1、NASA TECHNICAL NOTE NASA d. / TN - D-4448 LOAN COPY: RETURN TO KIRTLANO AFB, N MEX AFWL (WLIL-2) LARGE-SCALE WIND-TUNNEL TESTS OF A DEFLECTED SLIPSTREAM STOL MODEL WITH WINGS OF VARIOUS ASPECT RATIOS by V. Robert Page, Stanley 0. Dickinson, and WaZZace H. Deckert Ames Research Center Moffett FieZd C
2、aZ NATIONAL AERONAUTICS AND SPACE ADMINISTRATION WASHINGTON, D. C. MARCH 1968 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-I LARGE-SCALE WIND-TUNNEL TESTS OF A DEFLECTED SLIPSTREAM STOL MODEL WITH WINGS OF VARIOUS ASPECT RATIOS By V. Robert Page,
3、Stanley 0. Dickinson, and Wallace H. Deckert Ames Research Center Moffett Field, Calif. NATIONAL i ERONAUTICS AND SPACE ADMINISTRATION For sale by the Clearinghouse for Federal Scientific and Technical Informotion Springfield, Virginia 22151 - CFSTl price $3.00 I Provided by IHSNot for ResaleNo repr
4、oduction or networking permitted without license from IHS-,-,-LARGE-SCALE WIND-TUNNEL TESTS OF A DEFLEETED SLIPS= STOL MODEL WITH WINGS OF VARIOUS ASPECT RATIOS By V. Robert Page, Stanley 0. Dickinson, and Wallace H. Deckert Ames Research Center A wind-tunnel investigation was conducted to determine
5、 the longitudinal force characteristics of a large-scale model representative of a propeller- driven STOL transport aircraft. Longitudinal characteristics were obtained for a wing of aspect ratio of 5.7 that was fully immersed in the propeller slipstream and for wings of greater span (up to aspect r
6、atio 8.1) that were only partially immersed in the propeller slipstream. Test configurations included: three wing spans, full-span leading-edge slats, full-span triple- slotted trailing-edge flaps deflected from Oo to looo, two directions of propeller rotation, and spanwise variation of propeller th
7、rust. Test results show that lift coefficient increased and drag coefficient decreased as the wing tips were extended outboard. Maximum lift coefficient appeared to be limited by flow separation between the nacelles on all config- urations, even though the wing tip of the high aspect ratio configura
8、tion was not protected by the propeller slipstream. Leading-edge slats controlled the progression of flow separation and extended the angle of attack for maxim lift approximately 10 (e.g., for a thrust coefficient of 2.5, the angle of attack for maximum lift for the 80 flaps on the short wing was ex
9、tended from 16O to approximately 25). For each wing span tested descent capability could be improved by span- wise variation of propeller thrust. However, the spanwise variation of pro- peller thrust was most effective on the short span wing. INTRODUCTION Reference 1 indicated there was a lack of sy
10、stematic experimental results to aid in the design of advanced propeller driven STOL aircraft. Ames Research Center therefore studied a large-scale deflected slipstream configuration in the 40- by 80-foot wind tunnel. study is typical of a conventional propeller -driven transport airplane capable of
11、 operating in and out of 1000 to 2000 foot runways. The model employed in the The objectives of this investigation were to: (1) determine the basic longitudinal aerodynamic characteristics of a model whose wing was partially or fully immersed in the propeller slipstream, (2) determine the effect of
12、propeller rotation on the stall progression across the upper surface of the Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-wing, and (3) determine the effect of the spanwise variation of propeller thrust across the wing span on the lift and drag cha
13、racteristics of the model. b C - C CD CL Cm Cn D J L n q R r S T T; v X Y Y a. B 2 NOTATION wing span, ft wing chord parallel to fuselage center line, ft mean aerodynamic chord measured drag. CIS drag coefficient including thrust, measured lift qs lift coefficient including thrust, itching moment pi
14、tching-moment coefficient, P qsc normal-force coefficient propeller diameter, ft v propeller advance ratio, - nD lift including thrust, lb propeller rotational velocity, rps free-stream dynamic pressure, lb/sq ft - Reynolds number, I-L propeller blade radius, ft wing area, sq ft total thrust of all
15、four propellers, lb thrust coefficient, - T CIS free-stream tunnel velocity, fps chordwise dimension from leading edge vertical dimension perpendicular to chord lateral distance from airplane center line wing angle of attack, deg propeller blade angle, deg Provided by IHSNot for ResaleNo reproductio
16、n or networking permitted without license from IHS-,-,-propeller blade angle at 3/4 r for inboard and outboard propellers, re s pe c t ive ly , de g descent angle, deg total aft flap deflection relative to local wing chord, deg differential spanwise flap deflection. Numerator is for flap inboard is
