NASA NACA-TN-4405-1958 Free-flight investigation to determine the drag of flat - and vee - windshield canopies on a parabolic fuselage with and without transonic indentation betwee.pdf

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1、NATIONALADVISORYCOMMITTEEFOR AERONAUTICSTECHNICAL NOTE 4405FREE-FLIGHT INVESTIGATION TO DETERMINE THEDRAG OF FLAT- AND VEE-WI!NXHIELD CANOPIES ON A PARABOLICFUSELAGE WITH AND WITHOUT TRANSONIC INDENTATION BETWEENMACH NUMBERS OF 0.75 AND 1.35By Walter L. Kouyoumjian and Sherwood HoffmanLangley Aerona

2、utical LaboratoryLangley Field, Va.WashingtonSeptember 1958Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-TECHLIBRARYKAFB,NMNATIONAL ADVISORY COMMITTEE FOR AERONAUTICS IilllllllllllllllillllilllllillClDb7J87 -TECHNICAL NOTE 4405 FREE-FLIGHT INVESTIG

3、ATION TO DETEMINE TEEDRAG OF FLAT- ANDFUSELAGE WITH ANDMACHBy Walter L.WEE-WINDSHIELD CANOPIES ON A PARAEULICWITHOUT TRANSONIC INDEN12ATIONRETWEENNUM6ERS OF 0.75 AND 1.3!5Kouyoumjian =d Sherwood HoffmanSUMMARYA free-flight investigation was conducted between Mach numbers of0.75 and 1.35 to determine

4、 the effects on model total drag and pressuredrag of (a) canopy location (along a parabolic baly of revolution),(b) canopy windshield shape, (c) canopy fineness ratio, and (d) transonic- ._area-rule indentation.The results of the investigation indicated that moving a 63 swept-back flat-windshield ca

5、nopy rearward, from near the body nose to themaximum body diameter location, increased the model drag coefficientsat transonic and low supersonic speeds. Changing to a vee-shaped wind-shield resulted in a negligible change in drag coefficient compared withthat for the flat-windshield canopy. When th

6、e canopy fineness ratio waschanged from 7.00 to 4.50 by shortening the canopy afterbody shape thedrag coefficients obtained for the short canopy were appreciably higherthan those for the long canopy. The transonic-area-rule indentationproved effective in decreasing the pressure drag of sll the canop

7、y-fuselage combinations investigated to values within 10 percent of thepressure drag obtained for the basic parabolic body alone near a Machnumber of 1.00. The effectiveness of the transonic-area-rule indentationdecreased with increasing flight Mach number. Comparison of the theoret-ical and experim

8、ental pressure drag coefficients for approximately halfof the number of canopies investigated indicated that the area-rule theorypredicts the order of magnitude of the pressure drag and the qualitativedifference in pressure drag due to the configuration modifications attransonic and low supersonic s

9、peeds.INTRODUCT16NThe present investigationwas conducted to determine the drag char-acteristics of several canopy-body conibinationsat transonic speeds.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-2. NACA TN 4403a71Other investigations of canopy-b

10、ody combinationsare presented in refer-ences 1 and 2. The flight Mach number range for the present investigation uwas from 0.75 to 1.35 and the Reynolds number per foot varied from4.5 x 106 to 9.5 x 106 over the flight Mach-number range. The basic fuselage used in this investigationwas a smooth psra

11、bolic body of revo-lution with a fineness ratio of 10 and with the maximum dismeter locatedat the 40-percent body station. The canopies were designed to investi-gate some effects of windshield shape, canopy length, and canopy loca-tion on the hag of fuselages with and tithout transonic-area-ruleinde

12、n- tations. The canopies investigated consisted of flat-windshield canoPies _having equivalent body fineness ratios of about 7.00 and 4.50and a vee-windshi.eldcanopy having an equivalent body fineness ratio of about 7.00.These fineness ratios are referred to as nominal fineness ratios forthe purpose

13、 of identification only since the actual canopy equivalent_ _body fineness ratio changed slightly (table I) when the canopy positionwas varied and the fuselage indented.The models that were flight tested without area-rule indentationhad the same basic parabolic fuselage shape, whereas the models tha

14、twere indented according to the area rule were contoured symmetricallyfor a Mach number 1.00 indentation to have the same cross-sectionalareadlstributi.onand volume as the basic body alone. Although the canopy wlocations and shapes were varied, the indented models allow a compara-tive evaluation of

15、the local interference effects on pressure drag attransonic speeds. wSYMBOLSAaCDcg1Mmcross-sectionalarea, sq in.acceleration, tangent to flight trajectory, g titstotal drag coefficientbased on a. fuselage reference area of19.63 sq in.pressure drag coefficient (Total drag coefficient at supersonicspe

