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Aviation History
1958
1958 - 0049.PDF
10 January 1958 51 An operator on the head side inserts the rivet and places the hold-up tool; the operator on the panned side "draws up" and squeezes. This can be carried out on any rivet over an area 72in x 18in, after which the skin may be moved into the next position. The platforms are balanced and may be easily moved up or down by hand. The bottom skin component, with all its attachments sealed andriveted, is placed in a horizontal assembly jig which locates all essential points and maintains the skin contour. Spar and rib vertical membersare then attached and the top skin with its attachments lowered into position. The internal attachments are then made, working progressivelyoutwards from the centre. It is during this stage that the amount of work necessary inside the structure has to be kept to a minimum, sincethe gap for access is narrow, and through this the operators have to reach locations for the final attachment bolts. To provide the maximum spacepossible, the booms of the front and rear spars are left off until all the internal work is completed. The final attachment of these booms iscarried out by means of a special portable squeeze riveter. At this stage the tank unit is complete and is pressure tested. The attachment of theleading edge and trailing edge structures is carried out in a further jig. These structures are conventional. The joint for marrying the port and starboard wings is carried out bythe provision of suitable packings of Dural strip on the abutting edges of the top and bottom skins at the centre-line. These are machined to followthe aerofoil curvature, but in a horizontal plane while the wing is lying in its natural flying position at the 2 deg anhedral angle. This provides aparallel landing at the inboard end of each wing 10 accommodate the insertion of the wing centre rib and doubling plates on tae outer surfaceswhich make the joint. The present method of machining the packings requires a machinetool of our own design and construction. The completely assembled wing box is located in its true position. The path of the cutter to machinethe packings is controlled by a hydraulic copying attachment. This machines the packings on the top and bottom, and also machines theskin edges to provide the correct gap. The marrying jig takes care of the port and starboard wings locatedby their own fuselage pick-ups, in which position the centre rib is inserted and the drilling and reaming for the bolts through the buttstraps, skin edges, packings and rib is carried out. The wing to fuselage skin angles are also drilled at this stage with a drill jig gate to obtaininterchangeability. Machined items were not unduly complex, the wing centre rib beingthe largest in the wings. Owing to die necessity for weight consideration, die stampings could do little to avoid machining all over, draft angleshaving to be removed and required fillet radii usually being too small to forge satisfactorily. The main gain was in obtaining some external pro-files to shape and the elimination of the "hogging" of surplus metal, plus obtaining the correct grain flow. The wing centre rib (A in the photograph) is made from a solid billet,all the pocketing and internal surfaces being routed, the external profile surfaces being machined on a HydroteL This component was nottaken up as a die stamping owing to the cost of the dies, uncertainty of quantity and the fast rate of metal removal by the router. The main undercarriage bracket (B) as a die forging was well worthwhile compared with machining from solid. Machining was fairly straightforward, and boring the S.99 steel bearing cap in situ with thelight alloy bracket, using a carbide tool, presented no difficulty, approxi- mately 0.0005in ovality being evident at the cut interruption on thejoint face. To divert for a moment from the wing box, the items set out in thenext column are worth mentioning. A selection of machined components. The letters refer to the accom- panying text in which each unit is briefly described. The half-frame C is from one of the P.I A development aircraft, ahead of the cockpit. A half-frame (C) is machined from a solid forged billet in the "asforged" condition, roughed, heat treated, semi-finished and finished. Distortion of approximately Jin was satisfactorily machined out. Component (D) set quite a problem, consisting of double curvatureover 90 per cent of its surface, and can be seen as a rather frail work- piece in relation to its overall size. [It is the canopy frame—-ED.] The development forging (E) appears to be unduly massive, butthis had to be assessed in a hurry and allowance was made for prob- able and unknown distortion. The production forging (F) is a recent attempt by High Duty Alloysto press this component to finished size. A die closure tolerance of — .OOOin +.030in has been allowed, and the prospect of a satisfactoryconclusion is regarded with optimism. Component (G) is in S.99 Steel, 85 tons tensile, and tapers down toa finished thickness of O.OSin at the tail end. Component (H), a bearing housing fabricated by welding underrigid control, is in