1、 , . -%7+.: “,.iI!IIlunllml!lllllllmullllllllllA!fw 141947figure 2(b) presents the characteristics with thegap equal to 0.005c. Part of the data in figure 2 is re- +plotted in figure 3 to show the effect of gap on the varia- 1tion of ch with c1 for three typical values of angle wfof attack. Incremen
2、ts of drag caused by deflection of theflap are given as a function of flap deflection in figure4. The tab characteristics as a function of *ah deflec-tion at constant angle of attack for various flap deflec-tions are shown in fire 5. ,.?lQIRODYNAllIC SECTION CHARACTERISTICSLiftFigure 2 indicates tha
3、t the lift curves of the NACA0015 airfoil for the various flap deflections are of thesame general shape as the corresponding curves for theNACA 0009 airfoil (reference 2). At any given flap de-flection, however, the angle of attack at which the air-foil stalls was about 5 greater for the thicker air
4、foilthan for the thinner airfoil; consequently, the maximumlift coefficient of the thicker airfoil was greater by anincrement Acz -of about 0.4. This effect may be attrib-uted to the greater nose radius of the thicker airfoil.The slope of the lift curve c1 was 0.096 for theaflap with a sealed gap an
5、d 0.089 for the flap with the0.005c nose gap. The decrease in slope caused by unseal- -ing the gap agrees qualitatively with the results for theNACA 0009 airfoil. With the gap both sealed and unsealedthe slope for the thicker airfoil was, howerer, somewhatless than for the thinner airfoil.The effect
6、iveness of the flap in producing lift().af cl Was-0.58 for the flap with sealed gap and. . .Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-7-0.46 for the flap with the open gap. The lift, effective-ness of the flap on the thicker airfoil was practic
7、allythe same as that for the same chord flap on the NACA 0009airfoil. Thq fact that the effectiveness was greater whenthe flap nose gap was sealed than when it was un”sealedagrees with the test results for the NACA 0009 airfoil.The flap was effective in producing increments of lift atall deflections
8、 for all angles of attack at which testswere made. Because of separation phenomena, hoivever, theeffectiveness at large deflections was not so great as atsmall deflections.The parameter cl listed in table II, is aa(free)measure of control-free stability. The decrease in theslope of the lift curve wi
9、th a free-floating flap wasnearly independent of the flap nose gaps tested.Hinge Moment of FlapThe nature of the distribution of pressure over theflap on the NACA 0015 airfoil is, apparently, differentfrom that over the flap on the NACA 0009 airfoil. Thiscondition is indicated by the fact that the s
10、lope Chf. a.is much smaller for the thicker airfoil than for thethinner airfoil and that the curves for the thicker air-foil (fig. 2) are not so nearly linear over the entireangle-of-attack range as they are for “the thinner airfoil “(rqference 2). The air flow over the trailing-edge por-tion of the
11、 thicker airfoil is prolably similar to thatdiscussed in reference 3 for flaps of thickened profileand beveled trailing edges. The -aerodynamic character-istics of the plain flap on the NACA 0015 airfoil areremarkably similar to those reported in reference 3 forthe NACA 0009 airfoil yith a flap of t
12、hickened profileand a long beveled trailing edge.The hinge-moment parameters for both gaps are givenin table II. Becauseof the nonlinearity of the hinge-moment curves,” the parameters chfa and chf6f .measuredat 0 flap deflection and 0 angle of attack, respective-ly, represent the curves over only a
13、small range of angles.The values of the parameters for different gaps are indic-ative, however, of the relative merits of each particulararrangement. For a complete picture of the merits of eachProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-8 flap-g
14、ap arrangement, the entire set of hinge-momentcurves (fig. 2) must he taken into consideration and toomuch reliance should not be placed on the values of theslopes measured at one particular point.In general, the slope chf for the I?ACA 0015 air-afoil with .a 30-percent-chord plain flap was about on
15、e-third as great as that for a similar flap arrangement onthe NACA 0009 airfoil (reference 2). The slope chf6ffor the thicker airfoil was about one-half as great asthat for the thinner airfoil. The effect of aspect ratioon the various slopes-is discussed in reference 1.Figure 3 indicates that for sm
16、all flap deflectionsat angles of attack of -8 and 0 the airfoil with a0.005c gap had a smaller hinge-moment coefficient at con-stant lift than the airfoil with the sealed ga”p. At allother at$itudes of the airfoil and flap the hinge-momentcoefficient for the unsealed flap was greater. Corre-SpOn the
17、relative values, however, should be independent of tunnelProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-9effect, Increments of drag coefficient, plotted as a func-tion of flap deflection in figure 4, were determined bydeducting the drag coefficient
