1、Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NASA TM X-1665 EFFECT OF LARGE SIDESLIP ANGLES ON STABILITY CHARACTERISTICS OF A T-TAIL TRANSPORT CONFIGURATION By Edward J. Ray Langley Research Center Langley Station, Hampton, Va. NATIONAL AERONAUTIC
2、S AND SPACE ADMINISTRATION For sale by the Clearinghouse for Federal Scientific and Technical Information Springfield, Virginia 22151 - CFSTI price $3.00 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-EFFECT OF LARGE SIDESLIP ANGLES ON STABILITY CHA
3、RACTERISTICS OF A T-TAIL TRANSPORT CONFIGURATION By Edward J. Ray Langley Research Center SUMMARY An investigation has been made to determine the effects of large sideslip angles on I: the static stability characteristics of a typical T-tail transport configuration. In addition, damping-in-roll deri
4、vatives were determined for the basic T-tail arrangement over an bngle-of-attack range extending from about Ooto 36O. The effects of large sideslip varia- tions on the pitching- moment characteristics were also ascertained for selected configura- tions. The study was made in the Langley high-speed 7
5、- by 10-foot tunnel at a Mach num- ber of 0.30 and a corresponding Reynolds number (based on mean aerodynamic chord) of 1.20 x 106. The sideslip phase of this investigation was performed in two different manners. In the first method, the directional stability, lateral stability, and side-force param
6、eters were determined by assuming linear variations of the static characteristics over a side- slip range of -5O to 5O. The complete configurations investigated in this manner exhibited positive effective dihedral and directional stability throughout an angle-of-attack range extending from about -4
7、to 22O. In order to assess this assumed linearity and to deter- mine the lateral-directional characteristics over large sideslip ranges, several of the configurations were positioned at fixed angles of attack (range of Oo to 1l0) and varied through sideslip angles extending from -22O to 22O. These t
8、ests indicated significant non- linearities in the variation of yawing-moment coefficient with sideslip angle at relatively low angles of attack. Two aft nacelle locations were investigated and it was determined from this limited study that the static directional stability characteristics could be s
9、ubstantially influenced at moderate angles of attack and sideslip by the position of the nacelles on the rearward portion of the fuselage. The horizontal T-tail exhibited a strong end-plate effect which generally resulted in favorable increments in the effective dihedral and directional stabil- ity
10、of the configuration. Increases in sideslip angle resulted in increased nose-down pitching-moment contributions at angles of attack ranging from about 0 to 1l0. The brief steady-state, forced-roll study indicated that the basic T-tail configuration would exhibit positive damping-in-roll characterist
11、ics at angles of attack ranging from 00 to 360 except at angles of attack near the wing stall angle. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-INTRODUCTION In recent years, there has been a trend toward designing commercial and business jet air
12、craft with aft-mounted engines and with horizontal stabilizers mounted high on the vertical tail. The combination of T-tail and aft engine offers several distinct advantages at normal operating angles of attack (see refs. 1 and 2); however, when integrating an aft- nacelle arrangement with high hori
13、zontal-tail position, careful consideration must be given to the stability characteristics at high angles of attack. The high tail must ultimately pass through an airplane wake system which could be augmented by the wake system of the aft-mounted nacelles, and once this occurs it is possible to enco
14、unter large losses in tail effectiveness. This concern stimulated a great deal of interest in the aerodynamic characteristics of T-tail configurations, and because of the scarcity of documented infor- mation for this type of aircraft, the National Aeronautics and Space Administration ini- tiated a r
15、esearch program in 1964 to examine the stability and control characteristics of P typical T-tail aircraft. (See refs. 3 to 8.) The initial studies were directed primarily toward the longitudinal stability character is tics. The main purpose of the present wind-tunnel study was to determine the stati
16、c lateral and directional stability characteristics of a typical T-tail transport arrangement at large angles of sideslip in the normal operating angle-of-attack range. The basic model of the present investigation was identical to the T-tail configuration discussed in references 3 to 5. Selected res
17、ults which were determined for this “typical“ T-tail arrangement have also been utilized in the analyses presented in references 2, 7, 8, and 9. In addition to the static sideslip results, pitching-moment and lift characteris- tics were determined for several of the configurations at a sideslip angl
18、e of zero through an angle-of-attack range varying from about -4 to 22O. Pitching-moment characteristics through large sideslip ranges and the rate of change of rolling-moment coefficient with wing-tip helix angle were also determined for selected configurations. The investigation was conducted in t
19、he Langley high-speed 7- by 10-foot tunnel at a Mach number of 0.30 and a Reynolds number of 1.20 X 106, based on the wing mean aerodynamic chord. SYMBOLS The data presented in this paper are referred to the body-axis system with the exception of lift, which is referred to the stability-axis system.