16、eds - Total drag coefficient at = 0.8)canopy radius coordinate, in.acceleration due to gravity, ft/sec2length of fuselage forebody, in.free-stream Mach numberwProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-the third group consisted of the vee-windsh

17、ield canopy with a nominalfineness ratio of 7.00. The actual canopy fineness ratios (table 1)were obtained from equivalent bodies of revolution that had the samecross-sectional area distributions as the exposed canopies measured per-pendicular to the fuselage center lines of the models tested.The ba

18、sic cross section of the canopies used was a circular arc,the locus of the centers of which was defined by the distance ycmeasured from a canopy base reference line. The canopies used in theinvestigation were all patterned from the basic canopy. The solid coreof the canopy was hollowed sufficiently

19、to allow the canopy to touch thefuselage surface at the canopy foremost and rearmost points. Therefore,the location of the canopy base reference line was lowered and rotatedbecause the canopy was positioned on the fuselage surfacej and thedistance between the fuselage surface and the fuselage center

20、 line dimin.ished whereas the canopy coordinates remained constant. The individualProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-4canopies were faired to thethe canopy maximum width tomodels, the volume added byNACA TN 07a71fuselage by dropping vert

21、ical lines omthe fuselage suF?5?ace;for the indented .this method of fairing was considered andadded to the volume of the fuselage to be rmoved The flat-windshieldcanopy was obtained by cutting the basic canopy by a plane inclined 63fkxn the (vertical)Y-axis and intersecting the canopy at a point ju

22、stbefore the canopy maximum radius coordinate. The vee-windshield canopywas obtained by passing two cutting planes through the basic canopy so that the planes were at an angle of 45 tith.the locus of canopy radiuscenters and skewed at an angle of 28.4 from the horizontal. The inter-section of the tw

23、o cutting planes was a straight line inclined from thevertical by 61.6 and faired into the canopy body with a smooth curve.The short canopy (flat, with a fineness ratio of 4.50) had the seinewindshield shape and frontal area as the long canopy, inasmuch as theafterbody of the long canopy was shorten

24、ed to give the final profile for the short canopy.Fie 2 presents photographs of a typical nonindented fuselagemodel and tilsoa typical indnted fuselage model.Figure 3 showsclose-up photographs of all the canopy-fusele models tested duringthe investigation. Figure 4 presents a comparison of the cross

25、-sectional area distributions normal to the fuselage axis of all the “ e.models. .TESTS .The models were flight tested at the Langley Pilotless AircraftResearch Station at Wallops Island, Va. Each of the models was boostedto maximum flight velocity by a fin-stabilized 65-inch HVAR motor. Aphotogaph

26、of the booster motor and a typical model on a rail launcherprior to firing is shown in figure .The models were ballasted to trim out at very low trim lift coeffi-cients or approximately at zero lift. The experimental data for thisinvestigationwere taken from ground tracking radar by using a CW Doppl

27、erradar unit (and corrected for winds aloft) for velocity and a modifiedSCR-584 radar unit for trajectory measurements. Atmospheric conditionsand winds aloft were measured at the time of each flight by balloon-carried rawinsonde.DATA REDUCTION AND ANALYSISThe total drag coefficient for each model wa

28、s computed, during thedecelerating portion of each flight, from the relation,.wuProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-b.NACA TN 4405CD =- - also presented in fig-ure 8(a) are the theoretical drag coefficientspredicted by the supersonic-area

29、-rule theory. Froma comparison of the theoretical and experimentalcurves in figure 8(a), it is noted that there is an overall relative con-sistency in the level of predicted wave drag coefficientsand the experi-mental results; hence it seems feasible to use the area-rule theory topredict the pressur

30、e drag coefficientsexpected from a configurationmodification. In figure 4 moving the canopies rearward increased themaximum cross-sectionalarea of the configurationsand appesrs to increasethe rate of change of the total cross-sectionalarea distribution in thevicinity of the canopy. These changes cor

31、respondto the increase in dragas the canopy is moved rearward.The drag-rise coefficientsfor the indented fuselage models are pre-sented in figure 8(b). The results show that MD increases as thecanopies are moved rearward for transonic and low supersonic speeds,although this was not exactly the case

32、in the total drags shown infigure 7(b).Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NACA TN 4405 7Effect of Area-Rule Indentation. Figures 9 to 13 present the effect of area-rule indentation on thetotal dxag and the pressure drag coefficients for

