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Results for “DIRECTIONAL STABILITY”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS1952

Summary of Low-Lift Drag and Directional Stability Data from Rocket Models of the Douglas XF4D-1 Airplane with and without External Stores and Rocket Packets at Mach Numbers from 0.8 to 1.38 TED No. NACA DE-349

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.

Mitcham, Grady L.↗
NASA NTRS1961

Investigation at High Subsonic Speeds of the Use of Low Auxiliary Tail Surfaces having Dihedral to Improve the Longitudinal and Directional Stability of a T-Tail Model at High Lift

An investigation of the use of low auxiliary horizontal-tail surfaces to alleviate the pitch-up tendency at high lift of an airplane configuration having a T - tail has been conducted in the Langley high-speed 7- by 10-foot tunnel. The basic model had a wing with an aspect ratio of 3, a taper ratio of 0.143, and an unswept 80-percent chord line. The Mach number for most of the tests extended from 0.60 to 0.94 and the angle-of-attack range was from -2 deg. to approximately 24 deg. at the lowest test Mach number. A preliminary study of a systematic series of auxiliary tails indicated that the pitch-up tendency at high lift encountered on the basic model could be greatly alleviated by use of a relatively small, very low-aspect-ratio auxiliary horizontal tail. This tail was located radially with respect to the fuselage center line with 30 deg. negative dihedral and therefore provided a significant favorable increment to directional stability of the model throughout most of the test angle-of-attack range.

Sleeman, William C., Jr.↗
NASA NTRS1959

Dynamic Longitudinal and Directional Stability Derivatives for a 45 deg. Sweptback-Wing Airplane Model at Transonic Speeds

An investigation was made at transonic speeds to determine some of the dynamic stability derivatives of a 45 deg. sweptback-wing airplane model. The model was sting mounted and was rigidly forced to perform a single-degree-of-freedom angular oscillation in pitch or yaw of +/- 2 deg. The investigation was made for angles of attack alpha, from -4 deg. to 14 deg. throughout most of the transonic speed range for values of reduced-frequency parameter from 0.015 to 0.040 based on wing mean aerodynamic chord and from 0.04 to 0.14 based on wing span. The results show that reduced frequency had only a small effect on the damping-in-pitch derivative and the oscillatory longitudinal stability derivative for all Mach numbers M and angles of attack with the exception of the values of damping coefficient near M = 1.03 and alpha = 8 deg. to 14 deg. In this region, the damping coefficient changed rapidly with reduced frequency and negative values of damping coefficient were measured at low values of reduced frequency. This abrupt variation of pitch damping with reduced frequency was a characteristic of the complete model or wing-body-vertical-tail combination. The damping-in-pitch derivative varied considerably with alpha and M for the horizontal-tail-on and horizontal-tail-off configurations, and the damping was relatively high at angles of attack corresponding to the onset of pitch-up for both configurations. The damping-in-yaw derivative was generally independent of reduced frequency and M at alpha = -4 deg. to 4 deg. At alpha = 8 deg. to 14 deg., the damping derivative increased with an increase in reduced frequency and alpha for the configurations having the wing, whereas the damping derivative was either independent of or decreased with increase in reduced frequency for the configuration without the wing. The oscillatory directional stability derivative for all configurations generally decreased with an increase in the reduced-frequency parameter, and, in some instances, unstable values were measured for the model configuration with the horizontal tail removed.

Bielat, Ralph P.↗
NASA NTRS1977

Entry dynamics of space shuttle orbiter with lateral-directional stability and control uncertainties at supersonic and hypersonic speeds

A six-degree-of-freedom simulation analysis was conducted to examine the effects of the lateral-directional static aerodynamic stability and control uncertainties on the performance of the automatic (no manual inputs) entry-guidance and control systems of the space shuttle orbiter. To establish the acceptable boundaries of the uncertainties, the static aerodynamic characteristics were varied either by applying a multiplier to the aerodynamic parameter or by adding an increment. Control-system modifications were identified that decrease the sensitivity to off-nominal aerodynamics. With these modifications, the acceptable aerodynamic boundaries were determined.

Stone, H. W.↗
NASA NTRS1992

Thrust vectoring for lateral-directional stability

The advantages and disadvantages of using thrust vectoring for lateral-directional control and the effects of reducing the tail size of a single-engine aircraft were investigated. The aerodynamic characteristics of the F-16 aircraft were generated by using the Aerodynamic Preliminary Analysis System II panel code. The resulting lateral-directional linear perturbation analysis of a modified F-16 aircraft with various tail sizes and yaw vectoring was performed at several speeds and altitudes to determine the stability and control trends for the aircraft compared to these trends for a baseline aircraft. A study of the paddle-type turning vane thrust vectoring control system as used on the National Aeronautics and Space Administration F/A-18 High Alpha Research Vehicle is also presented.

Peron, Lee R.↗
NASA NTRS1955

Charts for Estimating Tail-rotor Contribution to Helicopter Directional Stability and Control in Low-Speed Flight

Theoretically derived charts and equations are presented by which tail-rotor design studies of directional trim and control response at low forward speed can be conveniently made. The charts can also be used to obtain the main-rotor stability derivatives of thrust with respect to collective pitch and angle of attack at low forward speeds. The use of the charts and equations for tail-rotor design studies is illustrated. Comparisons between theoretical and experimental results are presented. The charts indicate, and flight tests confirm, that the region of vortex roughness which is familiar for the main rotor is also encountered by the tail rotor and that prolonged operation at the corresponding flight conditions would be difficult.

Amer, Kenneth B↗
NASA NTRS1986

Low-speed wind-tunnel investigation of the effect of strakes and nose machines on lateral-directional stability of a fighter configuration

A series of low-speed static wind-tunnel force tests were conducted on a 0.15-scale model of a modern high-performance fighter aircraft. The tests identified the use of nose chines to enhance stability at high angles of attack. Results of this investigation showed that the strake was the major contributor to directional instability. The destabilizing forces were created by two mechanisms: (1) adverse flow in the region of the vertical tail, and (2) forces generated on the fuselage ahead of the center of gravity. Properly designed nose chines effectively negated the adverse flow near the vertical tail and created stabilizing forces on the forebody in the range of the stall angle of attack.

Brandon, J. M.↗
NASA NTRS1985

VORSTAB: A computer program for calculating lateral-directional stability derivatives with vortex flow effect

A computer program based on the Quasi-Vortex-Lattice Method of Lan is presented for calculating longitudinal and lateral-directional aerodynamic characteristics of nonplanar wing-body combination. The method is based on the assumption of inviscid subsonic flow. Both attached and vortex-separated flows are treated. For the vortex-separated flow, the calculation is based on the method of suction analogy. The effect of vortex breakdown is accounted for by an empirical method. A summary of the theoretical method, program capabilities, input format, output variables and program job control set-up are described. Three test cases are presented as guides for potential users of the code.

Lan, C. Edward↗