1、WIND-TUNNEL INVESTIGATION OF AN STOL AIRCRAFT CONFIGURATION EQUIPPED WITH AN EXTERNAL-FLOW JET FLAP by Lysle P. Purlett and Jumes P. Shivers Langley Research Center Langley Station, Humpton, Va. NATIONAL AERONAUTICS AND SPACE ADMINISTRATION WASHINGTON, D. C. AUGUST 1969 Provided by IHSNot for Resale
2、No reproduction or networking permitted without license from IHS-,-,-TECH LIBRARY KAFB, NM .-. 0132298 WIND-TUNNEL INVESTIGATION OF AN STOL AIRCRAFT CONFIGURATION EQUIPPED WITH AN EXTERNAL-FLOW JET FLAP By Lysle P. Parlett and James P. Shivers Langley Research Center Langley Station, Hampton, Va. NA
3、TIONAL AERONAUTICS 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-,-,-WIND-TUNNEL INVESTIGATION OF AN
4、 STOL AIRCRAFT CONFIGURATION EQTJIPPEDWITHANEXTERNAL-FLOWJET FLAP By Lysle P. Parlett and James P. Shivers Langley Research Center SUMMARY The present investigation was performed to provide information on the static longi- tudinal and lateral characteristics of a proposed short take-off and landing
5、(STOL) trans- port configuration utilizing the jet-flap principle. Longitudinal tests were conducted at engine gross-thrust coefficients of from 0 to 3.4 through a range of angle of attack which included the stall; and lateral tests were made, both power-off and power-on, through a sideslip range of
6、 +30 at angles of attack of 0 and loo. Untrimmed lift coefficients up to 7.8 were attained at a gross-thrust coefficient of 2.83 in the tail-off condition. With the tail on, nearly all high-lift conditions were charac- terized by a marked longitudinal instability (or pitch-up tendency) which began a
7、t an angle of attack of 7. The instability was apparently caused by the tip vortices which, under the influence of the highly loaded center section of the wing, were drawn into the region of the horizontal tail. The tail-on configuration was directionally stable and had positive dihe- dral effect at
8、 all flap and power settings tested; and in the take-off and landing conditions increasing power increased directional stability and decreased dihedral effect. With one outboard engine not operating, the model could be trimmed laterally and directionally up to lift coefficients of 4.2 in the take-of
9、f condition and 5.7 in the landing condition. Above these lift coefficients the model could not be trimmed in roll, but trim in yaw could still be attained. INTRODUCTION The external-flow jet-flap principle is incorporated in a recently proposed design for a medium-size four-engine jet transport int
10、ended to have short take-off and landing (STOL) capabilities. Previous investigations (refs. 1, 2, and 3) have demonstrated that an external-flow jet flap can produce the high lift coefficients required for short-field operation, but that the high lift coefficients may be accompanied by serious trim
11、 and sta- bility problems. and unsymmetrical span loading of powered lift which would vary with configuration. order to broaden the knowledge in the jet-flap field by testing a configuration significantly These problems are attributed primarily to downwash characteristics In I Provided by IHSNot for
12、 ResaleNo reproduction or networking permitted without license from IHS-,-,-different from those of past investigations, the NASA undertook to test a model of the pro- posed STOL transport. The wing of this configuration is more highly tapered and the engines are located relatively closer to the fus
13、elage than in the previous investigations. The tests provided general aerodynamic data for the take-off, cruise, and landing condi- tions, with emphasis on trim and stability studies in the high-power, high-lift conditions. Longitudinal and lateral forces and moments were measured at angles of attac
14、k up to 28O, at sideslip angles up to 30, and at engine gross-thrust coefficients up to 3.4. In terms of trim flight conditions for the proposed full-scale aircraft represented by the model, a gross-thrust coefficient of 3.4 would result in a thrust-weight ratio of approximately 0.6. SYMBOLS A sketc
15、h of the axis system used in the investigation is presented in figure 1. Lon- gitudinal forces and moments are referred to the wind-axis system; lateral and direc- tional forces and moments are referred to the body-axis system. b wing span, ft (m) CD drag coefficient, D/qS CL lift coefficient, L/qS
16、CL,O lift coefficient, power off CL, r jet -induced circulation lift coefficient cz rolling-moment coefficient, Mx/qSb Cm pitching - moment coefficient , My/qSE Cn yawing-moment coefficient, MZ/qSb CY side-force coefficient, Fy/qS aCY CYp = ap C 2 engine gross-thrust coefficient, mV,/qS local wing c
17、hord, ft (m) Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,- C D FA FN FY it L MX MY MZ m S T VE (Y P 6aux 6f length of mean aerodynamic chord, ft (m) drag, 1b (N) axial force, lb (N) normal force, lb (N) side force, lb (N) incidence of horizontal t
