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Jones, R. T.

Publications and source records attributed to Jones, R. T..

At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1976

Calculation of the motion of an airplane under the influence of irregular disturbances

The application of mathematical advances made in electricity and other branches to problems of airplane dynamics is demonstrated. The Heaviside-Bromwich methods of solution of linear differential equations are described and it is shown how these methods avoid the consideration of boundary conditions and of particular or complementary integrals. It is pointed out that if the solution of the differential equation is obtained for the case of a unit disturbance, the effect of varying disturbances may be found therefrom by Carson's theorem. A graphical solution of Carson's integral for irregular disturbances is given. The procedure of obtaining unit solutions of the equations is then taken up and the analogy between Heaviside's symbolic series solution and a physical procedure of approximation is shown. It is suggested that a fictitious impulsive disturbance be used in the treatment of initial motions.

Jones, R. T.↗
NASA NTRS1976

A simplified application of the method of operators to the calculation disturbed motions of an airplane

A simplified treatment of the application of Heaviside's operational methods to problems of airplane dynamics is given. Certain graphical methods and logarithmic formulas that lessen the amount of computation involved are explained. The problem of representing a gust disturbance or control manipulation is taken up and it is pointed out that in certain cases arbitrary control manipulations may be dealt with as though they imposed specific constraints on the airplane, thus avoiding the necessity of any integration whatever.

Jones, R. T.↗
NASA NTRS1976

The effect of lateral controls in producing motion of an airplane as computed from wind-tunnel data

An analytical study of the lateral controllability of an airplane has been made in which both the static rolling and yawing moments supplied by the controls and the reactions due to the inherent stability of the airplane have been taken into account. A hypothetical average airplane, embodying the essential characteristics of both the wind tunnel models and the full size test airplanes, was assumed for the study. Computations made of forced rolling and yawing motions of an F-22 airplane caused by a sudden deflection of the ailerons were found to agree well with actual measurements of these motions. The conditions following instantaneous full deflections of the lateral control have been studied, and some attention has been devoted to the controlling of complete turn maneuvers.

Weick, F. E.↗
NASA NTRS1976

A study of the two-control operation of an airplane

The two control operation of a conventional airplane is treated by means of the theory of disturbed motions. The consequences of this method of control are studied with regard to the stability of the airplane in its unconstrained components of motion and the movements set up during turn maneuvers. It is found that the motion of a conventional airplane is more stable when an arbitrary kinematic constraint is imposed in banking than when such constraint is imposed in yawing. Several hypothetical assumptions of piloting procedure, each of which is considered to represent a component of the actual procedure, are studied. Different means of two control operation are also discussed and it is concluded that a reliable rolling moment control that does not give the usual adverse secondary yawing moment should be most satisfactory.

Jones, R. T.↗
NASA NTRS1976

The reduction of aileron operating force by differential linkage

It is shown that the control force of ordinary ailerons may be reduced to zero over a range of deflections and at a given flight condition by the use of an appropriate differential movement. Approximations to the ideal motion obtainable with a simple linkage are discussed and a chart that enables the selection of an appropriate crank arrangement is presented. Various aspects of the practical application of the system are discussed and it is concluded that a small fixed tab, deflected to trim both ailerons upward, would be advantageous.

Jones, R. T.↗
NASA NTRS1976

Resume and analysis of NACA lateral control research

An analysis of the principal results of recent lateral control research is made. Two things are considered of primary importance in judging the effectiveness of different control devices: The (calculated) banking and yawing motion of a typical small airplane caused by a deflection of the control, and the stick force required to produce this deflection. The report includes a table in which a number of different lateral control devices are compared on these bases. Test flights demonstrated that satisfactory lateral control at high angles of attack depends as much on the retention of stability as on aileron effectiveness.

