1、NASA TECHNICAL NOTE WIND-TUNNEL INVESTIGATION OF AN EXTERNAL-FLOW JET-FLAP TRANSPORT CONFIGURATION HAVING FULL-SPAN TRIPLE-SLOTTED FLAPS Lnrzgley Research Center and C. Robert Carter NATIONAL AERONAUTICS AND SPACE ADMINISTRATION WASHINGTON, D. C. AUGUST 1971 Provided by IHSNot for ResaleNo reproduct
2、ion or networking permitted without license from IHS-,-,-TECH Ll8RARY KAFB, NM 1. Report No. I 2. Government Accession No. I 3. Recipients Catalog No. NASA TN D-6391 4. Title and Subtitle I 5. Report Date WIND-TUNNEL INVESTIGATION OF AN EXTERNAL-FLOW JET-FLAP TRANSPORT CONFIGURATION HAVING FULL- SPA
3、N TRIPLE-SLOTTED FLAPS 7. Authorb) Lysle P. Parlett, H. Douglas Greer, and Robert L. Henderson (Langley Research Center), and C. Robert Carter (Langley Directorate, U.S. Army Air Mobility R similar data from references 1 and 2 are shown for comparison. This plot shows that the partial-span flap arra
4、ngement of reference 1 had a more forward flap center-of- pressure and aerodynamic-center location than the full-span flap arrangements of refer- ence 2 and of the present study. In all cases the center of pressure moved rearward with increases in thrust and the aerodynamic center moved forward with
5、 increases in thrust through the low-thrust range and then began to move rearward with further increases in thrust. The longitudinal stability and trim characteristics of the model with tail on are plotted in figures 20 to 28 for the clustered-engine arrangement and in figures 29 to 31 for the sprea
6、d-engine arrangement. These data show, in general, that the model with flap down was longitudinally stable up to the stall and could be trimmed in pitch up to the 10 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-highest thrust settings by the appli
7、cation of blowing to the horizontal tail used in the tests. The utilization of blowing on the tail was not meant to imply that blowing would be needed in full-scale operation but was intended to give lift on the model tail which would be representative of a full-scale tail with a slotted elevator (a
8、 maximum CL of 2.5 would be expected). The longitudinal instability indicated in figures 22 and 23 is a result of tail stall caused by improper tail geometry for the particular tests involved. For example, for the data in figure 23 the chord of the tail leading-edge flap was reduced to one-half its
9、original length and this change caused the tail to be ineffective at the high thrust settings. The original tail leading-edge flap was used for all the remaining tests. Figures 24, 25, and 26 show the effect of changing the rear flap element to higher and lower settings for possible use in glide-pat
10、h control. Similar data are presented in figure 27 in which the flap element was deflected symmetrically for only the outer flap span. The data of figure 28 show the effect of symmetric spoiler deflection for possible use in glide-path control. In the tests of figure 28(e) the projecting slot lip wa
11、s removed to enlarge the slot of the inboard and center flap segments. A comparison of the data of figure 28 with data of figure 20(a) shows that a symmetric spoiler deflection of 30 pro- duced decremental lift coefficients of about 1.0 at the higher thrust settings. A comparison of the spread-engin
12、e data of figures 29 to 31 with the clustered- engine data of figures 20 to 28 shows no major differences in longitudinal stability and trim characteristics for the two engine arrangements. A summary of the pitching- moment characteristics from these data and the data from references 1 and 2 (see fi
13、g. 32) shows that !he static stability and trim characteristics for the model of the pres- ent investigation were generally similar to those for the models of references 1 and 2, but the trim requirements were greater. The results of flow surveys to measure the downwash characteristics in the vicini
14、ty of the horizontal tail are presented in figures 33 and 34 for the clustered-engine arrange- ment and in figures 35 and 36 for the spread-engine arrangement. These data are sum- marized in figure 37 in terms of the downwash factor 1 - plotted against thrust coefficient Cp for tests with and withou
15、t leading-edge blowing. Figure 37 shows that the horizontal-tail effectiveness generally decreased with increasing engine thrust. The use of leading-edge blowing resulted in an increase in horizontal-tail effectiveness for the spread-engine arrangement but generally produced adverse effects for the
16、clustered- engine arrangement. ( - :) Lateral Stability A few tests were made to determine the variation of the lateral aerodynamic coef- ficients with angle of sideslip. These tests were made with power off and power on and 11 Provided by IHSNot for ResaleNo reproduction or networking permitted wit
