1、NASA N h a- ? n z c $3 TECHNICAL NOTE AFWL TECHNICAL LI KIRTLAND AFB, NE I+ SUMMARY OF INFORMATION ON LOW-SPEED LATERAL-DIRECTIONAL DERIVATIVES DUE TO RATE OF CHANGE OF SIDESLIP! -A Paul L, Coe, Jr., A. Bruce Gruhum, and Joseph R. Chambers Langley R eseurch Center Hampton, Va. 23665 The George Washi
2、ngton University IJoint Institute for Acoustics and Flight Sciences / 76-197 n. CfJ pNATIONAL AERONAUTICS AND SPACE ADMlN - 0 WASHINGTON, D. C. $h?MBR W5 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-TECH LIBRARY KAFB, NM 1. Repcnt No. 2. Governmen
3、t Accession No. NASA TN D-7972 4. Title and SubtitleSUMMARY OF INFORMATION ON LCW-SPEED LATERAL-DIRECTIONAL DERIVATIVES DUE TO RATE OF CHANGE OF SIDESLIP 7. Authoris) Paul L. Coe, Jr., A. Bruce Graham, and Joseph R. Chambers 9. PerformingOrganization Name and Address NASA Langley Research Center Ham
4、pton, Va. 23665 2. Sponsoring Agency Name and Address National Aeronautics and Space Administration Washington, D.C. 20546 3. Recipients Catalog No. 5. Report Date September 1975 61 Performing Organization Code 8. PerformingOrganization Report No. L-10112 10. Work Unit No. 505-06-81-01 11. Contract
5、or Grant No. 13. Type of Report and Period Covered Technical Note 14. Sponsoring Agency Code 5. Supplementary Notes A. Bruce Graham is a graduate research assistant, The George Washington University, Joint Institute for Acoustics and Flight Sciences. _- - -6. Abstract The present paper summarizes th
6、e experience obtained by NACA and NASA concerning the low-speed lateral-directional aerodynamic derivatives due to the rate of change of side slip 8, and includes a comprehensive bibliography on this and related subject matter. The results presented show that the magnitudes of the aerodynamic stabil
7、ity derivatives due to rate of change of sideslip become quite large at high angles of attack for swept- and delta-wing configurations, and that such derivatives have large effects on the calculated dynamic stability of these configurations at high angles of attack. The paper also summarizes the win
8、d-tunnel test techniques used to measure the 6 derivatives and discusses various approaches used to predict them. Both the conventional oscillating-airfoil theory and the lag-of -the-sidewash theory are shown to be inadequate for predicting the vertical-tail contribution to the acceleration-in-sides
9、lip derivative CnP.; however, a flow-field-lag theory, which is discussed, appears to give qualitative agreement with experimental data for a current twin-jet fighter configuration. -17. Key-Words (Suggested -by Authoris) 18. Distribution Statement Lateral-dire ctional stability derivatives Unclassi
10、fied -Unlimited Acceleration-in-sideslip derivatives Stall/spin High angle of attack Subject Category 08 - - . -. . 19. Security Clanif. (of this report) 1 20. Security Classif. (of tHis pge) 1 21. No. of P- 1 22. Price For sale by the National Technical Information Service, Springfield, Virginia 22
11、161 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SUMMARY OF INFORMATION ON LOW-SPEED LATERAL-DIRECTIONAL DERIVATIVES DUE TO RATE OF CHANGE OF SIDESLIP fi Paul L. Coe, Jr., A. Bruce Graham,* and Joseph R. Chambers Langley Research Center SUMMARY Th
12、e present paper summarizes the experience obtained by NACA and NASA con cerning the low-speed aerodynamic stability derivatives due to the rate of change of side slip p. The report also includes a comprehensive bibliography on this and related subject matter. The data show that large values of the a
13、cceleration-in-sideslip derivatives CnB and cG are obtained for swept- and delta-wing configurations at high angles of attack. The physical flow phenomenon responsible for the derivatives is associated with (1) the establishment of leading-edge vortex sheets and flow separation on such wings at high
14、 angles of attack; and (2) an increment in the aerodynamic moments, produced by the separated flow, which lags the motion of the configuration. The 6 derivatives are found to be very dependent on the frequency of oscillation, with the larger values obtained for the lower frequency. The paper also sh
15、ows that the conventional use of rotary forced-oscillation data in the equation of motion to represent derivatives due to pure angular rates is erroneous at high angles of attack, where the derivatives are of significant magnitude. In addition, it is shown that the conventional oscillating-airfoil t
16、heory and the lag-of-the-sidewash theory are inadequate for predicting the contribution of the vertical tail to Cni. However, a flow-field-lag theory, devised in NACA RM L55H05 and extended herein, is found to yield values df CnP and Clb which appear to be in qualitative agreement with experimental
17、data for a current twin-jet fighter configuration. INTRODUCTION Recently, concern has arisen over the poor lateral-directional stability and control characteristics exhibited by many current high-performance military airplanes at high .- -*Graduate research assistant, The George Washington Universit
