1、j NASA TECHNICAL NOTE NASA I-LO. Kt AERODYNAMIC CHARACTERISTICS OF TWIN-PROPELLER DEFLECTED-SLIPSTREAM STOL AIRPLANE MODEL WITH BOUNDARY-LAYER CONTROL ON INVERTED V-TAIL hy Richard J. Margason and Gad L. Gentry, Jr. I Langley Research Center , t, bngley Station, Hampton, Vd. . ./ NATIONAL AERONAUTIC
2、S AND SPACE ADMINISTRATION WASHINGTON, D. C. NOVEMBER 1968 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-I TECH LIBRARY KAFB, NM I IIIIIIUHlllllllllllllllIIIIIllllI AERODYNAMIC CHARACTERISTICS 0F TWIN-PROPE LLER DEFLECTED-SLIPSTREAM STOL AIRPLANE M
3、ODEL WITH BOUNDARY-LAYER CONTROL ON INVERTED V-TAIL By Richard J. Margason and Gar1 L. Gentry, Jr. Langley Research Center Langley Station, Hampton, Va. NATIONAL AERONAUTICS AND SPACE ADMINISTRATION For sale by the Clearinghouse for Federal Scientific and Technical Information Springfield, Virginia
4、22151 - CFSTI price $3.00 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-AERODYNAMIC CHARACTEFUSTICS 0F TWIN- PROPE LLER DEFLECTED-SLIPSTREAM STOL AIRPLANE MODEL WITH BOUNDARY-LAYER CONTROL ON INVERTED V-TAIL By Richard J. Margason and Gar1 L. Gentr
5、y, Jr. Langley Research Center SUMMARY This report presents stability and control data for a small deflected-slipstream short take-off and landing (STOL) airplane model which had an inverted V-tail equipped with boundary-layer control. The results of the static wind-tunnel investigation are promisin
6、g and indicate that with further development, an inverted V-tail with boundary-layer control can be designed which would produce the longitudinal and directional trim required for an engine-out situation with no control input by the pilot. The data also show that the lateral control required for an
7、engine-out situation can be obtained from a spoiler with the attendant lift loss. The airplane can be trimmed with both engines operating with or without the boundary-layer control on the tail when the flaps are retracted (0 flap deflection); how ever, when the flaps are deflected (45Oflap deflectio
8、n), the boundary-layer control is needed to obtain trim up to a thrust coefficient of 2.10. The rudder is capable of producing large increments of yawing moment without changing directional stability and without causing cross coupling with rolling moment for both the flaps-retracted and the flaps-de
9、flected configuration. Both flap configurations (flaps retracted and flaps deflected) with and without the boundary-layer control on the tail have positive dihedral effect and are directionally stable through most of the test ranges of angles of attack and sideslip. INTRODUCTION Recent experience in
10、 developing a small deflected-slipstream short take-off and landing (STOL) airplane has shown a need for additional stability and control data on this type of configuration. Several wind-tunnel investigations of a powered model of a twin-propeller deflected-slipstream STOL configuration were conduct
11、ed to provide some of th as a result, the thrust coeffi cients are not constant for a particular range of angle of attack. For convenience, the average values of the thrust coefficient near zero angle of attack for the data presehted in this report (used as reference values throughout the report) ar
12、e listed in the following table : CT, s CT 0 0 0 .13 .14 .02 .31 .43 .05 0.31 0.43 0.05 .46 .83 .10 .69 2.10 .21 .84 5.10 .40 It is often desirable to use the propeller thrust coefficient based on slipstream velocity and propeller-disk area. Figure 5(a) is a plot of the relation between these two th
13、rust coefficients for the model tested. Also shown in the table are the values of the tail momentum coefficient Cp used with each thrust coefficient. These values represent the basic Cp range. The schedule of the thrust coefficients and the corresponding tail momentum coefficients used in this inves
14、tigation is presented in figure 5(b). This schedule is based on the engine-exhaust mass flow which could be obtained from a Pratt and Whitney T-74turboprop engine oper ating at sea level at a velocity of 50 knots (93 km/hr). The tail momentum coefficient for the model was determined from the measure
15、d static gross thrust of each internal ple num chamber nondimensionalized by the product of free -stream dynamic pressure and tail area. This area was measured normal to the tail surface, the span being equal to the length of both plenum chambers, 3.54 feet (1.08 meters), and the chord being equal t
16、o 1.00 foot (0.31 meter). RESULTS AND DISCUSSION The results of a wind-tunnel investigation of a model of a twin-propeller deflected-slipstream STOL airplane are presented in the following figures: 7 I 111 I IIIII I I Provided by IHSNot for ResaleNo reproduction or networking permitted without licen
17、se from IHS-,-,-Figure Longitudinal data: Effect of tail boundary-layer control: Cp range for several 6, (sf = go, CT = 0, a=00) . . . . . . . . . . . . . . . 6 Cp range for several 6e (sf = 450, CT = 2.10, CY = 00). . . . . . . . . . . . . 7 CIJ. range (6f = 45O, CT = 2.10, 6e = -15O) . . . . . . .
