments) and Elliott designsfunction by importing angular momentum to the fluid by a closely controlled constant-speed motor and extracting and measuringthis momentum by using it to deflect a turbine against a spring. The Elliott flowmeter is a Bendix design to which Elliott areadding an integration system incorporating an A.C. pick-off and amplifier which will give a gallons gone presentation. TheArmstrong Whitworth true mass flowmeter is now in the final stages of development, but it is likely that a new intermediatesize may be introduced that will be suitable for Dart engines. de Havilland Propellers had new propellers on show, the 16ftfour-blader of the CL-44 and the small propeller for the Gnome. The company also displayed their synchrophasing system. Thisis a useful way of reducing noise and vibration and can materially improve passenger comfort. Three phase-signals from alternatorson the master and slave engines are compared and anjr difference in speed or phase displacement is fed into the positional servocontrol of the slave actuator to bias the propeller controller.
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