17、for flap outboard coefficient of viscosity, slugs/ft-sec mass density of air, slugs/ft3 MODEL AND APPARATUS Figures l(a) and (b) are photographs of the model installed i.n the Figure 2(a) is a three-view drawing of the model. 40- by 80-foot test section. The model was tested, as shown, without a hor
18、i- zontal tail. The airfoil section of the wing was an NACA 632-416 with the reflex on the aft pQrtion of the lower surface faired out. The short wing span was 43.34 feet (fig. 2(a) with an aspect ratio Df 5.71. Short wing tip exten- sions changed the span to 47.94 feet, and longer tips extended the
19、 span to 56 feet with an aspect ratio of 8.06. Additional information about the wing and tail geometry is given in table I. A cross section of the wing leading-edge slat and trailing-edge triple- slotted flap is shown in figure 2(b). deflected 100 with respect to the wing chord line. For flap deflec
20、tions of 80 or less, the foreflap was set at half the total deflection of the aft flap. For a flap deflection of looo, the foreflap was deflected bo0. Coor- dinates for the wing leading-edge slat, trailing-edge foreflap, fixed vane, and aft flap are listed in table 11. The trailing-edge flap could b
21、e The geometric characteristics of the three-bladed model propellers are presented in figure 3. The solid aluminum propellers were 9.3 feet in dia- meter and had an activity factor of 121 per blade. Each propeller was shaft mounted on a gearbox and driven by an electric motor. The four motors were o
22、perated in parallel from a variable frequency power supply. 3 I Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-TEST AND PROCEDURE Tests were made at free-stream velocities from 31 to 49 knots (q = 3.1 to 8 psf, corresponding to a Reynolds number ran
23、ge of 2.4 to 4.1 million). During each run the angle of attack of the model was varied while the tunnel dynamic pressure, propeller speed, and propeller blade angle were held fixed. The propeller thrust (fig. 4) was calibrated from wind-tunnel tests with the model at the angle of attack for zero lif
24、t with the flaps retracted. Pro- peller thrust was defined as the sum of the measured thrust of the model with the propellers operating and the measured drag of the model with propellers removed. For runs with all propellers set for equal thrust, the inboard and outboard propellers were set at a bla
25、de angle of 16O at the three-quarter radius station. To obtain the spanwise variation of propeller thrust the inboard propeller blade angle was left at 16O while the outboard propeller blade angle was set at 0. assumed to be independent of outboard thrust, the two inboard propellers pro- duced a hig
26、h positive value of thrust while the two outboard propellers gave a slightly negative value. With this blade setting, and inboard thrust Aerodynamic coefficients were based on the flaps-retracted reference wing area for each of the three wing spans evaluated. Pitching-moment coefficients were comput
27、ed about a moment center at 0.25 c. CORRECTIONS Cook and Hickey (ref. 1, p. 447) suggested applying standard wind-tunnel wall corrections for this size STOL model. The following corrections were made to account for the wind-tunnel wall interference effects: Short -span wing a = a c 0.652 Cr, U Lu2 C
28、D = CQ + 0.01138 C Medium- span wing Long-span wing a, = a c 0.674 Ch U c 0.01176 c cD = crt. Lu = a -I- 0.706 ch U F2 CD = cDU c 0.01232 c 4 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-The subscript u stands for measured results uncorrected for
29、wind-tunnel wall effects. A drag tare correction (A!,= 0.03) was applied to account for the drag of the portions of the mounting struts exposed to the wind-tunnel air flow. RESULTS The main results of this investigation are summarized in figures 5 through 10. These figures are briefly discussed in t
30、he next section. In the interest of completeness, the basic data are presented (without discussion) in figures 11 through 13. Figure 11 presents the data for the short-span wing; figure 12 presents the data for the medium-span wing; and figure 1.3 pre- sents the data for the long-span wing. Table I1
31、1 is an index to these basic data figures. DISCUSSION Figures 5(a)l and (b) present the lift and drag coefficients for the three wing spans with trailing-edge flaps deflected 80 for two thrust coef- ficients. extending the lift curves, with only the top portion of the curves shown for clarity. These
32、 data show that, as the wing tips were extended, lift coeffi- cient increased and the drag coefficient decreased. Lift coefficient increased with wing span even though the portion of the wing outside the slipstream was not as highly loaded as that inside the slipstream. Some insight into this result
33、 is obtained from the pressure distribution data (ref. 2). and (b) present the span loading (normal-force coefficient versus spanwise position) of a short-span wing compared with the longer span wing and show that as the tip is extended beyond the slipstream, there is an additional increment of “lif
