ALBERT

Beschreibung: The effects of several wing leading-edge camber and deflected-tip modifications on the force and moment characteristics of a 1/20-scale model of the Convair F-102 airplane have been determined at Mach numbers from 0.60 t o 1.14 for angles of attack up to 14 deg. in the Langley 8-foot transonic tunnel. The effects of elevator deflections from 0 deg. to -10 deg. were also obtained for a configuration incorporating favorable leading- edge and tip modifications. Leading-edge modifications which had a small amount of constant-chord camber obtained by vertically adjusting the thickness distribution over the forward (3.9 percent of the mean aerodynamic chord) portion of the wing were ineffective in reducing the drag at lifting conditions at transonic speeds. Leading edges with relatively large cambers designed to support nearly elliptical span load distributions at lift coefficients of 0.15 and 0.22 near a Mach number of 1.0 produced substantial reductions in drag at most lift coefficients.

Beschreibung: An investigation was made of a 1/10-scale dynamically similar model of the North American F-86 airplane to study its behavior when ditched. The model was landed in calm water at the Langley tank no. 2 monorail. Various landing attitudes, speeds, and conditions of damage were simulated. The behavior of the model was determined from visual observations, acceleration records, and motion-picture records of the ditchings. Data are presented in tabular form, sequence photographs, and time-history acceleration curves. From the results of the investigation it was concluded that the airplane should be ditched at the nose-high, 14 deg attitude to avoid the violent dive which occurs at the 4 deg attitude. The flaps and leading-edge slats should be fully extended to obtain the lowest possible landing speed. The wing tanks should be jettisoned to avoid the undesirable behavior which occurs with the tanks attached. In a calm-water ditching under these conditions the airplane will run smoothly for about 600 feet. Maximum longitudinal and vertical decelerations of about 3g will be encountered.

Beschreibung: An investigation is being conducted to determine the dynamic stability and control characteristics of a 0.13-scale flying model of Convair XFY-1 vertically rising airplane. This paper presents the results of flight and force tests to determine the stability and control characteristics of the model in vertical descent and landings in still air. The tests indicated that landings, including vertical descent from altitudes representing up to 400 feet for the full-scale airplane and at rates of descent up to 15 or 20 feet per second (full scale), can be performed satisfactorily. Sustained vertical descent in still air probably will be more difficult to perform because of large random trim changes that become greater as the descent velocity is increased. A slight steady head wind or cross wind might be sufficient to eliminate the random trim changes.

Beschreibung: A supplementary investigation was conducted in the Langley 20-foot free-spinning tunnel on a 1/24-scale model of the Grumman F9F-6 airplane. The primary purpose of the investigation was to reevaluate the spin-recovery characteristics of the airplane in view of the fact that the ailerons had been eliminated from the flaperon-aileron lateral control system of the airplane. A spin-tunnel investigation on a model of the earlier version of the F9F-6 airplane had indicated that use of ailerons with the spin (stick right in a right spin) was essential to insure recovery. The results indicate that with.ailerons eliminated, it may be difficult to obtain an erect developed spin but if a fully developed spin is obtained on the airplane, recovery therefrom may be difficult or impossible. Flaperon deflection should have little effect on spins or recoveries.

Beschreibung: An experimental investigation has been conducted to determine the stability and control characteristics of a 0.13-scale free-flight model of the Convair XFY-1 airplane during take-offs and landings in steady winds. The tests indicated that take-offs in headwinds up to at least 20 knots (full scale) will be fairly easy to perform although the airplane may be blown downstream as much as 3 spans before a trim condition can be established. The distance that the airplane will be blown down-stream can be reduced by restraining the upwind landing gear until the instant of take-off. The tests also indicated that spot landings in headwinds up to at least 30 knots (full scale) and in crosswinds up to at least 20 knots (full scale) can be accomplished with reasonable accuracy although, during the landing approach, there will probably be an undesirable nosing-up tendency caused by ground effect and by the change in angle of attack resulting from vertical descent. Some form of arresting gear will probably be required to prevent the airplane from rolling downwind or tipping over after contact. This rolling and tipping can be prevented by a snubbing line attached to the tip of the upwind' wing or tail or by an arresting gear consisting of a wire mesh on the ground and hooks on the landing gear to engage the mesh.

