Air Force the Official Service Journal - Air Force Historical Studies ...

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technique ••• CO]\;Tl:"UED New Method of Static Testing By E. R. Weaver, Fuginccring Di\'ision, ATSC As larger aircraft with more criticallv designed wings have been developed for the AAF, methods of ground testing the strength of the planes under simulated flight conditions have undergone radical changes. 1'\e\\est method of static-testing aircruft structures climina tes the tradition;!! S~'stclll of pil ing shot-hags ;llId 1c;!d ,,'eights on \\'ings, fuselages and engine mounts to measure critical loading limits. The new system ntilizcs rubber-tometal adhesive tcnsiou patches that enable engiueers to simulate and measure flight stresses and strains more accurately. Actt;al loads arc appl icd by series of adhesive tension patches on the top-side of an airfoil and soft sponge pads on the under-side of the \\iug. l Ivclranlic jacks then proportion the applied loads through a system of heams and 1cn:rs to the patches and pads in accordance with the correct aerodynamic data for the airfoil sections incorporated in the specific design. Essentially, the tension lifting patch is a flat or curved plate (depending upon the surface to which it is applied) of steel, dural um in or plastic material. It may range in xi:«: from a. six-inch square to a 6 hy 24-ineh rectangle, or even an irregular shape. One surface which is applied to the structure under test is covered with a piece of tough, high te!lSile, rubber or neoprenc sponge. The thickness of the ruhberized patch or pad varies from YI of an inch to I ~~ inches and forms a lifting element on the structural skin by adhesion. 'The lifting pads or pressurc pads arc the same size and composition hut they arc applied to the underside of the airfoil. II und reds of tension pa tchcs and pressure pads arc needed to run a single test, far less, however, than the number of shot-hags required for the dead \\'eight method prcviouslv used. A single operator can load and unload the test struc- Shot-bags and lead weights were piled on wings. cn!;ine mounts and f11ScL1~cs to UW:l'\UT critical lO:ldin~ limits unclcr the old mot lrocl of .,t;\tic tnt iu~ .iirrr.rf t struct urc-. The operation was a tedious one, several da\s heing required to test an airplane completely. 42 turc in a few minutes. By comparison, it formerly took days to pile on the shot-hags for simulating loads, since an average of 27 different tvpcs of tests arc required to static test a military airplane completely. In the test of a C- 54 airplane, for instance, 300 tension patches and 300 pressurc pads were used. By this number of tension patches sufficient lifting forcc was exerted to cause complete failure of the wing. The adhesive tension patch docs not reinforce the plate stringer combination of the wing surface. \Vrinkle patterns clue to shear lag, which form under the patches in their natural ,,'ay, can be visunlly inspected and photogmphed during the tests. The sponge adheres tighth' to the surface deforlllations anc] has no influence on the structure. This method of appl~'ing load is purticul.ulv effective in the testing of cmdings, canopies, bomb doors, hatch doors, trim tubs and control surfaces. In testing a curved surface the patch bases arc moulded to the curvature so that the sponge sheet distributes the load cvcnlv to the structure. \\'ith cements now in usc it is possible to develop a load c.rpacitv of 2,000 pounds per square foot on any structure for nearly fi\"Chours. \\'rig!;t held's Aircraft LilJOratory 110\1' has tIHI of the new static test machincs-one with a lifting capacity of 100,000 pounds, the other with a lifting capacity of 1,000,000 pounds. The smaller machine is used for testing trainers, fighters or small glidcrs, while the larger machine tests aircraft with gross wcights cxcccd ing 1"3tons. By employing the new system, the complete airplane structure including the fuselage and horizontal tail lIlay be tested simultaneously. Controls and control surface operation em he studied during tests since there is no dead load inside the fuselage or piled on the wing to endanger personnel and interfere with control ,,'iring and operation. Absence of dead loads in the fuselage 111akcs it possible to inspect visually the stress reactions of the fuschge inside and outside during tests. All hydraulic lifting equipment and beams, lever systems, electric dr ivcn pump, high press nrc hvdr.iulic cylinders and auxiliary pumps and gaugcs arc portable. and thcv can he rcnclilv disassembled and couvc nicntlv stcnee!. . . Rubber-to-metal adhesive tension patches and prcssure pads, used with new stat ir-t cst machine, enable ell~illeers to measure flight stresses more .iccuratclv rh.ru thcv could for nu.rlv. Speed, too, is gained. One m.ui can load .md unload test structure in few minutes. AIR FORCE
