1、36 COPY SCCURITV INFORMATION RM A53C20 RESEARCH MEMORANDUM SUBSONIC STATIC LONGITUDINAL STABILITY AND CONTROL HAVING A POINTED WING OF ASPECT RATIO 2 CHARACTERISTICS OF A WING-BODY COMBINATION WITH CONSTANT-P ERC ENT- CHOR D TRAILING-EDGE ELEVONS By Donald W. Smith and Verlin Do Reed Ames Aeronautic
2、al Laboratory Moffett Field, Calif. materlal contalns lnformatlon affecting the Natlonal Defense of the Unlted States wlthln the meaning of ule esplonnge laws, Title 18, U.S.C., Seca. 799 and 794, the trsnsmlaslon or revelatlon of which in any manner to an vnautborieed prson le prohlblted by law. NA
3、TIONAL ADVISORY COMMITTEE FOR AERONAUTICS WASHINGTON May 22,1953 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-R NACA RM A53C20 NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS RESEARCH MEMORANDUM SUBSOMC STATIC LONGITUDINAL STABILITY AND CONTROL HAVING
4、 A POINTED WING OF ASPECT RATIO 2 CHARACTERISTICS OF A WING-BODY COMBINATION . WITH CONSTAI“-PERCENT-CHORD TRAILING-ED(=E ELEVONS By Donald W. Smith and Verlin D. Reed SUMMARY An investigation has been made to determine the static longitudinal stability and control characteristics of a tailless wing
5、4ody combina- tion having a pointed wing with an aspect ratio of 2 and trailing-edge elevons. The effectiveness of inset tabs in reducing the elevon hinge moment was also determined. Data presented include the lift, drag, pitching moment, elevon hinge moment, tab hinge moment, elevon load, and cente
6、r of pressure of elevon load. Data are presented for a range of angles of attack, elevon deflection, and tab deflection at Mach numbers up to 0.93. Most of the data were obtained at a Reynolds number of 3.0 million, but at a Mach number of 0.24 data were also obtained at Reynolds numbers up to 15.0
7、million. The effects of compressibility on the longitudinal characteristics were similar to those on other wing4ody conibinations having low-aspecb ratio triangular wings. The effectiveness of the elevons in producing both lift and pitch- ing moment increased with increasing Mach number. moment due
8、to elevon deflection increased rapidly as the Mach number was increased above 0.80. changed from negative to positive as the Mach number increased above 0.83. The effectiveness of the tabs in reducing elevon hinge moment increased with increasing Mach number. The elevon hinge The elevon hinge moment
9、 due to angle of sttack The data were used to estimate the longitudinal stability and con- trol characteristics of an assumed airplane, geometrically similar to the model. Two different types of longitudinal control systems were Provided by IHSNot for ResaleNo reproduction or networking permitted wi
10、thout license from IHS-,-,-2 NACA RM A53C20 considered for the analysis: a direct elevon control and a servotab contr 01. With the center of gravity at a location which would provide a minimum elevon-fixed static margin of 5 percent, both the direct elevon control and the servotab control provided a
11、bout the same maximum trimmed lift coefficient throughout the speed range. the stick force required for the elevons with the servotab system was much smaller than that required for direct elevon control. At the higher Mach numbers, INTRODUCTION Research is in progress at the various NACA facilities
12、to determine the aerodynamic characteristics of flaptype, trailingedge elevons on law-aspect-ratio wings at both subsonic and supersonic speeds. effects of elevan plan form and trailing-edge profile on the aerodynamic characteristics of elevons on a thin triangular wing of aspect ratio 2 have been d
13、etermined at high subsonic and low supersonic speeds and have been reported in reference 1. The As a part of this research, there are reported herein results of tests conducted in the Ames 12-foot pressure wind tunnel at Mach nuw bers up to 0.95 to determine the aerodynamic characteristics of consta
14、nt- percent-chord, flaptype, trailing-edge elevons on a pointed wing having an aspect ratio of 2. The effectiveness of inset tabs in reducing the elevon hinge moment is also presented. back 56.3O and the trailing edge was swept forward 26.6O. The wing leading edge was swept 3 NOTATION - a nom accele
15、ration, ft/sec2 b wing span, ft C local wing chord, ft b/2 c2dy $0 .bj2 ft so F wing mean aerodynamic chord, Ce elevon chord, ft Ca elevon chord through elevon centroid of area, ft Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NACA RM A53C20 3 Cr C
16、t g 2 max (L/D 1 MAe MAt M n 9 R r rO S Se W vg VV X X Y a elevon reference chord, ca x cos 6e, ft tab chord, ft acceleration due to gravity, ft/sec2 length of body including portion removed to accommodate sting, ft maximum lift-drag ratio Mach lnrmber first moment of area of exposed elevon behind h
17、inge line, ft first moment of area of exposed tab behind hinge line, ft3 normal acceleration factor, a/g freestream dynamic pressure, lb/sq ft Reynolds nuniber based on wing mean aerodynamic chord radius of body, ft maximum body radius, ft total wing area including the area formed by extending the l
