1、, t 1 crl 0 a0 U e RESEARCH MEMORANDUM LOW-SPEED INVESTIGATION OF A SMALL TRIANGUIAR WING OF ASPECT RATIO 2.0. III - STATIC STABILITY WITH TWIN VERTICAL FINS By Leonard M. Rose CLASSTFIZATIO$JANGED es Aeronautical Laboratory I , I Copy No. 3 - i UNCLASSIFIED Moffett Field, Calif. “I , NATIONAL ADVIS
2、ORY COMMITTEE FOR AERONAUTICS WASHINGTON August 24,1948 c “ .A Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-WING OF ASPECT RATIO 2.0. 111 - STATIC By Leonard M. Rose SUMMARY Low-speed wind-tunnel tests were made of a triangdm wing with two arrange
3、ments of twin vertical fbs. With these twin fins mounted either synmetricallg or wholly above the x4g chord phe, approximately conetant effectiveness in proportion to the fin size was obtained throughout the angle+f+.ttack range. The addition of these fins, however, resulted in a decrease in mi- m l
4、ift and a reduction in static longitudinal stability at lLft coefficients above 0.4. Previous testa of a single vertical tail in conibination with an approximate- tri- wing (reference 1, configurations 7 and 8) have shown marked lossee in dfrectioaal stability at high lift coefficients. Consideratio
5、ns of the flow about triangular wings at high lift coefficients (BS discussed in references 2 and 3) indicated that vertical fins mounted outboard of the center line of the wing would possibly provide mre desirable characteristics. In order to check the merits of outboard vertical fins, a short hves
6、tigation of twin verttcal fins on a triangular wLng was made in the Junes 7- by 10-foot wind tunnel. The chracter- istica of the model with fins mounted synnnetric8,ll.y about the wing-chord plane and fins mounted wholly above the wing-chord plane were investigated. Provided by IHSNot for ResaleNo r
7、eproduction or networking permitted without license from IHS-,-,-2 SYMBOLS m coEFF1cm NACA RM No. A8C03 The results are presented in the form of standard NACA coefficients. The mcments are referred tc the stability axe8 which axe illustrated in figure 1. The forces are referred to the wind axes whic
8、h are mutually perpendicular and dtsposed perpen- dicular and parallel to the relative wind. Both systems of axes have their origin 18 inches aft of the apex of the wing, as shown in figure 2. The Symbol6 and coefficients used are defined aE f OllOUS : . lift coefficient (9 pitching+noment coefficie
9、nt rollfng-mnment coefficient side-force coefficient dynamic pressure ( &pv2 ), pounds per square foot mss density of air, slugs per cubic foot air-stream velocity, feet per second wing mea, square feet mean aerodynamic chord of the wing, feet wing span, feet angle of attack, degrees angle of yau, d
10、egrees rate of change of yawing-rnoment coefficient with angle of yaw (%) Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-ESACA RM No. A8CO3 c, rete of change -L 3 of side-lforce coefficient with aagle of v of yaw (3 of rollhg-momnt coefficient with
11、angle HIDEL AlqD TEBT METEODS The model used fd this Investigation =E triangular in plan form with an aspect ratio of 2.0. The airfoil section was a dofile wedge with a maxiram thickness of 5 percent of the chord at 20 percent of the- chord. This was the model used previouelg (reference 2), except t
12、hat the interior of the model was modified to include a strab gage for the measuremnt of rolling moments. Two arrangemnts of twfn vertical fins were teated. The fins of one set -re geamstrfcally s3milar to the wing in plan form and were mounted sgrmnstrfcallg abuut the wing-chord plane as shown in f
13、igure 2. The lower halves of these fins were eliminated to form the other tail arrangement. Both sets of fins were located 72.8 percent of the semfspan &hrd of the uing center line. The f ina were made of l/l&ncbthck aluminum sheet. The teats were made at a Reynolds nuniber of 1.8 X l$ based an the
14、mean aerod.ynamtc chord of the wing. Since the alterations made in the model did not change the mounting arrangemsnt ede- ally, the previously determine6 st& tares and wind-tunnel-wall corrections (reference 2) were applied to the results presented herein. ESULTS AKD DISCCBSION The basic test result