18、y, Joint Institute for Acoustics and Flight Sciences. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-angles of attack. These poor characteristics have resulted in an alarming number of inad vertent stalls, post-stall gyrations, and spins, which have
19、 produced a significant number of losses of aircraft and aircrews as well as severe operational restrictions. In view of this problem, the National Aeronautics and Space Administration is currently engaged in a broad research program designed to provide fundamental information regarding the aero dyn
20、amic characteristics of fighter configurations at high angles of attack. It is intended that such information will serve as a basis for the design of future aircraft which will be either inherently spin resistant or which will use avionics and control-system concepts for automatic spin prevention. R
21、esearch conducted by NACA in the 1950s (refs. 1to 5) indicated that at high angles of attack, the magnitudes of the aerodynamic stability derivatives due to rate of change of sideslip became quite large for swept- and delta-wing configurations, and that such derivatives had large effects on the dyna
22、mic stability of these configurations. Unfortu nately, this research was conducted during a period of time when it was generally believed that future fighter aircraft would be standoff missile launchers, with no requirements for severe maneuvering or the attendant requirement for flight at high angl
23、es of attack. Because of an apparent lack of application of this research, the results of the past inves tigations were fragmented and are therefore generally not considered in current analysis techniques for flight at high angles of attack. Recent military experience, however, has indicated a renew
24、al of close-in, air-to-air combat involving strenuous maneuvering at angles of attack near the stall. The current stall/spin problems reflect this change in operational requirements, and it appears that a reconsideration of past research is required if future stall/spin problems are to be avoided. T
25、he purpose of the present report is to summarize, in some detail, pertinent infor mation produced by NACA and NASA with regard to the derivatives due to rate of change of sideslip, and to emphasize the significance of these derivatives on the dynamic lateral-directional stability characteristics of
26、high-performance swept-wing aircraft at high angles of attack. The report includes (1)a description of wind-tunnel test techniques used to measure the derivatives; (2) illustrations of typical results; (3) a discussion of the effects of derivatives on dynamic stability characteristics; and (4) a bri
27、ef description of concepts which might be used to predict the values of such derivatives. A chronological listing of publications, not included in the reference section, which pertain to the low-speed, lateral-directional dynamic stability derivatives of aircraft is presented. SYMBOLS All longitudin
28、al aerodynamic data are presented with respect to the wind system of axes. The lateral-directional aerodynamic data are presented with respect to the body 2 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,- system of axes, as shown in figure 1, unless
29、 otherwise noted. Dimensional values are presented herein in the International System of Units (SI) with equivalent values given parenthetically in the U.S. Customary Units. a nondimensional tail length, (e;2 + 0*5) b wing span, m (ft) -C mean aerodynamic chord, m (ft) - cV mean aerodynamic chord of
30、 vertical tail, m (ft) CD drag coefficient, FD/q,S cL lift coefficient, FL/q,S cz rolling-moment coefficient, MX/q,Sb Cm pitching-moment coefficient , My/q,S E Cn yawing-moment coefficient, MZ/q,Sb CY side-force coefficient, Fy/q,S FD drag force, N (lbf) FL lift force, N (lbf) FY side force, N (lbf)
31、 G unsteady circulation function IX moment of inertia about longitudinal body axis, kg-m2 (slug-ft2) IZ moment of inertia about normal body axis, kg-m2 (slug-ft 2) Ixz product of inertia, kg-m2 (slug-ft 2) J unsteady circulation function 3 Provided by IHSNot for ResaleNo reproduction or networking p
32、ermitted without license from IHS-,-,-k q, r S sV tl/2 YO a! P P h reduced frequency of oscillation, wb/2V vertical-tail reduced frequency, wEv/2V distance from origin of axis to “,/4, m (ft) rolling moment, m-N (ft-lbf) pitching moment, m-N (ft-lbf) yawing moment, m-N (ft-lbf) rolling velocity, rad
33、/sec free-stream dynamic pressure, N/m2 (lbf/ft2) yawing velocity, rad/sec wing area, m2 ($1 vertical-tail area, m2 (ft2) time required for oscillation to reach half-amplitude, sec velocity, m/sec (ft/sec) amplitude of lateral oscillation, m (ft) angle of attack, deg or rad angle of sideslip, deg or