18、eading and trailing edges to the plane of symmetry, sq ft exposed area of elevon behind hinge line, sq ft weight of assumed airplane, lb gliding speed, mph sinking speed, ft/sec longitudinal distance from elevon hinge line measured in the chord plane of the wing (negative to ress of hinge line),ft l
19、ongitudinal distance from nose of body, ft lateral distance normal to plane of symmetry, ft angle of attack of the body axis, deg Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NACA RM 5320 4 6e elevon deflection, with respect to wing-chord plane, m
20、easured in planes perpendicular to the elevon hinge line (positive downward), deg - tab deflection, with respect to elevon-chord plane, measured in planes perpendicular to the tab hinge line (positive aownwma), deg elevon deflection correction due to applied load (additive), tab deflection correctio
21、n due to applied load (additive), deg deg drag drag coefficient, - qs elevon load coefficient based on elevon load normal to wing- elevon load qSe chord plane, hinge moment 2qMb e levon hinge-moment coefficient , hinge moment 2qMAt tab hinge-mment coefficient, lift lift coefficient, - qs pitcbing-mo
22、ment coefficient about the 2Fpercent point of the * pitching moment wing mea aerodynamic chord, qsc rate of change of elevon normal-force coefficient with a change in angle of attack for a constant elevon angle and tab angle, acF/ the variation of elevon and tab hinge-moment coefficients with angle
23、of attack; and the variation of elevon load coefficients and the location of the center of pressure of elevon load with angle of attack. All basic data are given for uncorrected values of elevon and tab deflection. Pitching- moment data are presented about a moment center at the 2Fpercent point of t
24、he wing mean aerodynamic chord. Table I lists the figures presenting the basic data and shows the range of variables covered by the tests at each Mach number and Reynolds number. A summary of the effects of compressibility on the aerodynamic characteristics of the model and on the elevon and tab par
25、ameters is presented in figures 40 through 45. Results of application of the data to estimate the longitudinal stability and control characteristics of an assumed airplane geometri- cally similar to the model are presented in figures 46 through 49. Provided by IHSNot for ResaleNo reproduction or net
26、working permitted without license from IHS-,-,-NACA RM 5320 9 of the slope parameters. Because of the nonlinear variation of the forces and moments with angle of attack and elevon deflection, these parameters are applicable only at angles of attack and elevon deflec- tions near zero. Basic Character
27、istics Lift and Pitchina moment.- The effects of compressibility on the lift, drag, and pitching moment of the wing4ody combination with the controls whdeflected are summarized in figure 40. With the exception of the more forward location of the aerodynamic center, the character- istics of the wing
28、are similar to those previously measured on a tri- angular wing of aspect ratio 2 and reported in reference 3. The effectiveness of the elevons in producing lift and pitching moment is summarized in figures 41 and 42, respectively. effectiveness increased with increasing Mach number up to a Mach num
29、ber of about 0.93 but decreased abruptly as the Mach number was fur- ther increased to 0.97. The pitching-moment effectiveness Cqe of the elevons increased with increasing Mach number up to the highest Mach number of the test, 0.95. to 100 increased both the lift and pitching-moment effectiveness of
30、 the elevons but caused little change in the variation of the effectiveness with Mach nuniber. The lift Increasing the tab deflection from 0 A comparison of the lift and pitchingaoment effectiveness of the elevons with those of constant-chord and constanhpercent-chord elevons on a triangular wing ha
31、ving an aspect ratio of 2 (ref. 1) is also pre- sented in figures 41 and 42, respectively. tive in producing lift and pitching moment than the constant-chord elevons on the triangular wing. They were also less effective in pro- ducing lift than the constant-percent-chord elevons on the triangular wi
32、ng but were more effective in producing pitching moment. The elevons were less effec- The lift and pitching-moment effectiveness parameters were little affected by an increase of Reynolds number from 3a0 million to 15.0 million at a Mach nuniber of 0.24 (figs. 34 through 39). Elevon and tab parmeter
33、s.- The effects of compressibility on the elevon and tab hinge-moment parameters are presented in figures 43 and 44. The absolute magnitude of increased gradually with increasing Mach number up to a Mach number of 0.80, where a further increase of Mach number to 0.97 resulted in a very rapid increas
