1、ANDNASA TECHNICAL NOTE NASA TN D-7716*-JL. S. J.I(NASA TN-D-7776) WD LSTIGATION W IND-TUNNELS-P-I ESSGR A WOF A MODEL OF A FREE-FLIGHT(IACESS 76 pC C.I. COlGURATION 7-26y 3CSCL C UnclasWIND-TUNNEL FREE-FLIGHT INVESTIGATIONOF A MODEL OF A SPIN-RESISTANTFIGHTER CONFIGURATIONby Sue B. Grafton, Joseph R
2、. Chambers,and Paul L. Coe, Jr.Langley Research CenterHampton, Va. 23665NATIONAL AERONAUTICS AND SPACE ADMINISTRATION * WASHINGTON, D. C. * JUNE 1974Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-1. Report No. 2. Government Accession No. 3. Recipien
3、ts Catalog No.NASA TN D-77164. Title and Subtitle 5. Report DateWIND-TUNNEL FREE-FLIGHT INVESTIGATION OF A MODEL June 1974OF A SPIN-RESISTANT FIGHTER CONFIGURATION 6. Performing Organization Code7. Author(s) 8. Performing Organization Report No.Sue B. Grafton, Joseph R. Chambers, and Paul L. Coe, Jr
4、. L-968110. Work Unit No.9. Performing Organization Name and Address 501-26-04-02NASA Langley Research Center 11. Contract or Grant No.Hampton, Va. 2366513. Type of Report and Period Covered12. Sponsoring Agency Name and Address Technical NoteNational Aeronautics and Space Administration 14. Sponsor
5、ing Agency CodeWashington, D.C. 2054615. Supplementary NotesPaul L. Coe, Jr., is an Assistant Research Professor in Engineering, The George WashingtonUniversity, Joint Institute for Acoustics and Flight Sciences.Technical Film Supplement L-1152 available on request.16. AbstractAn investigation was c
6、onducted to provide some insight into the features affecting thehigh-angle-of-attack characteristics of a high-performance twin-engine fighter airplanewhich in operation has exhibited excellent stall characteristics with a general resistance tospinning. Various techniques employed in the study inclu
7、ded wind-tunnel free-flight tests,flow-visualization tests, static force tests, and dynamic (forced-oscillation) tests. In addi-tion to tests conducted on the basic configuration, tests were made with the wing planformand the fuselage nose modified.The results of the study showed that the model exhi
8、bited good dynamic stability charac-teristics at angles of attack well beyond that for wing stall. The directional stability of themodel was provided by the vertical tail at low and moderate angles of attack and by the fuse-lage forebody at high angles of attack. The wing planform was found to have
9、little effect onthe stability characteristics at high angles of attack. The tests also showed that althoughthe fuselage forebody produced beneficial contributions to static directional stability at highangles of attack, it also produced unstable values of damping in yaw. Nose strakes locatedin a pos
10、ition which eliminated the beneficial nose contributions produced a severe directionaldivergence.The investigation identified configuration features which promote spin resistance andalso defined test techniques and methods of analysis which can be applied early in design offuture configurations.17.
11、Key Words (Suggested by Author(s) 18. Distribution StatementStall/spin Unclassified - UnlimitedDynamic stabilityHigh-performance fighterSTAR Category 0219. Security Classif. (of this report) 20. Security Classif. (of this page) 21. No. of Pages 22. Price*nclassified UUnclassified I7 $4.00For sale by
12、 the National Technical Information Service, Springfield, Virginia 22151jProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-WIND-TUNNEL FREE-FLIGHT INVESTIGATION OF A MODELOF A SPIN-RESISTANT FIGHTER CONFIGURATIONBy Sue B. Grafton, Joseph R. Chambers,an
13、d Paul L. Coe, Jr.*Langley Research CenterSUMMARYAn investigation was conducted to provide some insight into the featuresaffecting the high-angle-of-attack characteristics of a high-performancetwin-engine fighter airplane which in operation has exhibited excellent stallcharacteristics with a general
14、 resistance to spinning. Various techniquesemployed in the study included wind-tunnel free-flight tests, flow-visualizationtests, static force tests, and dynamic (forced-oscillation) tests. In additionto tests conducted on the basic configuration, tests were made with the wingplanform and the fusela
15、ge nose modified.The results of the study showed that the model exhibited good dynamicstability characteristics at angles of attack well beyond that for wing stall.The directional stability of the model was provided by the vertical tail at lowand moderate angles of attack and by the fuselage forebod
16、y at high angles ofattack. The wing planform was found to have little effect on the stabilitycharacteristics at high angles of attack. The tests also showed that althoughthe fuselage forebody produced beneficial contributions to static directionalstability at high angles of attack, it also produced