18、of the airfoil with theflap and tab neutr from the drag coefficient with theflap deflected, with all other factors nonstant. At pOS-itive flap deflections and positive angles of attack, theincrement of drag coefficient Iras larger for the flap withunsealed gap than for the flap with the sealed gap.I
19、n these tests, the minimum profile-drag coefficient,uncorrected for tunnel effects, was found to he 0.0130for the NACA 0015 airfoil with the flap sealed at thehinge, Unsealing the gap increased the value of this co-efficient by 0.0004, an increment that is of the samemagnitude as the corresponding i
20、ncrment for an NACA 0009airfoil (reference 2).Tab CharacteristicsThe increments of lift and flap hinge-moment coeffi-cients caused by tab deflection (fig. 5) were obtained bydeduoting the coefficient with tab neutral from that withthe tab deflected, with all other factors constant. Thetab was effect
21、ive in producing increments of flap hingemoment at all tab deflections tested and, in general, was .more effective when the angle of attaok and the tab de-flections were of the same sign. The slope Ch5t - tias .roughly -0.001, a value that is of the same order of mag-nitude as the value of the slope
22、 for a similar tab on theNACA 0009 airfoil (reference 2)., (JihcThe lift effectiveness of the tal b wasclslightly greater than that for a similar tab on the NACA0009 airfoil (reference 2). With the flap deflected,however, the inurements of lift caused by tal deflectionwere of abut the same magnitude
23、 for both airfoils.The curve of the variation of tab hinge-moment coef-ficient with tab deflection was fairly linear, with aslope cht of approximately -0.005. with angle of at-tack, however, the slope of the tab hinge-moment-coeffi-cient curves chta was positive over a small range of.angles of attac
24、k. This fact can probably be attributed toProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-10the relatively thick trailing-edge profile on the NACA0015 airfoil and agrees qualitatively with the resultspresented in reference 3 for a flap of thickened p
25、rofile.The effect of profile thfckness of the flap, apparently,becomes greater as the flap chord is decreased.CONCLUSIONSThe results of the tests of the NACA 0015 airfoilwith a plain flap having a chord 30 percent of the airfoilchord compared with the results of previous tests of asimilar flap in th
26、e HACA 0009 airfoil indicate the fOl-lowing conclusions:1-. The slope of the lift curve for the NACA 0016airfoil was slightly less than that for the I?ACA 0009 air-foil and decreased when thG gap at the flap nose was un-sealed.2. The lift effectiveness of the plain flap on thel?ACA 0015 airfoil was
27、practicly the same as that of thesimilar flap on the NACA 0009 airfoil. Unsealing the gapat the flap nose appreciably decreased the flap lift ef-fectiveness.3. The hinge-moment curves for the NACA 0015 air-foil were not so nearly linear with angle of attack andflap deflection as those for the NACA 0
28、009 airfoil. Z%eslope of the curve of flap hinge-moment coefficient as afunction of angle of attack was about one-third and theslope of the curve of flap hinge-moment coefficient as afunction of flap deflection was al)out one-half of the cor-responding values for the similar plain flap on the NACA00
29、09 airfoil.4. In general, the results indicate that, on boththe NACA 0015 and the NACA 0009 airfoils, the plain flapgave a greater lift effectiveness with smaller hinge mo-ments with the flap gap sealed than with it unsealed.The effect was smaller, however, for the thicker than forthe thinner airfoi
30、l.5. The flap with a sealed gap gave a smaller minimumprofile-drag coefficient than the flap w“ith unsealed gap. . .Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-11”6. The. tab was effective in producing increments offlap hinge moment at all deflec
31、tions at which tests weremade and was slightly more effective when the angle ofattack and the tab deflection were of the same sign.Langley Memorial Aeronautical Laboratory,National Advisory Committee for Aeronautics,Langley Field, Va.-JProvided by IHSNot for ResaleNo reproduction or networking permi
32、tted without license from IHS-,-,-ai2REREREIICES1.2.3.4.5.Ames, Milton B., Jr. , d Sears, Rfchrfoj)q,3ocp/b/t7f/up0,20 Cf fobP/ai7 f/ap wii QO05C ua .K.-,n-,Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-.NACA Fig.2a4-72,I 1+.1 I I -i-6 :4 72 0 .2 .
33、4 .6 .8 1.0 12 1.4 1.6 1.8 2.0.4 - . ; . -_ ._ _ . _ _, .,.; - . . . :. ,” . A “. :.“Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NACA . Fig. 5CProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Fig.
34、5dNACAit!F19u20I I ! I I 1 ,-.I I ! I I I I I I111111K,(deg )o /2A8 on+00v -40 P -84 +2-1/ / /3 / (d)” =25 0.-ZO - -/6 -/2 -8 -f% -o-24Con*nd 7ub deflection.4 tde9are5.-A7ab sec+ion hinge-moment coeffic ienf Od increments of L7JfoJsecfion ltffcoeff icien ? and f/apsec+lon hinge -mome n+ coefff Cleh fcoused by d- .:. ,. -.-,- .:- . -. . . ,. . .-”.,.-”- “_. _.- - -Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