34、t carryover“ from the tip inboard. Figure 5(c) presents the effect of the leading-edge slats in Figures 6(a) The angle of attack for maximum lift was limited by flow separation With the first between the nacelles. of the foreflap (0.7) on the upper surface of the wing. direction Qf propeller rotatio
35、n (i.e., fl ) , separation began at low positive angles of attack and progressed rapidly to the leading edge of the wing. (i.e., f3 ) tuft observations indicated that separation was delayed, but this effect was not reflected in the force data. The leading-edge slats prevented this forward progressio
36、n of flow separation, and the angle of attack for maximum lift was extended approximately loo. The onset of flow separation occurred just forward With the second direction of propeller rotation On figure 5(a) the data for the long span wing were interpolated from measurements obtained at TL = 0, 2.0
37、, and 4.0. 5 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Incremental flap lift coefficient and drag coefficient as a function of flap deflection are presented in figures 7 and 8 for the medium-span wing for three thrust coefficients, with the lea
38、ding-edge slats retracted, and for an angle of attack of Oo. Figure 7 shows that the flap effectiveness approached theoretical values for T = 0 (ref. 3) up to flap deflections of 60. C Figure 9 presents the variation of drag with maximum lift coefficient for the three wing spans with leading-edge sl
39、ats extended, 800 flap deflection, three values of thrust coefficient, and with and without spanwise variation of propeller thrust. be optimum for all configurations tested at equal approach speeds. The results presented in figure 9 show that spanwise variation of propeller thrust greatly increased
40、descent angle (e.g., for a constant lift coefficient of 7 the descent angle was approximately doubled with TA given CL, descent angle decreased as the wing span was extended. Also, as the wing span was extended, spanwise variation of propeller thrust became less effective as a means of increasing de
41、scent capabilities. In terms of descent performance, the 80 flaps appeared to = 1.5 compared to T 6f 98/65 flight) with and without leading-edge slats installed on the model. The wing leading edge on the flight aircraft had a drooped nose (4.5 percent extended chord) outboard of the inboard nacelle,
42、 whereas the model had full span 0.2 slats as shown in figure 2(b). The correlation appears to be reasonable since the flight data fall between the wind-tunnel data for the slats retracted and slats extended configurations. CONCLUDING RFSIARKS As the wing tips were extended beyond the immersed porti
43、on of the wing, lift coefficient increased and drag coefficient decreased. For a given landing configuration, the descent angle decreased as the wing tip was extended. Spanwise variation of propeller thrust was effective in increasing descent capability, but was most effective when used on the short
44、 span wing that was fully immersed in the propeller slipstream. Maximum lift coefficient appeared to be limited by flow separation between the nacelles - not by flow separation over the unimmersed wing tips. Leading-edge slats were effective in controlling flow separation and, for each wing span tes
45、ted, extended the angle of attack for maximum lift approximately 10. In addition, the use of leading-edge slats allowed an increase in the angle of descent and rate of sink for a constant approach speed. Ames Research Center National Aeronautics and Space Administration Moffett Field, Calif., 94035,
46、 Nov. 16, 1967 721-01 -00 -16 -00 -21 6 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-RF,FERENCES 1. Conference on V/STOL and STOL Aircraft, April, 1966. NASA SP-116, 1966. 2. Page, V. Robert; and Soderman, Paul T.: Wing Surface Pressure Data From
47、Large-Scale Wind Tunnel Tests of a Propeller-Driven STOL Model. NASA TM X-1527, 1968. 3. DeYoung, John: Theoretical Symmetric Span Loading Due to Flap Deflection for Wings of Arbitrary Plan Form at Subsonic Speeds. NACA Rep. 1071, 1952 (Supersedes NACA TN 2278). 4. Quigley, Hervey C.; Innis, Robert
48、C.; and Holzhauser, Curt A.: A Flight Investigation of the Performance, Handling Qualities, and Operational Characteristics of a Deflected Slipstream STOL Transport Airplane Having Four Interconnected Propellers. NASA TN D-2231, 1964. Provided by IHSNot for ResaleNo reproduction or networking permit
49、ted without license from IHS-,-,- . Dimens ion TABLE I. - MODEL GEOMETRY - Area, sq ft Span, ft Mean aerodynamic chord, ft Aspect ratio Taper ratio Twist, deg Dihedral, deg NACA airfoil section Sweep of leading edge, deg Sweep of trailing edge, deg Root chord, ft Tip chord, ft - - - Short 329 43.34 7.80 5-7
