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Aviation History
1918
1918 - 0592.PDF
Lieut. C. B. Whyte, R. Scots., attd. R.A.F. 2nd Lieut. J. C.Wood, R.A.F. 2nd Lient. B. W. Wright, R.A.F. Prisoners. Lieut. D. C. Hopewell, R.A.F. Lieut. G. G. MacPhee, H.L.I. (T.F.) and R.A.F. Lieut. G. R. J. Parkinson, R.A.F. r The following are reported by the Admiralty:— Previously Missing, now reported Killed. Flight Sub-Lieut. J. L. Allison, R.N. Previously Missing, now presumed Killed. Skpr. R. Brown, R.N.R. (W.S.A. 10). Flight Sub-Lieut. J. E. C. Hough, R.N. Prob. Flight Officer G. H. Morang, R.N. Flight Sub-Lieut. G. B. G. Scott, R.N. Flight Sub-Lieut. J. H. Winn. R.N. Died of Injuries. F 13285 1st Gr. Air-Mech. F. R. Jones, R.N.A.S. Previously Missing, now reported Prisoner. Acting Flight Commander R. P. Minifie, D.S.C., R.N. The following are reported by the War Office :— Killed. Lieut. J. O. Allison, W. Ont., attd. R.A.F. Lieut. W. A. J. Buckland, Aus. F.C. Lieut. M. S. Kelly, Manit., attd. R.A.F. Capt. N. M. J. Kohnstamm, Manch., attd. R.A.F. Lieut. A. M. Martyn, Cent. Ont., attd. R.A.F. Capt. H. D. E. Ralfe, Aus. F.C. MAY 30, 1918. Previously Missing, now reported Killed. 2nd Lieut. A. Butt, Bedford, attd. R.F.C. 2nd Lieut. L. Cann, R.F.C. Lieut. J. A. Convery, Can. Cav., attd. R.A.F. 2nd Lieut. G. B. Craig, R.F.C. Lieut. A. C. Gilmour, Can. Rly. Trps.. attd. R.A.Fi Capt. H. Hewett, M.C., R. Berks, attd. R.F.C. - • " 2nd Lieut. B. Starfield, R.F.C. Accidentally Killed. Capt. G. Robinson, M.C., Can. Cav., attd. R.A.F. Wounded. Lieut. E. G. Grant, Alta R., attd. R.A.F. Lieut. J. Grimshaw, Manit., attd. R.A.F. Lieut. W. R. W. Henderson, Manit., attd. R.A.F. Missing. Lieut. C. A. Pelletier, Can. Eng., attd. R.A.F. Capt. P. R. White, E. Ont., attd. R.A.F. Previously Missing, now reported Prisoner* la German bands. 2nd Lieut. H. P. Blake, R.F.C. Capt. E. B. Cahusac, M.C., S. Staffs., attd. R.F.C. 2nd Lieut. R. Caldecott, R.F.C. 2nd Lieut. H. F. Dougall, R.F.C. . Capt. J. H. Hedley, R.F.C. and Lieut. E. W. Pickford, R.F.C. 2nd Lieut. D. W. Kent-Jones, R.E., attd. R.F.C. Capt. K. R. Kirkman, R.F.C. 2nd Lieut. A. T. W. Lindsay, R.F.C. • - , 2nd Lieut. C. J. W. McKeown, R.F.C. 2nd Lieut. G. P. F. Thomas, Dur. L.I., attd. R.F.C. Case 2.—similar to the last, except that the ends are clamped, that is, not free to bend sideways. r, • .. The couple is given by . ; THE SIDEWAYS BUCKLING OF LOADED BEAMS OF DEEP SECTION. By J. PRESGOTT, M.A., D.Sc, Mathematician on the Engineering Staff of the Daimler Co. IT is a well-known fact that a loaded beam whose depth is The buckling, when it occurs, takes place in the plane much greater than its breadth may buckle sideways before perpendicular to the planes of the couples. The buckling it will break by bending in a vertical plane. There is, in couple is given by fact, for a beam loaded and supported in any particular rT way, a critical buckling load, just as there is a critical load for a strut given by Euler's theory. If buckling were not possible, the strength of a beam of given sectional area under lateral loads would increase as the depth increases, but the possibility of buckling puts a limit to the depth for practical purposes. I have investigated mathematically the problem of side- ways buckling and have obtained results for several useful cases. These results are givem below. The analysis is not supplied at present, because it is very long and rather cumbersome in some of the cases. The buckling load depends on the flexural rigidity for sideways bending, and on the torsional rigidity of the beam. It is clear that torsional rigidity has something to do with the qnestion, because the beam could not buckle without twisting. The following are the meanings of the symbols used in the formulae :— E — Young's modulus. I = The smallest moment of inertia of the section [i.e. the one that occurs in the equations for sideways bending). N = The modulus of rigidity. :r ,. KN = Torsional rigidity of the beam. L = Length of beam. In every one of the following cases it is assumed that there is no twist at an end which is held or supported, that is, the sections of supported ends are held with the depth in a vertical line. By a " supported end " will be meant an end resting on supports with the depth held vertical, but the end not otherwise constrained^ By a " clamped end" will be meant an end differing from the supported end in having an extra constraint. This extra constraint keeps the tangent to the central line of the section fixed horizontally in the same position as when there is no buckling, but the theory assumes that the depth is so great compared with the breadth that the actual amount of bending in a vertical plane is always quite small. Case i .—Beam under a pair of equal and opposite couples, Case 3.—The beam is free at one end, where it carries a load P. The other end is held quite rigidly. The load, P, must be supposed to be applied at the middle of the end section. The critical load is given by PL* =4-01 VEINK. Case 4.—Beam carrying a load, P, at the middle and simply supported at the ends. . PL2 = 16-94 N/ETNK. - Case 5.—Similar to the last case, except that the ends are clamped against horizontal bending. Case 6.—The beam carries a load, W, uniformly distributed along the beam. The ends are simply supported as in Case 4. (L WL = 283 VFTINK. Case 7.—The beam carries a load, W, uniformly distributed along its length, is quite free at one end, and held rigidly at the other. WLU 12-86 v'EINK. *""-" In every case the load is supposed to be applied on the central line of the beam. If the load is applied at the top of the beam, it will clearly take a less load to buckle the beam. The constant, K, is the coefficient that occurs with N in the theory of the torsion of prisms. For most compact sections, such as ellipses, rectangles, and triangles, it has been shown to be nearly equal to •46 J • -z::i ::=:::; where A is the area of the section and J its polar moment of inertia. . . For a rectangular section of breadth b and depth d the approximate rule gives G at its ends, there. Ends free except that sections have no twist 40 T b* + d*)bd 12 590
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