Rotating Information Chart Pilots clearing the ATe's (Jth j'ern'illg Service St.it ion at "\J1cghcll\' Countv Airport, l'ithlJllrgh, I'u. c.m o!Jtlill cs- -cnt ial flight (Litl b~' a flick of a finger. This is m.tck. p(h,ible by un im provcd roLiting inf or ruut ion ch.nt. (!c,iglled bv S/Sgt. Arnold "'-I. Crccn .md imhIlled ill the oper~l!ion', officc, I'igurcs on tower frcqucncv. d ivt.mcc hy .urw.rv«. divt.mcc direct and true cour-;c, rcl.rt ivc to .urficldx to wh icl: flights Rotating information chart. ill u .c "t t hl' .vir Tr.m-port COll1' iu.mds (,th !"crn illL; Scnill' SLit ion , l',thll\tr'-':Ii. 1':1" i, depicted ill t lic above dr:l\\illL;, Clmcllp ,hmn Ili:;ht cl.it.: ])[milkd invt.mt lv I» t lu- huudv dcvi.«: to :1 pilot cll'lrill:; t lu- 'Lltioll for \\l"\ bv \LIkricl COllIIII;ll"]'i C(luipulcut labor.rt orv. Cllilliu:lks thc tu£; .mc] tI,C pull UO\l' C\IK'l"kd I", .uruu-n in ti£;hteuiuL; .nul lomcuillg t hc pre-cut ,tde lr.rr nc-«. I'r iucip.rl COlllpOUCU!\ :11T thc ";Idaptor," 1.1I11rled ,lid ill:; bal. .u«l thc Llh for lomcuillL;. both :llLwlrcd to tire IHt:ulgular h.r«: pl.rtc. '10 tighku thc lap har- 1]('" xtr.ip. t l«. ri:;ht li.md pull-, t l«. frcc l'l"1. To loo-«:n the J
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~J 1 AIR FOftCES * OCTOBER 1944
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Rendezvous Who Is He? Dear Editor:
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[us: ,dlat is tIle AAI'I'DC~ It is
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oads and bridges and military imtal
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Here's how controllers direct the p
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sengcr and courier service in areas
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GET WISE Here are a few of the easi
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Airborne soldiers. shown here durin
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Smoke in background is fruin [up.ui
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It has pronounced step characterist
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TIIC{"II""IIIi; ;lItidc j, till' I/
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OCTOBER,1944 The first thing the a\
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YOUR ENEMY All ;Iirer;!ft fllillg o
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->",i" .""tJnil'et hj/'- By Col. Do
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28 011 BOll~aiIldk is quicklv unloa
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the plane landed, a jccp would driv
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THE PHiliPPINES DISTANCES SHOWN IN
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The economic system of the Philippi
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The AAF's homing pigeons are recogn
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Our aviation engineers had to fight
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---- technique • -- - --- . RUNWA
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High Intensity Controlled Lighting
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Attached to a flyer's ear, the Oxim
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Automatic Pilot Trainer-A new train
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3 5 7 Surprised by the friendliness
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TIM ELY A D V ICE FRO M THE A I R I
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R.6 I:>:CJ: the AAF S helicopter, t
Page 56 and 57: SS I. You on the left, Buddy, appea
Page 58 and 59: ever .nrivc at a fir',t ~Iid stut i
Page 60 and 61: p:rinted on the outvi.lc wrt l: ,ih
Page 62 and 63: tanks and truck-borne infantry and
Page 64 and 65: FIGHTER CONTROL (Colltilltled from
Page 68 and 69: Property of tDe Library ARMY INDtJS
Page 70 and 71: For the Record I)e:lr h!Jtlll Rende
Page 72 and 73: he Allie's into German-held of the
Page 74 and 75: H Combat may make you Lazy By Maj.
