1、. VOPY 6 RM A54FlE - RESEARCH MEMORANDUM A COMPARISON OF THE LONGITUDINAL AERODYNAMIC CHARACTERISTICS AT MACH NUMBERS UP TO 0.94 OF SWEPTBACK WINGS HAVING NACA 4-DIGIT OR NACA 64A THICKNESS DISTRJBUTIONS By Fred B. Sutton and 3erald K. Dickson . Ames Aeronautical Laboratory Moffett Field, C with 45
2、g and 50 of sweepback, the aspect ratios were approxtitely 6 and 5, respectively. The tests were conducted through an angle-of-attack range at Reynolds numbers up to 10 million at 8 Mach number of 0.25, and at mch nmibers varying from 0.25 to 0.94 at a Reynolds number of 2 million. At low speeds, th
3、e lift coefficient at which static longitudinal instability first became manifest W8 with 4-digit sections than for the wings with 6411 sections. This effect of section w-as inconsistent with increasing Mach nmiber. For Mach ntiers near 0.80 and a wing sweepback of 4.00, the lift coefficient for sta
4、tfc instability was higher for the wing with 6ation were stiffer than the reference wing due to their reduced aspect ratios 8nd soEd steel construction, it is believed that the effects of aeroelcbstic deform8tion are negligible. Hence, no correc- tions h8ve been made to the data for these effects. T
5、ESTS 500. The wings were investigated with sweepback angles of however, the effects of wing section on the variation of inflection lfft coefficient with Reynolds number were small. Decreases in InfleCtiOn lift coefficient as large 88 8bOUt 30 percent were indicated for the wlngs when the angle of sw
6、eepback w whereas, for the 64A wing swept back 4-0 an over-all increase was indicated up to a Mach number of 0.80. At higher Mach num- bers the inflection Uft coefficients decreased. At Mach numbers near 0.80, the inflection lift coefficient for the 64A wing was higher than for the 4-digit wing but
7、at higher speeds the effect was reversed. A similar -_ .-. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NACA FN A54F18 11 trend is shown for the 6kA wing with considerably higher than that for the however, at the higher angles of sweep- back and a
8、 lift coefficient of 0.4, the effects of Mach number became more pronounced and more varied for the 6U wings than for the k-digit wings. This erratic behavior was mostly due to the low inflection lift coeffi- cients (generally less than 0.4) of the 64A wings at these angles of sweep- back. As previo
9、usly mentioned, it is possible that the Reynolds number of these tests (2 million) was not high enough to preclude sizable dynam%c scale effects in these results, Drag and lift-drag ratios.- The drag characteristics of the wings with the various angles of sweepback are shown in figure 12. At Mach mu
10、 at Mach numbers of 0.83, 0.86, and 0.88 for 45O of sweep- back; and at Mach numbers of 0.88, 0.90, and 0.92 for 50 of sweepback. These effects are shown to best advantage in figure 13 which shows the lift-drag ratios of the various wings as a function of lift coefficfent. It is believed that the dr
11、ag advantages of the 64A wings at these particu- lar Mach numbers stem from the separation phenomenon previously mentioned in the discussion of the pitching-moment characteristics. The higher lift- drag ratios of the k-digit wings when compared with those for the 64A wings at some subcritical Mach n
12、umbers (Mach number of 0.80 at 45O of sweepback, for example) were probably a result of deterioration of the model surface which would affect the drag characteristics of the 64A wings more adversely than those of the b-digit wings. The effect of Mach number on drag coefficient at several lift coeffi
13、- cients is shown in figure 17 for the wings with 40, 45O, and 50 of sweep- back. Drag divergence usually occurred.at slightly higher Mach numbers for the h-digit wings than for the 64-A wings. However, at the Mach numbers of drag divergence andat the same angle of sweepback the 64A wings usually ha