15、s are presented in figures 3 and 4. The static lateral stability. paramsters C 88 functions of angle of attack in figure 5. Examination of these test results indicates that both vertical-fin afiangemsnte contrib- uted directional stabflity approximately in proportion to their size. Although the resu
16、lts show a. reduction in directional stability at angles of attack greater than a*, the effectiveness of the fins was nearly canstant throughout the anglwf-attack % cv, % are II ! Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-4 - NACA FM No. A8C03
17、range. It was expected that the kge vertical fins would meinta5.n some effectiveness throughout the anglwf-attack range, since half of their area wa8 below the wing. To determine whether the fin area below the wing was more effectfve than that above, the small fins (which consisted of the upper halv
18、es of the large fins) were teated. It is evident from figure 5 that the effectiveness of the large end muall fins wa6 roughly proportional to thefin size and relatively unaffected by the change in area distribution. Although the twin vertical fins appeared to be satisfactory for producing directiona
19、l stability at all angles of attack up to the stall, these surfaces had adverse effects on the lift and pitching- - moment characteristics of the wing at high angles of attack. As shown in figure 3, the maximum lift was reduced approximately 0.2 by the addition of the large flns. Also shown is a red
20、uction in static longitudinal stabtlity at lift coefficients above 0.4. The results presented fn reference 1 indicate no losses in lift or longitudinal stability attributable to the redesigned single verti- cal tail. Wfnd-tunnel tests of twin vertical fins mounted on a triangular wing indicated that
21、 static directional stability w-as maintained throughout the asgle-of+ttack range with these vertical surfaces mounted either wholly above or symmetrically about the wing chord plane. Although the results indicated no -ked losses in vertical- fin effectiveness at high lift coefficients, a loss in bo
22、th naximum lift and static longitudinal stability resulted from the twin-fin installation. Ames AeronautFcal Laboratory, National Advisory Committee for Aeronautics, Moffett Field, Calif. 1. kvell, 5. Calvin, and Wilson, Herbert A., Jr.: Langley Nl- scaleel.Investigation of Maximum Lift and Stabilit
23、y Characteristics of an Airplans Zaving Approximately Triangular Plan Form (DM4 Glider). NACA RM No. 716, 1947. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NACA RM Ne. A&03 - 5 2. Rose, Leonard M. : Low-Speed Investigation of a Small Triangular W
24、ing of Aspect Ratio 2.0. I - The Effect of Combination with a Body of Revolution and Height Above a Ground Plane. NACA RM No. AZ03, 1947. 3. Anderson, mien E.: -fi Investigation at Low Speed of a Large Scale TrianguLar Wing of Aspect Ratio TKO. - 11. The Effect of Airfoil Section Modifications and t
25、he Detedtion of the Wake Downwash. NACA RM Bo. A7E28, 1947. c Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-t Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-. I 7 Provided by IHSNot for ResaleNo re
26、production or networking permitted without license from IHS-,-,-8 t Figure 2 .- The wing and twin verflcd- fin orfongemenfs investigot et#. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-I ft Ik .8 k W 0 Rqure 3.- The wariation of lift coefficient a
27、nd pitching-moment coefficient with angle of attack far the wing alone and in combinat/on with the large vertical fins. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-. . . . . . . . . tal Wing alone figure 4.- The ChOmCleriStiCS in yaw fin arrangem
28、ents. -lp -8 -4 0 4 8 IP Angie of yaw, 4, deg. Angle of yaw, +, deg. (c/ Snwil fim of the wing alona and in combinofion wlth the two reriical- - . . I . . . . . . . . . . . . P 0 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-I?ACA RM No. A8C03 - 0 0 /Q 20 30 40 Angle of affack, cr cksgrees T Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-t Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
