1、U.S. DEPARTMENT OF COMMERCENational Technical Information ServiceNACATM 490STRUCTURES OF THIN SHEET METALTHEIR DESIGN AND CONSTRUCTIONNational Advisory Committee for AeronauticsWashington, D.C.Dec 28Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MI-
2、I0I0Mi-It., 0M M IclrJ_ “0ra_i-4 H._ 21_t C/ Cl0ca _cl000 I_lo.0c_400,-10cl0,-1,-1H0c_40HIj 0ci_4oProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NATIONAL ADVISORY C0_gMITTEE FOR AERONAUTICS.iTECHNICAL MEMORANDUM NO. A90.STRUCTURES OF THIN SHEET META
3、L,THEIR DESIGN AND CONSTRUCTION.By Herbert Wagner.IntroductiQnThe advantages of light metals for airplane constructionoutweigh their disadvantages, at least for mmay airplane types.Consequently , many airplane builders, both at home and abroad,have adopted metal construction, either in _vhole or in
4、part.On investigating the sheet-metal construction of a number ofsuch airplanes, we are surprised at the great variety of methodsemployed. Every c_nstructor holds a different view of the pos-sible stresses and reactions in a piece of sheet metal and ofthe nature of their transmission.From the standp
5、oint of strength the fundamental differencebetween an all-metal airplane and, e.g., a steel-tubing airplane_consists in the coverings. In contrast with a cloth-coveredsteel-tubing airplane, in which the stresses are simply transmit-ted by the inner structure, an all-metal airplane enables thetransmi
6、ssion of a portion of the stresses by mesa_s of the outersheet-metal coverings. Since these coverings constitute alarge share of the weight of the cell, the economy of this typeof construction depends on how far the greater weight of the*“Ueber Konstruetions- und Berechnungsfragen des Blechbaues,“ a
7、preprint received from the Paris Office of the National AdvisoryCommittee for Aeronautics, August 15, 1928.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-N.A.C.A. Technical iiemorandum !To. 690 2“k ksheet-metal covering, as compared with fabric cove
8、ring, can beoffset by reducing the weight of the interior structure.I believe it is not going too far to say that the most im-portant characteristic of any typ_ of all-metal construction isthe manner of applying the sheet-metal covering. It not onlydetermines the inner structure cf the airplane, but
9、 greatly af-fects the choice ef the aspect ratio, the external bracing ofthe wings, etc.It would lead me too far if I should now take up in detailthe relations between the inner and outer structure, i willtherefore confine my remarks to a brief survey of the uses ofsheet-metal coverings in conjuncti
10、on with the inner structure.I will then elaborate on a special method of construction, onwhich I have worked during my connection with the Rohrbaeh firmand which enables simple and cheap shop v!ork combined with _reatsimplicity and lightness. Dr. Rohrbach has been so kind as toallow me to use photog
11、raphs of some of the experiments I per-formed while with the company. These photographs will make mydescriptions clearer.In connection with the discussion of this method of con-struction_ I will also touch upon other important questions re_garding the strength of sheet metal. I shall, however, only
12、in-dicate the most essential principles. As regards more detailedconsiderations and calculations, I refer you to the articles toappear later in the Zeitschrift f_r Flugtechnik und Motorluft-Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-N.A.C.A. Tec
13、hnical 7Lemorandum _o. _90 3schiffahrt. I shall not discuss the question of compre,_sivestrength, vThich is also importsmt in th construction of s_ll-metal airplanes.Constructional KethodsThe first successful builder of all-metal airplanes, Pro-lessor Junkers, made a special study of the method of a
14、ttachingthe sheet-metal covering to tile fr_m_ework. His conclusions foundexpression in the construction_tl method of his 1915 iron mono-plane end in a patent of that year.Tv_o kinds of stresses are developed in the sheet-metal ringcovering:I. Longitudinal stresses produced by the bending of thewhol
15、e _“ _.ins by the air forces (e.g , compressive stresses on then “_upper side _o. tensile stresses on the lower side of the _mn_);2. Shearing stresses, chiefly due to torsion.The numerous stiffeners, v:hich are welded to the sheet-metal covering, afford the only way to obtain buckling stremsth,both
16、against the shearing stud against the compressive stresses.In order, hoI_ 9_ -_ I_ “-“ IpJ+bl_O.I_Lq+_jo,ib/9._(IProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-iiiiiiiiiiiii_i_i_iiii!iiii!ii!iiiiii_i_i_5_iiiiiiiiiiiiii_i_ii!ili_Ti_ii_ili_iii_i!/iiii
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