18、ail, deg lift, lb (N) rolling moment, ft-lb (N-m) pitching moment (referred to 0.25E), ft-lb (N-m) yawing moment, ft-lb (N-m) engine mass flow rate, slugs/sec (kg/sec) free-stream dynamic pressure, lb/ft2 (N/m2) wing area, ft2 (m2) thrust, lb (N) engine exit velocity, ft/sec (m/sec) model body axes
19、angle of attack, deg angle of sideslip, deg deflection of auxiliary flap, deg flap deflection, deg jet deflection, deg 3 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-rudder deflection, deg spoiler deflection, deg vane deflection, deg downwash angl
20、e, deg JQTg$ T flap turning efficiency, Designations for flap settings are given in figure 2(b). MODEL AND APPARATUS The investigation was conducted on the four-engine high-wing jet transport model illustrated by the three-view drawing of figure 2(a). A typical section through the flap system and th
21、e relationship of the flaps to the engines are shown in figure 2(b). The leading-edge slat shown in figure 2(b) was extended for all test conditions. The flap com- binations are defined in the table of figure 2(b) and a plan view of the wing semispan is presented in figure 2(c). Photographs of the m
22、odel are presented in figure 3, and dimen- sional characteristics are listed in table I. The engines were of the ejector type (in which thrust resulting from gas flow through primary nozzles is augmented by a secondary flow of ambient air induced by the primary flow) and had the same external geomet
23、ry as a current turbofan engine. Flow of the primary gas (compressed nitrogen) to the section of the engine simulating the turbine was controlled independently of primary flow to the fan simulator so that the desired thrust was obtained at the desired bypass ratio (8 to 1). For some of the tests, th
24、rust deflector plates were installed on the outboard fan simulators as shown in figure 2(b). It may be noted that the use of these ejector engines did not allow inlet and exit mass flow rates to be simulated correctly at the same time, but for the present tests the exit mass flow was considered to b
25、e the more important of the two. The model was mounted on a six-component strain-gage balance and was strut- supported in the test section of the Langley full-scale tunnel. throat test section of 30 by 60 feet (9.14 by 18.29 meters), which allows models of the present size (8-foot (2.5-m) span) to b
26、e tested at high lift coefficients without introducing significant tunnel wall effects. This tunnel has an open- 4 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-TESTS AND PROCEDURES In preparation for the present tests, single-engine calibrations w
27、ere made to deter- mine net thrust and mass flow rates as functions of nitrogen drive pressure in the static condition and at the test free-stream airspeed at zero angle of attack. The tests were then run by setting the drive pressures for the fan and turbine simulators, respectively, to the desired
28、 values and holding these pressures constant through the ranges of angle of attack or sideslip. Jet deflection angles and flap turning efficiencies were determined from measure- ments of the normal and axial forces made in the static thrust condition with flaps deflected. The static thrust used in c
29、omputing turning efficiency was taken directly from the single-engine calibrations at the appropriate drive pressures. During the wind-on tests various changes were made to the flap geometry or to control-surface deflections; each condition was usually tested at values of 3.4 through a range of angl
30、e of attack of -4O to 28. All tail-off tests were made with both the horizontal and vertical tails removed. Sideslip runs were made over a range of angles of sideslip from -30 to 30. dynamic pressure of 11 lb/ft2 (527 N/m2), which corresponds to a velocity of 97 ft/sec (29.6 m/sec). aerodynamic chor
31、d of the wing. Cp of 0 to Nearly all wind-on tests were made at a free-stream The Reynolds number was approximately 0.8 X lo6 based on the mean No wind-tunnel jet boundary corrections were applied to the data because such cor- rections were computed for a somewhat larger high-lift model during a pre
32、vious investi- gation (ref. 3) and were found to be negligible. PRESENTATION OF DATA The test data are presented in the following figures. The four main headings corre- Figure Longitudinal characteristics, tail off 4-7 Longitudinal basic data, tail off, auxiliary flaps deflected 8 Summary of auxilia
33、ry-flap performance 9 Analysis of jet-flap effectiveness 10-12 spond to those in the Discussion section. Lift Characteristics . Longitudinal Stability and Trim, Symmetric Thrust Longitudinal characteristics, tail on, basic configurations 13 - 16 Photographs of smoke flow showing vortex system 17 5 P
