1、:L. . RESEARCH MEMORANDUM NlEASUREMENTS OF AERODYNAMIC CHARACTERISTICS OF A 35 SWEPTBACK NACA 65-009 AIRFOIL MODEL WITH$-CHOkD BEmLLED-TRAILING-EDGE FLAP AND TRIM TAB BY THE NACA WING-FLOW METHOD By Harold I. Johnson and B. Porter Brown Langley Aeronautical Laboratory Langley Air Force Base, Va. ,-
2、. c” - . . . . . . ”. . NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS WASHINGTON January 6, 1950 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NACA RM LgKLl 3 1176 01436 6984 NATIONAL ADVISORY C0MMI“IPA FOR AERONAUTICS 4 -.- RESEARCH ME“ MEASURESIENT
3、S OF AERODYNAMIC CHAFUEERISTICS OF A 35 SWEPTBACK NACA 65-009 AIRFOIL MODEL WITH $-CHORD BEXEXUD-TRAILIMG-EW E%AP AND TRIM TAB BY THE: NACA WING-FLOW METHOD By Harold I. Johnson and B. Porter Brown SUMMARY This investigation is the third of a series concerned with the determination of funhnental cha
4、racteristics of trailing-edge controls at transonic speeds. A 35 sweptback untapered airfoil model of aspect ratio 3 has been fitted with Various chord full-span flaps differing only in type of aerodynamic balance. The first series of tests was ruzl with a plain flap which represented the case of ze
5、ro aerodynamic balance. The second series of tests was run with a flap that had a reported previously. The tests described herein were made with a flap that incorporated a bevelled trafiing edge with an Included trailing- 4- I large horn balance. Results from these two series of tests have been t ea
6、ge angle of 23O. mortant results follow. The lift characteristics of the model and flap were similar to q. those measured previously with true-contour flaps on the model. Sealing the flap gap increased the lift-curve slope and the flap effectiveness appreciably and also caused a rearward shift in th
7、e center of pressure of the load due to flap deflection. The -flap-chord by -flap-span bevelled trim tab had poor trillnning characteristics at all speeds tested (M = 0.65 to 1.15), inasmuch as the hinge moment due to tab deflection reversed for various parts of the deflection range at different Mac
8、h numbere. The bevelled trail- edge eppeafs to be a.n unsatisfactory type of aerodynamic balance for airplanes required to . traverse a large speed range because at subsonic speeds the degree of balance was highly nonuniform and at low supersonic speeds most of the balancing effectiveness disappeare
9、d. 1 1 3 3 .- _. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-2 INTRODUCTIOM NACA RM LgKll A wing-flaw investigation is being made to determine the charac- teristics of conventional low-speed aerodynamic balmces at transonlc speeds. In this invest
10、igation a typical sweptback airfoil-flap combi- nation representing either a wing ora tail surface is being fitted with $chord full-span flaps differing only in ty-pe of aerodynamic balance. The primary objectives of the investigation are the determi- nation of flap hinge moments and flap effectiven
11、ess; however, it has been found convenient and desirable also to measure the lift and pitching-moment characteristics of the complete models. The first series of.tests was made with a plain flap which represents the case of zero aerodynamic balance (reference 1). The second series of tests was made
12、with a horn-balanced flap that- was designed to have a large degree of- aerodynamic balance at low speeds (reference 2). The present. series of tests was made with a bevelled-trailing-edge flap that had a trailfng-edge angle of 23O in planes perpendicular to the hinge line. The true-contour NACA 65-
13、009 section flap tested in reference 1 had a trailing-edge =;le of approximateu 6. The tests consisted of measurements of the lift, pitching moments, and hinge moments acting on a semispan airfoil-flap model having a sweepback angle of 35O, an aspect ratio of 3.07, a taper-ratio of 1.0, an NACA 65-0
14、09 section in planes perpendicular to the leading edge over the forward 75 percent of the chord, a full-span -chord bevelled- trailing-edge flap, and a -span 1 by moment ch model hinge-moment coefficient Model hin CL, variation of model lift coefficient with angle of attack, per degree (2) CLfj vari
15、ation of mo lift coefficient with flap deflection, c cma variation of model pitching-moment coefficient with angle of attack, per degree (2) Cms variation of model pitching-moment coefficient with flap Chai variation of flap coefficient with model angle of attack, per degree variation of flap hinge-
16、moment coefficient with flap deflection, per awFee (2) - aa ?E flap relative effectiveness (q2) - Y - I I I i I I I Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-4 a ?IT A )L A b C - C S bf SA ” MACA RM LgKLl angle of attack between model chord pla
17、ne and direction of relative wind flap deflection anghbetween flap chord line and airfoil chord line measured in plane perpendicular to hinge line trim-tab deflection in plane perpendicular to hinge line sweepback angle taper ratio aspect ratio model span normal to wind direction (corresponds to one
