REG NACA-RM-L8H10-1948 Effect of airfoil profile of symmetrical sections on the low-speed static-stability and yawing derivatives of 45 degrees sweptback wing models of aspect rati.pdf

1、.+. l . Cqps No. 134 RM No. L8HlO RESEARCH MEMORANDUAn- EFFECT OF AIRFOIL PROFILE OF SYMMETRICAL SECTIONS ON THE d 3 LOW-SPEED STATIC-STABILITY AND YAWING DERIVATIVES OF ,” 5 t: 45O SWEPTBACK WING MODELS OF ASPECT RATIO 2.61 G William L-etlco and Byron M. Jaquet Langley Aeronautical Laboratory Langl

2、ey- Field, Va., NATIONAL ADVISORY COtiMlTTEE FOR AERbNAUTlCS I WASHINGTON November 9, 1948 =- L -ZY 2. -j iEg . - E- - - Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-%prymoAtrnff 139A Tot Pfatr ibution PRQM: 1 SUA/SlSCUrity . Claaeificntion Office

3、r SUBJECT: Authority to Drscfaesify NACA/NASA Rocuuonts Dated Prior to January tr t960 v+-+ 7 - y?ao the leding edge: biconvex (12 percent thick), NAC!A 651-o12, sad mcl0.A 0012. The vings all were of aspect ratio 2.61. l The results of the teats Fndicate that, of the wings tested, the . biconvex wi

4、ng had. the lpwest lfft-curve slope asd the lowest value of . maximum lift coefffcient. Of the derlvativea resulting fram an angle of yaw or a yawing velocity, only the effective dihedral and the ronmoment due to yawing parameter were seriously affected by change In profile shape. Thevalues of both

5、these derivative8 were reduced as the sharpness of the wing leading edge increased. It appears that certain qualitative predictionney stability tunnel. The methods and conditiona of testing in yaw- flow are presented in reference 2. The models tested consisted of three untapered tinge of 45O sweepba

6、ck and aspect ratio 2.61. The models had the foIllowIng -profiles In planes normal to the leading edge: biconvex (12 percent thick), IWX 651-01.2, end NACA 0012. The plan form of the models a the three profiles are shown in fiJ?e 2. Also shown in figure 2 is the semispan le however, lIzhe % values a

7、re quite-important. At moderate Uft coefficients the negative values of C 9 for swept wings may contribute an appreciable amount to stability (of.the wings tested, the RACA 0012 wing is the most stable) but at high lift coefficients, the instability ( positive W of the swept wing may offset the stab

8、ility given by a vertical tail and, thus, may cause the complete airplane to be unstable. . Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-xAcARMmo.mETlo 7 The effects of alrfoil sections on c % however, are TmportXUt. The value of C 2* irr affectad

9、 both tith regard- to its maximum value and the lift coefficient at which the curves beg311 to deviate frm their initial linearity. Ingeneral,as theairfoilnoss shapewasmademorepofnted both them3ximumvalue of C 2* and the range over which the characteristics were lfnear decreased. The addition of the

10、 nose spoiler to the IKACA 003.2 xIng had very little effect on % - % but decreased slightly the maximum value of Cz . * The value of A at zero lif% coefficient for a 450 sweptback wing (=z % of aspect ratio 2.61, even by the theory of reference 4, IS 0.0055. This theoretical value is acmewhat less

11、than the experimental values with the exception of the value of 0.0050 obtained with the biconvex section. (See table I.) Most of the data in skai.zt flow were obtained tith a turbulence screen about 10 feet ahead of the model to obtain data in strafght flow withmore nearly+ which are considered to

12、be insieplif- r icant. There was very little effect on C +; however, there was a reduction of the maximumvalue of . “r and a slight decrease In the lift coefficient at which C2 began to deviate from linearity. r . - . From the similarity noted for the effects of airfoil section on C2 * and % it migh

13、t be expected that some .criterion might beselected which r would make it possible to make certain qualitative predictions of the trends in stability derivatives by using only basic lift and drag data. A etitable criterion for sweptback wings appears from reference 6 to be t $ e increment CL of drag

14、 not ideally associated with lilt or, roughly, CL, - x. This Lncre- * ment is plotted for the different tings in figure 8. The lift coefficient = at which this Increment bens to rise rapidly should indicate the beginning . of flow separation from 6ome point on the wing and it is at this lift coeffic

15、ient that changes would be expected to occur in the stability de- rivatives. The drag increment (fig. 8) beans to increase rapidly at about 0.6 lift coefficient forthe RACA OCl2 wing, and from figures 5 and 7 it Provided by IHSNot for ResaleNo reproduction or networking permitted without license fro

16、m IHS-,-,-can be seen that the values of for the IEACA 0012 wing beEACA RM No. L7D14, 1947. . Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-!cABLE I.- CWARIsrn OF m Am 9?HBxmIcAL vALm oFscmoF!tm mpcmlmTmoDyRAMIc PARAmJm3 at C =O “L, L % P at c,=o c

17、, P at CL=0 f Alrfoil seotion meary meoI7 Theory Theory Measwed (refereMe 4) (refeme 5) Measma (reference 4) Measm (refermice 4) iTAL ool.2 0.0420 ao .04o7 “0 -0395 0.0071 0x055 0.460 0.277 NACA 6yo12 A430 b .0422 b A418 .wJ- do55 .m 477 Biconvex .o3y .0383 c .0355 -00% m55 .400 a7 IucAoo with nose

18、.0420 %to7 a .o395 .0074 .0055 ,430 .277 spoiler aAseumed section li I I j 1, . Figure 3. - The 45 sweptback w mounted in the curved-flow test section of the Langley stability tunnel. NACA0012 airfoilsection. G Provided by IHSNot for ResaleNo reproduction or networking permitted without license from

19、 IHS-,-,-. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-l NACA FM No. I&U0 17 . Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-18 NACA RPllNo. L8EU-C . .Lw . .Lw cz, 0 -z t i i i i i i i i . Provi

20、ded by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NACA RM No. L8mO 7 32 Unfform sween h C/euf tonne/ I i i i i i i Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-20 . . ./ 0 r/ .2 0 rii 74 I I I I I Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NACA.RM No. L&O . 21 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-