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Copy y RM SL55B21 ■ at anf CMSSIPICATiTON OHAIIGE thority ot/ ed "^" CLASSIFICATION CANCELLED NACA py/coc- MEMORANDUM for the U. S. Air Force INVESTIGATION IN THE LANGLEY FREE-FLIGHT TUNNEL OF THE LOW-SPEED STABILITY AITD CONTROL CHARACTERISTICS OF A l/lO-SCALF MODEL SIMULATING THE CONVAIR F-102A AIRPLATTE By Peter C. Boisseau Lsingley Aeronautical Laboratory Langley Field, Va. class; This material contains information affecting^ of the espionage laws, Title 18, U.S.C.i manner to an unauthorized person is prohil DOCUMENT Defense of the United States within the meaning , the transmission or revelation of which in any NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS WASHINGTON /Vi MCA EM SL55B21 ^^CLASSIP SKiPHlie MTIOML ADVISORY COMMITTEE FOR AEROMUTICS RESEARCH MEMORANDUM for the U. S. Air Force INVESTIGATION IN THE LANGLEY FREE-FLEGHT TUNNEL OF THE LOW-SPEED STABILITY AND CONTROL CHARACTERISTICS OF A 1/lO-SCALE MODEL SIMULATING THE CONVAIR F-102A AIRPLANE By Peter C. Boisseau SUMMARY An investigation of the low-speed, power-off stahiliiy and control characteristics of a l/lO-scale model simulating the Convair F-102A air^ plane has heen made in the Langley free-flight tunnel. The model in its hasic configuration and with tvro modifications involving leading- edge slats and an increase in vertical-tail size was floim through a lift-coefficient range from O .7 to the stall. Only relatively low- altitude conditions were simulated. The longitudinal stability characteristics of the model were con- sidered satisfactory for all conditions investigated. The lateral stability characteristics were considered satisfactory for the basic configuration over the lift-coefficient range investigated, except near the stall, where large values of static directional instability caused the model to be directionally divergent. An 80-percent increase in vertical-tail area increased the angle of attack at which the model became directionally divergent. The longitudinal and lateral control characteristics were generally satisfactory. Although the adverse sideslip characteristics for the model were considered acceptable over the angle-of -attack range, analysis indicates that the adverse sideslip characteristics of the airplane may be objectionable at high angles of attack. 2 MCA EM SL55B21 IMTRODUCTION An investigation of the low-speed stability and control character- istics of a l/lO-scale model simulating the Convair F-102A airplane has been made in the langley free-fli^t tunnel at the request of the U. S. Air Force. !The F-102A airplane is a turbojet-powered^ interceptor- type airplane irith a 6o° delta i^ring and a 6o° delta vertical tail. It differs from the Convair TF-102 airplane of reference 1 by having a longer fuselage, a longer tail moment arm, a drooped leading edge which increases the iri.ng area slightly, and chordwise fences at the 65 percent ■(•ring semispan station. These changes were made to the free-flight- tunnel model of the IF-102 from specifications furnished by Convair in September 1955* Any changes to the full-scale airplane subsequent to this date were not incorporated in the free-flight-tunnel model. The investigation included fli^t tests of the model in its basic configuration and ^rLth several modifications involving leading-edge slats and an increase in vertical- tail size. Force tests of these con- figurations were also made to determine the static stability characteristics . In order to permit a better interpretation of the free-flight- tunnel tests in terms of the full-scale airplane, a conqjarison was made betoeen the results of force tests at a low Reynolds nxjmber (O .85 x 10^) in the free-flight tunnel and force tests made by Convair at a higher Reynolds number ( 5 . 316 x I 06 ) . SYMBOIS All stability parameters and coefficients are referred to the stability system of axes originating at the center of gravity. A sketch sho^ang the axes and the positive directions of the forces, moments, and angles is given in figure 1 . S wing area, sq ft S-j; exposed vertical-tail area, sq ft c mean aerodynamic chord, ft V airspeed, ft/sec b <1 wing span, ft dynamic pressure, Ib/sq ft •• MCA RM SL55B21 3 • • !