steel DTD.124 and S.92 and subsequently heat- treated as 45/50 tons tensile. Numerous difficulties can no doubt be as well imagined as described;such, for example, as preserving the aluminium cladding from damage during its progress through its operations, e.g., by use of coatings cfadhesive liquid envelope mixtures, and by sensible attention to footwear. Further problems were the accurate cutting of countersinks by handtools without damaging the immediate surrounding surface by either the tool or swarf, and the care required in milling the rivet heads. In this paper, we do not pretend or claim anything which is otherthan orthodox. It is a story of facts related to a typical aircraft problem, which is told unvarnished as far as security regulations will permit. Discussions on all three papers: page 61. THOUGHTS ON WS-110A (continued from page 44) in the Phase I stage far too long. A decision on the two competing pro-jects was made only on December 23 last, when the N.A.A. design was chosen. Choice of N.A.A. is curious, since this company—although excep- • tionally capable and no doubt with nearly all the tools and engineersnecessary for so mammoth an undertaking—is very heavily committed to a variety of new projects, some of which are comparable in magnitudewith WS-110A itself. N.A.A.'s progress into Phase II (prototype) development is beingpromoted with all possible speed, the weapon-system manager being Mr. Jack J. Jones. Undoubtedly the greatest possible use will be made of thewgrk already completed on the unsuccessful WS-104 (SM-64 Navaho) tarajct missile, which—with the exception of the launching phase—had aflight profile essentially similar to that of the new bomber. An accom- panying sketch, which is entirely unofficial, shows how the SM-64 air-frame could be used as a basis for the WS-110A. Stainless-steel sand- wich is certain to play a m?jor role in the new airframe, and enormousdemands will be made on specialist suppliers of high-temperature accessory systems. Announcement of N.A.A.'s selection was made by Mr. James Douglas,U.S.A.F. Secretary, on December 19. It was followed by a congratula- tory message to N.A.A. from the president of Boeing and by a statementfrom Mr. J. H. "Dutch" Kindelberger, chairman of the board of N.A.A., emphasizing the magnitude of the task ahead and saying: "We do notexpect an immediate manpower build-up . . . but there will be a gradual increase in employment as the programme develops. Ultimately it isexpected to have substantial effect on our own employment and that of our many suppliers and sub-contractors." First flight of the prototype—which will probably be designated XB-69—must take place within two years if the aircraft is to be truly competitive. It is not known whetherthe war load will comprise a long-range air-to-surface missile or a free- talhng bomb; the latter would be quite feasible since it is doubtful ifa stand-off bomb" could be devised with greater speed or evasive ability thaJ> .^t of the aircraft itself. With the exception of the Soviet Union, who are almost certain to bedeveloping a parallel weapon system, no aircraft remotely resembling WS-110A is even projected in any other country. We in Britain wouldhave had a smaller and less advanced aeroplane in the Avro 730 (these adjectives are only relative, and the Avro bomber would itself have beenfar in advance of any contemporary aeroplane and would have given us a valuable position in the realm of sustained supersonic flight). Doubtlessthe world's major trunk airlines will one day fly at the speed of the WS-110A, and it is difficult to see how any other nation can hope to com-pete in this field now that the American bomber is going ahead. W. T. G THE STATE AND THE INDUSTRY (continued from page 41) proper representation on the respective Boards it could promote betteimutual understanding of the needs and problems of both the industrial units and the body or Ministry responsible for national aviation policy.It could permit more economical financing, and facilitate this policy of re-grouping and rationalizing. It could lead to the elimination of manyof the present frustrating checks and inquiries which the system of attempted Ministerial control from the outside makes inevitable. More-over, it is also the fact that under any ownership some Minister will be expected to ask for a Parliamentary vote of many tens of millions ofpounds to meet the cost of research. There will not be the same defence justification in the future; the case will sound more convincing if thenation has a stake in the industry which the research is designed to support. In the last analysis, of course, the success of the aircraft industry mustbe dependent upon the skill and ingenuity of the technicians engaged in it; no organizational pattern can be a substitute for that. Equally cer-tainly, any pattern which cramps or frustrates technical initiative is . doomed to failure. Nevertheless, the finest technician will admit that he isdependent upon some backing from the State. In all the modern circum- stances the partnership between State and industry indicated above issurely worth considering.
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