Beschreibung: An experimental investigation has been conducted to determine the dynamic stability and control characteristics in hovering and transition flight of a 0.13-scale flying model of the Convair XFY-1 vertically rising airplane with the lower vertical tail removed. The purpose of the tests was to obtain a general indication of the behavior of a vertically rising airplane of the same general type as the XFY-1 but without a lower vertical tail in order to simplify power-off belly landings in an emergency. The model was flown satisfactorily in hovering flight and in the transition from hovering to normal unstalled forward flight (angle of attack approximately 30deg). From an angle of attack of about 30 down to the lowest angle of attack covered in the flight tests (approximately 15deg) the model became progressively more difficult to control. These control difficulties were attributed partly to a lightly damped Dutch roll oscillation and partly to the fact that the control deflections required for hovering and transition flight were too great for smooth flight at high speeds. In the low-angle-of-attack range not covered in the flight tests, force tests have indicated very low static directional stability which would probably result in poor flight characteristics. It appears, therefore, that the attainment of satisfactory directional stability, at angles of attack less than 10deg, rather than in the hovering and transition ranges of flight is the critical factor in the design of the vertical tail for such a configuration.

Beschreibung: This paper presents the results of an investigation of the dynamic stability and controllability of a model which approximately represents the Lockheed XFV-1 airplane to a 1/8 scale. The investigation consisted of hovering flights in still air at a considerable height above the ground, hovering flights very close to the ground, vertical take-offs and landings, flights through the transition range from hovering to normal forward flight, and sideways translational flights. The model could be flown smoothly and easily in hovering flight despite the fact that the uncontrolled pitching and yawing motions were unstable oscillations. There was a noticeable reduction in the controllability of the model when hovered very close to the ground but take-offs could be made easily and landings on a g,ven spot could be made accurately in spite of this adverse ground effect. Flights through the transition range from hovering to normal forward flight could be performed fairly easily. The model seemed to have stability of angle of attack and angle of roll over most of the transition range. The yawing motion was divergent in the very high angle-of-attack range but could be controlled easily. At the lower angles of attack, the model seemed to become stable in yaw. In sideways flight there was an increasingly strong tendency to diverge in roll as the speed was increased and finally, at a speed of about 25 knots (full scale), the model rolled off despite efforts of the pilot to control it.

Beschreibung: At the request of the Bureau of Aeronautics, Department of the Navy, National Advisory Committee for Aeronautics has conducted a preliminary investigation at high subsonic speeds of the static longitudinal and lateral stability characteristics of a 0.05-scale model of the Convair F2Y-1 water-based fighter airplane. The tests covered a Mach number range from 0.5 to 0.94 and corresponding Reynolds numbers, based on the wing mean aerodynamic chord, from 3.3 x 10(exp 6) to 4.3 x 10(exp 6). The maximum angle-of-attack range (obtained at the lower Mach numbers) was from -2 degrees to 25 degrees. Sideslip angles from -4 degrees to 12 degrees also were investigated. The investigation included effects of various arrangements of wing fences and of rocket packages.

Beschreibung: The static longitudinal stability characteristics of a 0.15-scale model of the Hermes A-lE2 missile have been determined in the Langley high-speed 7- by 10-foot tunnel over a Mach number range of 0.50 to 0.98, corresponding to Reynolds numbers, based on body length, of 12.3 x 10(exp 6) to 17.1 x 10(exp 6). This paper presents results obtained with body alone and body-fins combinations at 0 degrees (one set of fins vertical and the other set horizontal) and 45 degree angle of roll. The results indicate that the addition of the fins to the body insures static longitudinal stability and provides essentially linear variations of the lift and pitching moment at small angles of attack throughout the Mach number range. The slopes of the lift and pitching-moment curves vary slightly with Mach number and show only small effects due to the angle of roll.

Beschreibung: At the request of the Bureau of Aeronautics, Department of the Navy, an investigation at transonic and low supersonic speeds of the drag and longitudinal trim characteristics of the Douglas XF4D-1 airplane is being conducted by the Langley Pilotless Aircraft Research Division. The Douglas XF4D-1 is a jet-propelled, low-aspect-ratio, swept-wing, tailless, interceptor-type airplane designed to fly at low supersonic speeds. As a part of this investigation, flight tests were made using rocket- propelled 1/10- scale models to determine the effect of the addition of 10 external stores and rocket packets on the drag at low lift coefficients. In addition to these data, some qualitative values of the directional stability parameter C(sub n beta) and duct total-pressure recovery are also presented.