••• • • fO 9 99 P \J m P t 01 n ix ly iz % % X Y Z M H L air density, slugs/cu ft v/ei^t, Ib airplane mass, slugs relative-density factor, m/ pSb angle of sideslip, deg angle of yaw, relative to the tunnel axis system, deg for flight-test data, the angle hefereen the projection of the Y-axis of the model on the YZ-plane of the tunnel and the Y-axis of the timnel, deg angle of attack, deg inclination of principal longitudinal axis of airplane trith respect to flight path, positive when principal axis is above fli^t path at the nose, deg moment of inertia about longitudinal body axis, mkj^, slug-ft^ moment of inertia about lateral body axis, mky^, slug-ft^ moment of inertia about normal body axis, mkg^, slug-ft^ radius of gyration about longitudinal body axis, ft radius of gyration about lateral body axis, ft radius of gyration about normal body axis, ft longitudinal force, lb lateral force, lb normal force, lb pitching moment, Ib-ft ya-vri.ng moment, Ib-ft rolling moment, Ib-ft k MCA EM SL55B21 Cl Cd Cm Cn Cz Cj lift coefficient, lift/ q.S drag coefficient. Drag/ qS pitching-moment coefficient, M/qSc yawing-moment coefficient, IJ/ qSb rolling-moment coefficient, L/qSb lateral-force coefficient, Y/qS s°lr Sr rudder deflection, deg 5g elevator deflection (elevons deflected together for elevator control) , deg Sg, aileron deflection (elevons deflected differentially for aileron control) , deg APPARATUS AND MODEL The flight tests and static force tests were conducted in the langley free-flight tunnel, which is designed to test free-flying dynamic models. A complete description of the tunnel and its operation is presented in reference 2. Force tests were made ’irith a sting- type support system and an internally mounted strain-gage balance. The l/lO-scale model used in the investigation was obtained by modifying the original Convair YF-102 model used in the investigation of reference 1 so that it approximated the fuselage shape and accurately represented the other geometrical changes of the revised design, such as fuselage length, vertical-tail position, leading-edge mng droop, and wing fences. A three-view draT'fing of the model is shoim in fig- ure 2 and a photograph of the model is sho™ in figure 5* Table I gives MCA RM SL55B21 5 the scaled-up mass and dimensional characteristics of the model. MLdspan leading-edge slats and two different sizes of vertical tails were also tested on the model. (See fig. 2.) !Ehe vertical tails . tested were the basic tail I — & = increase in area ( 1 = 0 . 18 ), if = and a tail with an 80 -percent DEOERMIWATION OF STATIC STABIIZTT AND CONTROL CHARACTERISTICS OF FLIGHT-TEST MODEL Force Tests To Determine Longitudinal Stability and Control Force tests were made to determine the static longitudinal stability and control characteristics of the basic model and the model with modi- fications for an angle-of-attack range from 0° throu^ the stall. All the force tests were run at a dynamic pressure of 5*63 pounds per square foot, which corresponds to an airspeed of about 55*7 feet per second at standard sea- level conditions and to a test Reynolds nmber of O .85 X 10^ based on the mean aerodynamic chord of 2.32 feet. Static longitudinal characteristics of the basic and modified model are presented in figure 4. The data are presented for a center of gravity of 30*0 percent of the mean aerodynamic chord in order that comparisons can conveniently be made with the Convair IF-102 data from reference 1. The leading-edge slats of figure 2 were used on the model because they had a beneficial effect on the lateral stability character- istics at high angles of attack for the original model of the Convair yF-102 tested in the langley free-flight tunnel (ref. l) . The data of figure 4 indicate that these slats were obviously not the optimum configinration for producing the most satisfactory longitudinal character- istics for the model of the present investigation. The data show that the slats decreased the lift-curve slope, the maximum lift coefficient, and the static longitudinal stability parameter ^ comparison of the pitching-moment curves for the t^-ro conditions shows that the slats caused a slight pitch-up at the stall. The static longitudinal stability and control characteristics of the free-flight-tunnel models of the F-102A and