34、rovided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Figure Longitudinal characteristics, tail on, configurations intended 18-23 Horizontal -tail effectiveness . 24 to remedy longitudinal instability Lateral Characteristics, Symmetric Thrust Lateral charac
35、teristics, tail off 25-27 Lateral characteristics, tail on, basic configurations 28-31 Lateral characteristics, tail on, controls deflected . 32-35 Lateral and Longitudinal Characteristics, Asymmetric Thrust Lateral characteristics, tail on, asymmetric thrust and control . 36-38 Lateral trim capabil
36、ity, one engine out 39 Longitudinal characteristics, asymmetric thrust and control 40-45 Effect of thrust distribution on lift 46 DISCUSSION Lift Characteristics Basic longitudinal data for the model in the tail-off condition at flap deflections representing the cruise, take-off (two deflections), a
37、nd landing configurations are pre- sented in figures 4 to 7. The data show that the stall angle and maximum lift coefficient increased with increasing thrust coefficient, and that as flap deflection increased, the effects of thrust on the lift characteristics became more pronounced. lift coefficient
38、s up to 7.8 (untrimmed) at a gross-thrust coefficient.of 2.83. As would be expected, high lift coefficients are accompanied by large nose-down moments because of the rearward location of the flap loads. The leading-edge slat was extended for all test conditions. The landing flap deflection (fig. 7)
39、produced With the basic landing flap setting LDG, which produced the highest lift coefficients, auxiliary flaps were investigated as a means of providing glidepath control during a landing approach. Data which show the longitudinal characteristics with various auxiliary- flap deflections in the appr
40、oach condition are presented in figure 8 and are summarized in figure 9. thrust can produce increases in drag. These drag increases reflect the large induced drag which accompanies the induced lift at high flap settings in a high-lift system, and suggest that the auxiliary flap might be an impractic
41、al device for glidepath control, at least, in the usual sense, with large main-flap deflections. If the flap deflection for landing were lower, it is possible that the auxiliary flap would appear in a more favor- able light as a glidepath control system. Figure 9 shows that with the basic landing fl
42、ap setting LDG, increases in The effectiveness of a jet-flap system is usually analyzed in terms of CL, the jet-induced circulation lift coefficient. The quantity CL, r is significant because it 6 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-repre
43、sents a lift component not solely attributable either to the upward component of the deflected engine thrust or to the power-off lift of the wing, and is therefore an indication of the ability of the integrated engine-wing-flap system to utilize engine power to produce additional increments of lift
44、coefficient. A typical resolution of total lift coefficient into its three components is shown for a 60 flap setting in figure 10. represents the circulation lift normally developed by the wing and flap system in a moving airstream in the power-off condition. In the powered condition, the engine sli
45、pstream impinges on the flap system and is thereby deflected downward through the angle the term Cp sin 6. + ar represents the lift contribution due to this redirection of engine gross thrust. The flow of the engine slipstream through the flap system and down- ward from the trailing edge as a jet sh
46、eet not only produces the force represented by Cp sin 6. + a! 17, but also induces a flow which augments the circulation over the wing. This increased circulation gives rise to the third lift component, the jet-induced added circulation lift CL, r. CL, as the basis for comparison, the effectiveness
47、of the engine-wing-flap system of the present model is compared to that of the model of reference 2 in figure 11. The comparison is not exact because the data for reference 2 are for a jet deflection angle of 60, whereas the most nearly comparable jet deflection in the present investigation was 65.
48、comparison. The CL,r values produced by the model of reference 2 do not neces- sarily represent the ideal, but they have been considered generally representative of those to be expected from an efficient external-flow jet-flap system. jet-induced circulation lift for the present model compares unfav
49、orably with that of the model of reference 2 throughout the range of for which both models were tested. Analysis of the probable effects of geometric differences between the models seems to indicate that it is important to have the engine efflux flattened and spread more widely across the span than is the case for the present model. The CL at Cb = 0
