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Aviation History
1955
1955 - 1296.PDF
410 FLIGHT, 2 September 1955 THE MINISTRY'S CONTRIBUTION —to the S.B.A.C. Display: Kinetic Heating and Jet Flaps THE work of the Royal Aircraft Establishment, the NationalGas Turbine Establishment and the Technical Information Services will be typified on the Ministry of Supply Stand at Farn-borough next week. The R.A.E. exhibits are presented by the Structures Departmentunder the theme "structural research methods." To demonstrate kinetic heating infra-red lamps have been selected. The size ofthese can be small and convective losses low; there is no delay in gaining full power, with a certainty of transmission to the struc-ture. Quartz tubes for the lamp improve transmission whilst the dull black surface of the specimen aids absorption of the heatenergy. Pyrometers have been devised for measurement of the heat flux. A simulator has been developed to compare theoreticaland actual heat inflows, using known aerodynamic data and observed surface conditions, and it utilizes an assembly oflamps to which power is servo-controlled by the heat inflow error signal. The equipment will be demonstrated using a typical speci-men but applying relatively low-density heating—approximately one-tenth of maximum proposed. A model will show a typical test installation in which a mechani-cal loading system is augmented by heating equipment. Both mechanical and thermal loadings are applied simultaneouslyin a time-dependent manner. Incidentally, the quartz tubular infra- red filament heater to be shown in this display is so highly poweredfor its size that sufficient to operate all the possible electrical services of five homes can be concentrated into one square foot. To demonstrate the use of flutter-test equipment a wing will bedisplayed mounted on a part of a wall of the working section of a supersonic wind-tunnel. The wing flutters in modes of elasticdistortion and pitch about an axle fitted in the tunnel wall at the wing root. Under test the wing-pitching stiffness is reduced untilflutter occurs at the tunnel operating conditions. The oscillatory motion of the wing is displayed on an oscilloscope and recordedon a moving film. A safety catch is fitted which automatically clamps the wing before its flutter amplitude becomes excessive. The third exhibit will illustrate rocket technique for measuringwing forces whereby the wings are hinged to a rocket body and pitch about an upstream axis against a spring restraint. Thewings are oscillated at intervals during the rocket flight and a telemetry sender, on the rocket, transmits information on the wingoscillations to the ground. From a knowledge of the frequency and rate of decay of the wing oscillations the required aerodynamicderivatives can be determined. There will be, also, a representation of how records of complex vibrations associated with flutter and buffeting are recorded bya multi-channel recorder of a variable-area-photographic type. Other notable items will be the latest models of the compoundcounting accelerometer and fatigue meter, both designed at the R.A.E. The compound counting accelerometer is used to obtaingust data. A camera records at regular intervals the airspeed, altitude and vertical accelerations imposed on the aircraft, andwith a knowledge of the latter's aerodynamic character it is possible to convert the data obtained and to show magnitude andfrequency of occurrence of gusts at varying altitudes. The fatigue meter is a scaled-down counting accelerometer; it measures thenumber of times certain specified accelerations are exceeded during the life of the aircraft.A working model will show in sectional form the wings of an aircraft passing through flexible seals in the walls of a fatigue-testtank and a series of hydraulic jacks to apply wing loadings. The National Gas Turbine Establishment will feature the jetflap. In this arrangement the propulsive jet or, if the machine be airscrew-driven, the gas-turbine effluent, would be dischargedfrom the rear of the wing in the form of a long thin spanwise sheet as shown. In high-speed flight the jet would issue hori-zontally so that the machine would behave more or less like any other. In low-speed flight it would be inclined downwards as willbe shown, and so, after the fashion of a large conventional flap, would generate very high lift on the wing. The magnitude of thislift will readily be grasped by comparing two photographs illus- trating the flow around the same wind-tunnel model with andwithout its jet at a downward inclination of 58 degrees. Since the arrangement is essentially a type of flap, it requires forward motionand so cannot be used for vertical take-off, but only for the reduction of take-off and landing speeds. Representing the work of the Technical Information Bureauwill be a selection of M.o.S. unpublished reports; information on their availability will be given on request. Reports publishedby H.M.S.O. originating from the Ministry of Supply will also be on view. Specimen copies of Index Aeronauticus and the list ofjournals abstracted, bibliographies produced in T.I.B., and cata- logues of special report collection will be available for consultationby visitors. Information will be available on the activities of the CentralRadio Bureau, which is concerned with electronics information and provides a collecting and distributing service for Governmentdepartments, and on the Technical Mission in Washington, which maintains liaison with the U.S.A. on matters of mutual interest. Farnborough: a Visitors' Guide THE following information is mainly for the guidance ofintending visitors to the S.B.A.C. Flying Display on thethree "public" days, Friday, Saturday and Sunday, Septem- ber 9-1 lth, since those attending on the first four days will bethere by invitation or other special means of admission. On the public days, the gates will open at 10 a.m. and flying will beginat 3 p.m.—half-an-hour later than on the trade days. As detailed on p. 250 of our issue of August 19th, the programme will bedivided into six "circus" groups followed by 20 individual demonstrations.On Friday, the public premiere, admission prices will be: adults, £1; children under 14, 10s; cars, £1 (plus fees foroccupants); motor coach parking, £1. On the Saturday and Sunday the admission charges are: adults, 5s; children, 2s 6d;cars, £1 10s (including six occupants, excess passengers at normal fees); motor cycle parking, 2s 6d; coach parking, 10s. Ticketsfor the Friday only may be obtained in advance from Autoparks, Ltd., 1-31 Maclise Road, London, W.14. Approach routes to Farnborougb. are shown on the accompany-ing map. As traffic is heavy, particularly on the Saturday and Sunday, visitors by road are asked stricdy to observe the R.A.C.signposting, which begins on the various routes at the points marked by arrows on the map.As regards public transport facilities, the Aldershot and Dis- trict Traction Company have arranged for a high-frequencyservice of buses between Farnborough main railway station and the airfield and between Farnborough North station and theairfield. In addition, and in conjunction with the augmented Recommended routes: from the points arrowed, roads are R.A.C.- signposted. The nearest civil airfield is Blackbushe.
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