1、NASA TECHNICAL NOTE 1- NASA c. 1 TN I_ D-6058 WIND-TUNNEL INVESTIGATION OF A JET TRANSPORT AIRPLANE CONFIGURATION WITH HIGH THRUST-WEIGHT RATIO AND AN EXTERNAL-FLOW JET FLAP by Lysle P. Purlett, Delmu C. Freemun, Jr., und Churles C. Smith, Jr. Lulzgley Reseuwh Center Hdmpton, Vu, 23365 NATIONAL AERO
2、NAUTICS AND SPACE ADMINISTRATION WASHINGTON, D. C. NOVEMBER 1970 i I 1 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-TECH LIBRARY KAFB. NM I NASA TN D-6058 WIND-TUNNEL INVESTIGATION OF A JET TRANSPORT 1. Title and Subtitle AIRPLANE CONFIGURATION WI
3、TH HIGH THRUST-WEIGHT RATIO AND AN EXTERNAL-FLOW JET FLAP .- - I. Report No. 5. Report Date November 1970 6. Performing Organization Code I 2. Government Accession No. T Charles C. Smith, Jr. 9. Performing Organization Name and Address NASA Langley Research Center Hampton, Va. 23365 2. Sponsoring Ag
4、ency Name and Address National Aeronautics and Space Administration Washington, D.C. 20546 10. Work Unit No. 721-01-11-06 11. Contract or Grant No. 13. Type of Report and Period Covered Technical Note 14. Sponsoring Agency Code 5. Supplementary Notes 19. Security Classif. (of this report) Unclassifi
5、ed 6. Abstract An investigation has been conducted in the Langley full-scale tunnel to determine the aerodynamic and stability and control characteristics of a jet transport configuration that has a high thrust-weight ratio and is equipped with an external-flow jet flap. is powered by four high-bypa
6、ss-ratio turbofan engines. The model Maximum lift coefficients of about 8 were measured for test conditions which simulated a jet transport configuration having a thrust-weight ratio of about 0.5. Longitudinal insta- bility was encountered at high thrust coefficients because of adverse downwash vari
7、ations in the vicinity of the tail. This problem was solved by raising the tail and moving it forward to a more favorable downwash field. The model was laterally and directionally stable under al power conditions. The moments associated with an engine failure were too large to be trimmed out by conv
8、entional aileron and rudder control; spoilers alone provided enough con- trol to offset the engine-out rolling moments but the lift loss associated with the use of spoilers was severe. 20. Security Classif. (of this page) 1 21. Noi; Pages 22. Price* Unclassified $3.00 7. Key Words (Suggested by Auth
9、or(s) External-flow jet flap High lift Stability and control STOL 18. Distribution Statement Unclassified - Unlimited Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-WIND-TUNNEL INVESTIGATION OF A JET TRANSPORT AIRPLANE CONFIGURATION WITH HIGH THRUST
10、-WEIGHT RATIO AND AN EXTERNAL-FLOW JET FLAP By Lysle P. Parlett, Delma C. Freeman, Jr., and Charles C. Smith, Jr. Langley Research Center SUMMARY An investigation has been conducted in the Langley full-scale tunnel to determine the aerodynamic and stability and control characteristics of a jet trans
11、port configuration that has a high thrust-weight ratio and is equipped with an external-flow jet flap. The model is powered by four high-bypass-ratio turbofan engines. Maximum lift coefficients of about 8 were measured for test conditions which simu- Longitudinal lated a jet transport configuration
12、having a thrust-weight ratio of about 0.5. instability was encountered at high thrust coefficients because of adverse downwash varia- tions in the vicinity of the tail. This problem was solved by raising the tail and moving it forward to a more favorable downwash field. The model was laterally and d
13、irectionally stable under all power conditions. The moments associated with an engine failure were too large to be trimmed out by conventional aileron and rudder control; spoilers alone provided enough control to offset the engine-out rolling moments but the lift loss asso- ciated with the use of sp
14、oilers was severe. INTRODUCTION Recent interest in the development of jet-powered STOL transport aircraft has led to serious consideration of the external-flow jet flap as a means of producing the high lift required for STOL operation. Early experimental work (refs. 1 to 3) demonstrated the feasibil
15、ity of this concept for producing high lift, but interest in the idea decreased mainly because of the problems caused by heating of the aircraft structures. The more recent development of high-bypass turbofan engines with relatively cool exhaust has minimized this problem and made the concept much m
16、ore feasible from structural considerations. In the application of the jet-flap concept to STOL aircraft, consideration must be given to stability and control at very low speeds, particularly in terms of safe operation Provided by IHSNot for ResaleNo reproduction or networking permitted without lice