17、hout license from IHS-,-,-for both symmetric and asymmetric power conditions. The data, which are presented in figure 38, show that the aerodynamic coefficients varied fairly linearly with sideslip; hence, the remainder of the lateral stability studies were made in terms of sideslip derivatives dete
18、rmined from tests at k5O sideslip. Plots of the static lateral stability derivatives against angle of attack are presented in figures 39 to 46 for various model configurations and thrust levels, with and without leading-edge blowing. These plots show that in all tail-on configurations (figs. 40, 42,
19、 and 44 to 46) the model has directional stability +Cn and positive effective dihedral ( P ( -%) through most of the angle-of-attack range up to the stall. The directional stability is virtually unaffected by change in angle of attack; effective dihedral, however, increases with increasing angle of
20、attack up to the stall. In all tail-on configurations, the applica- tion of thrust produced notable increases in directional stability throughout the angle-of- attack range. At angles of attack near the power-off stall angle, thrust also produced large increments in effective dihedral. Leading-edge
21、blowing, which like thrust is effec- tive in delaying stall, markedly increases the effective dihedral near the power-off stall angle of attack. The spanwise distribution of the thrust appears to have very little effect on direc- tional stability or effective dihedral. Engine-out static stability da
22、ta, presented in fig- ures 41 (tail off) and 42 (tail on), are very similar to those for the corresponding all- engine cases presented in figures 39(b) and 40(b), respectively. Likewise, leading-edge- blowing data for the clustered-engine arrangement (fig. 40(b), for instance) are similar to those f
23、or the spread-engine arrangement (fig. 45(a). Spanwise discontinuity in flap deflection has no noticeable effect on the stability derivatives, as is shown by a compar- ison of figure 45(b) with figure 46. Basic Asymmetric Moments (Engine Inoperative) Lateral characteristics obtained for the model wi
24、th one engine inoperative are pre- sented in figures 47 to 50 for the clustered-engine arrangement and in figures 51 to 53 for the spread-engine arrangement. Because in a powered-lift system a loss of an engine results in loss of lift, plots of the lateral characteristics with one engine out are acc
25、om- panied by plots of the corresponding longitudinal characteristics. The data of figures 47 to 50 show that large rolling moments accompany an engine- out condition. As the angle of attack increased, the rolling moments generally increased because the engine-out wing tended to stall first. Compari
26、son of the corresponding lift data and the four-engine lift data shows that large losses in lift occur with an engine failure. Lower flap angle produced the expected reduction in engine-out rolling moments but increased the engine-out yawing moments. Provided by IHSNot for ResaleNo reproduction or n
27、etworking permitted without license from IHS-,-,-Lateral Control, With Asymmetric Thrust In reference 2 it was shown that the use of either asymmetric blowing over the ailerons or differential flap deflection offered a means of achieving roll trim under engine-out conditions. One of the problems not
28、ed in reference 2, however, was that the engine-out wing tended to stall first as angle of attack was increased and thus resulted in large roll asymmetries at the stall. In the present investigation these two methods of roll trim were studied in combination with leading-edge blowing as a possible me
29、ans of controlling the stall angle of attack and relieving the asymmetric roll problem. Clustered engines.- Tests were run with either the left outboard or the left inboard engine not operating. Since the left outboard engine was found to be the more critical, most of the engine-out tests were made
30、for this condition. The results of tests for the clustered-engine arragement with an engine out are presented in figures 54 to 69. Data for the model with differential flap deflection used for roll trim are presented in figures 54 to 58 for several nominal trim flap deflections. Some of the more imp
31、or- tant results shown by these data are that without leading-edge blowing there were large rolling asymmetries at the stall (see fig. 54) but that the use of leading-edge blowing on the engine-out wing relieved the asymmetric stall condition and therefore relieved the roll asymmetry (see fig. 55).
