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Aviation History
1919
1919 - 1079.PDF
Results of Tests on Aeroplane Ribs conducted in the Glenn L. Martin Laboratory. 0 7. ^2 2 i 2 7 8 9 10 12 < i 13 if. 17 IS I<1 20 21 22 24 25 26 28 2 9 30 Z2 33 34 3S V Type. A B B B C B B C B B B C D D D E F F G H H I Hand. Page Hand. Page Hand. Page [ Material. & birch veneer i\ birch veneer ,\ birch veneer ,\ birch veneer A spruce ,', veneer ,\ veneer i'„ spruce i\ veneer 8\ v#neer ,', spruce ^ veneer ,as spruce 4 spruce.. 4 spruce.. 4 spruce.. 1 spruce.. 4 spruce.. 4 spruce.. 4 spruce. 4 spruce.. 4 spruce.. 4 spruce.. 4 spruce.. 4 spruce.. Made in pr Made in pr Web (Between Beams). Grain. Horizontal Horizontal Horizontal Horizontal Horizontal Vertical .. Vertical . . Horizontal Horizontal Horizontal Horizontal Horizontal Horizontal Horizontal Horizontal Horizontal Horizontal Horizontal Horizontal Horizontal Horizontal Horizontal Horizontal Horizontal Horizontal oduction, sa oduction, sa A. i 4 It 1 1 irj * 4 f i i i t 4 I i i i i i i i i 1 1 1 Ki me me B. i i 13 1 11 IS HI 111, 1 A lo IS in I I I J I 1 i i I i 7 i I i I i .! bN as as 1 CD. i 4 i 1 i i i i i i t 4 J ii I 1 i J i i i i 1 1 o. Rib Rib * i i 4 i t t i i i i 4 i i I I I i i I i I i i 33 No. No. B. » t I I i 'i I l i 1 0 H I I I I I I i 5 I i i i i I I i 8 wa 3», 3°, 1 •'. 4 1 i i i i i i i i i 1 i i 1 I I 1 I 1 i i * 8 s re Ty Ty G. i 4 i i i i i 4 i i l 4 I 8 i 4 i i i i i i i 1 bui pr pe H. t i 1 I 1 i s f It I. I. Portals. Cut out horizontal grain Cut out, horizontal grain, with vertical side-strips Cut out, horizontal grain, with vertical side-strips Cut out, horizontal grain, with vertical side-strips Cut out, horizontal grain, with X side- strips Cut out, vertical grain, with double vertical side-strips Cut out, vertical grain, with double vertical side-strips Cut out, horizontal grain, with X side- strips Cut out horizontal grain, with double vertical sid«-strips Cut out horizontal grain, with double vertical side-strips Cut oiit horizontal grain, with double vertical side-strips Cut out horizontal grain, with single X side-strips Built up spruce f X A single X, wrapped and doped Built up | X ,*, veneer, double X, wrapped and doped Built up J X 4 spruce double X, wrapped and doped Built up Ax spruce double X, & vertical Built up spruce 3"5 X f double X, & vertical Built up spruce A x £ double X, & vertical Built up spruce ,\ x| double X, & vertical Built up spruce ,'jXl double X, & vertical Built up spruce ,", xf double X, & vertical Built up spruce ,',- x.f single X, & vertical Type 1 3 :i, x 4 vertical spruce, with diag. tension strips s'a .x i vartical spruce, with diag. tension strips with screws, but did not show fair test Tail. s\ veneer ,'3 veneer 3\ veneer jf veneer h spruce double-side strips 3 sj veneer ver tical grain :,\ veneer ver tical grain ,'„ spruce double-side strips s\ veneer horiz •A veneer horiz i\ spruce, no side strips 35 veneer, no strips a s, veneer, no strips /j veneer, no strips ;,\ veneer, no strips Sl veneer, no strips 3 vertical spr. portals 3 vertical spr. portals 3 vertical spr. portals 2 vertical spr. portals 2 vertical spr. portals