NASA NACA-TR-919-1948 Accuracy of airspeed measurements and flight calibration procedures《空速测量和飞行校准程序的精确度》.pdf

1、-,l, t,OFFLIGHTBy-_ . _ _ REPRODUCEDBY/t/4C_7- 7-a-. ,:Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-_ :7 -L_/L“Li_J .-./Di_ “ D,.0AERONAUTIC SYMBOLSSymboltForce FPower . Psp_i_ v:- Coefficient of viscosityt. FUNDAMENTAL AND DERIVED UNITSUMtMetricA

2、bbrevia-tionUniLEnglishAbbreviationmeber . m fnot (c,r mile) :_ft (or mi)second s seccmd (or hour) sec (or hr)weight _)f ! kilogram . , kg weight ,ff 1 pound _ . Ibi i .horsepower (metric) i . i -hocsept)wer . I hp_kllometer3 pur hour I kph miles per bour . Ii mphfeet per second_ i fl)s(meters r_er

3、_econd . l raps2. GENERAL SYMBOLSKinemtttic viscosityo Den,_ity (mass per unit volume)Standard densit,y of dry air, 0.12497 kg-m-_-s 2 at 15 Cand 760 ram; or 0.002378 lb-ft -_ see =Specific weight of “standard“ air, 1.2255 kg/m _ or0.07651 lb/cu flWeight-ragShmdard acceleration of gravit.y=9.80665 m

4、/s _or 32.174:0 ft;sec _gMoment of inertia=n_kL (Indicate axis ofradiu_ of gyration k by proper subscript.)3. AERODYNAMIC SYMBOLSi, Angle of setting of wings (relative to thrust line)i_ Angle of stabilizer setting (relative to thrusti_,(,)Q Result, ant moment_2 Resultant angular velocityR Rcynoht,_

5、mm_ber, p_Vl where I is a linear dimen-/asion (e.g., for an airfoil of 1.0 ft, chord, I00mph, standard pressure at 15 C, the corre-siren(ling Reynolds number is 935,400; or fi)ran _irfoil of 1.0 m chord, 100 raps, the corre-spop, di,g Reynolds number is 6,865,000)a Angle of attacke ku_,e of downwasi

6、_a0 A_n_Ie of _-_tta(:k, intinite aspect ratioa_ Aug!( of “_(tack, inducedeMPT(_X, PH.D. Chairman, Rcscarch and l)(wel(q)mcntBoar(i, National Military Establishment.:DWARD . ()Xl)ON, PH. I)., Director, National Bureau ofStandards.JAMES H. l)oot.ITWLr:, Se. D., Vice President, Shell Union OilCorp.R.

7、Mo AZEN, B. S., Director of Enginccring, Allison l)ivision,(ieneral Motors Corp.WILLIAM LITTLE_,VOOD, M. E., Vice President, Inginc(wing,American Airlines, Inc.THEODORE C. I,(tNNqUEST, Rear Admiral, United States Navy,Assislant Chief for Research and l)evelolmmnt, Bureau ofAeronautics.lh,w.xm, M. l)

8、(_u Hts, Mtj()r (;(qleral. lnil,d Slatrs Air l:(wc,Assislanl (hi(f,ff Air Staff-4.l(mx 1). Pttn(v, Vi(r .(tmiral, nit,.( Stat(,_ Navy, I)el)uty(Yhi(f of Naval ()l)(,ratiotls ( iri.AltTItt!R 1. llAYM(_NI), M. S., i(+ Pr(Md(nt, l:,+gin(,rin_,I)ouulas Aircraft (o., Inc.:RANIIS _V. II,;IClIEI,I)IqRFI.;R

9、, SO. |)., (hi_f, Inile(1 ,“;Tm,sVeal tmr l_m(,au.ll.:,;, l)J,;J,os iV. ll:xrzEL, Admimstral()r ,)f (ivil .(,r.mmlics,)l!parllll(!ll| ()f ( ()llllll(rfO,II()YT S. VANI)ENHER(;, (,(,n(,ral, (hi(.f ()f S)aff, .iwd S(at(,s Air20rc(,.TH_:()D()aE P. Vm_mr, St. )., Vice lre,id_,n_ for l,(,earch,Corn(dl Un