34、 rad rate of change of sideslip angle, rad/sec taper ratio sidewash angle (positive when effective sideslip at the vertical tail is reduced), deg or rad phase angles associated with separation effects, rad V Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IH
35、S-,-,-w frequency of oscillation, rad/sec PCnB, increment of Cnb due to vertical tail increment of C due to vertical tail (hCYP), yP Subscripts: k quantity measured under oscillatory conditions S stability-axes data exP experimental values obtained under static conditions the0 theoretical Stability
36、derivatives: acz aCY c2p = ap CYp = ap aCnClr = -rb cnr= -rba-2v a-2v CnP = a- Bb 2v BACKGROUND In the analysis of dynamic stability and control characteristics of airplanes, the lateral-directional stability derivatives due to fl have traditionally been neglected because (1) the magnitudes of such
37、derivatives were estimated to be small for the low values of angle of attack associated with the conventional flight envelope; and (2) little information was available regarding the magnitudes of the derivatives at high angles of attack. As will 5 Provided by IHSNot for ResaleNo reproduction or netw
38、orking permitted without license from IHS-,-,- 11 I 1111 I IIIII I II II 11111111 1111111111111111.1.11 II 111111 I 111111 II 11111111111.1.l.111.11.1.1111 be discussed, it was recognized that a lag of the sidewash at the vertical-tail location tended to increase aerodynamic damping in a manner simi
39、lar to the lag of downwash for the longitudinal case; however, the lag of the sidewash did not appear to have large effects at low angles of attack for configurations under consideration at that time. As pointed out in reference 6, in the early 1950s, several cases arose in which total disagreement
40、existed between theoretical predictions of lateral-directional stability char acteristics of certain swept-wing configurations and experimental results obtained during flight tests of dynamically scaled free-flight models and actual airplanes at high angles of attack. In these cases, theoretical met
41、hods generally predicted very unstable Dutch roll motions whereas flight tests showed highly damped stable motions. Subsequently, wind-tunnel test techniques devised to measure dynamic stability derivatives identified large values of derivatives at high angles of attack, which, when used in the equa
42、tions of motion, produced good agreement with flight tests. These wind-tunnel studies identified two principal sources of the j derivatives at high angles of attack: lag of sidewash at the vertical-tail location and lag of flow separa tion and attachment on highly swept wings. In both situations, th
43、e time lags involved in flow over the vehicle resulted in large values of rolling and yawing moments which were not in phase with the motion. The derivatives became quite large at angles of attack near the stall, where sensitivity of the flow to small motions became severe and large areas of stalled
44、 flow were in evidence. WIND-TUNNEL MEASUREMENT TECHNIQUES FOR j DERIVATIVES Accurate analysis of the dynamic stability and control characteristics of airplanes depends directly on accurate aerodynamic inputs for computing time histories of aircraft motions and the stability of these motions. Theore
45、tical prediction methods for the dynamic derivatives at high angles of attack have not advanced to the level of sophistication cur rently reflected in such methods for low angles of attack. Most of the information per taining to these dynamic derivatives has therefore been generated by specialized w
46、ind-tunnel test techniques. Rotary Forced-Oscillation Technique The most common wind-tunnel method in current use for obtaining dynamic stability derivatives is the rotary forced-oscillation technique illustrated in figure 2. In this tech nique, a wind-tunnel model is forced to oscillate in roll or
47、yaw at predetermined constant values of frequency and amplitude. A detailed discussion of the test setup and instrumen tation required for a typical forced-oscillation technique is given in references 7 and 8. 6 Provided by IHSNot for ResaleNo reproduction or networking permitted without license fro
48、m IHS-,-,-It should be noted that because of kinematic constraints produced by this type of test, the measured dynamic stability parameters are a combination of the dynamic stability deriva tives. For example, forced-oscillation tests in yaw produce a parameter Cnr - Cnp cos CY in body axes, or (CnI
49、-L - (“nil), in stability axes. Unfortunately, the combined deriva tives cannot be separated or individually identified by using rotary forced-oscillation techniques. Linear Forced- Oscillation Techniques In addition to the rotary-type forced-oscillation technique, several devices have been employed to provide a linear sidewise oscillator
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