IF-102 are presented in figure 5- These data show that the lift-curve slopes and the maximum lift coefficient for the F-102A are greater than those of the IF-102. The increase in the maximum lift of the F-102A over that of the IF-102 can be attributed mainly to the cambered leading edge of the F-102A. 6 MCA EM SL55B21 About 25 percent of the increase can be attributed to the fact that the 1***^ coefficients vrere based on the area of the YF-102 \ring, which was ; approximately 5 percent less than that of the F-102A wing. A comparison •••• of the pitching-moment curves shows that the models had about the same ® static longitudinal stability and elevator effectiveness over the lift- coefficient range. • •• Force Tests To Determine lateral Stability and Control Force tests were made to determine the static lateral stability and control characteristics of the model >rith the vertical tail off and on over a sideslip range from 20° to -20° for angles of attack from 0° to 56°. These data were obtained at the same dynamic pressure and center-of -gravity location as for the longitudinal stability and control data. Presented for comparison with the free -flight-tunnel data are higher Eeynolds number data obtained from tests conducted at Convair. The Convair data are presented for a center-of -gravity position of 27.5 percent of the mean aerodynamic chord. Basic design .- The lateral-stability characteristics determined from the free -flight-tunnel tests are presented in figure 6 for the basic configuration^, and a comparison of these (FFT) data and the Convair data is presented in figure 7* All free-fli^t-tunnel data are presented for an elevon deflection of -15°^ which corresponded approximately to the deflection needed to trim at hi^ lift coefficients. (See fig. 4.) The data of figure 6 show that the variation of the yawing-moment coeffi- cient and the rolling-moment coefficient C^ mth angle of side- slip p is fairly linear up to an angle of attack of 20° for the model ■(■ath vertical tail (fig. 6(b)). At an angle of attack of 24° the tail- off configuration (fig. 6(a)) shows a large increase in directional instability. This increase in negative slope of the yai-n.ng-moment curve for the tail-off configuration is also reflected in the data for the tail-on configuration at an angle of attack of 24°. At angles of attack of 26° and hi^er, the tail-on data show a destabilizing break in the yavring-moment curve at sideslip angles greater than approximately ±5°. A con^arison of the data of figure 7 shows that^ at low and moderate angles of attack, the yawing-moment and rolling-moment curves for both models had the same general characteristics. At high angles of attack, however, the Convair data indicated less directional instability than the free-f light-tunnel data. The data of figures 6 and 7 summarized in figure 8 in terms of the side-force parameter directional-stability parameter and the effective-dihedral parameter • Since the data of figures 6 and 7 nonlinear for some conditions, the data of figure 8 are pre- sented at low angles of sideslip (p = i2°) and hi^ angles of side- slip ( P = ±10°) . These data indicate that the free-fli^t-tunnel model MCA RM SL55B21 7 had lower directional stability over the angle -of -attack range than the Convair model and also became directionally unstable at a lower angle of attack than the Convair model. Because of the nonlinearities in the yawing-moment curves^ the directional stability determined for p = +10° decreased to zero at an angle of attack about 2° lower than that for 3 = +2°. The effective dihedral positive for both models over the angle-of -attack range, ’(•rith the Convair model having higher values of hi^er angles of attack for p = +2°. !The yavmng-moment data in figure 8 for the free-flight-tunnel model are shovm for a center-of-gravity position of 27-5 percent c as well as of 50.0 percent c in order that a direct comparison may be made \rith the Convair data. The data indicate that changing the location of the center of gravity of the free-flight-tunnel model from 50.0 to 27-5 percent of the mean aerodynamic chord had only a sli^t effect on the directional stability. Changing the center of gravity from 50.0 to 27.5 percent of the mean aerodynamic chord had a negligible effect upon the rolling moment of the model. 