10、iv,r,ity.ttrr;t:t I,. I)RYDIgN, PIt. D., Director of Aeronautical RrsearcbJOHN W. (R()WLt,:Y, JR., B. S., Associate Director of Aero,aatical R,sc_trchJOHN F. VI(TORY, I.L.M., t“,.rrc!Hire ,Secretar:tE. It. (_tIAMBERI,IX, Fx_c,tire OfftcerItE._RY J. E. tKli), Eng. l)., I)irector, I,anglcy Aeronaulica

11、l l,at)oratory, Lantdey FMd, Va.SmTU J. DEFrANCe, B. S., Director, Ames Aero)mmical Laboratory, Moffett Field, (alif.h)_VSRt) R. StIARP, S(:. D., l)ireclor, Lewis Fli_fl Propulsion I,al)ora(ory, (!lev(lan(l Airport, (lev_.land, ()lit)TECHNICAL COMMITTEESflk ERODYNAMICS ()PERATING PRoll I.EM_POWER )L

12、ANTS FOR AIRCRAFT INDUSTRY (ON,_UI.TINGAIRCRAFT (_ONSTRUCTIONCoordination of Ifesearch Needs :f Militarq apld (!icil AviationPreparation of Research Pro:/romsAllocation of troble.mPrevention of 1).plir_dionConsideration of l me.tionsLAN(H_EY AERONAUTICAL LABORATORY, LEwis FLIGHT PROPUI.NION LAII()IL

13、_.I()RY, AME.4 AERONAITI(AI. ,AB()RATORY).La|_t_ley Field, Va. Cleveland Airport, Clevela|,t, ()hio Moffett Field, (alif.Conduct. under unified control, for all a,qencies, of scientific researrh on the fundamental prohhms o.f .flightOFFICE OF AERONAUTICAl, INIEIA.I(IEN(TE)Vashinglon, D. C.Collertion

14、, rlm._sification, compilation, and dissemination of scientific and tcchnieal i.form_tion o,_ ._,.,.;.ticsIIProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-CONTENTSPag(_r M M AF+Y _ I NTII)I)I ; 28Airsl_illiogral)hy (owwing all mat(,rial reviewedand

15、judged to I)e of int.cr(,st, with the ex(e)tion of severalvahial)h_ British papers (if limited distribui,ion, has t)conprepared.SYMBOLS,-t area, feeCa spee(l of sound in dry air, feel_ per s(,(:Oll,iaw speed of sound in nloist, air, feet per se(_on(lB vohune eoeffici(qit of (,lasiicity, e(tllation (

16、20), feet aper poun(IC eapa(itan( of lr (.ontiiincr detl ned 1)y i,q ulition (18),fe(,t:_/(lti/fl 2)1Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-2 IEPOWI“ NO. 919-NATIONAI. A1)VIS(H_Y COMMITTEE FOR AEI_ONAUTICSC_cctcp_ (!vDe/pgHhiKkLmMItPrpPoq,qc

17、_RReTTO2Trvv0VW/SX.V_ ,rc 3,sairplane lift (oetti(ienlairfoil choM, f(,etairfoil sect ion lift (o(.fli(i(mtsp(,(qfi(: heats at vonslanl l)ressur( , and v()htn_e,resl)t,(livdy , Btu per l)OmM Fdiameter, feet,ratio of partial t)ressur( of warm V,l)O, in utmos-l)h,re t() slat.it t)r(ssurea(oh,rnlion du

18、o 1() gravily (32.174(I tt,sec _ forU.S. stan(lur(I atmOsl)hove )totnl pressure, )O)ll)d,_ )ev fo()t _at)solutt, altitud(, f(,et; surface h(,at-trnnsf(,r co(,fli-cient, Btu/(so(.) (ft 2) (F)pressure altitude, feetimpact oriti(e diameter, feetteml)(,rature re(ov(qy fa(t(,r detin(,(l by equa-l ion (46

