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Aviation History
1948
1948 - 0111.PDF
This structures test-rig is unique in permitting eight loadings to be simultaneously applied. to peacetime silence has brought about th4 pevelOpmentof tail pipes in sundry variations on a basic •theme. One of these, only recently introduced, has given results whichindicate thaj it is by far the quietest so far known; it has, at least, established that exhaust noise can be reducedbelow that of the airscrew. A rather interesting side issue warrants inclusion. Inorder to make the maximum use of noise tests carried out in flight, air-to-ground readings are taken and reports sub-mitted for the use of the Ministry of Town and Country Planning so that scientific up-to-date data are availablefor relation to the airport noise problem. It was many years ago that Rolls-Royce had it impressedupon them that the business of getting fuel from the tank to the engine figured as importantly as keeping the enginecool; thus the company became involved in fuel systems., (fljp was not very much of a problem, however, until fighters"were given two-speed superchargers and were taken up ton Scale model of a Merlin civil power-plant mounted in working section. ' 30,000ft in the summer; then i^. became acute. After in- tensive investigation Hucknall came to the conclusion that the answer to fuel boiling lay in having adequate booster pumps. Pressurized fuel tanks are vulnerable and heavy, whilst fuel cooling is not only vulnerable but also imposes restriction on flow and gives danger of freezing the fuel water content. Booster pumps so became a prime interest at Hucknall (they produced six thousand during the war as emergency relief) and now, in every case where a Rolls- Royce engine is used, the company makes itself responsible for the complete fuel system from tank to injector nozzle. This applies also to oil systems, with particular reference to the design of hot-pots in oil tanks, and is, of course, applicable both to piston engines and turbine units. Elaborate test rigs have been built for the simulation of .every conceivable operating condition, and the altitude -.,. test chamber erected some years ago was the first of its .'*"• kind in the country. It will accommodate a 200-gallon fuel tank and a complete fuel system, and evacuation is such as to simulate aircraft rates, of climb and altitudes up to 50,000ft, or higher if required. The fuel can also be pre-heated to increase the test period at boiling condition^ tile altitude at which fuel starts to boil being critically affected by the ground tempera- ture of the fuel. This problem of fuel boiling, or aeration, at altitude is not finally solved even yet, and flights at heights of the 50,000ft order are going to become normally accepted within the next ten years. To see a fuel system operating at a (simulated) altitude of even 25,000ft is a frightening thing. Of all the several fields of investigation penetrated at Hucknall none has entailed the degree of growth experienced by the aerodynamic section. This rapidly developed in size and' importance until, eventually, it was made a separate division in its own right. Equipped with one large wind tunnel and several test rigs, the department is responsible for
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