3 The variation of the lateral-stability parameters Cy^, C^p^ and id.th lift coefficient and angle of attack for the F-102A are com- pared in figure 9 ^■rith data from reference 1 for the IF-102. In general the variation of the lateral-stability parameters ^-rith angle of attack was similar for the two models. Becaxise of the difference in lift curves for the P-102A and the YF-102 at high angles of attack (fig. 5)^ the plots of Cnp against lift coefficient (fig. 9) show that the directional stability drops off less abruptly for the F-102A than for the YF-102. The effective dihedral positive for both models over the lift- coefficient range >;lth the F-102A model having slightly higher values of -C^p at the higher lift coefficients. Modified design .- In an effort to obtain satisfactory static lateral- stability characteristics at high angles of attack, force tests were made of the model "vrith increased vertical- tail size ( — = O.I8) and id-th Vs / leading-edge slats. (See fig. 2.) The data obtained in these tests are presented in figures 10 and 11. The data of figure 12 compare 'the lateral-stability characteristics of the basic model with those of the modified model at angles of attack of 24° and 50°. The data of figures 10 and 11 are summarized in figure I5 in terms of the lateral-stability parameters Cy^ :„p, and -C2p for angles of sideslip of +2° and +10°. The data of figure 12(a) show that at an angle of attack of 24°, increasing the size of the vertical tail = 0.l8^ caused the model to 8 MCA RM SL55B21 "become directionally static and also made the curve linear. For the basic tail the leading-edge slats produced a small increment in direc- tional stability at low angles of sideslip and a very large increment at large angles of sideslip so that the overall result was a fairly linear variation of the ya^rLng-moment coefficient ^'rLth angles of side- slip. The slats had little effect on the directional stability when they were used in combination with the enlarged tail. The data of figure 12(b) show that;, at a = 50°^ model ■S'fith the basic tail was directionally unstable and the model with the enlarged tail was about neutrally stable for sideslip angles of ±5°- The model with either tail and without slats had a sharp destabilizing break at a sideslip angle of about +5°* ibe slats caused a destabilizing effect for small angles of sideslip and a large reduction in the directional instability for large angles of sideslip. The effects of increased tail size and leading-edge slats are shc^ more clearly in the summary data of figure 13 . The aileron and rudder control effectiveness for the basic model are presented in figure lit. FUGBT TESTS Flight tests vrere made from a lift coefficient of about O. 7 O throu^ the stall in order to determine the dynamic stability and control char- acteristics of the model in its basic configuration and \fith increased tail size and leading-edge slats. Flight tests were made at a center- of -gravity position of 27*5 percent c. Id^t ■(■ring loadings were used in order to minimize damage to the model in crackups. The model was floTO with coordinated aileron and rudder control and ivlth aileron-alone control. Aileron deflections of ±15° and a rudder deflection of ±25° were used for all conditions. Only relatively low-altitude conditions were simulated. The model behavior during flight was observed by a pilot sitiiated just aft of the tunnel test section. The pilot's observations and supplementary data obtained by motion-picture records served as a basis for all discussion of the flight tests. FUGHT-TEST RESULTS AND DISCUSSION Interpretation of Fli^t-Test Resiilts In interpreting the results of the model flight tests in terms of the full-scale airplane, it is necessary to consider any differences bet\reen the static stability derivatives of the model and those of the g W W !IiiIDliM3IA.5 NACA RM SL55B21 9 full-scale airplane and any differences "between the scaled-up mass characteristics of the model and the mass characteristics of the air- plane. If there are no differences in these factors, then the airplane woixld he expected to ejdiihit dynamic characteristics similar to those of the free-flight-tunnel model. Althou^ no mass