20、 All the data contained in this paper are referred to a moment center located at the 0.40 point of the mean aero- dynamic chord of the wing. (See fig. 1.) The coefficients were nondimensionalized by using the geometry of the basic wing. (See table I.) 2 Provided by IHSNot for ResaleNo reproduction o
21、r networking permitted without license from IHS-,-,-The units used for the physical quantities in this report are given both in the U.S. Customary Units and in the International System of Units (SI). Factors relating the two systems are given in reference 10. reference wing span, 46.40 in. (117.86 c
22、m) mean aerodynamic chord of wing, 6.69 in. (16.99 em) Lift lift coefficient, - CIS rolling-moment coefficient, Rolling moment qSb effective change in rolling-moment coefficient due to horizontal tail effective change in rolling-moment coefficient due to combination of vertical and horizontal tails
23、aCl effective-dihedral parameter, - ap rate of change of rolling-moment coefficient with wing-tip helix angle pb/W Pitching moment pitching-moment coefficient, I_ qSE Yawing moment qSb yawing-moment coefficient, effective change in yawing-moment coefficient due to horizontal tail effective change in
24、 yawing-moment coefficient due to combination of vertical and horizontal tails directional- stability parameter, - aP Side force qs side-force coefficient, effective change in side-force coefficient due to horizontal tail effective change in side-force coefficient due to combination of vertical and
25、horizontal tails 3 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-aCY side-force parameter, - P rate of roll, radians per unit time q free- stream dynamic pressure, lb/ft2 (N/m2) S V velocity cyP aP area of wing, including body intercept, 1.92 ft2 (
26、0.1784 m2) it incidence of horizontal tail (positive when trailing edge is down), degrees a! angle of attack, degrees P sideslip angle, degrees Model component designations: F fuselage W basic wing Wf basic wing with fillets (see fig. 1) V basic vertical tail flat-plate vertical tail, leading edge s
27、wept forward V1 v2 flat-plate vertical tail, leading edge swept back H horizontal tail N Naft nacelle in basic location (leading edge at fuselage station 31.70 in. (80.52 cm) nacelle in aft location (leading edge at fuselage station 35.71 in. (90.70 em) MODEL DESCRIPTION The basic configuration of t
28、his investigation was identical to the basic model utilized in the wind-tunnel study described in reference 4. A drawing of the basic model is shown 4 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-in figure 1 and geometric characteristics of the mo
29、del components are presented in table I. Fuselage The typical cross section of the model fuselage had slightly flattened sides, a circular-arc bottom portion, and a larger circular-arc top portion. Except for small circular sections near the nose and the aft part of the fuselage, the fuselage was pe
30、ar- shaped. (See fig. l.) Wing v The wing was composed of NACA 64A409 airfoil sections oriented in the stream- wise direction. As shown in figure 1, the wing was affixed to the fuselage in a relatively low position. Several tests were conducted with the inboard portion of the wing trailing edge fill
31、ed in with fillets. (See fig. 1.) The fillets were constructed of 0.125-in. (0.318-cm) flat-plate material with beveled trailing edges. Horizontal and Vertical Tails The horizontal and vertical tails were made up of NACA 0009 airfoil sections oriented streamwise. Provisions were made to deflect the
32、entire horizontal tail for lon- gitudinal control. In addition to the basic vertical tail, a flat-plate vertical tail, having an identical planform with rounded leading and trailing edges, was investigated with the leading edge swept both forward Vi and back V2. (See table I.) The centroid of area o
33、f the flat-plate vertical tail was positioned at fuselage station 45.00 in. (114.30 cm) in both sweep conditions. Nacelles Details of the basic nacelle arrangement are illustrated in figure 1. The nacelles were investigated in the location shown in figure 1 and in a more rearward location. In the re
34、arward position, the nacelles were located 0.60c (4.01 in. or 10.18 cm) aft of the basic position shown in figure 1 with the lip of the nacelles at fuselage station 35.71 in. (90.70 cm). In both of the nacelle positions the orientation of the nacelle center line with respect to the model reference p
