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Aviation History
1959
1959 - 2243.PDF
214 FLIGHT In the main drawing office of Vickers-Armstrongs (Aircraft) at Weybridge: A. G. Elliott and W. H. Baggley discuss wing geometry of the VC.IO People and Projects . . of the VC.IO from thoughts at a drawing board to hardware onthe shop floor has begun. Aerodynamics at Bedford An inconspicuous turning offthe main A6 road just north of Bedford leads to the site of an impressive modern wind-tunnel facility. This is the home ofthe Aircraft Research Association, a unique co-operative venture which produces aerodynamic data of direct and immediate valueto most of this country's aircraft and missile companies. The main transonic tunnel (8ft X 9ft working section) beganmodel testing for the industry in February 1957, since when some 35 tests on 18 different models have accounted for a total fanrunning time of over 1,300 hr. The only break in continuity during this time followed a fatigue failure of the axial compressorblades in December 1957, which limited tunnel speeds to Mach 1 until repairs were completed in June 1958. Towards the end of last year a supersonic tunnel, with a workingsection of 2ft 6inX2ft 3in, was completed and brought into service. Capable of speeds between M 1.4 and 3.5, with possibleextension to M 4, this tunnel uses the eleven-stage, 13,750 h.p. axial compressor which normally provides the perforated-wallsuction in the transonic installation. Design features include a flexible-wall nozzle section and an injector slot in the diffuserjust downstream of the working section. Under chief executive Ronald Hills, the A.R.A. staff is groupedinto three divisions, with A. B. Haines, chief aerodynamicist, in charge of the two tunnels, instrumentation and computing;D. Grundy, chief engineer, concerned with the drawing office, model-making shop and plant engineering; and L. J. S. Dearlove,secretary, providing the administrative and security services. On the aerodynamics side it is of interest to follow the work ofthe A.R.A. through the eyes of the project supervisors, key men whose job it is to follow a particular project through all the wayfrom the first agreement with the company concerned to the final report of results. There are nine supervisors at A.R.A., severalof whom are concerned with testing in both tunnels and most of whom have several aircraft or missile projects under way at anyone time. There can hardly be any current British aircraft or missile thathas not been the subject of model testing at A.R.A. at an early stage in its life. When a new project has been allocated, theproject supervisor first discusses with the parent company the speed range to be covered, what information is wanted, who isto build the model, and other points. Except when existing models are used, the longest phase of thejob will be the initial period during which the model and, usually, the balance to be used with it, is designed and made. After initialscheming the project supervisor hands over to the drawing office for the production of detail drawings. The external profile willbe known but it is no easy task to fit in the many instrumentation connections needed when a large number of quantities are to bemeasured. As an example of the type of problem encountered, it may be necessary to test a combinationmodel of a missile-carrying aircraft and to obtain simultaneous readings of a total of upto 14 different forces and moments—six on the aircraft, six on the missile and two on thepylon. The size of the model may have to be suitable for other tunnels—such as one ofthose at the nearby R.A.E. Design and construction of a model fromscratch may take about a year. Shortly before completion of the model the project super-visor checks with the computing section that the appropriate programmes are being writtenfor the Zebra computer which is used for data reduction, and also co-ordinates the manyother aspects of preparation for testing. The model balance must be completed, gaugedand calibrated. The A.R.A. tunnel instrumentation hasbeen designed to handle a large amount of data in a very short space of time. While theactual tunnel running on a given model may take about two weeks, this can produce moredata than would be the case for most other tunnels. During the whole of this period thetunnel will be used exclusively for the testing of this particular model. In the tunnel con-trol room the project supervisor will be in charge of a team comprising one or two elec-trical engineers (controlling the tunnel and plant operation) and up to five men and girlsacting as tunnel observers. In some cases the customer company willsend a representative to assist during the tunnel-running period. Otherwise the flow of information backto the firm would begin with preliminary test notes sent within a few days of the start of the run. In projects of high priority pro-cessed films of pressure measurements have been given to the company representative on the day following a test, but this isexceptional. Depending on the amount of data reduction and analysis to be carried out, the time taken before the final reportsare written and sent to the firm could be up to six months. From the first discussion to final report, then, could mean15-18 months, assuming no subsequent series of further tests. On the other hand, using an existing model for a high-priorityproject in the supersonic tunnel, this time could be reduced to three months. It is not exceptional for a supervisor to have fourprojects under way at once—one model being tested, one being designed, one project being discussed and one being written up. Experimental Development at Yeovil Of the four cur-rent products of Westland Aircraft, three—the Widgeon, Whirl- wind and Wessex—are at various stages of their productionprogrammes while the fourth, the Westminster, is an evaluation machine which is available for production in a number of applica-tions. Production of the Wessex antisubmarine helicopter for the Royal Navy is now well under way, and the Whirlwind andWidgeon are also being produced for operators in this country and abroad. An experimental Gnome-powered Whirlwind hasflown, and among the company's other recent developments are the acquisition of Saunders-Roe Ltd. and the opening of theWestland Heliport on the Thames at Battersea. Control room of the A.R.A. supersonic tunnel at Bedford
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