34、e of The elevon hinge moment due to angle of attack changed from %a C Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-10 NACA RM A53C20 negative to positive as the Mach number was increased above 0.83. In the Mach number range from 0.60 to 0.9, both
35、the elevon hinge moment due to angle of attack and that due to elevon deflection were generally smaller than the binge moment for the elevons on the triangular wing which were reported in reference 1 (fig. 43). . An increase of tab deflection resulted in a more negative value of Ch8, above a Mach nu
36、mber of 0.65. above a Mach number of 0.40 and a more negative value of Cha and the hinge-moment , The tab effectiveness, as measured by parameter, Chtst, increased with an increase in Mach number (fig. 44). The effects of Reynolds number on the elevon and tab hinge moments at a Mach number of 0.24 a
37、re shown in figures 34 through 39. of the data sh.ows that the absolute magnitudes of both and Chest lion to 15.0 million, while Cba and mtst remained essentially unchanged. Analysis C for the second, the tab is directly connected to the control stick and movement of the stick changes the elevon def
38、lection by changing the angle for zero hinge moment (elevon floating angle ) . Characteristics of e airdane in the b al- .- The variations with balanced lift coefficient (Cm = 0) of the drag coeffi- cient, the lift-drag ratio, the angle of attack and the elevon and tab deflection are shown in figure
39、 46. represented by the lift-drag ratio is about the same for both the plain- elevon and the servotab control at the Mach numbers above 0.80. However, at the lower Xach num3ers the airplane with the plain elevons was the more efficient for lift coefficients less than about 0.50. The decre- ment in m
40、aximum lift-drag ratio due to balancing the assumed airplane varied from about 25 percent at low speeds to about 10 percent at the intermediate Mach numbers, becoming about 23 percent a5 the Mach number was further increased to 0.92. The efficiency of the airplane as An apparent loss in elevon pitch
41、ing-moment effectiveness for both control systems was shown by the nonlinear manner in which the elevon deflection varied with balanced lift coefficient. This apparent loss appeared at all Mach numbers and increased with an increase in Mach number. There were two factors which contributed to the los
42、s in effec- tiveness. The first of these factors was an actual loss in elevon effectiveness at the larger elevon deflections, while the second was a rearward shift in the aerodynamic center of the wing4ody combination with an increase in lift. A study of figures 4 through 11 shows that the position
43、of the aerodynamic center (at CL = 0) did not vary greatly with an increase in Mach number up to about 0.90; with further increase in Mach number it moved rapidly rearward. However, as the lift coeffi- cient WS increased there was a point at which there was a rapid increase in stsbility, and this ra
44、pid increase occurred at progressively lower lift coefficients as the elevon deflection was increased negatively to balance the sirplane. If this point of rapid increase in stability is arbitrsrily defined as the point at which the slope of the pitching- moment curve exceeded -0.15, then the followi
45、ng observations may be made: At a blsch number of 0.24 there was a rapid increase in stability st an mgle of attack of about 21 while at a Mach number of 0.90 this incresse occurred at an angle of attack of about 100. The angle of sttack st which the stability increased was relatively unaffected by
46、elevon deflection. For the servotab control, the variation of the tab deflection with balance lift coefficient was of such 9 nature 9s to preclude use of a simple linked tab. Due to the highnegstive value of C (for aOO) resulted in a smaller stick force linear stick travel, in. for the same range of
47、 gliding speeds. 01 forces for a longltudina7lu hnmed e - plane in kvel a ecce-.- In level flight at an altitude of 30,000 feet, a total change of elevon deflection of less than 2O was sufficient to balance the airplane at Mach numbers from 0.60 to 0.95 for wing loadings up to 60 pounds per square f
48、oot (fig. 48). The vari- ation of elevon angle with speed was such as to indicate stick-fixed stability up to a Mach number of 0.90, but, BS the Mach number was fur- ther increased, more negative elevon angles were required to balance the airplane. This increase in negative elevon angle with increas
49、e in speed above a Mach nuniber of 0.90 was due primarily to the rapid rear- ward movement of the aerodynamic center. With the servotab control, the variation of tab angle with speed was such as to indicate stick- fixed instability, more positive tab angles being required to balance the airplane as the speed increased. The variation of stick force with speed was such as to indicate stick-free instability for eit
