1、1tFOR AERONAUTICSTECHNICAL NOTE 4109LOW-SPEED YAWED-ROLUNG CHARACTERISTICS ANDOTHER ELASTIC PROPERTIES OF A PAIR OF40-DNCII-DIAMETER, 14-PLY-RATING,TYPE VII AIRCRAFT TIRESBy Walter B. Home and bert F. SmileyLangley Aeronautical LaboratoryLangley Field, Va.WashingtonJanuary 1958+g.Provided by IHSNot
2、for ResaleNo reproduction or networking permitted without license from IHS-,-,-TECHLIBRARYKAFB,NMNATIONAL ADVISORY COMMlZ!3EEFOR AERONAUTIC Illllllllillllluillllllllllli3tlbL8blTECHNICAL NOTE 4109LOW-SPEED YAWED-ROILING CHARACTERISTICSANDOTHER ELASTIC PROPERTIES OF A PAIR OF40-KIH-DIAMGTER, 14-PLY-R
3、ATG,TYPE VII AIRCRAFT TIRESBy Walter B. Home and Robert F. SmileySUMMARYThe low-speed (up to 4 miles per hour) yawed-rolling characteristicsof two 40 x 12, 14-ply-rating, type VII aircraft tires under straight-yawed rolling were determined over a range of inflation pressures andyaw angles for two ve
4、rtical loadings. One load was approximately equalto the rated vertical load and the other load was approximately equal totwice the rated vertical load for these tires. Static tests were alsoperformed to determine the vertical, lateral, torsional, and fore-and-aft elastic characteristicsof the tires.
5、 The qutities measured ordetermined included lateral or cornering force, drag force, twistingmoment or self-aliningtorque, pneumatic caster, vertical tire deflec-tion, lateral tire distortion, wheel twist or yaw angle, rolling radius,9and relaxation length. Some supplementary tests which included me
6、asure-ments of tire footprint area and the variation of unloaded tire radiusu and width with inflation pressure were made.During straight-yawedrolling the normal force generally increasedwith increasingyaw angle within the test range. _Thepneumatic castertended to decrease with increasingyaw angle.
7、The sliding-drag coeffi-cient of friction tended to decrease with increasingbearing pressure.Measureddecrease withrespectively.In orderlandings withlateral and torsional spring constants appeared toincreasing amplitude of tire lateral distortion or twist, IWIRODUCTIONto cope with airplane landing an
8、d taxiing problems such asyaw, wheel shimy, and ground handling, designers ofProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-2 NACA TN 4109landing gears must have reliable data on many elastic properties of air-plane tire6 under such conditions. Unti
9、l recently, the experimentaldata on such tire elastic properties, most of which are summarized anddiscussed in reference 1, were limited in both scope and quantity.Recently, a program was initiated by the National Advisory Committee forAeronautics to alleviate this lack of experimental data by deter
10、miningexperimental values of some essential tire parameters for a range oftire sizes under static, kinematic (low-speed steady-state),and dynamic(transientand high-speed) conditions. Sstatic force-deflectiontestsof the program have been completed and the results were reported in ref-erence 2. The lo
11、w-speedyawed-rdling and some other elastic character-istics were reported in reference 3 for two -inch-diameter, 24-ply-rating aircraft tires and in reference 4 for two 26-inch-diameter,12-pl.y-ratingaircraft tires. The present paper gives results from partsof the kinematic and static test programs
12、for two 40-inch-diameter,40 x 12, 14-ply-rating,type VII aircraft tires. Most of the investigation consisted of towing the tire specimensalong a straight path in a yawed condition. The angle-of-yawrange cov-ered was from 0 to 245and the Inflation-pressurerange was from about74 pounds per square inch
