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Aviation History
1912
1912 - 0883.PDF
SEPTBMHK 1 No . 'o f Ex periment . R 28, Section. I 4 of A in. sq. 2 ! 4 .. i * a'jin. 3 1 7, & in-sq- 4 l6>. A 5 4»i 6 i „ i 7 4« A 8 4» 4 ' 77 II ,7 • 1 sVin. 9 * ,, & ^-"l- 10 II 12 13 <4 •5 8 „ A 2„£ 16 „ A 16 „ A 4 »> s i .. 1 «6 |24 »» A '7 24 >> A i« 7 ,A B7 T7 -J- 11 17 ,, 77 77 7 7 77 77 77 77 1912. Length . Inches . 9'5 9'5 9'5 io-o io-o IO'O 9-5 9"5 95 10'0 io-o 100 io-o IO'O I0"0 io-o 100 io-o lO'O Stretch . Pe r cent . 10 10 10 5 S 5 10 10 10 5 5 5 5 5 5 5 5 5 5 GENERAL TABLE A.—SW/ion Weight . Ozs . State. •0775 DT •0863 •°735 -298 •352 •318 •o775 •0863 °735 150 •176 •298 •298 •352 •318 •446 •446 '540 •600 If I) .• . ,) II -** **- ••* Pure soft soap 77 77 • • • Commcicial liquid... 17 "• 77 French chalk and soft soap Commercial liquid ... French chalk and sofi soap Commercial liquid... French chalk and soft MixtureC.L.andS.S. Commercial liquid .. i X 309 344 389 I5u 158 14S 568 554 577 373 375 268 296 296 267 187 203 203 187 and En d Pull . Ozs . 18 '9 — 73 75 56 24 28 21 37 37 81 74 83 52 — — — i — Lubricant Varit if -a! •§ lis 81M H m 2'l6 2-40 i'55 i8-oo i6'40 1170 2-94 3'4» 2-66 6-00 5'7o 18-40 19-30 23-00 12-90 34-8 30-8 39'0 6ro •872 1 -loo •686 7-320 7-320 5-400 i -no •375 933 2414 2-440 7-400 7'5«o 8-76 6-iS 14-73 12-03 15-67 22-7 d. Full Tests -!*S •404 •458 •443 •407 •447 •462 •377 •398 35 •402 •427 '4°3 376 •38 "477 •420 •390 •402 •372 .J a 8-815 12-76 874 3600 37-80 26-00 20-6 24-9 176 29-4 299 64-8 72-1 84-7 53"7 90-0 8o-o 1044 138-0 • E Lubricate d EDr y _ — — — 2-34 i-88 2 02 — — 170 201 2-24 2-06 — — _ — M c 1 1,920 3,36 1,900 '.930 1.730 i,3io 4.500 4.430 3.830 3.140 2,900 3.480 3.880 3.850 2,700 3.23° 2,870 3.090 3.680 IRICHT # Remarks. Clean fracture. Clean fracture. Fractured at itftag fastening end loop Fractured nl stiin^; fastening end loop Fractured at both loops before section failed. P, g-in. Whitworth bolt and wing-nut controlling the spring- balance. m The readings were taken in the following manner:—After winding the cable of rubber to the required degree, the winder was locked by the pointer, C. Next the wing-nut was screwed down until the tension introduced through the spring-balance, overcoming the pull of the rubber on the lever and shaft, caused the balls and race to lose contact. Then the wing-nut was gradually unwound until contact was just restored, the reading on the spring-balance giving the end-pull of the rubber. A suitable weight was then placed in the scale-pan, and the sliding-carrier moved along the lever till perfect balance was obtained, the bed of the apparatus being sharply tapped the while. It will be noticed that owing to the tension of the spring-balance, there is, at the moment of reading the torque, no end pressure whatever on the bearing, to which fact the sensitiveness of the instrument is due—the error in the value of the torque being less than I per cent, (moving the carrier T,'„ in. at 7 in. radius changes the direction of rotation of the lever). The following remarks apply generally to all the experiments :— The tests were of two kinds—full tests and partial tests. In the former, readings of torque and end pull were taken every few revolutions as the sr>ecimen was gradually wound up to the point of fracture, the final reading of the torque being obtained by producing the graph in each case. In the partial tests only a few readings were taken in order to obtain the values at fracture. It was noticed that if the twisted skein were left for a few seconds, an appreciable drop in torque resulted, especially in the later stages of the experi ment. For this reason care was taken that each test should be conducted at a uniform rate. Reference to the general table will show that not only is rubber extremely variable in quality, but also is greatly influenced by exterior conditions, such as age, lubrication, &c, and so every care was taken that each series of experiments should be carried out under the same conditions. It was for this reason that one strand, whatever be its form or section, was adopted as the unit in the formula; given below instead of the actual area of cross section. 20 J) 15 N O I U Z " 10 u D 0 O h 5 C Gl _ 16 STRAN DRY J LUBR1C/ I LUBRICfl os OF- rb"* ITED LIOUIC TED SOPT £ 1 6 *4 SOL" R)2 ( / 1 *n A a.'* f*-« 1 m 1 ff 20 40 60 BO IOO 1Z0 MO lbO ISO 2.0O ZZO Z40 REVOLUTIONS nrZ _ • i / 260 2&0 K>0 520 883
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