GITHRU ICODEI (CATEQORYI

Transcription

1 5 GITHRU z ICODEI (CATEQORYI

2 1M NATIONAL ADVISORY COMMI'ITEE FOR AERONAUTICS RESEARCH MEMORANDUM for the Bureu of Aeronutics, Deprtment of the Nvy ZEXO-LIFT DRAG OF THE CHANCE VOUGHT REGULUS I1 MISSILE AT MACH NUMBERS BEWN.8 AND 2.2 AS DE-D FROM THE FLIGHT TESTS OF 'IN.l2-SCALE MODELS TED NO. NACA AD 398 By Jmes D. Church SUMMARY Two noninstrumented.12-scle models (with internl flow) of the Chnce Vought Regulus I1 missile were flight tested to investigte drg chrcteristics of the missile for rnge of Mch numbers from.8 to 2.2. Mesured totl-drg-coefficient dt were reduced to externldrg-coefficient dt by using qulittive estimtes of internl nd bse-drg coefficients. Both the totl drg s mesured on the two models, the externl drg of the present tests, nd some unpublished preliminry wind-tunnel test dt show tht differences in the drg level occurred for rnge of supersonic Mch numbers between 1.3 nd 2.. These differences in the drg, believed to be cused by the dditive drg chrcteristics of the inlet, leve the exct drg level of the configurtion investigted in question. INTRODUCTION At the request of the Bureu of Aeronutics, Deprtment of the Nvy, the Ntionl Advisory Committee for Aeronutics hs mde n investigtion of the drg chrcteristics ner zero lift of the Chnce Vought Regulus I1 missile (XRSSM-N-9). This drg investigtion utilized two.12-scle rocket-boosted models, which were flown in the speed rnge proposed for the full-scle missile. These flight tests were conducted t the Lngley Pilotless Aircrft Reserch Sttion t Wllops Islnd, V.

3 2 This pper presents the results obtined from the flight tests of two noninstrumented drg models hving internl flow. Mesured totldrg coefficients re presented for rnge of Mch number from.8 to 2.2. In ddition, the vrition of externl-drg coefficients hs been estimted over the sme speed rnge by use of qulittive vlues of bse nd internl drg. 9 SYMBOLS X L MGC A S M longitudinl distnce, mesured from the nose, in. model length, 81.5 in. wing men geometric chord,.873 ft cross-sectionl re, sq in. totl wing re (including body intercept), 2.8 sq ft Mch number 9 dynmic pressure, lb/sq ft R m/% CD Reynolds number (bsed on MGC) rtio of mss flow of ir through the duct to mss flow of ir through free-strem tube of re equl to projected inlet frontl re (6.68 sq in.) drg coefficient, Drg/qS Subscripts : t i b e totl internl bse pressure externl

4 3 b MODELS AND TESTS I t Two models of the Regulus I1 missile were tested. Ech model ws.12-scle version of the full-scle missile with the exception tht it hd smller duct exit nd, hence, lrger bse nnulus (7.6 sq in.) in order to more nerly simulte the internl flow of the missile. A three-view sketch of the.12-scle model is presented in figure 1. The fuselge consisted of nose section (contour coordintes presented in tble I) with ' 2 body "flt" tht led into n underslung boundrylyer bleed nd inlet system. The inlet fce ws included in plne swept forwrd 43.8' nd the initil internl lip ngle ws 14.3' (design M = 2.3). Flow from the inlet went through double minimum duct which exhusted t the bse of the fuselge. The cross-sectionl re of the duct ws reduced from the lip to minimum, incresed to constnt re, then reduced gin to second nd smller minimum ner the exit of the duct (see tble 11). The boundry-lyer bleed ws split t the intke to dischrge from ports locted under ech wing. The wing nd til surfces were mounted on the fterbody nd hd slightly modified biconvex irfoil sections, s well s blunt triling edges (see tble I). 'I '. i' The nose section, the csting for the inlet-boundry-lyer bleed, nd the solid wing nd til surfces were of luminum lloy. The duct in the wooden fterbody ws fbricted from fiberglss reinforced with short luminum sleeve inserted in the exit. A plot of the longitudinl distribution of cross-sectionl re is presented in figure 2. The re distribution of this figure hs been djusted for mss flow rtio by subtrcting the equivlent free-strem-tube re t M = 1. (projected inlet frontl re multiplied by reference 1. m/%) s suggested in I The two models, which were identicl within construction tolernces, were ccelerted to pek Mch number by two different booster-rocket systems. Model 1 ws propelled by single ABL Decon booster nd model 2 by double Decon booster. Photogrphs of the model nd the two model-booster combintions re shown in figure 3. "he models were flown ner zero lift by virtue of center of grvity tht ws fr forwrd. The totl drg ws computed from dt obtined during the decelerting portion of flight tht followed seprtion from the booster. This drg computtionlmethod (presented in ref. 2) utilized the following mesurements of ech flight: model velocity by CW Doppler rdr (corrected for flight-pth curvture nd winds loft), model position in spce by rdr trcking set, nd tmospheric dt by rdiosonde. I

