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Aviation History
1931
1931 - 1204.PDF
FLIGHT, NOVEMBER 13, 1931 The end of the assembly line of Rolls-Royce " Kestrel " engines. The distance at theback of the photograph gives some idea of the size of this workshop. (FLIGHT Photo.) investigating the problems of evaporative cooling. Rolls-Royce as a firm can probably claim to have a greater knowledge of this form of cooling and all the problemsinvolved than any other engine firm. They have carried out, and are still continuing, numberless tests with con-densers of varied shapes and capacities, and have now arrived at the stage when their knowledge is great uponthe subject. We understand that, contrary to general belief, the engine does not, to all intents and purposes,have to be modified at all. What this form of cooling really comes to is this. Instead of the cooling water beingtaken away from the cylinder head before it has absorbed all the heat it can, i.e., before it is boiling, it is arrangedto be circulated so that when it does come away it is a mixture of steam and heavily ladened water vapour. Thisis then taken to the condenser which is not at all unlike a normal radiator, but of smaller size, where it is condensedback into water. This water then falls to the bottom to a collector tank, whence it is pumped back into the enginecooling system. By this method the decrease in size of the condenser as compared to the normal radiator saves a gooddeal of weight, and Ihe fact that the whole weight of water in the radiator is done away with still further contributesto this saving. On the test bed we saw a " Kestrel " engine running with an airscrew, and the condenser soarranged that it could be raised or lowered out of the slipstream at will The equipment at Derby necessitates a large number oftest beds, and there is a double row under cover where the engines may be tested on the brake.A " Kestrel " engine was undergoing such a test, during our visit, in the self-contained test house which is provided for each brake.To get even a clear idea of such a works as those at Derby one wouldhave to spend several days there going round quietly and not like we wereable to do for merely a matter of a lew hours. We had, therefore, to chopabout from shop to shop, seeing that which we thought was most interesting. In one of the first shops was anassembly line of " Kestrel " engines. Just behind this line was the Averyconnecting-rod balance ; an example of the care which is taken to ensure thatevery part of the various Rolls-Royce engines is as near perfect as possible.This shop was just one of the few large machine shops which could hardly bedistinguished one from another by a stranger. They are all laid out on thesquare principle with overhead shafting to drive the machinery. The cleanli-ness of all these shops strikes every observer, for, although such is usuallyfound in any aero engine works, one does not expect it in a motor carworks ; probably this is just one of the reasons why the Rolls-Royce motor caris labelled " the best in the world." In the test department we found Mr.Plattford, who is in charge, showing a group of French journalists round ; heis proud of his department, and well he may be. It is in here that all the en-gines are stripped down after test and then reassembled after very carefulinspection. A visit to the light alloy foundry dis-closed the fact that Rolls-Royce have little to learn about the casting of lightalloy parts. They were among the pioneers of research work on lightalloys, and have now turned their knowledge of the metal itself over toHigh Duty Alloys, Ltd., who produce the ingots from which Rolls-Roycethemselves make their cast parts. Mr. Hall, who was responsible for the workdone in this direction has established himself as one of the leading expertsin the country on this particular sub- jec^ Casting such a part as the outercylinder block of a "Kestrel" engine is no etisy job, but to see the way the workmen do it here one would think that it was merely ahobby. As a matter of fact the men working on the aero engines do seem to treat their work as a hobby if one isto judge from the keen interest in it which they take. This attitude was very apparent and undoubtedly accounts toa large extent for the excellence of their workmanship, and thus the wonderful results which are consistently expectedfrom, and obtained from, these engines. Anyone who is interested in machine tools will find agreat deal to attract him in this factory. Naturally in machining up the parts of the engine there are manyintricate operations which entail the use of extremely interesting machine tools. For example, the diffuser andthe rotor of the blower have to be finished with an almost glass-like finish, as the speed of the mixture through theblower may be as high as 1,000 ft./sec, and any irregu- larities would cause serious disturbance to the flow. Asone would naturally expect, all the bearings are most care- fully lapped, and in the case of the crankshaft, at anyrate, this operation is done by machinery. Another test department which is no less importantthan the engine test house is the shop where carburettors and superchargers are tested. Here one finds an assort-ment of apparatus, which will give the efficiency of these parts and also a rig for testing out the petrol pumps.That such tests are necessary is shown by the fact that the gear pump for pumping the fuel supply of a standard" Kestrel " engine has to pass a proof test which is equivalent to sucking from a depth of 12 ft. and dis- A corner of the Test Shop ; the inspectors are examining a series of " Kestrel parts, while Mr. Plattford (on the right) explains some technical details to hi» visitors. (FLIGHT Photo.) 1128
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