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At least 55 records · Page 3

The Use of the Rolled-up Vortex Concept for Predicting Wing-tail Interference and Comparison with Experiment at Mach Number of 1.62 for a Series of Missile Configurations Having Tandem Cruciform Lifting Surfaces

The method for predicting wing- tail interference whereby the trailing vortex system behind lifting wings is replaced by fully rolled-up vortices has been applied to the calculation of tail efficiency parameters, lift characteristics, and center -of-pressure locations for a series of generalized missile configurations. The calculations have been carried out with assumed and experimental vortex locations, and comparisons made with experimental data. The measured spanwise locations of the vortices for the inline case were found to be in good agreement with the asymptotic values computed from the center of gravity of the vorticity using the method of Lagerstrom and Graham. For the interdigitated configurations the measured spanwise locations were in only fair agreement with the asymptotic locations computed for the inline case. The vertical displacement of the vortices with angle of attack for both inline and interdigitated configurations was small. The method utilizing the rolled -up vortex concept was shown to give good results in the prediction of tail efficiency variations with angle of attack for inline configurations. Not as good correlation with experiment was shown for the interdigitated configurations. Complete configuration lift -curve slopes and center -of-pressure locations, obtained using t ail efficiency calculations together with the characteristics of the components obtained from available theoretical methods, showed excellent correlation with experimental results.

Grigsby, Carl E↗

Aerodynamic Characteristics of Missile Configurations with Wings of Low Aspect Ratio for Various Combinations of Forebodies, Afterbodies, and Nose Shapes for Combined Angles of Attack and Sideslip at a Mach Number of 2.01

An investigation has been made in the Langley 4-by-4-foot supersonic pressure tunnel to determine the aerodynamic characteristics of a series of missile configurations having low-aspect-ratio wings at a Mach number of 2.01. The effects of wing plan form and size, length-diameter ratio, forebody and afterbody length, boattailed and flared afterbodies, and component force and moment data are presented for combined angles of attack and sideslip to about 28 degrees. No analysis of the data was made in this report.

Robinson, Ross B↗

Aerodynamic characteristics of missile configurations based on Soviet design concepts

The aerodynamic characteristics of several missile concepts are examined. The configurations, which are based on some typical Soviet design concepts, include fixed-wing missiles with either forward- or aft-tail controls, and wing-control missiles with fixed aft stabilizing surfaces. The conceptual missions include air-to-air, surface-to-air, air-to-surface, and surface-to-surface. Analytical and experimental results indicate that through the proper shaping and location of components, and through the exploitation of local flow fields, the concepts provide generally good stability characteristics, high control effectiveness, and low control hinge moments. In addition, in the case of some cruise-type missions, there are indications of the application of area ruling as a means of improving the aerodynamic efficiency. In general, a point-design philosophy is indicated whereby a particular configuration is developed for performing a particular mission.

Spearman, M. L.↗

Aerodynamic characteristics of a series of airbreathing missile configurations

Due to the interest in the application of airbreathing propulsion to missiles and the lack of a suitable data base, an experimental program has been conducted to contribute to such a data base. The configurations investigated were with twin-inlets, either two-dimensional or axisymmetric, each located at three circumferential locations. The effects of a wing located above the inlets and of tail configuration were investigated. Longitudinal stability and control and lateral-directional stability were included in the data obtained. This paper presents a summary of the program and some of the results obtained. Certain trends of the data, as well as problem areas, are discussed. Due to the large volume of data obtained, a detailed analysis is not presented.

Hayes, C.↗

Aerodynamic characteristics of a series of airbreathing missile configurations

The results of an experimental program conducted in order to compile a data base useful in the application of airbreathing propulsion to missiles are presented. The configurations investigated used two-dimensional or axisymmetric twin inlets located at three alternative circumferential positions: 90, 115 and 135 deg to the vertical centerline. The effects of a wing located above the inlets and of various tail configurations were investigated, with a view to longitudinal stability/control and lateral-directional stability characteristics. It is noted that of the three tail configurations tested, the 'X' tail showed (1) the most linear pitch-moment curve, (2) control effectiveness, and (3) positive lateral-directional stability.

Hayes, C.↗

Flight Investigation of a Roll-stabilized Missile Configuration at Varying Angles of Attack at Mach Numbers Between 0.8 and 1.79

A missile research model was flown at supersonic speed to determine the quality of automatic roll stabilization at varying angles of attack. Aerodynamic rolling and pitching derivatives were determined from the flight record. It was concluded that the combination of the gyro-actuated automatic pilot with wing-tip ailerons provided adequate roll stabilization under conditions encountered in flight.

INSTRUMENTS↗

Force, Surface Pressure and Flowfield Measurements on Slender Missile Configurations at Supersonic Speeds

This paper describes a series of wind tunnel experiments carried out with the aim of providing data suitable for evaluating the performance of Computational Fluid Dynamics (CFD) codes. The configurations and flow conditions studied are most relevant to slender supersonic missiles. However, the data obtained, which includes forces and moments, surface pressures, flowfield surveys and a selection of flow visualization images, should he of interest to other CFD practitioners. Results for three test cases are presented and discussed in this paper. These cases have been the subject of a collaborative study concerned with the evaluation of Navier-Stokes solvers for missiles, carried out under the auspices of The Technical Cooperation Programme (TTCP).