18、 . . . . . . . . . . . . . 8 Basic Cp range (6f = 45O, 6, = Oo) . . . . . . . . . . . . . . . . . . . . . 9 to 12 Effect of tail incidence (6, = OO): 6f= Oo, Cp = 0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13 to 15 6f = OoJ basic Cp range . . . . . . . . . . . . . . . . . . . .
19、 . . . . . . . 16 to 17 6f=450; Cp = 0 . . . . . . . . . . . , . . . . . . . . . . . . . . . . . . . .18 to 22 6f = 450, basic Cp range . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 to 25 Effect of elevator deflection (basic Cp range): 6, = OoJ it = Oo . . . . . . . . . . . . . . . . . .
20、. . . . . . . . . . . . . . .26 to 28 tif = 450J it = 0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29 to 32 6f = 450J it = loo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33 to 36 Lateral-directional data: Lateral-directional stability (basic Cp range) : Flaps re
21、tracted (6f = Oo) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 Flaps deflected (6f = 45O) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 Effect of tail boundary-layer control (6f = 45O, basic Cp range) . . . . . . . 39 to 42 Effect of rudder deflection (basic Cy r
22、ange): 6f = 00 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43 to 45 6f = 45 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .46 to 49 Effect of loss of power from one engine (6f = 45O): Effect of engine out . . . . . . . . . . . . . . . . . . . .
23、. . . . . . . . . . . 50 to 52 Effect of control deflections with engine out . . . . . . . . . . , . . . . . . . 53 to 55 Summary plots . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 to 57 Longitudinal Data Effect of tail boundary-layer control.- One of the primary reasons for
24、incorporating blowing boundary-layer control under the elevator was to increase the down load capability of the tail by increasing its maximum lift coefficient so that sufficient longitudinal control would be available to trim the diving moments produced by the flaps. The longitudinal aerodynamic ch
25、aracteristics showing the effect of tail boundary-layer control are pre sented in figures 6 to 12. In figure 6, the longitudinal characteristics as a function of tail momentum coeffi cient are presented for several elevator deflections on the flaps-retracted configuration at 8 Provided by IHSNot for
26、 ResaleNo reproduction or networking permitted without license from IHS-,-,-a thrust coefficient of zero and an angle of attack of 00. For a given elevator deflection, increasing the tail momentum coefficient results in an increased down load at the tail, which in turn produces an increment of nose-
27、up pitching-moment coefficient and reduces the lift coefficient. For a given tail momentum coefficient, the down load is increased by negative deflections of the elevator, as would be expected. However, at higher tail momen tum coefficients, there is an increase in elevator control effectiveness. pi
28、tching moment due to a change in elevator deflection is increased.) In addition, the (The increment of boundary-layer control makes the elevator effective to much higher deflections. For a given value of tail momentum coefficient, the net drag depends on elevator deflection. At low elevator deflecti
29、ons, there is a reduction in the net drag on the model because of the jet thrust at the tail; but at higher elevator deflections, the net drag increases because of the drag due to the increased lift on the tail. These same trends can be seen in the results presented in figure 7, which shows the long
30、itudinal characteristics as a function of tail momentum coefficient for several elevator deflections on the flaps-def lected configuration at a thrust coefficient of 2.10 and an angle of attack of Oo. The effect of the variation of tail momentum coefficient on the aerodynamic charac teristics of the
31、 flaps-deflected configuration at a thrust coefficient of 2.10 through a range of angle of attack is presented in figure 8. These data show that the effects (decreased Cp) found at an angle oflift and increased nose-up pitching moment with increase in attack of 0 hold throughout the entire angle-of
32、-attack range of the tests. The data in figures 9 to 12 present the aerodynamic characteristics for the model configuration with the flaps deflected through the basic schedule of thrust and tail momen tum coefficients. The nominal values of these coefficients are presented in the section on tests an
33、d corrections and plotted in figure 5(b), which represents the basic CT,C schedule for the data in this report. The variation in thrust coefficient from one run to another (for example, fig. 9(c) is caused by fluctuations in test conditions, such as thrust and free-stream dynamic pressure. In additi
