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At least 37 records · Page 2

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↗

Explicit determination of lateral-directional stability and control derivatives by simutaneous time vector analysis of two maneuvers

An extension of the time vector technique for determining stability and control derivatives from flight data is formulated. The technique provides for explicit determination of derivatives by means of simultaneous analysis of two maneuvers which differ by a dependent control input. The control derivatives for the dependent input are also explicitly determined. This extended technique is preferable to the application of the time vector method to single maneuvers in that no estimates of derivatives are required. An example illustrating the application of the technique is given.

Gilyard, G. B.↗

Wind-tunnel investigation of longitudinal and lateral-directional stability and control characteristics of a 0.237-scale model of a remotely piloted research vehicle with a thick, high-aspect-ratio supercritical wing

A 0.237-scale model of a remotely piloted research vehicle equipped with a thick, high-aspect-ratio supercritical wing was tested in the Langley 8-foot transonic tunnel to provide experimental data for a prediction of the static stability and control characteristics of the research vehicle as well as to provide an estimate of vehicle flight characteristics for a computer simulation program used in the planning and execution of specific flight-research mission. Data were obtained at a Reynolds number of 16.5 x 10 to the 6th power per meter for Mach numbers up to 0.92. The results indicate regions of longitudinal instability; however, an adequate margin of longitudinal stability exists at a selected cruise condition. Satisfactory effectiveness of pitch, roll, and yaw control was also demonstrated.

Byrdsong, T. A.↗

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.↗

Space shuttle: Directional and lateral stability and interference effects of cruise engine location on a 0.015 scale space shuttle

The results are presented that were obtained from a wind tunnel tests to improve space shuttle booster baseline lateral-directional stability, control characteristics, and cruise engine location optimization. Tests were conducted in a 7 x 10-foot transonic wind tunnel. The model employed was a 0.015-scale replica of a space shuttle booster. The three major objectives of this test were to determine the following: (1) force, static stability, and control effectiveness characteristics for varying angles of positive and negative wing dihedral and various combinations of wing tip and centerline dorsal fins; (2) force and static stability characteristics of cruise engines location on the body below the high aerodynamic canard; and (3) control effectiveness for the low-mounted wing configuration. The wing dihedral study was conducted at a cruise Mach number of 0.40 and simulated altitude of 10,000 feet. Portions of the test were conducted to determine the control surfaces stability and control characteristics over the Mach number range of 0.4 to 1.2. The aerodynamic characteristics determined are based on a unit Reynolds number of approximately 2 million per foot. Boundary layer trip strips were employed to induce boundary layer transition.

Buchholz, R. E.↗

Wind-Tunnel Investigation at Subsonic and Supersonic Speeds of a Fighter Model Employing a Low-aspect-ratio Unswept Wing and a Horizontal Tail Mounted Well above the Wing Plane - Lateral and Directional Stability

The static lateral- and directional-stability characteristics of a high-speed fighter-type airplane, obtained from wind-tunnel tests of a model, are presented. The model consisted of a thin, unswept wing of aspect ratio 2.3 and taper ratio 0.385, a body, and a horizontal tail mounted in a high position on a vertical tail. Rolling-moment, yawing moment, and cross-wind-force coefficients are presented for a range of sideslip angles of -5 deg. to +5 deg, for Mach numbers of 0.90, 1.45, and 1.90. Data are presented which show the effects on the lateral and directional stability of: (1) component parts of the complete model, (2) modification of the empennage so as to provide different heights of the horizontal tail above the wing plane, (3) angle of attack, and (4) dihedral of the wing.

