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Aviation History
1937
1937 - 0927.PDF
APRIL 8, 1937. FLIGHT. g f^vrwocas /toiVy accidents or ot damage to the engine. A switch controlled by the dynamometer water inlet prevents starting unless the water is turned on. A similar electric contact control on the starting dog makes it impossible for this to be engaged when an engine is already run ning- Again, belore starting, the dynamometer sluices must be closed, that is, offering mini mum brake resistance to the starter, and an indicator bulb is placed on the 'main control panel to show the closed position. Various other safeguards, operated by the flow of brake water dropping, by over-revving an engine, or by lack ot cooling air, are also fitted. The Heenan and Froude dynamometer is of a modified form with an extended torsion arm to the control room, and the new remote con trol from the panel. It is capable of absorbing up to 2,000 h.p. for either left- or right-hand rotation. The following sequence of operations is em ployed for starting an engine on the beds: (1) Turn on the dynamometer water; (2) engage the starter dog; (3) switch on first the main, then the graduated fan motor control by degrees, allowing time for the fan, which is directly driven, to pick up; (4) set the main butterfly valve at about three- quarters open ; (5) turn on the oil, and, if necessary, the oil heater, and wait for it to circulate, as shown by a glass indicator in the return pipe ; (6) close the brake sluices ; (7) switch on the starter motor and accelerate slowly; (8) turn on the petrol and prime the engine from the accelera tor pump—that is, quickly open the throttle wide once or twice ; (9) contact—switch on the ignition after scan ning the dials of the engine instruments. The majority of the instruments on the main panel need no explanation. Thermometers and pressure gauges record fully the state of air and induction mixture at the carbu- m The ground floor plan of the Alvis works shows the positioning of all important departments and machines MILLWR.IOWTS r HE, -CAPSTAN LATHES Oaorcurt/nq iSL#-fT3Cv 7hrood TUftRET 1..\./ OVToiyTy t/fit/inq—LATMES OWcws *LT B^f iV Zfn//iry \tiorrsar*9/ Bering -4- ouf Tab, r'.L fr*xt>a#*y Making a small adjustment on the single-cylinder experimen tal test bed. Part of the cooling duct is raised to give access to the engine. _• a A.I.R-feJ MAIM FQOWT OFFICES rettor intake, between carburettor and blower, and at the induction port. A spring-loaded " Detonindex" and a thermo-couple in each cylinder indicate the behaviour of the charge and its temperature, and an exhaust gas analyser, from the final state of the gases, shows mixture efficiency. Two special switches working in conjunction with the petrol pressure gauge show separately the pressure at each diaphragm of each petrol pump. The various mercury columns seen in the control room record air pressures in the tunnel, air depressions in the altitude box, and boost pressures. A barometer is included in the equipment to give absolute readings during the tests, and humidity is shown by a hygrometer. A petrol flowmeter is shown in the illustration, and above it are two 2-litre graduated glass bulbs for direct consumption checking by timing. Three types of fuel are stored underground in tanks outside the test house. Artificial Altitudes The large hand-wheel on the main panel controls the valve on the altitude depression box, one half-turn making a pressure difference of 1 mm. of mercury. Artificial alti tudes of up to 15,000ft. are attainable. Oil consumption is measured by weighing on an Avery balance, so that temperature differences do not affect read ings as in the case of measurement by volume. The oil is passed through an Alfa-Laval size 1,500 centrifugal cleaner, and a glass section in the return pipe shows when the oil is flowing. After having been itself tried out with a Gnome-Rhone 14.K engine, the main experimental bed is now being used for testing an initial batch of 15 1,000 h.p. 14-cylinder Pelides Major engines which are nearing completion. One of the first of these engines is at the present time being prepared for type test. Provision has been made for the manufacture of a further 75 engines following the com pletion of the 15. The large 1,300 h.p. 18-cylinder Alcides and Alcides Major will be the next Alvis engines to reach production, while drawings are nearing completion for the small-diameter, two-row, 14-cylinder Maeonides Major, to give 650/700 h.p Fractional h.p. Motors A NEW series of fractional horse-power electric motors is announced by Brook Motors, Ltd., Empress Works, Huddersfield. This "Cub" series, as it is called, includes capacitor, split-phase, and 2- and 3-phase types. The motors are stated to be silent in operation and are all fitted with special type sleeve bearings. No oil-bath is necessary, and attention to lubrication is reduced to a minimum by the use of oil wicks which, it is claimed, also give long bearing life. The motors are fitted with cast-iron feet to present standard measurements, and are finished in cellulose with heavily plated bright parts.
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