1、- NASA TECHNICAL NOTE h h h W in=Y a LOAN COPY: RETURN I$!=9 llz AFWL (DOUL) -m I-KIRTLANB AFB, N. M. -z 4 z vi 4 z FLIGHT-DETERMINED DERIVATIVES AND DYNAMIC CHARACTERISTICS OF THE CV-990 AIRPLANE , by Glemz B. Gilyard Flight Research Center Edwards, Cali$ 93523 NATIONAL AERONAUTICS AND SPACE ADMINI
2、STRATION WASHINGTON, D. C. MAY 1972 I i Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-TECH LIBRARY KAFB,NM . 1. Report No. 2, Government Accession No. 3. Recipients Catalog No. TN D-6777 I I14. Title and Subtitle 5. Report Date May 1972 FLIGHT-DETE
3、RMINED DERIVATIVES AND DYNAMIC CHARACTER-6. Performing Organization CodeISTICS OF THE CV-990 AIRPLANE 7. Author(s1 I 8. Performing Organization Report No. Glenn B. Gilyard I H-693 10. Work Unit No. _ 9. Performing Organization Name and Address I126-62-10-00-24I 11. Contract orNASA Flight Research Ce
4、nter P. 0. Box273 1 Edwards, California 93523 12. Sponsoring Agency Name and Address I National Aeronautics and Space Administration Washington, D. C. 20546 . . 15. Supplementary Notes 116. Abstract Grant No. II 13. Type of Report and Period Covered I . Technical Note 14. Sponsoring Agency CodeII Fl
5、ight-determined longitudinal and lateral-directional stability and control derivatives are presented for the CV-990 airplane for , various combinations of Mach number, altitude, and flap settingthroughout the flight envelope up to a Mach number of 0.87. Also presented are the dynamic characteristics
6、 of the aircraft calculated from the flight-obtained derivatives and the measured phugoid characteristics. The derivative characteristics were obtained from flight records of longitudinal and lateral-directional transient oscillation maneuvers by using a modified Newton-Raphson digital derivative de
7、termination technique. Generally the derivatives exhibited consistent variation with lift coefficient in the low-speed data and with Mach number and altitude in the high-speed data. Many also varied with flap deflection, notably spoiler effectiveness and directional stability. 17. Key Words (Suggest
8、ed by Authorb) 18. Distribution Statement Subsonic transport Flight -dete rmined derivatives Unclassified - Unlimited Dynamic characteristics -this page) Unclassified Unclassified 65 $3.00 *For sale by the National Technical Information Service, Springfield, Virginia 22151 Provided by IHSNot for Res
9、aleNo reproduction or networking permitted without license from IHS-,-,-FLIGHT-DETERMINED DERIVATIVES AND DYNAMIC CHARACTERISTICS OF THE CV-990 AIRPLANE Glenn B. Gilyard Flight Research Center INTRODUCTION Although jet transports have been in operation about 10 years, there is little pub lished info
10、rmation on the basic aerodynamic characteristics of this class of aircraft. Documentation of the stability and control derivatives and characteristics of a repre sentative aircraft of this class would provide useful baseline data for comparison with design trends of future transports and for use in
11、simulation studies. To provide such documentation, a flight program was conducted on a NASA-operated CV-990 transport which included investigations of stalls (ref. l), landings, ground effects, noise (ref. 2), handling qualities (refs. 3 and 4), and aerodynamic characteristics. This report documents
12、 a wide range of aerodynamic stability and control derivatives obtained from stability and control maneuvers by using a newly developed digital-computer matching program (Newton-Raphson method described in ref. 5). The report also includes the calculated longitudinal short-period and Dutch roll char
13、acteristics of the airplane as well as measured phugoid characteristics. The longitudinal and lateral-directional derivatives are presented for flight condi tions from 120 knots to 195 knots indicated air,speed at an altitude of approximately 3960 meters (13,000 feet) with the airplane in various la
14、nding configurations and for Mach numbers from 0.40 to 0.87 at altitudes of 6096 meters and 10,670 meters (20,000 feet and 35,000 feet) in the cruise configuration. SYNIBOLS Physical quantities in this report are given in the International System of Units (SI) and parenthetically in U. S. Customary
15、Units. The measurements were taken in Customary Units. Factors relating the two systems are presented in reference 6. an normal acceleration at center of gravity, g units at transverse acceleration at center of gravity, g units b wing span, meters (feet) Provided by IHSNot for ResaleNo reproduction
16、or networking permitted without license from IHS-,-,- - - - - CL lift coefficient, Lift6s rolling-moment coefficient, Rolling moment qSb - acl ,per radian clP 8% ac, -L 2, rb , per radian a2v acL-2ga a , per radian -,per radian .Cm pitching-moment coefficient, Pitching moment tjSC acm Cmq - ,per rad