33、each canopy tested.Also presented are the curves for the basic body alone in order to pro-vide a convenient method of comparing the effects of the mea-ruleindentation. In general, the area-rule indentation served to reduce thetotal drag and the pressure drag at the transonic and low supersonicspeeds

34、 for all the models investigated. The results also show that theeffectiveness of the area-rule indentation decreased as the flight Machnumber increased. Figure 14 is included to present a summary plot ofall the indented models tested during this investigation. Since all theindented models had the ss

35、me area distribution and volume, the differencesin drag rise shown near M . 1.0 are due to both local interference andexperimental error.Effect of Canopy Fineness RatioThe curves of figures 15 and 16 present the variation of total andpressure drag coefficients for the flat-windshield canopies of fin

36、enessratio 7.00 and 4.50 mounted on the nonindented and indented pmabolicbodies.The curves of figure 15 show that for a nonindented model the shortcanopy has higher total and pressure drags than the long canopy. Thetheoretical calculation of pressure drag predicted that the short canopywould have a

37、high pressure drag coefficient and the experimental resultsverified the prediction.Figure 16 shows the effect of indenting the fuselage for the shortcanopy and it appears that the total and pressure drags of the shortcanopy are still noticeably higher than those of the indented model withthe long ca

38、nopy.Effect of Windshield ShapeFigure 17 presents the variation of total and pressure drag coeffi-cients for the flat- and vee-windshield canopies of fineness ratio 7.00mounted on the nonindented fuselage. The curves show that there wasrelatively little difference in total drag between the two winds

39、hieldshapes investigated. The theoretical calculations of pressure drag pre-dicted also that the vee windshield would have slightly higher pressuredrag than the flat windshield.Figure 18 presents the results for the two windshield shapes mountedon indented fuselages. The results inticate a negligibl

40、e vsriation inProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-8 NACA TN 4403total and pressure drags at the transonic and low supersonic speeds andthere appears to be an increasingdifference in total and pressure drags *for the two windshields as the

41、 flight velocity increases. .CONCLUDINGREMARKSThe present investigationwas conducted to determine the total dragand pressure drag coefficients of several canopy-fuselagecombinations and to determine the effect on the drag coefficient of canopy locationalong the basic parabolic fuselage, windshield s

42、hape, canopy finenessratio, and aea-rul.e indentation. The flight tests were conductedwithfree-flight models flown through a Mach number range of 0.75 to 1.35.The data included comparison of experimental results with the theoretical pressure rag coefficientswhich were computed for some of the mtiels

43、 .-tested by-using the supersonic-area-ruletheory. .The tests of the canopies on the parabolic fuselage showed thatthe total drag and pressure drag increased as the canopy location wasmoved rearward to the maximum body dismeter”station. There was,a neg-ligible difference in drag due to windshield sh

44、ape. The effect offineness ratio was to increase the drag en the canopy fineness ratio *was decreased. Indenting the fuselage for a Mach number of 1.00 lowered the total.drag andressure drag coefficientsat the :ransonic and low supersonicspeeds for all the canopies tested. The effectiveness of the i

45、ndenta-tion decreased with increasingMach number. Comparison of the modelpressure drag determinedby the area-rule theory with the experimentalresults indicated favorable correlation in the ability of the area-ruletheory to predict pressure drag variationswith canopy configurationmodifications. Since

46、 the five indented models tested had the same total .-cross-sectionalarea snd volume distributions,the differences in dragobtained at transonic snd low supersonic speeds, for these models, were due to both local interference effects and experimental error. Langley Aeronautical Laboratory,National Ad

47、visory Committee for Aeronautics,Langley Field, Vs., September 2, 1958.” .-*“Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-REFERENCES.NACA TN 4405 91. Welch, Clement J., and Morrow, John D.: Flight Investigation atMach Numbers From 0.8 to 1.5 of th

48、e Drag of a Canopy Located atTwo Positions on a Parabolic Body of Revolution. NACA RML51A29,1951.2. Cornette, Eldon S., and Robinson, Harold L.: Transonic Wind-TunnelInvestigation of Effects of Windshield Shape and Canopy Locationon the Aerodynamic Characteristics of Canopy-Body Combinations.NAcARML

49、55m8, 1955.3. Van Driest, E. R.: Turbulent Boundary Layer in Compressible Fluids.Jour. Aero. Sci., vol. 18, no. 3, w. 1951, pp. 145-160, 216.4. Morrow, JohnD., and Nelson, R. L.: Large-Scale Flight Measurementsof Zero-Lift Drag of 10 Wing-Body Configurations at Mach Numbersmmmo.8to 1.6. NACARML52D18a, 1953.5. Jones, Robert T.: T