FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Atlas
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
1932
1932 - 0279.PDF
MARCH 25, 1932 19 THE AIRCRAFT ENGINEER SUPPLKMBNT TO FLIGHT centre-plane cross-bracing; in this case a similar wire to the maximum drag bracing wire is taken. Since all members have now been given a length and an area, calculation by " Strain Energy " methods may be com menced. The first case to be examined will be with a front outer lift wire broken. There will be four redundancies, three incidence wires cD, jK, Lm and the drag bracing wire in the top centre plane, Egr. Loads are first calculated ignoring the redundant members. These are tabulated in column 3 of Table III. It can be seen that the transference of lift from the front to the rear truss produces large end loads in the rear spar. On the undamaged side, the lift comes straight through the front truss. These unsym- metrical forces on the centre-section pro duce loads in the cross-bracing wires considerably higher than those in any of the lift wires. Alternatively, had the cross wires been chosen as the redun dancy, there would have been correspond ingly large loads in the top centre-plane drag and incidence wires. It is not necessary to design these wires for such loads, for it is recognised that large relief is given by the incidence wires. In normal calculations for " cut wire " cases it is usual to assume pairs of wires broken, i.e., corresponding wires on both port and starboard. This assumption removes all unsymmetrical forces. In the next step wires cD, jK, Lm and E</, are given tensions Tx, T„, T3 and T4, respectively. The loads induced in the remainder of the structure are tabulated in columns 4, 5, 6 and 7 of Table III. Partially differentiating with respect to T, for the whole table and equating to zero. TABLE III. Front Outer Wire Cut—Calculated Loads. Column. Member To p Fron t II Win g Btm . fron t Btm . rea r Lif t Wire s Rea r Fron t Incidenc e wire s To p win g Dra g wire s fAC CE < EG GJ [JL fa c ce i eg gj 111 fBD J DF 1 HK [K M fbd Jdf ] hk (.km f AD J C F ' JH (.LK fad Jef Ijh Llk [Ab j cD 1JK LLm faC eE \ Eg Gj LJI Sg£: j Dt c = i1 hK - ,L.kM £t feN III )ep |sf -\ EP c^i (gn 1 Area :< 1.-1- 10-5 1-2 1-2 1-2 1-2 1-2 1-0 1-0 1-0 1-0 1-0 1-0 1-0 10 10 0-8 0-8 0-8 0-8 0-30 0-50 0-50 0-30 2 Lngth 2-75 2-0 10 2-0 2-75 3 P +0-075 L -0-675 L -0-675 L -0-275 I, 2-75 —0-550 L 2-0 !-0-950 L 1-0 -0-950 L 2-0 j — 2-75, — 2-75 -0-275 L 2-0 -0-475 L 2-0 1+0-275L 2-75 — 2-75 — 2-0 + 0-550 L 2-0 ! — 2-75 — 3-40 — 2-83 +0-283 L 2-83 +0-566 L 3-40 +0-340 L 0-15' 3-40 +0-340 L 0-25 2-83+0-283 L 0-251 2-83 — 0-151 3-40 — 0-10 0-15 0-15 0-10 0-13 0-20 0-20 0-20 013 2-24 +0-224 L 2-24! — 2-24' — 2-24 — 2-93 +0-293 L 2-24 +0-224 L 1-41 — 2-24 — 2-93 — 0-13J 2-03 +0-293 L 0-20 2-24 +0-224 L 0-20 2-24; — 0-131 2-93 — 0-13 1-41 +0-142 L 0-13 1-41 — 0-20 1-41+1-344 L i 0-20 1-41;+1-344L 4 0T: -0-8921] + 1-784 Ti + 1-784 T! +0-892 Ti — + 1-262 Xi -1-262 Ti + 1-0 Tx -1-00 Ti -1-00 Ti 5 (,T2 -1-784 T2 -0-892 X2 + 1-784 T2 +0-892 T2 — + 1-262 T2 -1-262 T2 +1-0T2 -1-0 T2 -10 T2 -0-631 Xi — — i— 0-631 Tg i-2-521 Ti +2-521 T2 1-2-521 Ti +2-521 T2 6 »T3 +4-236 T3 + 3-344T +1-226 I3 -4-236 T3 -2-452 I3 -3-344 T3 -1-226 T3 +2-452 T3 -1-262 T3 -1-516 T3 + 1-262 T3 + 1-516 T3 + 1-0I3 +1-0X3 + 1-307 X3 _ 1+1-OTj +1-307 X3 !+0-631 T3 —6000T3 -6-000 T3 7 dl* — — — — — — — +1-0I4 — +1-0 -10 1-1-0 -1-0 8 Final load -0-215 L -0-431 L -0-415 L -0-137 L -0-550 L -0-370 L -0-370 L -0-244 L -0-277 L -0-275 L -0-185 L +0-015 L -0138 L + 0-550 L +0-277 L +0-693 L +0-590 L +0-169 L + 0-340 L -0-127 L -0-024 L + 0-171 L +0-224 L +0-325 L +0-132 L +0-113 L +0-293 L -0-101 L + 0-069 L -0-019 L +0-148 + 0-293 L -0-101 L -0-019 L +0-148 L + 0-006 L -0-080 L + 0-111 L +0-111 L 0-892 0-075L-0-892 T, +^l-784 -0-950 L 1-262TX + ~j| 1-262 0-283 L 1-262 T, +^T1 1-784 T, + ~°2 1-784 - 0-950 L + 1-784 T, + ~ - -^ i (>224 L ~ 1'° Tl » " 0-20 °'2M L ~ 10Tl > 2_:° 1-2 2-83 0-892 -0-475 L + 0-892 T, +*., 1-262 0-o 0-283L 141 0^13 0-631 0142L- 0-6311!+ 1-0T. - 2 1-41 0^20 p|Q 2 FR-ONT OUTER WIRE CUT H +015 FINAL LOADS IN MEMBERS 260 c
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
