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Aviation History
1937
1937 - 0787.PDF
MARCH 25, 1937. FLIGHT. 301 accommodate them. They cannot, of course, take their turn, but must be dealt with at once, if not sooner. Experiments must be made and there must always be experimental aircraft, but could their production not wait until the vital shortage of tried and proved fighting machines has been made good? If they simply cannot be kept waiting, could they not be produced separately and right away from the '' bread and butter " jobs, with a self-contained inspection room, stores, etc. ? Material could then be obtained in known quantities from the usual outside suppliers, and used for the XYZ direct. Dimensional Theory Our third point affects the design staff. For some occult reason every drawing office whose work I have had the doubtful privilege of translating suffers from a maddening complex. It is that they will'not use one medium of expression in terms of the first, second or third dimension. To take a very simple instance of the untold wasting of time caused by this deplorable habit, let us assume that a piece of Dural sheet of a thickness of tsin. has to be cut to a rectangular shape. . The blue-print will have a small space headed " Material Specification,'' in which will be the information given above, i.e., "Dural ^in. sheet." The length of the rectangle required will be given, let us say, as 1.750 in. and the width as 28.575 nam. The whole is required to have a common tolerance of plus or minus five thousandths of an inch. First, the man to whom the job is assigned will check the thickness of the sheet issued, using a micrometer graduated in thousandths or ten-thousandths of an inch. This involves a little sum converting a vulgar fraction into a decimal reading. The second measurement he can check with a vernier, and this should be no bother to him. Next he must convert 28.575 mm. into inches and decimals thereof. Now, all this will take time, the book of conversion tables is probably lost, or the page he wants is missing, so perhaps he goes to the charge-hand, who, proud of his superior learning, does the calculation on the wall and gets it wrong. Try multiplying this delay by a number equal to that of the men engaged on machine jobs, milling, grinding, and so forth, then, again, by the inspectors who have to check the finished article. Now take a really complicated draw ing giving twenty or thirty dimensions, including radii, diameters, and chamfer angles, and try to get an idea of the kind of mass-meeting that congregates round the blue print all '' helping '' to find out what the whole thing means in terms that they understand and to which they can work with the instruments provided. Calling'in the D.O. After a suitable lapse of time someone will 'phone the drawing office, and the man who produced the drawing will come along (in his own good time) and indulge in cheap sarcasms at the expense of the puzzled one. Of course, ultimately the man gets to know the job more or less by heart, and his gauges will show if he is going off the rails. But it may take weeks before he is fully con versant with a particular component, or assembly of com ponents, during which period he spends half his time struggling with a nightmare of meaningless figures. If only the drawings and blue-prints would show all dimensions in the decimal system! If this is held to be impossible, then show every equiva lent. It cannot possiblv take one draughtsman longer to work out the whole collection of figures once than it takes for a fitter or machine operator to work them out daily, recruiting as much help as he can from his fellow workers for an indefinite period. A lesser handicap is very often imposed by failing to give the overall figures at all, so that if we assume the desired information equal to AE, the method of finding AE in volves adding AB (1.257 in.) + BC (3 7/32 in.)+-CD (which we will call the diameter of a circle with a radius of 27.34 mm.) 4- DE (which is again in decimals). Our fourth question concerns the fact that " A bad work man always blames his tools." If the old saw is true, all workmen engaged on aircraft production are bad. Tools may be divided into two categories, the firm's and the worker's own. Taking the latter first, there is no kind of standard tool kit set down in print as the model outfit. Everyone has his own ideas, and no two kits are anything like the same. If Bill, George, Tom, and Frank are fitters, all engaged upon erection work connected with the ABC single-seater fighter, Tom will have half a dozen Woolworth vices and no screwdriver; George boasts three hammers and one vice ; Bill has no punches or spirit level, while Frank seems overburdened with six of everything. Bill, George and Tom cheerfully lend and borrow among themselves, '' making do '' and '' worrying through '' some how, wasting time sorting out each other's belongings and all wanting the spirit level at once. Frank gets straight on with his job, earns his bonus, and has a good chance of promotion. But it is a bit rough on the others. Why not give a man a printed list of what he must have when he joins the firm, and have a periodical kit inspection once a week, letting a man replace at cost price anything he may have lost* damaged or broken ? Our friend Frank is perhaps a trained engineer, who has served his time as an apprentice and been an aircraft fitter for years. He knows what is what without being told,' but George, Bill, and Tom have come to help their country out in an emergency and will do their cheerful best; but it could be made a much better best by a little guidance on the subject of equipment. Works Tools As regards the gear provided by aircraft firms it is diffi cult to generalise. In a small shop, building only one special machine, the apple of a certain firm's eye was four dozen pairs of riveting toggles. At another concern the entire works, for both military and civil aircraft, had two pairs only, 95 per cent, of riveting being snapped by hand, with a boy to hold up the dolly. When I was there they had perhaps eighty machines in various stages of assembly, and I would not care to estimate the time wasted by the use of snaps throughout all the stages of production. Another star example was a firm which kindly provided an electric or hydraulic riveter for nearly every fitter, but whose efforts stopped short of having more than one-third of the plug points needed. Anyone strong enough to secure a plug point first thing in the day lost it the moment his back was turned. There is one type of person who is suited down to the ground by these methodless methods. Always, in any walk of life, one finds men who somehow establish a reputation for hard work, while in point of fact they do hardly a stroke. Such a one will wander about for half an- hour holding a lead lamp, ostensibly looking for an empty socket into which he can plug the cable. Having decided they are all in use, he changes his search, and hunts for a junction piece, and if lucky enough to find one, will spend another twenty minutes tinkering about with adhesive tape, binding it here and there, poking at it with a screwdriver and "cleaning" the points. Next, he finds a join in someone else's cable line, breaks it, and inserts his junction piece. As soon as the cable line is severed pandemonium is let loose. Follow long- winded explanations and profuse apologies to the man whose light has gone out, or whose drill has stopped. By the time both sections of cable are live, and our lead- swinging friend is ready to use his lamp, he suddenly dis covers that the cable is not long enough to reach his job. This kind of thing happens ad nauseam with some people, and they always have such wonderful excuses, but two such men in a busy shop can do untold damage in hold ing up production.
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