19、) ; pit or-st at it-tube (all brat ion factorthermal (on(h,etivity, Btu/(se() (ft 2) (F/f).)length, fe(,t; (onstant, equation (47)(,(luivah.n( mass, (slugs/fiat,footMa(h number (l/a)loa(l factor; (.onslant, (quati(m (47)Pramltl numl)tq (c_,#g/c)stati(, lm,SSUr( _, l)ounds l)er fooC or inches of wate

20、rs(,a-h,vtd lm,SSUr( , in standard atmOsl)h(,r(, (2116.229ll)/f( z or 4(17.-) in. watt,r)dynami( 1)ressure, pounds 1)or fooff(_ pl_; _ l,il )imt)a(.t pressme, difleren(e I)t,lweon iota) pressureand static t)ressure, pounds 1)er foot e(olllpt(,ssion ratioconstant in perfect gas htw ZL -RgT; r(,sistnn

21、(e toPtlui(I th)w detin(,d I)3- (qua t io)l (17), 1)(rand-setore Isl)(r foot _Reynolds numl)er ( I 7)p,“_)t(qnl)(,ratur(, of fro(, stream, F al).,;tmlly exists I)c(aus040 4 ! /y_:.o_o _. _“ 1o:o , +.o+!,.ooa _ .4 “.002 .2 “-.001 .1806O4OL_6t.452(a) I 1-,AMA / l/ tct de(r:)_-_ ,_.0.,I/tq_ : 0.01/.o _

22、.8 -o.o/,- -“_ _H -0.01-_ _ _ _o,(bl.4.1 ._ .8 .4 .5 .6 .7 .5 .9 /.0Much number, M(at Error in q+and p of 0.5 inch of _:ml.(b) Error in 11, q+,and p of 1 I.rc,nr.FIGURE 1. _t(!h IIIllIll*l!r (_rror corresp_mding to varJol.k+ eYrors ilt _)I_SS, II_ l_QSSILlrl_leIlt.Provided by IHSNot for ResaleNo rep

23、roduction or networking permitted without license from IHS-,-,-4 REPORT NO. 9 1 9-NATIONAL ADVISORY COMMITTEE FOR AERONAUTICSIn figure 1 (a) the effect is shown of an error Aq_ of 0.5inch of water which exists because of an equivalent error,Ap:-0.5 inch of water, in the static-pressure system.The cu

24、rves of this figure arc based on the following equation,which can be obtained fronl equation (6) when ill(: measure-ment of H is considered exact and thus dq,= -dp:AM M2- 5= - M2-t- 5- AP (6a)7M _ pThe curves have not 1)een extended beyond a “stall line“which is arbitrarily l)ased on the assumption

25、that the Ma(hnmnber for stall at any altitude is given by M,m_:O.l_/_po/plFigure 1 (a) shows that except at very high altitudes or atlow Mach numbers a precision either of l percent or of0.01 in the Mach mmlber is achieved if an error of only-t-0.5 inch of water exists in q_ and p. Errors inherent i

26、nthe measurement pro(ess itself, however, may introdu(einaccuracies which materially increase the value of 4-0.5 inchof water.The precision of 211 corresponding to a 1-perccn(_ value ofpressure defect is given in figure 1 (b). A pressure (tefectas used in this paper is the pressure error expressed i

27、n non-dimensional form, as Ap/p, Ap/q_, and so forth. The curvesfor hH/q (p, exact) and Ap/q_ (H, exact) are useful in theinterpretation of calibration curves of pitot-static tubes.The curve for Aqdp (H, exact) represents an error in q_which exists because of 1-percent error in p. In order todetermi

28、ne the ell(,(,( on 211 of errors in static pressure alone/A _.(_ 0.01; q_, exact), the curve for AIt/q_ may be usedsince l.a 1-per(ent error in either the numerator or the denominatorof the compr(,ssion ratio q_/p results in the same magnitudeof error in M.Figures 1 (a) anti I (b) (an be used to det

29、ermine the errorin 211 for other conditions sin(.e A21I and AAI/Jt are (tir0(llyproportional to the error in H, p, or qo They may also I)eused to estinmte the precision necessary in pressure measure-ment to achieve a (h,sired minimunl error in 211.PRECISION OF TEMPERATUREThe temperature of tim free