13、 to 143 pounds per Square inch. The twovertical-loadingconditions investigatedwere 15,000 and 28,300 poundsper tire. The 15,000-pound vertical load represented approximatelytherated load for this type of tire as specifiedby reference 5, whereasthe 28,300-pound vertical load represented approximately
14、 twice the ratedload. For each yawed-rolling run, the towing speed was held constantand did not exceed 4 miles per hour. The quantitiesmeasured or deter-mined included vertical tire deflection, lateral force, drag force, self- a71alining torque, pneumatic caster, rolling radius, and relaxation lengt
15、h.Relaxation-lengthmeasurements were also obtained for the case of zeroyaw for a standing and rolling tire. L?!Drag tests were conductedwith the wheels locked to obtain measure-ments in the fore-and-aftdirection of the maximum and sliding coeffi-cients of friction and the stiffness of the tires for
16、both wet- and they are listed only for convenience in referring to the test data.) In tables 11, III, and IV, data are pre-sented for three different test series (B, E, and F) which representdifferent vertical loadings. The variation of normal force *,r,eJself-aliningtorque ,r,e, and pneumatic “cast
17、er with yaw angle iSshown in figures 6 and 7 for all vertical loads and inflationpressurestested. The rolling radii are plotted in figure 8 as functions of tire . .inflationpressure and vertical tire deflection.The buildup of cornering force with horizontal distance rolledduring the initial stages o
18、f the yawed-rolling runs is illustrated in cfigure 9 for several inflationpressures and two vertical loadings.inasmuch as for most runs there was a slight initial residual force orpreload in the tires, the original test curves did not always passexactly through the origin. The test curves shown in f
19、igure 9 havebeen horizontally shifted (if necessary) so that the extrapolation ofeach curve passes through the origin.Relaxation-LengthTestsThree types of relaxation length were determined in this investi-gation, namely, static relaxation length L.s,Unyawed-rollingrelaxation .length Lf, and yawed-ro
20、lling relaxation length . The definitions bfor these relaxation lengths are given in reference 3. The Kthods used _to determine these relaxation lengths are as follows:YProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NACA TN 4109 9Static relaxation l
21、ength L.- The standing tires were given initial-d lateral deflections by pulling outward, by means of hydraulic rams, plateslocated underneath the tires. The lateral distortion of the center tiretread relative to the wheel center plane was then measured at severalpoints around each tire circumferenc
22、ebetween the fmtprint edge and apoint l however, the vertical load on the tires decreased slightlywithincreasing drag force as a consequence of the moment produced by thedrag force. This change in vertical force was taken into account in thecomputation of friction coefficients. (It was not taken int
23、o account inthe other tests, since the effect was small for those conditions.)Most of the experimental data obtained from the locked-wheel dragtests are presented in table VII. Also, typical data are shown in fig-ure 11for the buildup of fore-and-aft force with horizontal distancepulled for several
24、runs. Static Vertical-ElasticityTestsIn the static vertical-elasticitytests the vertical loading on eachtire was increasedby increments from zero loading to a maximum value andins-thenreducedby increments to zero, the vertical tire deflection wasnoted for each value of vertical loading, and the unlo