data were available for the full-scale airplane, the data of reference 1 show that the values of the scaled-up moments of inertia for the model of the Convair YF-102 were generally similar to those of the airplane at normal gross wei^t. Therefore, the mass data presented in table I for the scaled-up moments of inertia for the model of the F-102A are expected to be representative of those of the airplane at normal gross weight. It has been shown that the static stability characteristics of the free-flight-t unn el model at low Reynolds number are in fair agreement with the characteristics of the Convair model at higher Reynolds number. It is likely, however, that the abrupt changes noted in the stability parameters at high lift coefficients ■vri.ll occur at somewhat higher lift coefficients for the airplane than for the model. The dynamic behavior of the airplane is therefore expected to be similar to that of the free-flight-tunnel model, except that corresponding dynamic behavior might occur at higher lift coefficients. It should be pointed out that the full-scale airplane should be easier to fly than the model because its angular velocities will be only about one-third as high as those of the model. Another factor which should facilitate the pilot’s control of the airplane is the fact that he has independent aileron and rudder control rather than the coordinated aileron and rudder control which was used on the model. In interpreting the lateral-control characteristics of models in temns of full-scale airplanes, it has been found necessary in some cases to consider the differences in piloting technique between the models and the airplanes. A free-fli^t-tunnel study has revealed that airplanes which have high yavring inertia and low rolling inertia, such as the F-102A, tend to execute a pure rolling motion about the principal longi- tudinal axis of inertia, at least dirring the early stages of a rolling maneuver. VJhen these airplanes roll in this manner, an adverse sideslip angle about the stability axis is produced which is approximately equal to the angle of inclination of the principal axis times the sine of the angle of bank (t) sin . For instance, for a given angle of inclination of the principal axis of 20°, an airplane of this type when banked 50° vrill have an angle of adverse sideslip of 10° about the stability axis. Since the pilot of a free-flight-tunnel model flies the model from a remote position and can perform only very limited maneuvers, he does not object to the model’s executing essentially pure roll about the prin- cipal axis and apparently cannot detect the resulting adverse sideslip about the stability axis that might be objectionable to the pilot of the 10 MCA EM SL55B21 »••• • • : : ••• • • • • full-scale airplane. The estimation of the adverse sideslip character- istics of the airplane "based on the model flight tests is therefore expected to he optimistic. In the discussion of the fli^t tests, it should he pointed out that what the pilot observes is the yaw of the model in the tunnel, except in cases of violent motions of translation. This in effect is the same as sideslip, except for sign. In the discussion that follows, the terms yaw and sideslip are used interchangeably, yaw being used to imply that the attitude in the tunnel is the significant thing at the time and sideslip being used when the aerodynamic effects of sideslip are under consideration. Similar considerations apply to the usage of angle of attack and pitch. The results of the present investigation are illustrated more graphically by motion pictures of the flints of the model than is possible in a ■Hritten presentation. For this reason a motion-picture film supplement to this paper has been prepared and is available on loan from the MCA Headquarters, Washington, D. C. Longitudinal Stability and Control The longitudinal stability and control characteristics of the Convair F-102A were similar to those of the Convair YF-102 and were considered satisfactory for all conditions investigated. Although the longitudinal characteristics of the model were considered to be generally satisfactory, some diffic\ilty was encountered in flying the model in the high lift-coefficient range because of the large variation of drag •irLth lift, which is generally a characteristic of 1 ot 7 aspect- ratio delta tjlngs (ref. 5) • This large variation of drag with lift caused large variations of the glide angle "VTlth lift coefficient and necessitated almost continuous corrections to tunnel angle and airspeed in order to maintain fli^t in the txinnel. lateral Stability Basic design .