1、NASA h 0 d n z + 4 m 4 z TECHNICAL NOTE NASA TN p-4076 c.7 STATIC STABILITY CHARACTERISTICS AT MACH NUMBERS FROM 1.90 TO 4.63 OF A 76“ SWEPT ARROW WING MODEL WITH VARIATIONS IN HORIZONTAL-TAIL HEIGHT, WING HEIGHT, AND DIHEDRAL by Dennis E. Faller I LLtngZty Research Center 1 ?A , .*I -“ 7 rJ LngZty
2、Station, Hampton, Vu. F n m z L NATIONAL AERONAUTICS AND SPACE ADMINISTRATION WASHINGTON, D. C. AUGUST 1967 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-TECH LIBRARY KAFB, NM Q high with 5O, Oo, and -5O dihedral; and low with Oo and 5O dihedral. T
3、he vertical tail had 450 leading-edge sweep and consisted of a flat-plate section with beveled leading and trailing edges. The horizon- tal tail had a symmetrical airfoil section with 52O leading-edge sweep. Five horizontal- tail positions varying from below the fuselage (position 1) to near the top
4、 of the vertical tail (position 5) were utilized. line) had less exposed area than the horizontal tail in the other positions. The horizontal tail in position 2 (on the fuselage center 60 742.81 73 153.37 104 593.46 276 686.60 377.487.96 Tunnel Tests were conducted in both the low and high Mach numb
5、er test section of the Langley Unitary Plan wind tunnel, which is a variable-pressure continuous-flow tunnel. The test sections are approximately 4 feet (1.24 m) square and 7 feet (2.13 m) long. The nozzles leading to the test sections are of the asymmetric sliding-block type which permits continuou
6、s variations in Mach number from about 1.5 to 2.9 in the low Mach num- ber test section, and from about 2.3 to 4.7 in the high Mach number test section. Test Conditions The test conditions for the investigation were as follows: I 1 _- Stagnation Mach temperature number 2.96 3.96 4.63 _ OK 339 339 33
7、9 352 352 . -. -_ - Stagnation pressure Longitudinal data lb/sq in. 13.21 15.92 22.79 40.13 54.75 - N/m 91 079.74 109 764.53 157 131.51 276 686.60 377 487.96 _. . Reynolds number per foot 3.0 X 106 3.0 3.0 3.0 3.0 per meter 9.144 x lo6 9.144 9.144 9.144 9.144 I Lateral data j per foot 2.0 x 106 2.0
8、2.0 3.0 3.0 - per meter 6.096 X lo6 6.096 6.096 9.144 9.144 - The configurations were tested through an angle-of-attack range from about -4O to 20 and through an angle-of-sideslip range from about -4O to 8O. Sideslip derivatives were obtained from angle-of-attack polars at p = Oo and 4. The stagnati
9、on dewpoint was maintained below -3OO F in order to avoid condensation effects. Strips of carborundum grains 1/16 inch (0.159 cm) wide were affixed around the body 1 inch (2.54 cm) from the nose and on the wings 1/2 inch (1.27 cm) from the leading edge in a streamwise direction. Number 60 carborundu
10、m grit (0.0108 in. (0.0274 cm) nominal diameter) was used for the 4 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-nose and number 80 carborundum grit (0.0076 in. (0.0193 cm) nominal diameter) was used for the wings and tail surfaces. Measurements A
11、erodynamic forces and moments were measured by means of a six-component electrical strain-gage balance housed within the model. The balance, in turn, was rigidly fastened to a sting support and thence to the tunnel support system. The balance-chamber pressure was measured for each model and test con
12、dition. Accuracy The accuracy of the individual measured quantities, based on calibrations, is esti- mated to be within the following limits: CD CL Cz Cm . Cn cy cu,deg p,deg Mach number: 1.90 to 2.96 3.96 and 4.63 . *O .0004 *0.005 *o. 0002 *0.0005 *0.0003 *0.003 *o. 10 *o. 10 *0.015 *0.050 Correct
13、ions Angles of attack were corrected for tunnel flow angularity and angles of attack and sideslip were corrected for deflection of the balance and sting support due to aerodynamic loads. The results were adjusted to free-stream static pressure at the model base and typical chamber drag coefficients
14、are shown in figure 2. PRESENTATION OF RESULTS The results of the investigation are presented in the following figures: Figure Effect of horizontal-tail height variation on aerodynamic characteristics in pitch. High wing; Oo dihedral . 3 in pitch. High wing; 5O dihedral . 4 Effect of horizontal-tail
15、 height variation on aerodynamic characteristics 5 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Figure Effect of horizontal-tail height variation on aerodynamic characteristics in pitch. High wing; -50 dihedral 5 in pitch. Low wing; Oo dihedral .