25、aded-tire inflationpresse P. and loaded-tire inflationpressure p were also measured.This procedure was followed for all test inflation pressures.aThe static vertical-elasticitydata obtained are presented in fig-ure 12. This figure shows thevariation of vertical loading with verti-cal tire deflection
26、 for the two tire specimens at the test inflation for approximatelytwice the rated loading (fig. 7), the normal force .did not reach its maximum value within the tested yaw-angle range W(up to 24.57.fProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NA
27、CA TN 4109 13*-4Cornering Force y,r,eThe steady-state cornering force follows substantiallythethat were described for the normal force, as is shown in figuretwo typical loading conditions.The vsxiationinflation PressureCornering Power Ntrends19 forof cornering power with vertical tire deflection and
28、for the two vertical loadings tested is shown in fig-ures 20(a) and 20(b), respectively. These data, which were derived fromthe initial slope of the curves for the variation of normal force withyaw angle given in figures 6 and 7, indicate that, for constant verticaltire deflection, the cornering pow
29、er increases with increasing inflationpressure and that, for constant inflation pressure, the cornering powerdecreases with increasing vertical tire deflection.In order to compare the present test results for the 40-inch tireswith the results of previous tests on other tires of the same generaltype
30、(type VII; see ref. 5), cornering-powerdata from the present testsare compared in figure 21 with data for 56-inch-diametertires from ref-erence 3, for 26-inch-diameter tires from reference 4, and for 32- and4-inch-diametertires frm reference 6. These data are presented inthe form of a plot of the di
31、mensionless ratio R against(+ o.11)#60y) where is the minimum rated bursting pressure of the tire astaken from reference 5. (The form of these ratios is based on theresults of a study of tire characteristicsgiven in ref. 7.) F and at comparablebearing pressures, both the sliding-drag and yawed-rolli
32、ng coefficients of friction followed approximatelythe same trends and magnitudes that were reported for 56-inch-diameterand 26-inch-diametertires in NACA Technical Notes 3235 and 3604.6. me static torsional spring constant, for a given vertical lmadand inflationpressure, decreased appreciablywith in
33、creasingamplitudeof tire twist.Langley Aeronautical Laboratory,National Advisory Committee for Aeronautics,Langley Field, Vs., July 24, 1957.*a71vProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NACA TN 4109REFERENCES211. Hadekel, R.: The Mechanical C
34、haracteristics of Pneumatic Tyres.S Aircraft Pneumatic Tire.Military Specification,w-c-1, Sept. I-6,2949; Amendment-2,Feb. 8, 1951.6. ElS, R. D.: Cornering Power of Airplane Tires. The Goodyear Tire52Wall thickness at tread center line(includingtread), in. . . . . . . . - 0.83 0.80Depth of tread (at
35、 tread centerline), in. . . . . . . . . . . . . . 0.29 (min.) 0.34 0.34Casing weight, lb . . ., . . . . . 95 (.) 85 85Tread pattern . . . . . . . . . . . Rib Rib RibInner tube:Thickness, in. . . . . . . . . . . . . . . . . . . . 0.1 0.1WeightJ lb. . . . . . . . . . . . . . . . . . . . . 14 13Wheel:R
36、imdiameter, in. . . . . . . . . . . . . . . . . . 21 a7100 21.00Weight, lb. . . . . . . . . . . . . . . . . . . . . 76 77.%?ype VII is an extra-high-pressuretire.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-well m 4m9 23Run12:567891011u?1314:21718