5 4..- em eoe eo The possible rndom error of the dt is experience to be within the following limits: estimted from previous Subsonic Supersonic M... to. 1 to. 5 c ~.... *.3 io. 2 Although these estimtes pply to the bsolute vlue of the quntities, the probble error in these vribles cn be considered to be roughly one-hlf s lrge s tht shown. The vrition of Reynolds number with Mch number for both model flights is presented in figure 4. Since n estimte of internl drg will be presented, the estimted mss-flow rtio m/mo is lso shown on this figure. RESULTS AND DISCUSSION The mesured totl-drg coefficients for the two models tested re presented in figure 5; lso shm re qulittive estimtes of bse nd internl drg coefficients nd the corresponding externl drg coefficients. I Totl Drg The totl-drg-coef f icient (CD~) curves shown in figure 5 () indicte tht the.12-scle model hd drg-rise Mch number of pproximtely.95. The totl drg coefficients of models 1 nd 2 were in good greement between M = 1.16 nd M = 1.37; nd it is interesting to note tht pproched the sme level for ech CDt model t its highest test Mch number. However, in the Mch number rnge between 1.4 nd 2., the drg levels of the two models differ by n mount lrger thn the estimted ccurcy of the dt. It is believed tht this discrepncy in my hve resulted from differ- CDt ences in the mss-flow rtes of the two models. Externl Drg In n ttempt to extend the usefulness of the test results, these totl-drg vlues were reduced to externl drg by subtrcting qulittive estimtes of the internl nd bse drg of ech model. The

6 estimted mss-flw rtio m/% of the models used in the present tests is presented in figure 4. Vlues of m/q, nd totl pressure recovery were obtined over the intermedite Mch number rnge of the present tests from unpublished wind-tunnel results supplied by Chnce Vought. These test points were then fired nd extended over the required Mch number rnge by use of clculted vlues of flw prmeters - these clculted vlues were obtined by ssuming the duct recovery nd the choking t the minimum section ner the exit. Vlues of the internl drg coefficient, s usully defined for internl flow systems, CQ, were determined by substituting the estimted flw pr- eters into the eqution contined in the ppendix of reference 3. Further clcultions indicted tht for firly wide vrition in flow rte the ssocited chnges in the mgnitude of cdi were quite smll when compred to the mgnitude of CD~. The single cdi curve presented in figure 5(b) is therefore considered to be good qulittive estimte for both models. Bse pressure drg C% ws empiriclly estimted from compi- ltion of results obtined from rocket-propelled models. These results consisted of bse pressure mesurements mde on numerous ducted models with bse nnuli tht were flown with choked exit condition. The nnulus re of the.12-scle model ws used in conjunction with these bse-pressure coefficients to yield the qulittive estimte of shm in figure 5(b) for both models. The externl drg CD~, lso shown on figure 5(b), ws obtined by subtrcting the clculted CD~ nd C% vlues from the CD~ curves of both models. Also presented in figure 5(b) re preliminry test points obtined in the Lngley 4- by 4-foot supersonic pressure tunnel on ducted.65-scle model of the missile. These dt re presented for the mss-flw rtios estimted for the flight models, shown in figure 4. The test Reynolds numbers bsed on the model men geometric chord (5.78 in.) were R = 1.91, 1.83, nd 1.57 X lo6 for M = 1.41, 1.61, nd 2.1, respectively. As shown in figure 5, the difference in the estimted externldrg level of the two models is reflected into the mesured totl drg. Moreover, comprison of the tunnel dt nd the rocket model dt shows these unexpected differences in the externl drg which indicte tht the inlet my not be functioning properly. It is believed tht t ny prticulr Mch number the flow rtes of ech flight model differed from the ssumed m/m, vlues presented in figure 4. As previously stted, internl-drg vritions resulting from differences in flw