Spruce, single X St vertical Nose. vs veneer 3sa veneer ^ veneer 3\ veneer i\ spruce cut-out ;,\ veneer vertical JV veneer vertical rV spruce cut-out ontal grain ontal grain ifi spruce j, veneer a'j veneer s'j veneer :!'i veneer ,\ veneer yV spruce i:'„ spruce Va spruce l\ spruce ,•',., spruce ,"„ spruce Capstrip Spruce, A, by 4 plain § set-in 4 set-in 4 set-in 4 set-in 4 set-in 4 set-in 4 set-in 4 set-in 4 set-in 4 set-in | set in ,"„ set-in 4 set-in 4 set-in 4 set in 4 set in 4 set-in 4 set-in 4 set-in 4 set in 4 set-in 4 set-in 4 set in Beams Fastened Rigidly Rigidly From floor From floor From floor From floor From floor From floor From floor From floor From floor From floor From floor From floor From floor From floor From floor From floor From floor From floor From. floor From floor From floor From floor From floor From floor i S I 15 t6 10 19J ib* 164 184 204 204 184 13* I9J 17 iS '4 134 124 u ir* II «>4 10 to ro 12 12 .lbs . 1 0 •a K O 358 624 383 322 350 274 2 75 600 660 868 +59 378 662 637 703 533 624 610 309 626 665 54 *' 43 fi 37o 230 615 45' 4-8 8-4 5-2 4'4 4-7 37 3-7 8-i 89 n-7 6-2 31 9-0 8-6 9'5 7-2 8-4 8-2 69 8-3 9-0 7-4 59 5-0 8-3 6-1 Inches Total ' Deflection Divided . F.S. bv —• 2 — •077 • 104 •094 •061 •135 •13S •053 •050 •047 •048 •077 •072 •046 •041 •046 •044 • 046 •047 •046 •041 046 •037 — — 035 •050 Failure. Station. 9-bottom 12-bottom ir-bottom 13-bottom Portals . . 1 r-bottom n-bottom 8-top gus set 8-bottom gusset 13-bottom gusset. 11 tail 9-10 bot tom 3-top 3-top 5-top, web and cap n-web bot tom 4-5 bottom 5-bottom web 3-bottom web 3-4 bottom web r4-tail 3-4 bottom 3-tension strip 3-tension strip 3-web split 4-bottom 5-top Cause. Shear Bending.. Shear Shear Shearing.. Bending.. Bending.. Bending.. Bending.. Shear Bending. . Local Bowing of portal Bowing of portal Local Split Shear Splitting Splitting Splitting Bending. . Shear Torn loose Torn loose Bending Splitting Remarks Method of fastening true only lor ribs close to box ribs and drift struts. Method of fastening true only for ribs close to box ribs and drift struts. Humps over portals for last third of load. Veneer had diagonal grain at point of failure. Turning moment between upper and lower sides sheared portals. Sharp failure. Sharp failure. Shape good to 450 lbs., then humped in centre (secondary failure at Sta. r3K Humps over central portals. Shape good throughout, failure sharp. Tail portals weak without side-strips. Tail portals sheared at about half load. Central X portals weak, and crumpled under eccentric load. Central X portals weak, and crumpled under eccentric load. Portals bowed out at about 425 lbs. loa'd. Front portal crumpled inward a t about 375 lbs. load. Humps over portals. X portals had a Jin. block at their cross points to bow them out in centre. s"» mahogany veneer beam gussets. Beam brace blocks partially cut away. Horizontal spruce beam gussets. Vertical spruce beam gussets. Tail took strong crescent shape. /, mahogany veneer beam gussets. Tail took strong crescent shape. g\ mahogany veneer beam gussets. A. mahogany veneer beam gussets. • Web at 4, 3, 6 had diagonal and spiral grain.
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