18、-half of span of complete wing) model chord parallel to wind direction model mean aerodynamic chord (M.A.C.) total area of model (corresponds to one-half of area of complete wing) flap span along hinge line ( corresponds to one-Kf of span of fdl-span flap on complete wing) .- flap root-mean-square c
19、hord perpendicular to hinge line flap chord parallel to wind direction flap area rear of hinge line included trailing-edge angle of flap trim-tab sp however, small errors were =de in the con- struction of the flap so that the model aspect ratio was changed The model was nachined from solid duralumin
20、 and an end plate of gap.between the flap leading edge and the basic airfoil model was the gap was closed dong64 percent of the flap spas by 0.002-inch-thick sheet rubber installed as shown in figures 4 and 5. . from 3.04 to 3.07 and the flap-chord ratio was changed from 0.25 to 0.24. , however, an
21、additional two flights were made with gap sealed in which the model w at the highest test speed, these accuracies shauld be approximately four times be%ter. A large part of the loss in accuracy was attributable to shifts in instrmnent zeros t4at occurred Wadually during a flight. Eence, the errors i
22、n the data appear for the most part asemors in anaes of zero lift, angles of zera pitching moment , and angles of zero hinge moment. Because the data at any given Mach mber were obtained within a very short period of tbe (less than 1 sec), the slops of the various- force- and moment-coefficient curv
23、es should be accurate to a degree approaching the instrument capabilities, which, in the present. case, add up to about 2 percent at Intermediate test speeds. b PRESENTATION OF DATA ll force and mament coefficients.are presented in accordance with standard NACA conventions regarding definitions and
24、signs. Pitching moments were measured about an axis located 18.1 percent chord forward of the leading edge of the mean aerodynamic chord. In accordance with past procedure (see reference 2) dl the basic data are presented without shoxtng test points. However, in order to show the quality of the data
25、, two typical plots of basic data are shown in figure 7. These plots shar the number of test points evaluated at each Mach nuniber from the continuous records of force, moment, and position. The following tables give the order of treatment of the results as wen as a key to figures 8 to 30. In genera
26、l, each figure consists of two parts. The first part shows data from the high-dive ms (higher maxFrmrm Mach number, lower ReynoXds numbers) and the second part shows data from the level-flight runs (higher Reynolds numbers, lower I 1 i I I I I Provided by IHSNot for ResaleNo reproduction or networki
27、ng permitted without license from IHS-,-,-8 PSACA RM 9n1 - maximum Mach number). The basic daw are generally given for Mach number increments of 0.05 through the Mach number range tested. “ I BASIC DATA . . 1 Characteristics I Content , ,. + i Figure Open and sealed 8 Sealed 9 Open and sealed LO Sea
28、led 11 Open and sealed 12 Sealed 13 Open and sealed 14 Sealed 15 Open and sealed 16 Sealed 17 Open and sealed 18 Sealed 19 Sealed 20 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MACA RM LgKll 9 ? 1 c Characteristics Lift Pitching moment Hinge mome
29、nt - SUMMARY DATA Content CLaY CL6Y Figure Gap 21 Open and sealed against M asf ,(a z 00; 6f = 00) Effect of 6f on Ck 23 Open and sealed %, hy a.c. c.p. due 22 (b 1 Sealed Effect of a on CL6 =(a) Sealed to Qo against M (a. wo y 6f = oO) I Effect of 6f on % Sealed Effect of a. on Cm6 Sealed Effect of
30、 Sf on a.c. Sealed Effect of a on c.p. Sealed due to sf C lift in the low and moderate angle-of-attack ranges. At angles of attack near loo, however, a sharp break occurred in the- lift curves in the region M = 0.95. This break disappeared at M = 1.05 and higher speeds. As may be seen, the test rang
31、e (a, = 18) was insufficient to yield information on the variation of-maximum lift coefficient with Mach number. However, such Fnf-ormat-ion may be found for the model with a plain flap in reference 1. effect on shape of the lift curves of changing the flap angle from 0 to 5 was practically negligib
32、le. One of the small systematic changes noted was a delay to larger angles of attack in the occurrence of the sharp break in the lift curve near M = 0.95. I. Sealing the flap gap had a beneficid effect on the lift characterist.ics of .the model at angles of attack below approximately 8. Inasmuch as
33、only 64-percent of the gap length was sealed in the tests (refer to fig. 4), further gains in lifting ability could be expected from sealing a ;rester length ofthe flap gap. m Lift due to flap deflection (figs. 10 and Ll).- The bevelled- trailing-edge flap showed generally good flap effectiveness. T
34、here was a considerable loss in effectiveness at-small flap angles at M = 0.95 *: (fig. lo( however, the balance at small deflec- tions was mintained to higher Mach numbers with the gap sealed. The data indicate the hinge moments with gap open were very irregular at low speeds near zero deflection.