- In general, the lateral stability characteristics for the basic configuration of the F-102A were similar to those for the basic configuration of the YF-102 tested in reference 1. At angles of attack below about 25° the model was easy to fly and the lateral stability was considered satisfactory. The lateral (Dutch Roll) oscillations were well dandled for all fli^t conditions. The directional stability decreased ■^/Ith increasing angle of attack, and at an angle of attack near the stall (a = 26°) the model became directionally divergent. A typical fli^t record of the model at an angle of attack of 26° is shorn in figure 15(a-) • The model could be flown at this angle of attack as long as the pilot was ^BOirra B EmaiL MCA EM SL55B21 11 aBle to keep the angle of sideslip small. It appeared, however, that, once an angle of sideslip of approximately 5° reached, the model could not he recovered and it diverged rapidly to larger angles of sideslip and snap-rolled into the tunnel wall. The directional diver- gence of the free -fU^t- tunnel model was evidently caused hy the large values of the static directional instahility at the hi^er angles of attack. The increased rate of the divergence at the moderate and large angles of sideslip is attributed to the sharp destabilizing break in the yawing-moment curve which occurred at the hi^er angles of attack. Another factor which might have contributed to the directional diver- gence was the decrease in positive effective dihedral in the hi^er angle -of -attack range. As flights were attempted at angles of attack above 26°, it became more difficult for the pilot to keep the model at small angles of side- slip and the divergence became more violent. Flights attempted at an angle of attack of 30° were very short because the model diverged soon after take-off. A flight record of the model at an angle of attack of approximately 30° is presented in figure 15(a) . For this case the model sideslipped to an angle greater than 30° and rolled to an angle of about 30° before crashing into the tunnel wall. More effective xise of the rudder yawing moment co\ild probably have been obtained if the riiidder had been deflected independently, but even the maximum available yawing moment of the rudder would be insufficient to balance out the ya^fing moment due to sideslip at sideslip angles greater than approximately +5° at an angle of attack of 30°. In con^jaring the force-test data of figure 8, it is seen that the free-fli^t-tunnel model becomes directionally unstable at an angle of attack approximately 5° lower than that for the Convair model} this difference \ras probably partly caiised by differences in Reynolds number. Since the flight tests showed that the free-flight-tunnel model could be floim at an angle of attack about 5° higher than that at which became negative, it is possible that the airplane, because it will be operating at much higher Reynolds numbers, might not experience a directional divergence before it stalls. Other factors that might influence the high angle-of -attack behavior of the full-scale airplane are its slower yairing motions and independent rudder control which might enable the pilot to control the yawing motion fairly well and prevent a divergence in most cases, even at high angles of attack. The danger of a directional divergence >rill still exist, hcnrever, since the airplane might inadvertently reach the divergent conditions if the pilot becomes engrossed in some action, such as an evasive maneuver in combat. Modified design . - 8o percent ~ 0-l8^ Increasing the size of the vertical tail by did not eliminate the directional divergence but did increase the angle of attack at which the divergence occurred. 