30、air 7 is not indicated 1)y atlmrmonwler moving it speed 31 r(,lativ(, to the free streambut nmst 1)e COml)Ul(,(I from the relation!1+9 ,_)1 K.1l=whet(, ill(, temperature r(,covery factor K may have a wfluevarying between 0.3 and 1.0 for different inshfllaiions. Thevalue of Y used in e(tm_ti()tl (3)

31、may, (wrefore, m in errorbecause of limitations in the precision with whi(h the valut, sof T, K, and .1I may be determined. Based on a value of3,= 1.4, (his (,rror may be (,xpressed t)y the root-meah-squarcof the (ont ributing errors:/,AT,: (7_r :t:-_.,( r ) +(,i-+O.2Km:) L_, M ) K J /In many instal

32、lations, (he value of K may not be knownwith a pre(ision greater ltmn 10 per(-enl. At Mathnundwrs less (han 0.3 although A3I/AI is as large an 4-10per(nt, T may easily be determined with a precision grmmrthan l l)oreent. As ._I approa(hes 1, howl,re, in (mh,rto achieve an a(r(.uragiwd) the elonga-ti

33、on is equivalent to an effective in(,rt,ase in the wdr|e of i/D,and the magnitude of the total-pressure defect at It givenangle of at tack will bc less than i_ imli(:,led 1)y tig|re 2.Investigation of the total-t)r(,_s_re _lofect for 0.3ehiml the stalic -Pq K-K 1 . The vari-lition of static (lefect

34、with Rcynohis nunlber in(ii(ates a lowerlhnit lit high altitude for the dianleter of static hea(Is andrakes for wake silrve3“s.SERVICE P1TOT-STATIC TUBESVVith (.onnner(ially availat)h, 1)i(ot-slatic tub(s, ditterentialo1 (nil)lit| presstne could 1)e nieaslired wiili gr(iat aocllraey ifinterferen(e e

35、tte(ls of the airl)hln( and liig and instrument(rlOlS W(IP (lot present. Pl(SSllle defects el)rained in cali-1)rations at zi,ro angle of attack of two standard pitot-statictui)es (r(,f(,r(,n(, 23) ill() given in figur( 4. In figure 4 thetotlil-I)ri,ssur( (hfect is (,at(rely due to the (hiiin holes.T

36、he (hf(ts ill oilier angles (if atla(k can I)e ext)e(te(t tovlirv floni lhose given in figure 4. Since lhese tubes haverlilios i/I) of a|)onl 0.3, lh(, defect hi ll would 1)e negligible(,ss lnln _ I)er(enl) for alig(,s of attack up Io ill least 6 orS . Since the nest, shat)(,s are (,longal(,(1, the

37、total-pressure(h,fe(q ill gl(qllor angles of alta(k wouht un(Iouble(lly besnlliler l lain lhe (lalli for heniis|)heri(al noses would indicate(fig. 2), but l)ul)ished (ietaile(t (,alitwations are lacking._irois ill to(ill l)r(sslii( can )e exl)e(ied vith these headstiowever, wiien use(I in li eli(ing

38、-edg( position.Uniform sliiti(. (h,fc(l ov(,l Ii whh, liili_e ()f _ll(.li nuniberresults froni the addilion of li (ollar oi fin lhal (onil)cnsalesfor the ii0glilive defect lisso(iale(I with flow over the iiosc;the resulllinl positive sliil it (lefe(l illn()llnls 1o 2 ()1 :/ )ereentof qo Allhough thi

39、s defect could inlodme an error nf 1 to1.5 I)er(eni in Xaeh liUnil)(T, ih( (OiT(!(liolls (lescril)od inthe section entiile(I “Flitch( (bilil)itiliou of Airspeed andTenll)erature nst.alllitions“ lillow for it.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IH