17、unstable values of dampingin yaw. Nose strakes located in a position which eliminated the beneficialnose contributions produced a severe directional divergence.The investigation identified configuration features which promote spinresistance and also defined test techniques and methods of analysis wh
18、ich canbe applied early in design of future configurations.*Assistant Research Professor in Engineering, The George WashingtonUniversity, Joint Institute for Acoustics and Flight Sciences.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-INTRODUCTIONEx
19、perience has shown that many high-performance fighter airplanes aresusceptible to a lateral-directional divergence (sometimes referred to asnose-slice) at high angles of attack. (See, e.g., ref. 1.) This type ofdivergence usually leads to inadvertent spins, and spin recovery forpresent-day fighters
20、is often difficult or impossible. Therefore, there is anurgent need to develop guidelines for use in the design of future tacticalaircraft in order to eliminate instabilities and insure good inherentcharacteristics at high angles of attack. The National Aeronautics and SpaceAdministration currently
21、has a broad research program underway to provide theseguidelines. One element of the program involves identification of airframedesign features which promote good stall and spin characteristics.The present investigation was conducted in order to provide some insightinto the features affecting the st
22、ability characteristics at high angles ofattack of a high-performance twin-engine fighter which in operation hasexhibited outstanding stall and spin characteristics. These characteristics,which result in a general resistance to spins, include positive directionalstability through the stall with no t
23、endency to diverge and no significantadverse yaw due to aileron deflection at high angles of attack.A wind-tunnel investigation was made with a 0.17-scale model of theairplane in order to define some of the more important geometric and aerodynamiccharacteristics responsible for the good stall and sp
24、in characteristics. Thestudy included wind-tunnel free-flight tests, flow-visualization tests, staticforce tests, and dynamic (forced-oscillation) force tests.In addition to the tests conducted for the basic configuration, testswere made with the wing planform changed to swept and delta designs. The
25、 basicand delta wings were also tested in a high position on the fuselage, andfuselage forebody strakes were added in order to determine the effects ofthese features on stability and control at high angles of attack.Selected scenes from a motion picture of the free-flight tests have beenprepared as
26、a film supplement available on loan. A request card and adescription of the film (L-1152) are included at the back of this report.2Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SYMBOLSAll longitudinal forces and moments are referred to the wind-axi
27、s systemand all lateral-directional data are referred to the body-axis system shown infigure 1. All force-test data are referred to a moment reference centerlocated longitudinally at 18 percent of the mean aerodynamic chord for thebasic wing. The vertical location of the moment reference center was
28、0.02 per-cent of the mean aerodynamic chord above the wing-chord reference line at theplane of symmetry. All measurements were reduced to standard coefficient formon the basis of the geometric characteristics of each individual wing planform.In order to facilitate international usage of data present
29、ed, dimensional quan-tities are presented both in the International Systems of Units (SI) and in theU.S. Customary Units. Measurements and calculations were made in the U.S.Customary Units. Conversion factors for the two systems may be found in refer-ence 2.b wing span, m (ft)c mean aerodynamic chor
30、d, m (ft)CA axial-force coefficient, FA/q SCD drag coefficient, FD/q SCL lift coefficient, FL/q SC rolling-moment coefficient, MX/q.SbCm pitching-moment coefficient, My/qaScC yawing-moment coefficient, MZ/q SbCN normal-force coefficient, FN/qS5Provided by IHSNot for ResaleNo reproduction or networki
31、ng permitted without license from IHS-,-,-C side-force coefficient, Fy/qSf frequency of oscillation, HzFA axial force, N (Ib)FD drag force, N (Ib)FL lift force, N (lb)FN normal force, N (lb)F side force, N (lb)IX moment of inertia about X body axis, kg-m2 (slug-ft2 )Iy moment of inertia about Y body
32、 axis, kg-m2 (slug-ft2)IZ moment of inertia about Z body axis, kg-m2 (slug-ft2)wb Ck reduced-frequency parameter, 2 or 2VMX rolling moment, m-N (ft-lb)My pitching moment, m-N (ft-lb)MZ yawing moment, m-N (ft-lb)p roll rate, rad/secq pitch rate, rad/secq. dynamic pressure, N/m2 (ib/ft2 )4Provided by
33、IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-r yaw rate, rad/secS wing area, m2 (ft2)U,vW components of resultant velocity V along X, Y, and Z bodyaxes, respectively, m/sec (ft/sec)V free-stream velocity, m/sec (ft/sec)X,Y,Z body reference axes (fig. 1)a angl
