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Aviation History
1941
1941 - 0220.PDF
JANUARY 23RD, 1941. Correspondence The Editor does not hold himselt responsible for the views expressed by correspondents. The names and addresses of the writers, not necessarily for publication, must in all cases accompany letters. THE OBSERVER CORPS Dilly and Dally Resurrected ? I HAPPENED to pick up a copy of your paper recently andnoticed what I consider a very timely article written, pre- Klimably, by a member of the Observer Corps.This article voices the almost unanimous feelings of the Observer Corps over a very large area, if not the whole country.Surely, after all these months and all the lessons we should have learnt, the present condition of this corps would makeone believe that our old friends, Dilly and Dally, were by no means extinct. "CANADIAN SCOT." THE SLIP-WING BOMBER Problems of Production WITH reference to Mr. Pemberton-Billing's slip-wingbomber, I am rather surprised that so far none of your correspondents has raised the obvious objection of productiontime. G ranted that the machine would do everything claimed forit, what would have happened if the Air Ministry had said: " Go ahead with it " in the early part of 1939 ? Well, "P.-B." at least ought to know. First, find a factorymid then equip it. The skilled staff required would have to be cither conjured out of a top hat or poached fromother factories.The same remarks apply to aircraft parts, materials, and acces- sories. Now at least one year would have gone by the time that" P.-B." was ready to start, and, having started production, I estimate that five years would elapse before the slip-wingbombers would be produced in squadron numbers. The Vickers Wellington (B 9/32) took six years to getmoving in any quantities worth having; a more recent bomber will take a total of four years from the time that the designwas finally settled. So that, starting from scratch, the slip-wing design wouldhardly have been ready before 1945 as a practical proposition. The views of the designer would be of very great interest in thisconnection because of his previous experience of production. JOHN V. HEWES. SUB-CONTRACT DRAWINGS Connecting Link Wanted THIS correspondence has covered a lot of ground since itsstarting point. The fundamental which emerges is that all correspondents seem agreed that production problems needtackling pretty seriously; where they differ is about who should do the tackling ! Logically, there are two lines of approach: (a) from thedesigner's end ; and (b) from the sub-contractor's. If you start from (a) you postulate a designer or production engineer whois au fait with the whole production position throughout indus- try—remembering that as his particular sub-cOntractors haveprobably still to be settled, personal contact on doubtful points is impossible at this stage. The constant comparison with themotor industry seems rather unfair in this connection, in that the motor designer has long experience of design for mass pro-duction behind him; also, he has got most stages of production " under the same roof," which, under the sub-contract system,the aircraft designer has not. Starting from (b) presents the individual sub-contractor witha fait accompli to turn out in large numbers as best he can, at a stage when, as " Observer " points out, any change to facili-tate production is bound to bo wasteful in one way or another. Hence my original suggestion that he should be given theclosest possible co-operation in the matter of drawings and information—for which I was rather roughly handled byanother correspondent! Somewhere between these two extremes lies a method thatwould enable the designer to get what he wants, and the sub- contractor to give it to him without extra difficulties.When in doubt as to how to do a lot of big things, it is instructive to think how one would do a few small ones. Sohow does a small productive business tackle a comparable problem? In my own, for instance. 73 per cent, or more of all work comes in by post with perfectly clear instructions,and goes out the same way; there you parallel the straight- forward sub-contract jobs which give no trouble and go throughas simple routine. The other 25 per cent, raise some " snag " ; here I come on the picture, find out that the customer wantsso-and-so drawn in such-and-such a way (Stage 1), and then come back to my drawing office and fight out with thedraughtsman how it can be done (Stage 2). Without taking any practical hand at either end, one can speed and simplifyproduction purely as a "communication line," and by know- ing what each side wants to do and what they are up againstin doing it. If the customer represents the designer and the draughtsmanthe contractor, here is quite a good analogy to a sub-contract job. Doesn't the weakness o. X)ut which so many correspon-dents complain boil down to the fact that production to-day is practically all Stage 1 and very little Stage 2? (If t*mass production enthusiasts were given their heads at t designer's expense, we should reverse the order probably withno better results.) And isn't what is lacking in our parallel some connecting link between design as a whole and sub-contract as a wliole? Granted that individual contact can do much, and is essential at many stages, something bigger isneeded to enable the average designer to turn out every time a drawing that won't present headaches to any average sub-contractor. Many of us think the "something" should have been anindustrial census, at the beginning of the war or even before; but that is hardly relevant to the present argument. Thealternative is some semi-official body set up by the industries for their own convenience. It wouldn't issue regulations orclog the wheels in any way; it would be advisory and infor- mative to the utmost degree. For instance, if approached bythe design end on some doubtful point it would say '' if you make this hole that size, there are a few firms who can startproduction at once—if they aren't doing something else, if you want bigger production, alter your dimension by so muchand you can take your pick from a hundred firms with the tools to do the job." This is an elementary example, butwill serve to show what I mean. It wants a mass of information up its sleeve, and a practicalstaff who know what they are talking about to interpret the facts. Given the real co-operation of the firms concerned,anyone who has had any practical experience of collating information on a big scale will agree with me that it couldbe done, and done very usefully indeed. Possibly the S.B.A.C. and the Ministry of Aircraft Produc-tion are already doing most of this job. If not, they—together with a representative body from the motor trade—seem thepeople to forge such a "connecting link." And with respect to all the varied opinions that have been expressed in thiscorrespondence, I still think it would be worth the effort. GAVIN STAREY. DESIGNING FOR PRODUCTION Call In Steel Body Designers AS a contribution to your controversy regarding "Designingfor Production," I, as a newcomer to the aircraft industry, would like to mention a few of my impressions. First, the needless number of parts often used where two orthree would do if properly designed. Why not more flanging of webs in place of angles- riveted on everywhere ? Nose ribsin particular suffer from this complaint. Why do not aircraft designers realise that by the time allthese parts have been tooled up and jigged up, the cost is much in excess of the cost of two or three slightly larger tools ?Besides this consideration the production costs might be down to as low as 20 per cent, of the Heath Robinson design whichthe poor manufacturers are trying to mass produce these days. Secondly, I endorse " Six-year Apprentice's " remark aboutthe accuracy of drawings. More than half the queries arising in aircraft production appear to trace back to nothing morethan carelessness in drawing preparation and checking. Lastly, the lack of allowance made for production variationsof sheet-metal parts is lamentable. The draughtsman who thinks that large shcet-mctal parts can be constanty made to
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