35、lanes remained constant. TESTS AND CORRECTIONS This experimental study was made in the Langley high-speed 7- by 10-foot tunnel with the slots in the test section closed. The average test conditions during the 5 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from
36、 IHS-,-,-investigation were a free-stream Mach number of 0.30, a free-stream dynamic pressure of 124 lb/ft2 (5937 N/m2), and a Reynolds number based on of 1.20 x 106. The test models were sting mounted and the forces and moments were measured by means of a six-component strain-gage balance mounted w
37、ithin the fuselage. (Only five components of data have been presented herein. Drag results have been excluded from this stability analysis since the drag characteristics for these configurations were presented in detail in ref. 4.) The angles of attack and sideslip have been corrected for combined d
38、eflection of the sting-support system and balance under load. Jet-boundary corrections calculated by the method of reference 11 have been applied to the angle-of- attack values. Blockage corrections determined by the method of reference 12 were utilized in the reduction of the data. u The sideslip r
39、esults of this study were obtained by utilizing two different test tech- niques. In the first of these methods, the various test configurations were affixed at a sideslip angle and then displaced through an angle-of-attack range which extended from about -4 to 22O. The sideslip angles investigated w
40、ere 5O, Oo, and -5O. In this method, the sideslip parameters Czp, Cnp and Cy which are included in figures 2 to 8 were P derived by assuming that the model sideslip characteristics were linear over the sideslip range of -5O to 5O. Since the primary purpose of this investigation was to determine the
41、static lateral-directional characteristics of the T-tail arrangement at large sideslip angles, and since there was concern regarding the linearity of the sideslip variations, data were also obtained by placing the test configurations at a fixed angle of attack (0.20, 5.60, and 11.00) and displacing
42、the test configurations through sideslip ranges extending from about -220 to 60 and/or -6O to 22O. The data which were obtained in this manner are shown in figure 9. I The steady-state forced-roll technique used to determine the change in the rolling- moment coefficient with wing-tip helix angle Czp
43、 is described thoroughly in refer- ence 13. Because of the length of the fuselage, it was necessary to position the model center of mass well ahead of the center of rotation of the forced-roll test equipment. Tests which were conducted with different longitudinal locations of the model, as well as t
44、heoretical estimates? indicated that the roll results could be corrected satisfactorily for this “offset“ position, but the corrected yaw and side-force parameters were inconsistent and appeared to be questionable. The yaw and side-force derivatives Cnp and Cy therefore, have been omitted from the r
45、esults in this paper. P PRESENTATION OF RESULTS The data which were determined in this wind-tunnel investigation are presented in the following figures. The configuration code is defined in the section entitled ttSymbols.“ 6 Provided by IHSNot for ResaleNo reproduction or networking permitted withou
46、t license from IHS-,-,-Figure Variation of CL, Cm, Clp, CnP, and Cy with cy: 2 P F, FW, andFWV F, FV, andFVH 3 F, FW, andFWN 4 FWN, FWVN, andFWVHN . 5 FWVH, FWVHN, andFWVHNaft 7 FWNaft, FWVNaft, and FWVHNaft . FWV, FWVH (it = -0.5O), and FWVH (it = -5.0) . Variation of Cl, Cn, and Cy with P: FW . 9(
47、a) 2 FWV 9(b) FWV1 S(C) FWV2 9(d) 6 8 FWVH . 9 (4 FWVHN . 9 (f) FWNaft . 9 (g) FWVNaft 9 (h) FWVHNaft . 9(i) FWfVHNdt . 9 (9 FWVNaft 1O(b) FWVHNaft WC) Variation of Cm with P: FWVH . lO(a) Summary characteristics: Vertical horizontal- tail contribution to lateral- directional st ability of Horizonta
48、l-tail contribution to lateral-directional stability of the Vertical horizontal-tail contribution to lateral- directional stability of the nacelles-off configuration 11 aft-nacelle configuration 12 the aft-nacelle configuration 13 Variation of Cl with Q! for FWVHN 14 P DISCUSSION Static Aerodynamic
49、Characteristics at Small Sideslip Angles As mentioned previously, the sideslip parameters shown in figures 2 to 8 were obtained by assuming a linear variation of the lateral-directional and side-force 7 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-characteristics over a rang