Beschreibung: An investigation of a vortex-generator configuration on the wings of a l/4-scale model of the X-1 airplane having a 10-percent-thick wing was conducted in the Langley 16-foot transonic tunnel. The effect of the vortex generators was determined by comparing the model aerodynamic characteristics, wing-pressure distributions, and wing-wake patterns for model configurations with and without vortex generators on the wings. Results are presented from tests at 0.1 increments in Mach number from about 0.69 to 0.99, at Reynolds numbers of about 4.1 x 10(exp 6) to 4.7 x 10(exp 6), and through an angle-of-attack range up to 1.5 deg at lower speeds and up to 5 deg at the highest speed. In general, little difference in the aerodynamic characteristics was observed, except at a Mach number of 0.90 where a rearward movement of the shock on the upper surface of the wing with the vortex generators installed resulted in less separation.

Beschreibung: An investigation of a 1/24-scale model of the Grumman F9F-6 airplane has been conducted in the Langley 20-foot free-spinning tunnel. The erect and inverted spin and recovery characteristics of the model were determined for the normal flight loading with the model in the clean condition. The effect of loading variations was investigated briefly. Spin-recovery parachute tests were also performed. The results indicate that erect spins obtained on the airplane in the clean condition will be satisfactorily terminated for all loading conditions provided full rudder reversal is accompanied by moving the ailerons and flaperons (lateral controls) to full with the spin (stick right in a right spin). Inverted spins should be satisfactorily terminated by full reversal of the rudder alone. The model tests indicate that an 11.4-foot (laid-out-flat diameter) tail parachute (drag coefficient approximately 0.73) should be effective as an emergency spin-recovery device during demonstration spins of the airplane provided the towline is attached above the horizontal stabilizer.

Beschreibung: An investigation has been conducted in the Langley 20-foot free-spinning tunnel on a l/20-scale model of the Consolidated Vultee XFY-1 airplane with a windmilling propeller simulated to determine the effects of control setting and movements upon the erect spin and recovery characteristics for a range of airplane-loading conditions. The effects on the model's spin-recovery characteristics of removing the lower vertical tail, removing the gun pods, and fixing the rudders at neutral were also investigated briefly. The investigation included determination of the size parachute required for emergency recovery from demonstration spins. The tumbling tendencies of the model were also investigated. Brief static force tests were made to determine the aerodynamic characteristics in pitch at high angles of attack. The investigation indicated that the spin and recovery characteristics of the airplane with propeller windmilling will be satisfactory for all loading conditions if recovery is attempted by full rudder reversal accompanied by simultaneous movement of the stick laterally to full with the spin (stick right in a right spin) and longitudinally to neutral. Inverted spins should be satisfactorily terminated by fully reversing the rudder followed immediately by moving the stick laterally towards the forward rudder pedal and longitudinally to neutral. Removal of the gun pods or fixing the rudders at neutral will not adversely affect the airplane's spin-recovery characteristics, but removal of the lower vertical tail will result in unsatisfactory spin-recovery characteristics. The model-test results showed that a 13.3-foot wing-tip conventional parachute (drag coefficient approximately 0.7) should be effective as an emergency spin-recovery device during demonstration spins of the airplane. It was indicated that the airplane should not tumble and that no unusual longitudinal-trim characteristics should be obtained for the center-of-gravity positions investigated.

Beschreibung: The possibility of overshooting the anticipated normal acceleration as a result of the artificial-feel characteristics of the F-89C airplane at a condition of minimum static stability was investigated analytically by means of an electronic simulator. Several methods of improving the stick-force characteristics were studied. It is shown that, due to the lag in build-up of the portion of the stick force introduced by the bobweight, it would be possible for excessive overshoots of normal acceleration to occur in abrupt maneuvers with reasonable assumed control movements. The addition of a transient stick force proportional to pitching acceleration (which leads the normal acceleration) to prevent this occurring would not be practical due to the introduction of an oscillatory mode to the stick-position response. A device to introduce a viscous damping force would Improve the stick-force characteristics so that normal acceleration overshoots would not be likely, and the variation of the maximum stick force in rapid pulse-type maneuvers with duration of the maneuver then would have a favorable trend.

Beschreibung: NACA instrumentation has been installed ii the X-J4 airplanes to obtain stability and control data during the acceptance tests conducted by the Northrop Aircraft Corporation. This report presents data obtained on the stalling characteristics of the airplane in the clean and gear- down configurations. The center of gravity was located at approximately 18 percent of the mean aerodynamic chord during the tests. The results indicated that the airplane was not completely stalled when stall was gradually approached during nominally U accelerated flight but that it was completely stalled during a more abruptly approached stall in accelerated flight. The stall in accelerated flight was relatively mild, and this was attributed to the nature of the variation of lift with angle of attack for the 001-614 airfoil section, the plan form of the wing, and to the fact that the initial sideslip at the stall produced (as shown by wind-tunnel tests of a model of the airplane) a more symmetrical stall pattern.