7 6 rte re smll compred with vritions of the totl drg; however, it is believed tht chnges in flow rte nd duct chrcteristics could cuse pprecible vrition of the externl drg s result of the influence of scoop spillge. This dditive drg due to scoop spillge is considered prt of the externl drg, nd by virtue of such fctors s inlet shock oscilltions, chnges in trim ngles, smll differences in geometry, etc., could chieve sufficient mgnitude to ccount for the discrepncies encountered in the externl drg. SUMMARY OF RESULTS The results of flight tests of two.12-scle models of the Chnce Vought Regulus I1 missile re presented for rnge of Mch numbers from.8 to 2.2. Mesured totl-drg-coefficient dt were reduced to externl-drg-coefficient dt by using qulittive estimtes of internl nd bse drg coefficient. The externl drg of the present tests nd some preliminry wind-tunnel test points shred difference in the drg level for the rnge of supersonic Mch numbers between 1.3 nd 2.. These differences in the drg re believed to be cused by the dditive drg chrcteristics of the inlet; determintion of the exct drg level of this configurtion will therefore require dditionl dt. Lngley Aeronuticl Lbortory, Ntionl Advisory Committee for Aeronutics, Lngley Field, V., July 15, Approved : JKS (++% w / I/ Joseph A. Shortl Chie of Pilotless Aircrft Reserch Division Jmes D. Church Reserch Scientist

8 7 *" REFERENCES 1. Hll, Jmes Rudyrd: Comprison of Free-Flight Mesurements of the Zero-Lift Drg Rise of Six Airplne Configurtions nd Their Equivlent Bodies of Revolution t Trnsonic Speeds. NACA RM L53J21, 19%. 2. Wllskog, Hrvey A., nd Hrt, Roger G.: Investigtion of the Drg of Blunt-Nosed Bodies of Revolution in Free Flight t Mch Numbers From.6 to 2.3. NACA FW L53Dl&, Merlet, Chrles F., nd Putlnd, Leonrd W.: Flight Determintion of the Drg of Conicl-Shock Nose Inlets with Vrious Cowling Shpes nd Axil Positions of the Center Body t Mch Numbers From.8 to 2.. NACA RM L54G2l, b ' I

9 8 TABLE I.- PERTINENT MODEL COORDI3ATES Body nose contour (in.) Wing irfoil contour (percent chord) Sttion Rdius X Y t Stright line J * om.Olog n.83.w2.2 ie firing Stright -1 from tngent to cons tnt leding-edge rdius of.4 inch to tngent of.1 chord. J

10 2M eo. e eo oe mo..e TABU 11.- DUCT AREA PERPENDICULAR TO DUCT CENTER LME Are t first sttion is the projected inlet frontl re.

11 c I p f c i L B Y P 3 I IC fi cd k! I fi

12 # r- (D in r( dc t.9 CJ

13 ( ) Three- qurter-rer view. L Y L (b ) View of i n l e t nd boundry-lyer bleed rrngement. Figure 3. - Photogrphs of the models.

14

15 l i e cu cv. cu e ri 1D e rl * ri % cu ri ri cv ri e # P

16 e::.....e : m i.. NACA RM SL54HO2:,* :,....: CDt M () Mesured totl-drg coefficient. 'j.6.4 cd o 2.2 m (b) Estimted externl-drg coefficient nd estimted internl nd bsepressure drg coefficients. Figure 5.- Vrition of mesured nd estimted drg coefficients with Mch number. NACA-Lngley