17、ian a2v - Em %Y- aa!,per radian acm-m6 Me ,per radian e cN normal-force coefficient, Normal force ss ZNcNq =- ,per radian a;TV , l/second a! angle of attack at center of gravity, radians (unless otherwise noted) 04: instrument indicated angle of attack, degrees P angle of sideslip at center of gravi
18、ty, radians (unless otherwise noted) Pi instrument indicated angle of sideslip, degrees h, i a! and p rates, radians/second A incremental change 6 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-E Subscript s : i 0 average aileron, rudder, spoiler, e
19、levator, and Fowler flap deflection, respectively; positive: trailing edge of rudder left, aileron and spoiler deflections which produce right roll, elevator trailing edge down, Fowler flap trailing edge down; radians (unless otherwise noted) wheel displacement, positive clockwise, degrees angle bet
20、ween body X-axis and principal X-axis, positive when body axis is below principal axis at nose of airplane damping ratio Euler angle of pitch and roll, respectively, radians (unless otherwise noted) 8 and 9 rates, radiandsecond (unless otherwise noted) indicated initial AIRPLANE DESCRIPTION The CV-9
21、90 airplane (figs. 1and 2 and table 1)is representative of the low-wing jet transports now in operation. It has a design cruise Mach number of approximately 0.85 between 10,670 meters and 12,192 meters (35,000 feet and 40,000 feet) altitude. The wing and tail are both swept 35O at the 30-percent-cho
22、rd line. The dihedral of the wing is 7; the dihedral of the tail is 7.5“. The basic commercial version has a dry weight of 67,132 kilograms (148,000 pounds) and a design gross takeoff weight of 111,585 kilograms (246,000 pounds). The version tested was unfurnished and had a dry weight of 56,700 kilo
23、grams (125,000 pounds) and, with maximum fuel, a gross takeoff weight of 101,152 kilograms (223,000 pounds). Normal flap deflections are 27 for takeoff and 50“ for approach and landing. The airplane has two antishock bodies on each wing that are used to store fuel and to reduce transonic drag rise.
24、The propulsion is provided by four General Electric C5805-23 aft-fan turbojets which are pod-mounted and suspended below and forward of the wing on highly swept pylons. Longitudinal Controls The primary longitudinal control is the elevator, which is operated by the aero dynamic forces of the mechani
25、cally operated elevator flight tabs. The limits of the elevator are 25O up and 12O down; the flight tab limits are 12O up and 25 down with respect to the elevator. The control column forces are minimized by the aerodynamic 7 Provided by IHSNot for ResaleNo reproduction or networking permitted withou
26、t license from IHS-,-,- balance of the tabs. A completely movable horizontal stabilizer provides the gross longitudinal trim required on takeoffs and landings and the Mach trim required in the tuck region. The limits of the horizontal stabilizer are 2.5 leading edge up and 13.25O leading edgedown. S
27、lotted (Fowler) flaps are incorporated in the trailing-edge section of each wing, on either side of the ailerons. The flaps are hydraulically actuated and have five detent positions corresponding to O, lo, 27, 36O, and 50 (full down). There are eight leading-edge (Krueger) flaps on each wing. Each f
28、lap has two positions (fully retracted and fully extended), is hydraulically actuated, and is controlled by the trailing-edge flap lever according to the following schedule: Trailing-edge (Fowler) flaps Leading-edge (Krueger) flaps -O0 All retracted loo and 27 I All extended 36 and 50 All extended,
29、except inboardI flap Lateral Controls The ailerons are positioned by aileron tabs and operated from the pilots wheel. The maximum deflection of the pilot s wheel mechanically commands the maximum aileron flight tab travel of QOo which, through the aerodynamic boost, operates the ailerons with a maxi
30、mum travel of *15O. The spoilers, which provide approximately 80 percent of the roll control power, are directly connected to the copilots wheel. The maximum spoiler deflection is 75“ for the inboard spoilers and 60“ for the outboard spoilers for indicated airspeeds of less than 200 knots. For airsp
31、eeds greater than 200 knots, the spoilers have a blow-down feature, because the actuators do not have enough power to command full de flection. The outboard spoilers can reach the maximum deflection in l second, whereas the inboard spoilers require 1.25 seconds. The spoilers can be disconnected from
32、 the lateral control system to permit aileron-only control. The pilot s and co pilot s controls are interconnected in the cockpit. The variation of aileron and spoiler deflection is presented in figure 3 for the normal range of wheel usage. Directional Controls In normal operation, the rudder is hyd
33、raulically actuated and has a total travel of pertinent aircraft conditions are given in table 3. All the data were ob tained at preselected Mach and altitude conditions, but at existing weights and center of-gravity positions. Although the gross weight and center of gravity were measured, correspon