Beschreibung: This report presents the results of wind-tunnel force tests which were conducted to determine the low-speed stability and control characteristics of a full-scale Northrop XSSM-A-3 missile. Tests were made through a range of angles of attack, sideslip, and control deflection, and at various Reynolds numbers. Characteristics of the complete missile are compared with the characteristics of the missile with the landing skids extended, with the vertical tail removed, and with the fuselage alone. No analysis of the data has been made in order to make the results available as soon as possible.

Beschreibung: A theoretical investigation has been made to determine the effect on the lateral stability of the Douglas D-58-II airplane of an autopilot sensitive to yawing velocity. The effects of inclination of the gyro spin axis to the flight path and of tire lag in the autopilot were also determined. The flight conditions investigated included landing at sea level, approach condition at 12,000 feet, and cruising at 50,000 feet at Mach numbers of 0.80 and 1.2. The results of the investigation indicated that the lateral stability characteristics of the D-558-II airplane for the flight condition discussed should satisfy the Air Force - Navy period-damping criterion when the proposed autopilot is installed. Airplane motions in sideslip subsequent to a disturbance in sideslip are presented for several representative flight conditions in which a time lag in the autopilot of 0.10 second was assumed.

Beschreibung: The investigation of the lateral stability of an automatically controlled glide bomb led also to the attempt of clarifying the influence of a phugoid oscillation or of any general longitudinal oscillation on the lateral stability of a glide bomb. Under the assumption that its period of oscillation considerably exceeds the rolling and yawing oscillation and that c(sub a) is, at least in sections, practically constant, the result of this test is quite simple. It becomes clear that the influence of the phugoid oscillation may be replaced by suitable variation of the rolling-yawing moment on a rectilinear flight path instead of the phugoid oscillation. If the flying weight of the glide bomb of unchanged dimensions is increased, an increase of the flight velocity will be more favorable than an increase of the lift coefficient. The arrangement of the control permits lateral stability to be achieved in every case; a minimum rolling moment due to sideslip proves of great help.

Beschreibung: An investigation of the longitudinal stability and of the all-movable horizontal tail and aileron control of a 1/80-scale reflection-plane model of the Consolidated Vultee Skate 9 seaplane has been made through a Mach number range of 0.6 to 1.16 on the transonic bump of the Langley high-speed 7- by 10-foot tunnel. At moderate lift coefficients (0.4 to 0.8) and below a Mach number of 1.0 the model was statically unstable longitudinally. The static longitudinal stability of the model at low lift coefficients increased with Mach number corresponding to a shift in aerodynamic center from 37 percent mean aerodynamic chord at a Mach number of 0.60 to 64 percent at a Mach number of 1.10. Estimates indicate that the tail deflection angle required for steady flight and for accelerated maneuvers of the Skate 9 airplane would probably not vary greatly with Mach number at sea level, but for accelerated maneuvers at altitude the tail deflection angle would probably vary erratically with Mach number. The variation of rolling-moment coefficient with aileron deflection angle was approximately linear, agreed well with theory, and held for the range of aileron deflections tested (-17.1 deg to 16.6 deg). At low lift coefficients the drag rise occurred at Mach numbers of 0.95 and 0.90 for the wing alone and the complete model, respectively. The effects of the canopy on the model were small. For the ranges investigated, angle-of-attack and Mach number changes caused no large pressure drops in the jet-engine duct.

Beschreibung: A model of the Convair Y2-2 airplane was tested in Langley tank no. 2 to determine whether satisfactory stability in yawed landings was possible with a certain ventral fin. Free-body landings were made in smooth and rough water at two speeds and two rates of descent with the model yawed 15deg. The behavior of the model was determined by visual observations and from motion-picture re.cords. It was concluded that satisfactory stability was possible with the ventral fin as tested but that the characteristics of the model shock absorbers and the settings of the elevon control surfaces had an appreciable influence on behavior.

Beschreibung: The data obtained from the flight of a simplified (dummy) rocket-propelled model of the MX-656 have been analyzed to determine the booster-model characteristics and the model-alone characteristics up to a Mach number of 1.3. The data indicate that the model-booster combination is satisfactory. The model alone is longitudinally stable i n the Mach number range covered by the test (0.9 to 1.3) with the center of gravity at -15 percent of the mean aerodynamic chord. With the stabilizer setting at 0 deg. the variation of normal-force coefficient with Mach number is not large. The total-drag-coefficient variation with Mach number is not unusual. About 12 percent of the total drag at a Mach number of 1.3 can be attributed to body base drag.