1、. “u-.,w-%=-NATIONAL ADVISORY COMMITTEE FOR AERONAUTICSWAlwmll. Itlm)lrr“cORIGINALLY ISSUED July1942asA. Genero.1 ConditionsA pierequisite for the Lcvelopnent of a sr.tifactoyoporatiag teclmiquc for powczd-mot.el tests is the uclcc-tion of the airT)lanc owcr co:lilitions ilat should ?36 Sifilu-lated
2、, 1.asmuch as the adverse. e-ff.ectsof power on thech.a72.cterist5.cs of tk.e. airplano kesult frow. the propellerslipstream and the direct rOJC.er iorcos, reproduction% of the power conditions for which the slipstream vel.oci- ,ties anti i3ro;?eller force are .f;reate:jtwill be flesirable. As the -
3、sirmlanc often oper.akes without poner? that is$wi.tb-the ropeiler wind.milling,*6 and may have unsatisfac-tory cilare,cteistics i.nthis condition, the windmillfng!i!hepro-oel.ldr-removodst,ate mst also be j.nvestigatedaondi.tion is never cncountcrccl in flight, l)itdata forthir$ condition are alway
4、s d.csira%e for purposes of com-parison.“-.* .Longitudinal Characteristics,The airplane innornal flight may operate. over its.,.speed range with any one of sovcraj. p,ower conditionsincluding level-”flight powc, constailt,ang.c-of-clim?l.powcr, constant pcwcr, aild idling engines. Wi”nd-tunn c1dati.
5、 nay b ol)taincd either by siimlating ihc appropriatepower condition on thc iodcl throughout its ailgl-of- *attack range or .by repcatin.-.,OZA POW3ZREI)MODELa i/5-scale model of a low-wingsi,ngle-eng.lne, pursuit-type airpane. It was made ofmahogany with a hollow fuselage inn.which the motor andthe
6、 hinge-noment balances wore installed A threoviewdrawing of the model is shown in figaro 1.Test cond.j.tion.sand nroced.urc.- The tests were made.in the NAGA 7- Dy 1,0-foot :indtunnel (references 12” an”i13) at a dynamic press-tire of 4.09 poancls Per square foot,corresoilding to a velocity of a-out
7、 40 ,miles per b-our atstandard sea-level conditions. The test Reyu-olds number,eased on t“nis speed and. a mean aerodynamic chord of 16.32inches was about 500,00C. The turbulence facor of thec+t- b37 0-fot t-nnel is 1S67 so that tie effective R.eynOldsn.mler was e,-DOU% 80CI,000. Te test procedure
8、was similarto that indicated in part 11.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-xlAll. corrections are ail.d.edto tunnel iLnta-tliors (10), (11), and (12)correc-(15)(11)C?cgrao. . .7a. .Provided by IHSNot for ResaleNo reproduction or networki
9、ng permitted without license from IHS-,-,-I. ,. KESTJN! s.The results of the pitchmower conditions are RivenOIlaracteristics in vitch.-tests of the uodel with various -illfig-.nes9 to 12s Examination of these figures revltaisthe following facts:1, The effect of prope?.te operation wa destr.bil.i:j-i
10、ng whether or not pcwer was ayplied (figs. Sl(a)”and S(b),The windmillifig propeller decreased. the slope of the CurVeof pitching nonent a,ainstflift shout 25 percent bolow thepropellsrureaoved VZ.ued A-pplicatior. of power decreasedthe sloye of this curve still further, hut” the decreasewas apparcn
11、tly not a diect furction of the power applied.,.%.-. .-1. .2, Theapplication of power iucreased tho slope oftho lift curve anti th increase was approximiely pro-portional to the amount of po,.mr(figs. 9(zL) and 3(3).The maximum lift coefficient also increased with pov?er-(fig. 9(a)*3. An incrc?.so i
12、n royeller-bla.de angle slightly de-creased the slope of the pitching-monent curve for. thefu.il.-power Condition (fig, 1(.-)but hmd no apprec,ie “effect on the slope for the propeller windmillir.g condi-=tion (fig, 10(3).4. The stabilizer effectiveness was constant tkcrough-out the lift rc.nge for
13、the propeller-windm.illing contrition,just as it usnally is for the ower-orff condition. Thiseffect is shown by the pitching-moment cur.esof figure11(o), whicl?.are approxiae.tely linear and parallel. The “st,nbilizer effectiveness p-creased with increasing tk.rustcoefficient for pOiVer-On opeu,tion
14、. This effect is shownby the di-rerging pitching-moment c.ures of figure Ii(b)where the slope of tb-e civcs decreases with decro.asir.gpositive values of Stal)ilizer angle. (The thrust cooffi-tier.t ,in.creases with-l lift coefficient,)5. The elevator effecti=eness s.nd the sloe gf thepitching-momen
15、t curves for the ariov.sdeflections (fig.12) :?.ndpower conditions were ;zffectcd ih.thd saroe waytb-at tho ste.biliztir effectiveness and sl.opc WC1*C ficcted.Characteristics in yaw.- lke resul$s of the yaw testsof tie model are presented in fg-ares 13 to 17. The fol-lowing points are worthy of note:Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