Wetzel, Benton E.↗

Hypersonic lateral and directional stability characteristics of aeroassist flight experiment configuration in air and CF4

Hypersonic lateral and directional stability characteristics measured on a 60 deg half-angle elliptical cone, which was raked at an angle of 73 deg from the cone centerline and with an ellipsoid nose (ellipticity equal to 2.0 in the symmetry plane), are presented for angles of attack from -10 to 10 deg. The high normal-shock density ratio of a real gas was simulated by tests at a Mach number of 6 in air and CF4 (density ratio equal to 5.25 and 12.0, respectively). Tests were conducted in air at Mach 6 and 10 and in CF4 at Mach 6 to examine the effects of Mach number, Reynolds number, and normal-shock density ratio. Changes in Mach number from 6 to 10 in air or in Reynolds number by a factor of 4 at Mach 6 had a negligible effect on lateral and directional stability characteristics. Variations in normal-shock density ratio had a measurable effect on lateral and directional aerodynamic coefficients, but no significant effect on lateral and directional stability characteristics. Tests in air and CF4 indicated that the configuration was laterally and directionally stable through the test range of angle of attack.

Micol, John R.↗

Flight Measurements of Lateral and Directional Stability and Control Characteristics of the Grumman F8F-1 Airplane

This paper presents the results of flight tests to determine the lateral and directional stability and control characteristics of the Grumman F8F-1 airplane with three vertical-tail configurations. The data presented herein have no bearing on the performance characteristics of the airplane, which were not measured but which were considered to be exceptionally good. The conclusions reached regarding the lateral and directional stability and control characteristics may be summarized as follows: 1. It was found that the directional stability was poor with the production vertical tail. Addition of a 12-inch extension to the vertical fin and rudder produced a desirable improvement in directional stability and control characteristics. However, further enlargement of the vertical tail would be required to make the directional stability satisfactory in all respects. 2. There was a tendency for the rudder control force to overbalance at large angles of right sideslip with the modified vertical tails. There was no such tendency with the production tail configuration which included a dorsal fin. It was concluded that the dorsal fin should have been retained on the modified vertical tails. 3. The aileron control characteristics were better than those of many comparable airplanes which have been tested. However, the ailerons did not satisfy the Navy requirements for satisfactory flying qualities with regard to either control forces or rolling effectiveness. 4. The power of the rudder trimming tab proved to be inadequate and the tab should be enlarged and/or be provided with an increased deflection range.

Crane, H. L.↗

Locally linearized longitudinal and lateral-directional aerodynamic stability and control derivaties for the X-29A aircraft

The locally linearized longitudinal and lateral-directional aerodynamic stability and control derivatives for the X-29A aircraft were calculated for altitudes ranging from sea level to 50,000 ft, Mach numbers from 0.2 to 1.5, and angles of attack from -5 deg to 25 deg. Several other parameters were also calculated, including aerodynamic force and moment coefficients, control face position, normal acceleration, static margin, and reference angle of attack.

Budd, G. D.↗

Lateral and Directional Stability and Control Characteristics of a C-54D Airplane

Data are presented showing compliance of C-54D with Army and Navy lateral and directional stability and control specifications. The airplane met requirements except for the rolling effectiveness pb/2V, the aileron forces in rolling, and the rudder forces in the asymmetric power conditions which were marginal. Also, the results of special tests concerning asymmetric power, asymmetric loading, and pitch due to yaw requested by the Airplane Handling Qualities Subcommittee of the Air Transport Association are presented.

AIRPLANES - SPECIFIC TYPES↗

Measurement of Flying Qualities of a Dehavilland Mosquito F-8 Airplane (AAF No. 43-334960) I: Lateral and Directional Stability and Control Characteristics

The data presented have no bearing on performance characteristics of airplane, which were considered exceptionally good in previous tests. Some of the undesirable features of lateral and directional stability and control characteristics of the F-8 are listed. Directional stability, with rudder fixed, did not sufficiently restrict aileron yaw; rudder control was inadequate during take-off and landing, and was insufficient to fly airplane with one engine; in clean condition, power of ailerons was slightly below minimum value specified; it was difficult to trim airplane in rough air.

Gray, W.E.↗