34、e of attack, degSrate of change of angle of attack, rad/secP angle of sideslip, degrate of change of sideslip, rad/seca aileron deflection (per side), positive for left roll, dega5fle leading-edge flap deflection, degSh horizontal-tail deflection, positive for nose-down pitch, degS rudder deflection
35、, positive for nose-left yaw, degrincremental rolling-moment coefficientC incremental yawing-moment coefficientnACy incremental side-force coefficientCD angular frequency, 2iTf, rad/sec5Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-c cn acyCI = CnP
36、 = 6 Cy =Cndyn Cn - I- C sin a6C 6 Cn 6CYCIp=l pb Cn Y = pb2V 2V 2Vc acn acy2 n YC = C Cy =Cr rb Cnr rb CYr rb2V 2V 2V6C 6CN 6CACm C CA =2V 2V 2Vm N CAC -CN. CA -fa 61 a2V 2V 2VMODEL, APPARATUS, AND TESTING TECHNIQUESBasic ConfigurationA three-view sketch showing the basic configuration of the model
37、 ispresented in figure 2, photographs of the model are presented in figure 3,and mass and geometric characteristics are listed in table I. The model was6Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-constructed primarily of molded fiberglass and wa
38、s a 0.17-scale model of thefull-scale airplane.The model was powered by compressed air which was brought into the topof the model by flexible plastic tubing and ejected from metal tubes locatedinside the model near the rear of the fuselage. This ejector system simulatedflow through the engines, sinc
39、e the model was tested with the engine inlets andinterior of the model open.The longitudinal control surface consisted of an all-movable horizontaltail, the lateral control surfaces were conventional ailerons, and thedirectional control surface was a conventional rudder. For manual control bythe pil
40、ot, the control surfaces were actuated by electropneumatic servos whichprovided a full-on or full-off flicker-type deflection. Each actuator had amotor-driven trimmer which was electrically operated by the pilots so thatcontrols could be rapidly trimmed in flight. The systems for pitch and rollcontr
41、ol were also connected to individual rate damper systems. The rate dampersconsisted of rate gyroscopes driven by compressed air which actuated thesurfaces in proportion to pitch and roll rates. The control-surface deflectionsused during the flights were as follows:Pilot Damper Maximum(flicker) (prop
42、ortional) availableHorizontal tail, deg . . . . . 5 5 5 to -25Ailerons (per side), deg . . . 0 5 30Rudder, deg . . . . . . . . . 10 to 30 - 30Deflection of the horizontal tail on the full-scale airplane is limited to 170trailing edge up, but increased travel was provided for the model in order toinv
43、estigate angles of attack beyond those obtainablein lg flight at full scale.Modified ConfigurationOne airframe component expected to have significant effects on thestability and control of the model at high angles of attack was the wing.Past studies (see refs. 3 and 4, e.g.) have shown that wing pla
44、nform7Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-characteristics, such as sweepback and taper ratio, together with the verticallocation of the wing on the fuselage can have large effects on lateral-directional stability at high angles of attack.
45、 In order to evaluate theeffects of wing modifications, the additional wings and wing-fuselagecombinations shown in figures 4, 5, and 6 were tested. In addition to thebasic wing, a swept wing (similar in planform to that employed by theconfiguration of ref. 1) and a delta wing were tested. As shown
46、in figure 5,the basic wing and the delta wing were also tested in a high position withmodified engine inlets. (The engine inlets were modified in order to smooththe intersection of the high wing and the fuselage.) All wings were of equalarea and of relatively equal weights, so that the flight tests
47、were conductedwith a constant value of wing loading. Aspect ratio and wing span varied witheach wing design. (See table I.) The location of the 0.25E point was constantfor all configurations tested. The additional wings incorporated conventionalailerons for roll control. Plan views of the configurat
48、ion with the variouswings are shown in figure 6.Tests were also conducted to determine the effects of the symmetrical nosestrakes shown in figure 7. The strakes were designed to eliminate asymmetricyawing moments and unstable values of damping in yaw at high angles of attack,as discussed in referenc
49、e 5. As a further element of studies of the effects ofthe fuselage nose, the aerodynamic characteristics of the isolated nose of thebasic configuration were determined in tests of the nose alone (fig. 8).Free-Flight Test TechniqueThe test setup for the free-flight tests is shown in figure 9. The modelwas flown without restra
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