16、6 in pitch. Low wing; 5O dihedral . 7 in pitch. Horizontal-tail position 2 . 8 Effect of horizontal - tail height variation on aerodynamic character is tics Effect of horizontal-tail height variation on aerodynamic characteristics Effect of wing height and dihedral variation on aerodynamic character
17、istics Effect of wing height and dihedral variation on aerodynamic characteristics in pitch. Horizontal-tail position 5 . 9 Summary of horizontal-tail and downwash characteristics 10 Effect of horizontal-tail deflection on aerodynamic characteristics in pitch. High wing; Oo dihedral 11 in pitch. Low
18、 wing; Oo dihedral 12 High wing; Oo dihedral High wing; 5 dihedral High wing, -5 dihedral . 15 Low wing; Oo dihedral 16 Low wing; 5O dihedral 17 Horizontal - tail posit ion 2 18 Horizontal-tail position 5 19 Effect of horizontal- tail deflection on aerodynamic characteristics Effect of horizontal-ta
19、il height variation on sideslip parameters. 13 Effect of horizontal-tail height variation on sideslip parameters. 14 Effect of horizontal-tail height variation on sideslip parameters. Effect of horizontal-tail height variation on sideslip parameters. Effect of horizontal-tail height variation on sid
20、eslip parameters. Effect of wing height and dihedral variation on sideslip parameters. Effect of wing height and dihedral variation on sideslip parameters. 6 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-DISCUSSION Longitudinal Characteristics Long
21、itudinal aerodynamic characteristics of the model with variations in horizontal- Fig- tail height, wing height, and wing geometric dihedral are presented in figures 3 to 7. ures 8 and 9 present a composite of the effects of wing height and geometric dihedral for the horizontal tail in positions 2 an
22、d 5, respectively. Geometric dihedral generally leads to small losses in stability at the higher lift coefficients. The results presented in figure 8 show the low-wing configurations to have a lower level of stability at moderate-to-high lift coefficients than the high-wing configurations through th
23、e test Mach number range. In figure 9, the effects of wing height tend to be masked by pitching-moment-curve nonlinearities associated with the high horizontal tail (position 5). The data indicate a reduction in longitudinal stability for both the high- and low-wing configurations at moderate lift c
24、oefficients and at the lower test Mach numbers (fig. 8(a). For the higher test Mach numbers (for example, fig. 8(e), the stability loss is still well defined for the low-wing configurations but is not in evidence for the high-wing configura- tions. The improved stability characteristics of the high-
25、wing configurations are a result of the high dynamic pressure field created beneath the wing at the higher Mach numbers acting on the aft section of the fuselage at the higher angles of attack. For the low-wing configurations, the high dynamic pressure field has little effect on the aft fuselage. It
26、 should be noted that the horizontal tail in position 2 has less exposed area than the horizontal tail at the other test positions. Nevertheless, the contribution for the hori- zontal tail in position 2 is generally as good as or better than that for the horizontal tail in position 1, except at the
27、higher angles of attack for the low-wing configuration. With the horizontal tail mounted above the fuselage (positions 3, 4, 5), there are significant losses of tail contribution with increasing angle of attack, particularly at the lower test Mach numbers. These losses in contribution lead to rather
28、 severe nonlinearities in the model pitching-moment curves (figs. 3 to 7). The adverse stability effects incurred with the horizontal tails located above the fuselage occur as the horizontal tail enters an unfavorable flow field in the wing wake region. In an attempt to define better the adverse loc
29、al flow field incurred by the high horizontal tails, the parameter 6cm/6h is presented in figure 10 to provide an (6Cm/6h)=oo indication of the horizontal-tail effectiveness at some angle of attack with respect to the tail effectiveness at CY = 00. 7 Provided by IHSNot for ResaleNo reproduction or n
30、etworking permitted without license from IHS-,-,-The values of E, adverse downwash at the tail, were obtained from the data of fig- ures 11 and 12 by using the relation E = a! + 6h - at where at (horizontal-tail angle of attack) is assumed to be zero for those angles of attack at which the tail-on C
31、m intersects the tail-off Cm curve. At other angles of attack, the relation at = was used. For M = 1.90 the loss in contribution for the high horizontal tail with increasing a may be deduced to be a result of adverse downwash with little change in tail effective- ness. At M = 4.63, however, variatio
32、ns in tail effectiveness and downwash are both in evidence. Generally, any loss in tail contribution for the high horizontal tail is realized earlier for the high-wing configurations than for the low-wing configurations. The low horizontal tail generally exhibits linear pitching-moment contributions