Page 76 and 77: ..... -; ... The results of two yea
Page 78 and 79: Production charts show the disaster
Page 80 and 81: all key points of the factory's 3-+
Page 82 and 83: HE Fortresses T wings to the took o
Page 84 and 85: ';:'4"'~' .~~~c ~)'~ ~J ~~~ ~" . "
Page 86 and 87: 'l'h is was a YClr ago, but these a
Page 88 and 89: Pulling in His Ne-:I:. Reeelit de,c
Page 90 and 91: When a radio operator makes a mista
Page 92 and 93: Lifeline to the US,S R BY HERBERT R
Page 94 and 95: Ten o'clock of a December morning a
Page 96 and 97: THE MAN WITH THE PRIVATE BREEZE By
Page 98 and 99: THE AIR WAR IN THE SOUTHWEST PACIFI
Page 100 and 101: STANDARD FLIGHT INSTRUMENT PANEL E
Page 102 and 103: It 11c:l!,illg l.ot h sidc
Page 104 and 105: , , ,CO:-iTI:-iUI:D ]'\o\\', pacbgi
Page 108 and 109: INSTRUMENT PANEL (Continued from Pa
Page 110 and 111: LIFELINE TO THE US S R ( Cout iuucc
Page 112 and 113: F\lr:RCF'\~CY FOUrp\lr:,\'T luvpcct
Page 114 and 115: 50 COMBAT MAY MAKE YOU LAZY (Contin
Page 116 and 117: EN of the AAF-including the hundred
Page 118 and 119: .I In. ]~rhO:S-':cl the'mll-it:IIT
Page 120 and 121: August 7. Patton kept moving his he
Page 122 and 123: l'Iiavigation Training En Masse. Th
Page 124 and 125: "WE arc not going to bubble over wi
Page 126 and 127: A wood block support; injured legs
Page 128 and 129: Burma. A Japanese light antiaircraf
Page 130: ~ ~,C"= =~=.~7~~ ---,- .... _._. __
Page 134 and 135: HOW ,SHARP ARE YOU? A 'hoto Test of
Page 136 and 137: .. ' Back to the Philippines PART I
Page 138 and 139: Tacloban strip \\";IS not sC'ITicca
Page 140 and 141: All Tile Illftl, \\ ,(("d If iii, ,
Page 142 and 143: :lIe fbttle of Hrit.un. IC\i" intru
Page 144 and 145: Underground. ,'~ group of worried m
Page 146 and 147: volunteers between the agcs of II .
Page 148 and 149: I f By Capt. Greer Williams Air SlI
Page 150 and 151: Flaming debris (If njllI, ])1]]1:ll
Page 152: ground fire the pilot should look f
Page 155 and 156: two weeks: Cincinnati. one week: Pi
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At 5.000 fed. the pilot opened the
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cardboard bombs on their choice of
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turn to Traffic Scction, Crcnicr Fi
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Oil refineries arc gooel targets, T
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Tile air campaign to choke off fuel
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fallen into Allied hands, thus maki
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Hamburg i lPolilz IMagdeburg 1 I r
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He's the guy who holds the life of
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46 V4ba\'s vnong V4itbtbis pictUfe1
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j ._3 Thirteen days after the 13th
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THE ABC OF D-DAY When an invasion i
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By all AIR F( )RCl-: ()\"t'rsc;/s S
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The fighters called for help and th
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A jeep, laden with leftover explosi
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THE ABC OF D-DAY t Cont inu.xl [r o
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By Capt. E. E. Churchill co, isu. A
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- ~ --'fftJMlGa ~II.I - , • - '--
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We're more than 2,300,000 individua
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