12 MCA RM SL55B21 Flights were obtained at angles of attack up to about 33° ''■rf-th the enlarged tail. Men flints were attempted at an angle of attack of 35° hi^er, the model diverged in sideslip but the divergence ims less violent than with the basic tail at lower angles of attack. Records of the model with the enlarged tail are presented in figure 15(b) for model angles of attack of approximately 30° and 33°- The addition of leading-edge slats did not increase the angle of attack at which the model became directionally divergent. In fact, it appeared that the model diverged at a slightly lower angle of attack •^-Tith slats on than with slats off. The force -test data of figure 13 show that, for sideslip angles of i2°, the addition of the slats increased the static directional instability at angles of attack greater than about 28°. A fli^t record showing a directional divergence of the model for an angle of attack of approximately 33° is presented in fig- ure 15 (c). The fact that the use of slats in combination with increased tail size failed to eliminate the directional divergence of the F-102A model in the high angle-of -attack range as they had done for the ^-102 can be explained by the force-test data of figure 16. These data are for the t^ro models with the large vertical tail and leading-edge slats and show that, at the hi^er angles of attack, the F-102A had much greater static directional instability and much lower effective dihedral than the YF-102. This slat configuration, which had been selected on the basis of exploratory force tests on the YF-102 model, apparently \Tas not satisfactory for use on the F-102A model. A more suitable slat configuration for the F-102A could probably have been found from addi- tional exploratory force tests with this model, but such tests were considered beyond the scope of this investigation. lateral Control The lateral control characteristics of the basic and modified con- figurations were considered satisfactory over the lift- coefficient range investigated and were generally similar to those obtained for the YF-102 model in reference 1. Althou^ the control characteristics could not be evaluated throu^ the stall for the basic configuration, it is believed that they would be similar to those of the model ’t-rith increased tail size. Ill flints of the model idLth increased tail size near the stall, some adverse sideslip with aileron alone was obtained because of the adverse yairing moments due to aileron deflection (fig. 14(a)). This adverse sideslipping was eliminated, however, by using the rudder in combination with the ailerons for coordinated control. In the higher angle-of -attack range, the model could be controlled satisfactorily until a directional divergence occurred. As previously pointed out, full-scale flight test of airplanes which have high yaid-ng inertia and low rolling inertia, similar to the mCA RM SL55B21 15 • ••• • • • • »• • • • »• • • ••• F-102A, indicated more severe adverse sideslip characteristics than were demonstrated hy the models of these airplanes in the free-fli^t tunnel. It is possible, therefore, that the adverse sideslipping behavior of the full-scale airplane may be objectionable at the hi^ angles of attack. CONCLUSIONS Eesxxlts have been presented from a free-fli^t-tunnel stability and control investigation of a l/lO-scale model simulating the Convair F-102A airplane. The model was flora throu^ a lift-coefficient range from 0.7 to the stall, and only relative low-altitude conditions were simulated. From the results, the foUorang conclusions were drawn; 1. In general, the fll^t characteristics for the basic configura- tion of the Convair F-102A airplane model were similar to those for the basic configuration of the Convair IF-lOE airplane model previously tested. 2. The longitudinal stability characteristics were considered satis- factory for the basic and modified configurations over the lift-coefficient range investigated. 5 . The lateral stability characteristics for the basic configuration were considered satisfactory over the lift-coefficient range investigated except near the stall where large values of static directional instability caused the model to be directionally divergent. it. An 80-percent increase in vertical- tail area Increased ihe angle of attack at which the model became directionally divergent. 5 . The use of leading-edge slats in combination with an 80 -percent increase in vertical-tail area did not eliminate the directional diver- gence throu^ the stall on the F-102A model as they did for the YF-102 model. 