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Aviation History
1945
1945 - 0127.PDF
JANUARY I8TH, 1945 MONOCOQUES CONTINUED In the Flying Fortress the framesand stringers are closely spaced, as shown on the right. Thestringers pass through holes in the frames, none of the flanges,., being cut. * y formers in a monocoque faSelage, it seems evident the & economical arrangement has yet to be found. Many monocoques retain four longerons, or at least have those stringers reinforced which occupy the place formerly taken up by the longerons, add if carefully positioned they serve the excellent purpose of providing load carry-through members for large openings. In the case of high-powered, single-engined fighters they are necessary to transmit the highly concentrated loads of the engine mounting into the largest possible area of skin plating. Bombers require two strong longitudinal members to carry the beams supporting the bomb carriers. A very large number of different sections are used as stringers and formers. For lightly loaded machines the Z-section stringer and former are much in evidence. For the more heavily loaded types lipped top-hat section stringers are popular. - Stringer Arrangements There seems some doubt as to whether the stringersshould be attached to the formers at the point of inter- section. In theory, in certain cases, there is no need forsuch a fixing, as the stiesses will be transmitted by the skin. In other cases there is no doubt that a positivejoint results in a more stable and stronger structure. An unusual scheme is used on the Boeing Fortress. Thestringers pass through holes in the formers that retain the flange of the former itself. Both stringers and formers arethus continuous over the intersection. The stringers are not joggled, but rise gently over the flange oiJXe formerat each intersection. On the de Havilland Flamingo, notches in the formersfor the passage of the stringers were furnished with a little tag thavr was riveted to the stringers. This was not somuch a strength measure, but rather done to facilitate pro- duction, the stringer being held conveniently in place priorto the attachment of the skin covering. It has been suggested that a saving of weight mightresult from the use of tubular stringers, which would also have the following advantages: — 1. No outstanding flanges, or flanges riveted to theskin, result in greater stability. 2. Mechanical properties are superior to those of stripsections. An investigation at R.A.E., Farnborough, did prove thatsolid-drawn tubular stringers are lighter for the same strength, or stronger for the same weight, than construc-tions using stiffeners formed from strip material. Comparative tests on panels with tubular and extruded-angle stringers showed that constructions using tubular stringers are 15 per cent, more efficient than constructionsusing similar extruded angle section stringers. There has been no published evidence of a fuselage withtubular stringers. The advantages claimed must be con- sidered in conjunction with the difficulty of riveting andalso the danger of corrosion inside the tubes. If "pop" and "explosive head" rivets and anodic treatment canovercome these disadvantages, it is probable that some enterprising manufacturer will produce a specimen fuselage.It will be interesting to compare this with one of more conventional construction. , (To be concluded next week.) MOSQUITOES' DOUBLE NIGHT ATTACKSM ORE than 50 Australians fly with Bomber Command'sLight Night Striking Force of Mosquitoes, which on the nights of January 4 and 5 made two attacks a night onBerlin. The last was the force's 97th attack on the capital. Like all the air crew of the force, the Australians are pickedmen, most of them having had previous operational experience, although some with special ability have gone to the force directfrom training or other non-operational work. The A.O.C. of the Force, Brisbane-born Air Vice-MarshalD. C. T. Bennett, C.B., C.B.E., D.S.O. (R.A.F.), who also commands the Pathfinder Force, said that as well as theusual medical tests the Mosquito crews had to undergo a special decompression test to ensure suitability for the heights atwhich the Mosquitoes of the night force fly. The Air Vice-Marshal revealed that the Mosquitoes whichcarried out the daring daylight "tunnel busting" raid on New Year's Day had bombed Berlin six hours previously—an instance of the increasing scale of the Mosquito force's activi-ties. The force was one of the largest Mosquito forces ever to bomb Berlin. "The Mosquitoes-landed, were checked and refuelled, andwere off again at dawn with fresh crews to bomb the tunnels," he said. "Altogether, about 12 tunnels were attacked in thearea that really mattered—behind Rundstedt's salient. STILL AT THE VERY BEGINNING T ORD BRABAZON, in an address on "Aviation" at lastJL' week's meeting of the British Association in London, said that the jet engine, with its gas turbine, opened up new vistasof flight with revolutionising effects on aircraft design and speed, and also as power units in other fields. "We are still at the very beginning of it all," he declared."Not only is lavish research necessary on flight, but it is justified because it repays itself by its repercussions on andstimulation of other industries."
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