32、Comparison of the corresponding lift data shows that higher lift coefficients were achieved with leading-edge blowing and that stall was more gradual and occurred at a higher angle of attack. For none of the configurations tested was complete roll trim achieved over the entire angle-of-attack range
33、with the outboard engine out and at the highest value of Cp (Cp = 2.81). In many tests, however, the model was almost completely trimmed in roll, and a very small amount of additional differential flap deflection, or spoiler deflection, would be expected to give complete trim. Presented in figures 5
34、9 to 62 are results of engine-out tests of the model with only the inboard one-third of the flap deflected differentially. A general inspection of the data gives the impression that the inboard flap segment was just as effective for roll trim as was the full flap span, and the only direct comparison
35、 that can be made (figs. 55(c) and 59(c) indicates that the inboard flap segment was slightly more effective. Presented in figures 63 to 69 are data for the engine-out condition with symmetric flap deflection and with various combinations of asymmetric leading-edge and aileron blowing and wing-tip s
36、poiler deflection. In these tests complete roll trim was not achieved for the 60 flap deflection for the higher thrust range. %read engines.- The results of tests with an engine out and differential flap deflec- tion for roll trim are presented in figures 70 to 75 for the spread-engine arrangement.
37、Figures 70 to 73 show the effect of differential deflection of several different sparwise 13 I Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-segments of the flap; these data indicate that, because of the larger engine-out moments for the spread-eng
38、ine arragement, the flaps alone were not as effective for providing roll trim as they were for the clustered-engine arrangement. Also, unlike the clustered- engine arrangement, full-semispan flap deflection for the spread-engine arrangement appeared to be more effective for roll trim than individual
39、 deflection of any one of the spanwise segments. This result suggests, as might be expected, that the spanwise flap loads for the spread-engine arrangement extended much farther outboard than for the clustered-engine arrangement. The data of figure 74 show that the use of leading-edge and aileron bl
40、owing in combination with differential flap deflection more than trimmed the engine-out rolling moment at low angles of attack but, at the higher angles of attack, roli trim was not achieved at the higher thrust levels. Presented in figures 76 to 78 are the results of tests for the model with an eng
41、ine out and symmetric flap deflection, with aileron blowing and spoiler deflection used for control. These figures show that for these condittons additional control would be required for roll trim, possibly in the form of differential aileron deflection in combina- tion with increased aileron blowin
42、g or spoiler control. Lateral Control, With Symmetric Thrust Presented in figures 79 to 83 are the results of tests with the spoiler deflected for roll control. Comparisons of the data of figures 79(a) and 79(c) show that leading-edge blowing increased the spoiler effectiveness and resulted in the s
43、poiler remaining effec- tive to a higher angle of attack. The use of a small-chord flap spoiler in combination with the wing spoiler did not increase the effectiveness of the spoiler system. (Compare figs. 79 and 80.) The use of only the outer one-third of the wing spoiler (fig. 81) pro- duced avera
44、ge rolling-moment coefficients of about 0.05, and increases in engine thrust generally produced much smaller increases in spoiler effectiveness than for the full- span spoiler. Maximum values of rolling-moment coefficient for the full-span spoiler were about 0.23 for the 60 flap angle. Presented in
45、figures 84 to 86 are the results of rudder tests for several test condi- tions. The data of figure 86 show that the rudder effectiveness was increased by the use of boundary-layer control on the rudder surface up to values of Cn of about 0.23 for a cw of about 0.038. This value of Cn is great enough
46、 to trim the greatest yawing moments encountered in engine-out conditions, even with corrective roll control applied. Presented in figure 87 are the results of tests with the inboard trailing-edge flap segments deflected differentially as ailerons for roll control for the cruise condition (trailing-
47、edge flap deflection of 0). These tests show that the control effectiveness of these flap segments is greatly increased by engine power. At CF = 0, which most 14 .“ “. . Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-closely approximates a cruise th
48、rust setting, however, the rolling moment per degree of deflection of the inboard flap segments is only about one-half that provided by the con- ventional ailerons of a similar jet transport configuration, as reported in reference 4. SUMMARY OF RESULTS From a wind-tunnel investigation of an external
49、-flow jet-flap transport configura- tion having inboard pod-mounted engines and full-span triple-slotted flaps, the following results were obtained: 1. The use of full-span triple-slotted flaps appeared to offer little improvement in aerodynamic performance over the more conventional double-slotted partial-span flaps. In either case, however, it is necessary that the flap chords be large enough to achieve good sp
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