17、nse from IHS-,-,-with a critical engine inoperative. Very little experimental information of this type is available from which basic problem areas can be identified and from which effective design features can be established for practical hardware application. One recent experi- mental study (ref. 4
18、) provided some information on the stability and control characteris- tics of a jet STOL aircraft equipped with a jet flap, but there is a need for much more experimental work of this type to provide more complete research information. For this reason, the present investigation was undertaken and, i
19、n order to expedite the testing, an existing model was used. Even though the model had been used in a previous study to simulate an aircraft with a fairly low thrust-weight ratio (see ref. 5), the configuration seemed desirable for simulation of an STOL transport with a high thrust-weight ratio for
20、several reasons: (1) The model had a high wing to minimize adverse ground effects, (2) the wing was swept to help in spreading the jet exhaust over the flap, and (3) the hori- zontal tail was located high on the vertical tail to help in minimizing adverse downwash effects. In the present investigati
21、on, tests were made over angle-of -attack and angle-of- sideslip ranges for several thrust coefficients and for several flap deflections. In addi- tion, tests were made under various conditions of asymmetric thrust and asymmetric control deflections. Also, flow survey measurements were made in the v
22、icinity of the horizontal tail to determine the downwash variation for a jet-flap configuration operating at very high lift coefficients. SYMBOLS The longitudinal data are referred to the stability-axis system and the lateral data are referred to the body-axis system. center-of-gravity position (0.4
23、46 mean aerodynamic chord) shown in figure 2. (See fig. 1.) The origin of the axes was at the In order to facilitate international usage of the data presented, dimensional quanti- ties are presented both in U.S. Customary Units and in the International System of Units (SI). Equivalent dimensions wer
24、e determined by using the conversion factors given in reference 6. b wing span, ft (m) CD drag coefficient, FD/qS CL lift coefficient, FL/qS CZ rolling-moment coefficient, MX/qSb 2 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-acz P aP Cz =-,per de
25、g Cm pitching-moment coefficient, My/qSe Cn yawing-moment coefficient, MZ/qSb CY side-force coefficient, Fy/qS CYp = ap per deg engine gross -thrust coefficient, kVE/qS local wing chord, in. (cm) mean aerodynamic chord, in. (cm) axial force, positive rearward, lb (N) drag force, lb (N) lift force, l
26、b (N) normal force, positive upward, lb (N) force along X-axis, positive forward, lb (N) side force, positive to the right, lb (N) horizontal-tail incidence angle, deg tail length (measured from center of gravity to c/4 of horizontal tail), in. (cm) rolling momeiit, ft-lb (m-N) pitching moment, ft-l
27、b (m-N) 3 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-yawing moment, ft-lb (m-N) engine mass-flow rate, slugs/sec (kg/sec) free-stream dynamic pressure, pV2/2, lb/ft2 (N/m2) radius of curvature, in. (cm) wing area, ft2 (m2) thrust, lb (N) free-st
28、ream velocity, ft/sec (m/sec) engine exit velocity, ft/sec (m/sec) body reference axes stability reference axes tail height (measured from top of fuselage to horizontal tail), in. angle of attack, deg angle of sideslip, deg deflection of left aileron, positive when trailing edge is down, deg deflect
29、ion of right aileron, positive when trailing edge is down, deg elevator deflection, positive when trailing edge is down, deg deflection of forward segment of trailing-edge flap, deg deflection of aft segment of trailing-edge flap, deg (cm) deflection of left trailing-edge flap, deg (6f1/6f2)R 4 defl
30、ection of right trailing-edge flap, deg Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-jet deflection, deg j 6, rudder deflection, positive when trailing edge is to the left, deg downwash angle, deg downwash factor a aa 1 - jFA2+FN2 T flap turning e
31、fficiency, P air density, slugs/ft3 (kg/m3) MODELANDAPPARATUS The tests were made in the 30- by 6O-foot (9.1- by 18.3-m) open-throat test sec- tion of the Langley full-scale tunnel with the model mounted about 10 feet (3.05 m) above the ground board. The model was so small in proportion to the test
32、section that no wind- tunnel wall corrections were needed or applied. Normal corrections for flow angularity were applied. The investigation was conducted on the four-engine, high-wing, jet-transport model illustrated by the three-view drawing of figure 2(a). The model was the same as that used in r
33、eference 5 except that the leading-edge slats were replaced with leading-edge flaps and the chord of the aft segment of the trailing-edge flaps was doubled. The dimen- sional characteristics of the model are given in table I. A detailed sketch of the flap assembly and engine-pylon arrangement is sho