33、 through the test angle-of-attack range and at the higher Mach number generally produces more pitching- moment contribution than the high tail. curve ACm 6cm/ 6h The effects of horizontal-tail deflection on the pitch characteristics of the high- and low-wing configurations are shown in figures 11 an
34、d 12. exposed area for the low tail is less than that for the high tail. tail deflection of -100 generally resulted in greater absolute tail effectiveness for the high tail than for the low tail. numbers, the effectiveness of the low tail, due to the more favorable local flow field, exceeds that for
35、 the high tail in some cases. It should again be noted that the Therefore, a horizontal- However, at the higher angles of attack at the higher Mach (See figs. ll(d) and ll(e), for example.) Later a1 -Directional Char act e r ist ic s The effects of horizontal-tail height on static directional and la
36、teral stability are presented in figures 13 to 17, the effects of wing height and dihedral being summarized in figures 18 and 19. directional stability at the lower angles of attack of all the test configurations. directional stability decreases with increasing angle of attack for each configuration
37、 but the decrease is somewhat less for the high tail (position 5). (All configurations become directionally unstable at the higher test angles of attack.) The horizontal tail in position 1 results in the highest level of The The low-wing tail-on configurations are generally more stable directionally
38、 than the high-wing configurations at all Mach numbers and angles of attack (figs. 18 and 19) for each horizontal-tail position. because of a favorable induced sidewash on the vertical tail. This stability is inherent for a low-wing configuration (See ref. 1.) For the low-wing model, positive geomet
39、ric dihedral generally leads to slight losses in C throughout the angle-of-attack range. For the high-wing model, positive geometric dihedral generally leads to a slight loss in at low angles of attack but “P c“P 8 Provided by IHSNot for ResaleNo reproduction or networking permitted without license
40、from IHS-,-,-produces generally higher values of Cn at the higher angles of attack. An opposite effect is noted for the negative geometric dihedral with the high-wing model. P The effective dihedral in the low angle-of-attack range is the least with the low-wing models and the greatest with the high
41、-wing models throughout the Mach number range. This result is typical of that which also occurs at subsonic speeds and is due to the dif- ferential angle of attack induced near the wing root by the body cross-flow component. The use of geometric dihedral in producing CzP is also effective throughout
42、 the Mach number range and produces results similar to those that occur at subsonic speeds, that is, an increase in -Czp with positive geometric dihedral and a decrease in -CzP with negative geometric dihedral. The effects of wing height and geometric dihedral are addi- tive such that the most negat
43、ive values of Cz with the high wing and 5O of geometric dihedral; or the increase in dihedral effect caused by a high wing can be offset to some extent through the use of negative geometric dihedral. generally occur for the configuration P At the lower Mach numbers, slightly more negative values of
44、Cz were obtained with the high horizontal tail (fig. 19) than with the center-line tail (fig. 19). This condi- tion is a result of the increase in side force on the vertical tail induced by the endplating effect of the high horizontal tail. This effect disappears at the higher Mach numbers. P CONCLU
45、SIONS Results of wind-tunnel tests to determine the effects of horizontal-tail height, wing height, and dihedral on the longitudinal and lateral-directional stability characteristics of a 760 swept arrow-wing airplane model at Mach numbers from 1.90 to 4.63 indicate the following conclusions : 1. Ge
46、nerally, for the angle-of-attack and Mach number range presented herein, the horizontal tail mounted above the fuselage will pass through an adverse flow region and result in pitching-moment nonlinearities. 2. The horizontal tail mounted below the fuselage resulted in noticeably higher directional s
47、tability in the low angle-of-attack range than did the horizontal tail in the other locations. The decrease in directional stability with increasing angle of attack, however, generally was least with the high tail. 3. The low-wing configurations provided higher directional stability than did the hig
48、h-wing configurations at all test Mach numbers and angles of attack. 4. Positive increments in effective dihedral were produced by the high wing and by positive geometric dihedral, the opposite effect being produced by the low wing or by 9 Provided by IHSNot for ResaleNo reproduction or networking p
49、ermitted without license from IHS-,-,-negative geometric dihedral. A positive increment in effective dihedral was also pro- duced by the high horizontal tail at the lower Mach numbers. Langley Research Center, National Aeronautics and Space Administration, Langley Station, Hampton, Va., February 23, 1967, 126-13-02-04-23. REFERENCES 1. Spearman, M. Leroy; and Robinson, Ross B