40、S-,-,-8 II,P_)I(I“ N_. !Jl !_-N,VII(_N,kl, AI)VIS(H_T (:OMM1TIEI“_ I“(1 AEI_ONAUTI(S.010_kJ-.0/-.022LJj -JJo DI rIi_ /3.59815.94.5 I.4 .6 .8 LOMuch nun, be G M/.2J.O2.010-.0/2f-_3.4 .6 .8 1.0Moch numbe_M1.2.16o _l /0 J _jS tern-042 .4 .6“ .8 /.0Math numl_e,q, M1.2.08.040a- n(_hlslltIll_)ll. l_tl_rtl

41、:+t_ 17.04“.040i2 ,4 .8 .8 LOCompression ro#io, qclp(h) Cl|ar tit isllUl(t 2c h.,hin(| stAlie (_lifi(_!s. lh 1,4:1/, _ t_ - I:UII,L() AllElCol:dlalik lrhe;lliqllll!rilta|llUSr, halld!-tyllr Ttllw, .t_ :;/);l,_-ll/),_;lvlrliql(e_2.(f :_.11_21(, of ;tl hlk for S_,lni_,llipsf44al lil),q_, 2 %-;_I/_D; I

42、)S (,2S/1: 2“._i 2“1)1i5; ICIIIIIC( 2JJ,_l_J ITII_: :. ,tlrill ioll of gla! i(IHu$glrl _ drfeet _f i)ihd-sh:ir f ll_l,_ 1“_t|l IAlbe I_!OllSlI u:l i(ll, 1lath l).UlHbl%_ tll_|l, of l 1_1,I-:, ;il tlyllllS lllllllbl_! “, All llJlll(llSifHl: 4 1_ |)_qt.l| On tlllw t.i:lIIl( (_r,Provided by IHSNot for

43、ResaleNo reproduction or networking permitted without license from IHS-,-,-ACCUI/ACY OF AIRSPEED MEASUREMENTS AND FLI(;HT CALIBt_ATION PROCEI)URES 9r r Tl Tr T r( I x _ o _ _ .OZ -f/uch ,numberS-G 70 ./ .2 3 4 .5Compression raho, q_/p(a) I:SS(“ nllniber 1N T- 4.5,15 llillI-Mati(! ruby.(|) F:(! lllll

44、llJWr N T-4554 ifil()l-shllic lilt)(_IG1RI:; 4, TyldIUd lohH- tlli(J _.l:lti(,-i)res,-;Hrq ih,fvels of two airs|lo(,d heads al z(ro ;ln_h,Of :klT_l(k. Jhit_l fIOlll IPfPI(qI(“I! 22_.THE FIELI) OF FLOW ABOUT AN AIRFOILTh( l(uracy r(,quird in each of several measured quan-tities in oM(,r 1o a(hieve n

45、sl)e(ilie(I accuracy in airspeed lill_I)een discussed. Tl,is discussion was followed t)y a sunmmryof the avaiJalde lnalerial Oll the deviations in pressure lllons-lll(qllellt |O J)( eXl)tqlo(J fr()lli (lie isohite(I (ohfl- or stativ-l)ressme head. In lh(, following set!lion tile IM(I of th)wabou( an

46、 airfoil is dismissed aim availal)h, (hlta are sum-nnlrize(I in oMm lhal qualitative (,slimales niay I)( made ofthe (,rr()rs fronl (his (aus(, (hat thus( I)(, (,xlletq(,(l anti alh)we(lfor wh(,n llitot-stali(_ d(,vi(,s arc al(a(h(,d It)an Mrllhuw.Th(, dir(,(qion and v(,1o(it y of the flow all(JUt m

47、airfoilvary, in gen(,ial, from )(fin! to lit)tilt wilh the sllilli( an(lthi(.kn(,ss ratio of tile airfoil, with the lift (_oelli(i(,nt, antiwith th(, Ma(h nunili(,r. As a r(,sult of (h(,s(, variations, th(,st ati(-pr(ssur( error assoeilli(,d with the flow (an l)e exli(,(t edto vary; in a(hlilion, l)oth s(llti(- an(l total-llr(,ssure lit,adsmay I)(, in crr()r l)e(nus(, of indinati(m ()f the flow with respe(tto th(, h(ti(I.Th( r(suJis of li nuinii(T of lh(oreti(til iili(J (,xl)erinienialinv(,._ligali