14、d lower drag than the b-digit wings. The Mach numbers for drag diver- gence and the corresponding drag coefficients are shown for the wings at the various angles of sweepback in the following table: . A = 4.00 A = 450 A - 500 CL WV %iV MaiV I %iv MaiV I %iv . 4-alat 64 4-aigit 64 4-aigiti64 llcaigit
15、 64 4-aigit 64 f4-digit 6.4 0.20 o:g 0.88 o:; however, at supercritical speeds and at 40 and 45O of sweepback the k-digit wings had slightly higher maximum lift-drag ratios than the wings with 64A sec- tions. Decreases in maximum lift-drag ratio with increasing angle of sweepback occurred at subcrit
16、ical speeds for both wings. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NACA RM A54Fl8 13 It is of interest to note that increasing wing sweepback had only small effect on the maximum lift-drag ratios of the k-digit wings at a Each number of 0.90
17、. It would appear that as the sweepback was increased at this Mach number, the drag decrease due to the increase in the Mach num- ber for drag divergence was nullified by the increase in induced drag resulting from the lower aspect ratios wch accompanied the increase in sweepback. Flow Studies In an
18、 attempt to gain some insight into the separation occurring on the wings as affected by wing section, wing plan form, and test conditfons, tuft studies were made on the wings at 4.0 and 50 of sweepback. The results of these stuafes are presented in figures 19 and 20. Inasmuch as the addition of tuft
19、s to the wing surfaces affected the flow on the wings, the differences in separation due to ting section as shown by the results of the flow studies are probably somewhat obscured. However, as anticipated, it was indicated that the 6 .6 i .4 f 2 .2 0 -.4 -4 0 4 6 I2 I6 20 24 ( For R ” 2,000,OOO ; M
20、= 0.25) Angle of attack, a, deg (a) A = 4-O Figwe 4.- The effect of wing section at low speed and at q everal Reynolds nW?XS on the Hft cllaxacteristice of the wing. N P Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-ID t .- -I 2 0 -.2 I I I I I I I
21、 I I I I, I I, I I I, I I II L t I I II 1 IIIIIIIIIIIIIIIIII AC4 -.4 -4 0 4 6 12 16 20 24 ( For R = 2,000,OOO; M = 0.25 1 Angie of attack, a, deg (b) A = 45 E Figure 4.“ Continued. t I , 4 1 1 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-.4 r. I -
22、4 0 4 8 12 I6 20 24 I For R m 2,000,OOO; M = Angle of attack, a,deg (cl A = ;o” Figure b.- Concluded. 0.25 ) Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-.4 .I2 .08 .04 0 -.04 -.08 (For R=2,000,.000; M-0.25) Pitching-moment coefficient, C, E (a) A
23、 = 4o” ii Figure 5.- The effect of wing section at low qeea and at several Reynolds numbers on the 8l pitching-moment characteristics of the winge. G G . , , Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-, , c ,A Unflagged : Flagged : I I I I I I I
24、 I I I I I I I I I I I I I I I I I I I -IO8 .04 0 -.04 -DE ( For R = 2,000,OOO; M = 0.25 ) Pitching-moment coefficient, C, (b) A = 45 Figure 5.- Continuea. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-1.0 .08 .04 0 -.04 -08 (For R- 2,000,OOO; M-0.
25、25) Pitching-moment coefficient, C, (c) A = 5o” Figure 5.- Concluded. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-r 1.4 1.2 I.0 J .-. ” .u ., IX I I -.4 0 x)2 x)4 .06 .08 JO .I2 .I4 .I6 .I8 .20 ( For R = 2,000,OOO; M = 0.25) Drag coefficient, C,
26、(a) A = 4Q” Figure 6.- The effect of wing eection at low speed and at several Reynolds nunibere on the drag characteristics of the wings. 3 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-I I I I I I I Unflagged: 4-digit m Flaaaed: 64A 0 .02 .04 .06
27、x)8 .I0 .I2 .I4 .I6 .l8 .20 ( For R = 2,OOC M n 0.25 ) Drag coefficient, C, (II) A = 45O Figure 6.- Continued. . Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-. , I I I I I I I I I I II I I I I I I I I I I I I I I I I IT?71 02 .04 .06 DE .I0 .I2 .I4 .I6 .I8 .20 ( For R a 2,000,OOO; M = 0.25 ) Drag cmfficient, C, (c) A = so0 Figure 6.1 Concluded. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