6. The longitudinal and lateral control characteristics were generally satisfactory. Although the adverse sideslip characteristics for the model were considered acceptable over the angle-of -attack • • JLU XO 14 mCA EM SL55B21 range, analysis indicates that the adverse sideslip characteristics of , the full-scale airplane may he ohjectionahle at high angles of attack. • • • • ■ • Langley Aeronautical Laboratory, '•** national Advisory Committee for Aeronautics, langley Field, Va., February 7# 1955* Peter C. Boisseau Aeronautical Research Scientist Thomas A. Harris Chief of Stabilliy Research Division JKS REFERENCES 1. Johnson, Joseph L. , Jr., and Boisseau, Peter C. : Investigation of the Low-Speed Stability and Control Characteristics of a l/lO-Scale Model of the Convalr YF-102 Airplane in the Langley Free-Fll^t Tunnel. MCA RM SL55HA-, U. S. Air Force, 1955- 2. Shortal, Joseph A., and Osterhout, Clayton J. ; Preliminary Stability and Control Tests in the MCA Free-Fli^t Hind Tunnel and Correla- tion With Full-Scale FU^t Tests. MCA TN 8l0, 1941. 5* McKinney, Marion 0., Jr., and Drake, Hubert M. : Flight Character- IstiQS at Low Speed of Delta-Wing Models. MCA RM L7K07, 1948. MCA EM SL55B21 15 >••• »• • • » • • • • •• • • • • • ••• • • TABJE I SCAIED-UP MASS AlH) DBOTSIONAL CHARACTERISTICS OP A 1 / 10 -SCAIE MODEL SIMOLATHTG THE COWAIR F- 102 A AIRPIAlffi TESTED DT THE LMTGLEI PREE-PUGHT TUKHEL Weight, Ib 19 , 1*^0 Wing loading, W/S, Ih/sq ft 27 - 5 ^ Relative density factor, Moments of inertia: l x, Slug-ft 2 17,580 ly, slug-ft2 119,300 I2, slug-ft^ 124,600 Ratios of radii of gyration to wing spaa: 0.1426 0.572 0.3801 Wing: Airfoil ..... Area, sq ft Span, ft Aspect ratio Root chord, ft Tip chord, ft Ifean aerodynamic chord c, ft Longitudinal distance from leading-edge of root chord to leading edge of c, ft Svreephack of leading edge, deg Sweepforward of trailing edge, deg Dihedral, deg Incidence, deg IIACA 0004-65 (modified) 695 58-134 2.09 35.628 0.801 23.72 11.96 60 5 0 0 Slats; Span, percent wing span (two) 5I.7 Chord, ft 1.36 Elevens ; Area behind hinge line, percent wing area (two) SJpan, percent wing span (two) Chord, parallel to fusel^e reference axis: Root, ft Tip, ft Basic tail = 0 . 10 ^; Airfoil section Exposed area, sq ft * Span, ft Aspect ratio .. .......... Enlarged tail If Es^osed area, sq ft Span, ft Aspect ratio ... Rudder (same for both tails) : Area, sq ft Span, ft Root chord, ft Tip chord, ft 10.12 69-0 3-15 2.04 UACA 0004-65 (modified) 68.2 8.66 1.1 118.5 11.54 1.12 10.54 5-72 2.09 1.59 MCA EM SL55B21 y Figiire 1,- The stability system of axes. Arrows indicate positive direc- tions of moments, forces, and angles. This system of axes is defined as an orthogonal system having the origin at the center of gravity and in which the Z-axis is in the plane of symmetry and peipjendiciilar to the relative -V'ri-ndj the X-axis is in the plane of symmetry and perpen- dicular to the Z-axis j and the Y-axis is perpendicular to the plane of symmetry. At a constant angle of attack, these axes are fixed in the airplane . NACA RM SL55B21 CONFIDENTIAL CONFIDENTIAL L-85596 Figure 5*- Photograph of l/lO-scale model simulating the Convair F-102A airplane tested in the Langley free-flight t\mnel. D O MCA EM SL55B21 Figure 7»- Comparison of lateral statilily cliaracteristlcs of model tested in the langley free -flight tunnel and model tested hy Convair» g HH ee -16 -8 0 8 16 24 iS.deg •24 -16 -8 0 8 16 24 ^.deg Figure 10.- Lateral characteristics of the model tested in the Langley free-fli^t tunnel. 5g = ^ = 0.l8. 16 24 -24 -16 -8 (b) ^ = 0.10, O Figure 11.- Continued. • •• Figure 11.- Concluded. 4 8 12 16 20 24 28 32 36 a, deg of the model tested in the Langley . 6 ^ = - 15 °. mCA EM SL55B21 • ••• • • • ••• »••• » •• e • • »e» e • ••• » # • «• • »••• 15 20 25 30 36 a ,deg )S Sr o 0 +20 □ 0 -20 o 2+20 ^ +2 -20 -5 +20 c, +5 .20 Q -10+20 o +10-20 0 -15 +20 o +15 -20 (a) Incremental force and moment (b) Force and moment coefficients coefficients due to aileron due to rudder deflection, deflection. 5a = ^15°- Figure l4. - Control effectiveness of the model tested in the Langley free -flight tunnel. 6e = -15° J ^ = 0.10.