Birch, T. J.↗

Stability and control characteristics of a monoplanar missile configuration with triform-tail-fin arrangements at Mach numbers from 1.70 to 2.86

A wind-tunnel missile model with either a lower vertical tail fin with a pair of horizontal fins having 0 deg, 22.5 deg, or 30 deg dihedral or an upper vertical tail fin with horizontal fins having 0 deg, -22.5 deg, or -30 deg dihedral was investigated. The results indicated that those configurations with horizontal fins at or below the horizontal plane had nearly linear pitching-moment characteristics, while those with the horizontal fins above the horizontal plane experienced pitch-up which increased with increasing horizontal-fin-dihedral angle. At zero angle of attack, the configurations were directionally stable at most test Mach numbers. Generally, those configurations with the upper vertical fin had positive effective dihedral at zero angle of attack, while those with he lower vertical fin had negative effective dihedral. For roll control, three deflected tail fins produced more total roll control than two horizontal fins. For yaw control, three tail fins deflected equally or differentially produced more total yaw control than the single vertical fin.

Lamb, M.↗

Prediction of unsteady transonic flow around missile configurations

This paper describes the preliminary development of a method for predicting the unsteady transonic flow around missiles at transonic and supersonic speeds, with the final goal of developing a computer code for use in aeroelastic calculations or during maneuvers. The basic equations derived for this method are an extension of those derived by Klopfer and Nixon (1989) for steady flow and are a subset of the Euler equations. In this approach, the five Euler equations are reduced to an equation similar to the three-dimensional unsteady potential equation, and a two-dimensional Poisson equation. In addition, one of the equations in this method is almost identical to the potential equation for which there are well tested computer codes, allowing the development of a prediction method based in part on proved technology.

Nixon, D.↗

Control characteristics for wrap-around fins on cruise missiles configurations

This paper presents selected results of a panel loads study conducted as part of the final phase of an extensive investigation of an air-breathing missile concept employing wrap-around aerodynamic surfaces. Typical results for M = 2.36 are presented for the fin load results, plus a brief review of basic results of the previously reported tests. Vapor screen results are also discussed. The present results indicate that the fin load characteristics are nearly identical for planar and curved fins having the same projected planform and would permit the use of planar-surface predictions for supersonic speeds in the preliminary design stages of missiles employing wrap-around curved fins.

Sawyer, W. C.↗

Stability and control characteristics of a monoplannar missile configuration with two low-profile tail arrangements at Mach numbers from 1.70 to 2.86

An experimental wind tunnel investigation has been made to determine the longitudinal and lateral aerodynamic stability and control characteristics of two tail fin arrangements of a monowing missile model. Both a conventional cruciform and a low profile tail arrangement were tested. The results indicate that the tail surfaces of both configurations were effective in producing pitch control. It was also concluded that both are effective in producing roll and yaw control that is accompanied by proverse yaw and roll, respectively. The conventional cruciform tail produces the most roll and yaw control.

Blair, A. B., Jr.↗

Summary of Rocket-Model Tests at Zero Lift of the Northrop MX-775B Missile Configuration from Mach Numbers of 0.9 to 1.8

Flight tests were conducted between Mach numbers of 0.9 and 1.8 over a Reynolds number range of 9(exp 6) to 30(exp 6) to determine the zero-lift drag and some rolling-effectiveness characteristics of the Northrop MX -775B missile with small and large body. The MX-775B is a proposed long range, supersonic, ground-to-ground missile having an arrow wing with 67.5 degree leading-edge sweep, 15 deg trailing-edge sweep, and a modified NACA 0004 airfoil section. The configuration has no horizontal tail but has wing trailing-edge elevons which serve a dual purpose as elevators and ailerons. The ratio of body frontal area to wing plan-form area is 0.0127 for the small-body configuration and 0.0330 for the large-body configuration. Five 1/4-scale models were flown permitting determination of the drag coefficient for the basic small-body configuration, the incremental drag due to the large body, the incremental drag resulting from a blunt wing trailing edge, the wing-plus-interference drag, and some rolling-effectiveness data. Results indicated that the MX-775B has low supersonic zero-lift drag, the maximum zero-lift drag coefficients being respectively 0.0125 and 0.0155 at a Mach number of M = 1803 for the small- and large-body configurations. The effect of a blunt wing trailing edge, obtained by cutting off 10 percent of the wing chord, was to increase the zero-lift drag by 13 to 21 percent. Wing-plus-interference drag accounted for 78 percent of the total drag at M = 0.9 and 70 percent at M = 195 for the small-body configuration. The ailerons produced positive rolling effectiveness for the wing stiffness of the test models and the dynamic pressures of the test.

Arbic, Richard G.↗