34、ding moments of inertia were estimated (table 3) on the basis of limited data from the manufacturer. Because of the uncertainty of the inertias, the derivatives are presented in dimensional as well as nondimensional form. Pullup and release maneuvers were used to determine the longitudinal derivativ
35、es. The phugoid mode was also excited to measure phugoid characteristics. The lateral-directional set of maneuvers consisted of a rudder doublet, aileron-plus-spoiler doublet, and an aileron-only doublet. All the maneuvers were started from a level trim condition at a selected altitude with the Mach
36、 trim and yaw damper off except for four maneuvers made with the yaw damper on. DATA AND ACCURACY ANALYSIS Data Analysis The longitudinal short-period damping ratio was high enough (0.4 to 0.8) to make simple methods of analysis impracticable. However, the lateral-directional maneuvers were lightly
37、damped (g 0.075) so that control-fixed free oscillations could be analyzed by using the time vector method (ref. 7). The vector method results were used pri marily to check the derivatives obtained with the more versatile, newly developed, Newton-Raphson derivative extraction technique used througho
38、ut the analysis (ref. 5). The equations used in the analysis are presented in appendix A, and the application of the Newton-Raphson technique during this investigation is discussed in appendix B. 9 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-The
39、basic principle of the Newton-Raphson technique is that deviations between flight and calculated time histories of airplane response to control inputs are minimized. The calculated time histories were based on the mathematical model described in ap pendix A. Typical matches, which represent the land
40、ing and cruise codgurations, are presented in figures 5 and 6 for the longitudinal short-period mode and Dutch roll mode, respectively. The frequency, damping, and dynamic characteristics were calculated from the final set of flight derivatives. Although only one longitudinal maneuver for each fligh
41、t condition was considered necessary for analysis purposes, three lateral-directional maneuvers were required to provide sufficient dynamic data to obtain consistent results. The need for several lateral-directional maneuvers first became evident when separate matches of several available maneuvers,
42、 for any one flight condition, did not yield a unique set of derivatives. That is to say, some of the derivatives obtained from matching independ ently a rudder doublet, an aileron doublet, and an aileron-plus-spoiler doublet were significantly different. However, by matching all the lateral-directi
43、onal doublet maneuvers simultaneously at a specific flight condition, a unique set of derivatives was apparently obtained. Although the ailerons and spoilers did not move together in a precise ratio, the phasing of their motions was so nearly identical that the effectiveness of each surface could no
44、t be determined individually by the Newton-Raphson method. The aileron-only doublet, however, provided the additional information required to simultaneously separate the two control derivatives. The aileron control derivatives are determined primarily from the information content of the aileron-only
45、 maneuvers and the spoiler derivatives are determined from the information contained in the aileron-plus-spoiler maneuvers. In all instances the consistency of the derivatives increased with the number of maneuvers being matched simultaneously. Early in the program, aileron-only doublet data were no
46、t obtained, hence a yaw damper-on doublet was also matched with the rudder and aileron-plus-spoiler doublets for improved accuracy. A data sample rate of 10 points per second was used to match the time histories of the longitudinal mode, whereas a 5-point-per-second rate was used for the lateral-dir
47、ectional mode. Because the aircraft inertias were not accurately known, the cross product of inertia was assumed to be zero. Available data from the manufacturer also indicated that this assumption was valid. Further information on assumed inertias and data sample rate is presented in appendix B. Ac
48、curacy Analysis With the Newton-Raphson method an indication of the quality or the confidence level of each derivative is computed in terms of a variance. The variance is determined with respect to every other derivative and variable of a particular match and is defined as the lower bound of the sta
49、ndard deviation, provided certain assumptions about the data are valid. The basic assumption is that the data being analyzed can be accurately described by the model with only white noise superimposed. Reference 5 shows that although this basic assumption is not exactly met, for engineering purposes it is 10 Provided by IHSNot for ResaleNo reproduction or networking permitte