34、on to the data for the basic Cp range, data for zero Cp and for the configuration with the tail off are also presented in these fig ures. These data illustrate the nose-up pitching-moment increment produced by the tail without boundary-layer control and the increased increment produced by the tail w
35、ith boundary-layer control. Effect of tail incidence (6e = Oo).- The effect of tail incidence on the longitudinal aerodynamic characteristics of the flaps-retracted configuration (sf = Oo) at several thrust coefficients is presented in figures 13 to 15 for zero tail momentum coefficient and in fig u
36、res 16 and 17 for the basic range of tail momentum coefficient. These data (part (b) of figs. 13 to 17) show that the model is stable and can be trimmed by utilizing tail incidence through nearly the full range of lift coefficient for the values of thrust coefficient pre sented. These data also show
37、 at zero elevator deflection that the boundary-layer 9 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-control has little effect on the longitudinal aerodynamic characteristics of the flaps-retracted configuration over the range of tail momentum coef
38、ficient used. (Compare figs. 14 and 15 with figs. 16 and 17, respectively.) The effect of tail incidence on the longitudinal aerodynamic characteristics of the flaps-deflected configuration (sf = 45O) at several thrust coefficients is presented in fig ures 18 to 22 for zero tail momentum coefficient
39、 and in figures 23 to 25 for the basic range of tail momentum coefficient. The data for the flaps-deflected configuration with out boundary-layer control (figs. 18 to 22) show that trim can be obtained to at least 0.9 of the maximum lift coefficient at each thrust coefficient with the tail incidence
40、s presented. These data also show that the model is stable up to a thrust coefficient of 0.83 (figs. 18 to 20), that the model is neutral at a thrust coefficient of 2.10 (fig. 21), and that the model is unstable at a thrust coefficient of 5.10 (fig. 22). The data for the flaps-deflected configu rati
41、on with boundary-layer control (figs. 23 to 25) show that trim can be obtained up to the maximum lift coefficient at each thrust coefficient with the tail incidences of the tests. These data also show that the stability is essentially unchanged by boundary-layer control on the tail. However, at a th
42、rust coefficient of 2.10, the tail with boundary-layer control (fig. 25(b) produces much larger nose-up increments of pitching moment than the tail without boundary-layer control (fig. 21(b). As a result, a trimmed stable configuration with boundary-layer control on the tail can be obtained at all t
43、hrust coefficients presented by shifting the moment center forward. Effect of elevator deflection. - The effect of elevator deflection on the longitudinal aerodynamic characteristics is presented for the flaps-retracted configuration (6f = 00, basic Cp range, it = Oo) in figures 26 to 28 and for the
44、 flaps-deflected configuration (6f = 45O, basic Cp range) in figures 29 to 32 (it = 00) and in figures 33 to 36 (it = 100). The data for the flaps-retracted configuration (Q = Oo, part (b) of figs. 26 to 28) show that with elevator deflections between O0 and loo, the model can be trimmed up to lift
45、coeffi cients as high as 1.80 with high stability levels (aCm/aCL 5 -0.15). For the flaps-deflected configuration (df = 45O), the Oo tail incidence (part (b) of figs. 29 to 32) provides slightly higher levels of stability and provides trim to slightly higher lift coefficients than the loo tail incid
46、ence (part (b) of figs. 33 to 36). For thrust coefficients between 0 and 0.83, both tail incidences were capable of providing trim up to lift coefficients of approxi mately 4.0 with high stability levels (aCm/aCL 5 -0.14). At the highest thrust coefficient presented (CT = 2.10) the 00 tail incidence
47、 (fig. 32(b) provided trim to a lift coefficient of at least 5.00 with a stability level of approximately aCm/aCL = -0.10, whereas the 100 tail incidence (fig. 36(b) provided trim to a lift coefficient of 4.80 with neutral stability. Trim throughout the angle-of-attack range of the tests can be obta
48、ined from elevator deflections which ranged between 00 and 150 for the go tail incidence or which ranged between -150 and approximately 50 for the 100 tail incidence. AS shown in figures 29 to 32, the elevator can be deflected up to -500 to provide for longitudinal control after trim has been achiev
49、ed. 10 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-These data show that the inverted V-tail with boundary-layer control is capable of pro viding trim, stability, and control for the model up to a lift coefficient of at least 5.0. Lateral-Directional Data Lateral-directional stability. - The variations of effective dihedral parameter I Clp, directional-s