37、19202122232b25262728.2930313233343.536Po)lb3qin.7474747474;:Tb7593939293939393z951131131131131131131131131331331331331321321301331325,lb3qin.%7878787877-g97$979796g9798rL6LI.6116L15115IL9116I-I-81341351371*1351341321341348in.3.43.4;:3.5;:;3.53.52.9;:3.02.93.0;:;:2.62.62.62.62.72.62.72.72.32.k2.k2.k2
38、A2.k2.42.k2.4TABLE II.-MU$TESTDATA(a)SeriesB; Fz. 15,000 pounde8,in.;:2H;:;4.6k:2.9;:3.23.43.4;:;:;2.6;:2.93.23.1;:;2.42.42.62.62.72.62.82.62.7+,aeg1.753.5;:10.514.017.521.o24.51.733.5;:10.514.017.517.521.o2k.51.75;:10.514.017.517.521.o1.75?:7.010.514.017.517.5a.oFy, r,e,lb1,2402,4k04,5904,5206,4108
39、,1109,3709,900L0,4001,5002,9705,E7,1037,l%9,5XLO,AO(a)11,090lo,k70%alue couldnotbeaccuratelydetermined.Fx,r, e,lb2003001,mm1,;$%200m1,0007cKl1,7002,3003,4txl3,11XI3,9004,400Km200SQo1,m2,5033,0003,1003,600100200l,lm1,lCC)1,yxl2,4oo3,100;,g11,2402,k4,6704,5906,8,4409,90010,6(XIn,1601,5102,9805,9205,62
40、08,1109,760U,290lo,5.173.;(b)b)b)%alue notdetermined.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-24Rur3738;:414243Ek647484950515253545556;:5960616263Fojlb3q in.959595959395.-95z95115.:.115 “11511511511511511511513513513313513513513513510410510510
41、5105105105105105105125124122125124124125125124142143142143Ikl143143142TARLE II.-YAW-TE5TDATA - Concluded(b) SeriesE; z =28,500 poundso6,fn. in.5.2 5.35.1 5.35.2 5.25.1 3.35.2 5.35.1 5.45.2 5.75.2 5.75.1 5.95.3 6.54.5 4.54.5 4.64.5 4.74.5 4.74.5 .o4.6 5.44.5 5.34.5 5.54.6 5.74.0 4.24.0 4.04.1 4.14.0
42、4.14.0 4.24.0 4.44.0 4.e4.0 5.01.7;1.7:3.53.57.07.0LO.5LO.5L4.OL7.51.7;3.5;:LO.5L4.OL4.OL7.5L7.51.E1.7:;:7.010.5L4.0L7.5y,r,e4302,9105,7W5,7W8,770Ll, 530L3,900x r,e.ib700300eoo7001,1001,4002,5002,2003,6004,7001008001,3001, m2,4CX)3,7003,6004,8Q04,900100h?1,4001,5002,3003,700y,oooaValue couldnot be a
43、ccuratelydetermined.$,r,e:lb1,1201,0301,9101,9003,310;,;n2*Z3:492.43(a)(a)8.9(EL)7.8(;)681210.1(b)11.810.48.610.5(a)(a)10.1(b)(b)(a)1:213.19*512*1M .4(b)r.w%alue not determined. -Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NACA TN 4109 25TABLE lZ
44、l.-ROLLING-RADIUSDATAF(2RSW l%WNGm Test q,seriesdeg64 B o65 B o65 B o67 B o68 E o69 E 1.770 E o71 E 1.72 E o73 E 1-77k E 1.7l-l75 F o76 F o77 F OPo)lbIq in.749311313395951151151351351357395125Tire AI I r IT77 14,S0096 14,m115 14,goo134 14,m105 28,400lc4 28,4cmEZ4 28,4ooI-24 28,4w143 28,400142 28,4oo
45、142 28,4oo77 (b)97 (b)I-26 (b)3.43.02.62.45.1:;4.54.04.04.02.42.11.717.8 (a)18.0 (a)18.318.5 a)a)17.6 a)17.6a)17.9 (a)17.9a)18.1a)18.1 (a)18.0 (a)18.219.6118.519.6z18.819.7CPo)lbIqin.7931131339595115U51351351337555112Tire BP F 8.,lbq in. 1: in.1 I77g6 ;E;:;115 15,0002.6135 15,c002.41 28,2CUIlc4 28,2
46、00I-24 28,200u 28,200143 28,200142 28,200143 28,203m%.luenot measured.%etween9,003and10,OKlPounds.TABLE Iv.- PARAMmmS EVALUATEDFROM YAW-T=T DAYAaRunaltog10to 192oto!2728%03637to464#0;!4.5k.o4.04.0%,rs %,r,e,mlb-in. lb-in.aeg11b 25,cmb 24,(x)ob) 23,030b) 22,0006,100 Y5,0006,700 51,0307,m 49,mre rzin.
47、 in.17.8 a)18.1a)18.4(a)18.5(a)17.6 a)17.6a)17.9a)17.9a)18.1a)18.1a)L8.1(a)18.219.6C18.519.6418.719.G%nl.yapproximatevaluesof pressureand verticaldeflectionare listedin this table.All listedmaximumvaluesof forceand mcmentwere establishedwith the aid of the fairedcurvesinfigures6and7.%aluecouldnotbea
48、ccuratelydetermined.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-26 NACA TN 4109TABLE v.- STATIC RELAXATION-LENGTHDATAhln787980818283848586Tire ATest PO, P,series F 5., L=,lb lb zS lb in. in.B 74 78 14,400 3.9 18.3B 93 97 14400 3.2 15.5B 93 100 14,400 3.3 15.7B 113 116 14,400 2.5 16.6B 133 (b) 14,400 2.5 13.4E 96 105E 2%4005.0 12.695 105 28,4oo 4.9 L2.6E 117125 28,4oo 4.4 15.5E 134 140 28,4oo 3.9 13.3PO)lbsq in.7493931131339695115135789795119(a)104104124140Tire BFz, 50,lb in.14,