35、These irregularities were eliminated completely by sealing the gap. Hhge moment due to ab deflection (fig. 20).- The trim-tab effectiveness is indicated.by.the vertical spacing of the curves of figure 20. At-Mach numbers below 0.90, the tab gave increasing hinge moments of the correct sign with incr
36、easing tab deflection at zero flap deflection. At large positive flap angles the tab effectiveness reversed at small tab angles; whereas, a% large negative flap angles the tab effectiveness usually reversed at larger tab angles. At”ach nm- b8qs above 0.90 the tab effectiveness usually reversed.at mo
37、derate tab angles for all except large positive flap angles. Within the accuracy of the data, therefore, it appears .the tab tested would constitute a weak if not entirely unsatisfactory trbming device. c c SUMMARY DAW Lift Characteristics Lift-curve slope (figs. 21 and 22(a).- The lift-cwve slopes
38、showed a general increase with increasing speed up to a bhch number of at least 1.0. At higher speeds the lift-curve slope fell off slightly. - Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NACA m LIUI - : 13 i Sealing the flap gap was definitely b
39、eneficial to increasing the lift- curve slope at all transonic speeds tested. The maximum lift-curve. slope measured with gap sealed was 9 percent higher than the corre- sponding maxFmum lift-curve slope with gap open (fig. 21(a). Reynolds number effects on lift-curve slope were small. The effect of
40、 flap deflection on lift-curve slope was small and inconsistent (fig. 22(a). At transonic speeds, deflecting the flap 5O reaced the lift-curve slope slightly. Flap effectiveness (figs. 21 and 22(b).- The absolute flap effectiveness (CQ) showed a gradual decrease over the speed range tested with 8 ad
41、ditional abrupt lOS6 and recovery in effectiveness between M = 0.90 and M = 1.05. Sealing the gap gave a general increase in flap effectiveness over the speed range of about 25 percent. Other effects of the,seal were to raise the Mach number of minimum flap effectiveness from 0.95 to 1.0 and to rais
42、e the minm flap effective- ness by about 35 percent (fig. 21(a) ). , The data obtained from the level-flight runs (fig. 21(b) were not as clear-cut as the high-dive data, but disregarding the apparent inconsistencies in the gap-sealed data, these data are in fair agreement with those of figure 21(a)
43、. The effectiveness of the bevelled flap compared favorably with that of the plain flap-and horn-balanced flaps of references I and 2, respectively. The variations of flap relative effectiveness aa. with Mach num- asf ber were similar to those of absolute flap effectiveness (Q). The effect of increa
44、sing the angle of attack on flap effectiveness (fig. 22(b) was to iron out variations in effectiveness due to com- pressibility. This result is in agreement with previous tests (reference 2). Pitching-Moment Characteristics Pitchiqg-moment coefficient per degree angle of attack (figs. 23 and 2 howev
45、er, at supersonic speeds the strong negative floating tendency still appeared. As explained in reference 2, it is believed the strong negative floating tendency at supersonic speeds isla feature common to all conventioiml tmes of subsonic balance which affect the parameter Cb. In any -event the larg
46、e changes in hinge-moment characteristics with angle of attack measured for the bevelled flap lead to the conclusion that this type of balance is undesirable forapplication to an airplane required to traverse any appreciable speed range. Flap restoring tendency % (figs. 28 and 29).- Comparison of th
47、e bevelled-flap data (fig. 28) with that of the Blain flap from reference 1 shows that the bevel was very effective as an aerodynamic balance in the. subsonic range. However, in general, the degree of balance obtained from the bevelled trailing edge was far from uniform, ranging anywhere from one-ha
48、lf of complete unbalance to overbalance. As in the case of the variations of hinge moment with angle of attack, the degree of flap balance for deflection increased with either Mach number or Reynolds number in the subsonic speed range. At supersonFc speeds the flap quickly lost balance as was the ca
49、se with the horn-balanced flap of reference 2. Sealing the flap gap tended to delay the loss of balance at supersonic speeds, but the trends of the curves leave little hope that the bevelled trailing edge tested could be an effective supersonic balancing device. Changing the angle of attack fram Oo to 5O (fig. 29) had little effect on the subsonic balancing characteristics. The main effec