34、wn in figure 2(b). Details of the leading- edge flap Configuration and the jet exhaust deflectors employed during the tests are pre- sented in figures 2(c) and 2(d), respectively. static force tests in the Langley full-scale tunnel is presented in figure 3. A photograph of the model mounted for To f
35、acilitate configuration changes and to insure accurate flap deflection angles, the wing of the model was designed with removable trailing edges. To convert the model from the clean configuration to each of the flap-deflected configurations, the clean trailing edges were replaced with trailing-edge f
36、laps constructed with fixed gaps, overlaps, and deflection angles. The leading-edge flaps were designed so that they could be fastened to the wing leading edge at fixed positions when desired. Because of this arrangement, only the leading- and trailing-edge flap deflections shown in figure 2 could b
37、e achieved for the tests. The model engines represented high-bypass-ratio turbofans and were installed at -3O incidence (referred to the X-axis) so that for the basic condition the jet exhaust 5 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-impinge
38、d directly on the trailing-edge flap system. In addition, in an attempt to achieve better spreading and to improve the turning efficiency of the system, several jet-exhaust deflectors (see fig. 2(d) were tested and the most promising deflector was employed in most of the tests. The engine turbines w
39、ere driven by compressed air and turned fans which produced the desired thrust. All of the tests were made with an internal strain-gage balance and conventional sting which entered the rear of the fuselage. TESTS AND PROCEDURES In preparation for the tests, the engines were calibrated to determine g
40、ross thrust as a function of engine rotational speed in the static condition - at zero angle of attack with the thrust deflectors off. The tests were then run by setting the engine rotational speed to give the desired thrust and holding this speed cohstant through the ranges of angles of attack or s
41、ideslip. Jet deflection angles and flap turning efficiency were determined from measure- ments of normal and axial forces made in the static thrust condition with flaps deflected. The static thrust used in computing turning efficiency was taken directly from the engine calibrations at the appropriat
42、e rotational speed. During the wind-on tests various changes were made to the flap geometry or to control-surface deflections. 6f1/6f2 = 200/400 and 6f1/6f2 = 3Oo/6O0 for a range of Cp from 0 to 3.5 and a range of angles of attack of -5Oto 30. Sideslip runs were made over a range of angles of side-
43、slip from 15O to -15. All wind-on tests were made at a free-stream dynamic pressure of about 3 lb/ft2 (143.6 N/m2), which corresponds to a velocity of 50 ft/sec (15.24 m/sec) and to a Reynolds number, based on the mean aerodynamic chord, of 0.35 X lo6. Most tests were made for flap deflections of In
44、 addition to the force tests, a few flow survey measurements were made in the vicinity of the horizontal tail to determine the downwash variation with changes in thrust coefficient. The measurements were made with a simple vane of balsa wood which was free to pivot for alinement with the local flow.
45、 A potentiometer connected to the wooden vane produced electrical signals which indicated the flow angle. RESULTS AND DISCUSSION At the beginning of the test program, the wing of the model was equipped with the leading-edge slat arrangement described in reference 5. This slat arrangement was of conv
46、entional design and was effective at the low thrust-weight ratio of the jet-flap simu- lation of reference 5. It was found in the preliminary tests of the present investigation, 6 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-however, that at the h
47、igher thrust coefficients the leading-edge flow conditions with the original slat configuration were very unsatisfactory. Tuft studies, for example, showed that the wing leading edges were stalled at angles of attack of about 5O. It was found that lowering the slats and sealing the gaps between the
48、slats and wing resulted in much better leading-edge flow conditions. Also, when the outboard slats were altered by increasing the chord and adding much more camber, it was possible to prevent the wing tips from stalling prematurely. With this leading-edge arrangement, identified as leading-edge flap
49、s in the present paper, the wing stall could be delayed to angles of attack of about 20. Lift Characteristics Wind off.- Because the jet-induced lift is highly dependent on the direction and velocity of the engine slipstream as it leaves the flap system, the flap system must be capable of turning the slipstream efficiently through large angles. In th