Weick, F. E.↗
NASA NTRS1976

The influence of lateral stability on disturbed motions of an airplane with special reference to the motions produced by gusts

Disturbed lateral motions have been calculated for a hypothetical small airplane with various modifications of fin area and dihedral setting. The modifications of the airplane include changes of dihedral and changes of weathercock stability. Fin area and wing dihedral were found to be of primary importance in side gusts. It was found that the rolling action of the wing with as much as 5 deg dihedral was distinctly unfavorable, especially when the weathercock stability was small. It is pointed out that the greatest susceptibility to lateral disturbances lies in the inherent damping and coupling moments developed by the wing.

Jones, R. T.↗
NASA NTRS1976

Operational treatment of the nonuniform-lift theory in airplane dynamics

The method of operators is used in the application of nonuniform lift theory to problems of airplane dynamics. The method is adapted to the determination of the lift under prescribed conditions of motion or to the determination of the motions with prescribed disturbing forces.

Jones, R. T.↗
NASA NTRS1976

Transient effects of the wing wake on the horizontal tail

The effect of wing wake on the lift of the horizontal tail surfaces was studied. In the development of expressions for this effect, the growth of wing circulation and wing wake, the time interval represented by the tail length, and the development of lift by the tail were considered. The theory has been applied to a specific case to show the magnitude of the effect to be expected. It is shown that, for motions below a certain frequency, the development of lift by the tail may be represented by a simple lag function. The lag is, however, somewhat greater than that indicated by the tail length.

Jones, R. T.↗
NASA NTRS1976

An analysis of the stability of an airplane with free controls

The conditions essential to the stability of an airplane with free control surfaces are studied. Calculations are based on typical airplane characteristics with certain factors varied to cover a range of current designs. The effects of reducing the chord and of eliminating the floating tendency of the surface, of changing the wing loading and of decreasing the radius of gyration of the airplane are indicated. An investigation has also been made of the nature of the motion of the airplane with controls free and of the modes of instability that may occur. Stability with the controls free generally depends more critically on the design of the control system than on the stability characteristics of the airplane.

Jones, R. T.↗
NASA NTRS1976

A graphical method of determining pressure distribution in two-dimensional flow

By a generalization of the Joukowski method, a procedure is developed for effecting localized modifications of airfoil shapes and for determining graphically the resultant changes in the pressure distribution. The application of the procedure to the determination of the pressure distribution over airfoils of original design is demonstrated. Formulas for the lift, the moment, and the aerodynamic center are also given.

Jones, R. T.↗
NASA NTRS1976

Theoretical correction for the lift of elliptic wings

In the wing section theory the magnitude of the circulation, and hence of the lift, is determined by the velocity that would be induced near the trailing edge of the section in a non-lifting potential flow. In three dimensional flow the problem is complicated by the presence of the wake and no simple basic solution has been found. Treatment of the problem of a wing of finite span is reported on the basis of the two dimensional theory, corrected for the effect of the wake.

Jones, R. T.↗
NASA NTRS1976

Notes on the stability and control of tailless airplanes

Problems involved in the stability and control of tailless airplanes are discussed. Such factors as the location of the aerodynamic center and its effect on the longitudinal stability, longitudinal trim with high lift devices, the effects of various changes in the shape of the wing on lateral stability, and the effects of nacelles are covered. It appears that sufficient stability and controllability can be secured without sweepback. With sweepback, a flap over the center section of the wing may be used to serve the dual purpose of elevator control and high lift device. Sweepback introduces undesirable stalling characteristics, however, and may require auxiliary devices to prevent stalling of the tips.

Jones, R. T.↗
NASA NTRS1976

Wind-tunnel investigation of control-surface characteristics. 5: The use of a beveled trailing edge to reduce the hinge moment of a control surface

Wind tunnel tests have been made to investigate the possibility of reducing the hinge moments of a control surface by beveling the trailing edge. The tests were made with a 9 percent thick airfoil having a 30 percent chord plain flap. A faired beveled shape, 5 percent of the airfoil chord in width and having a thickness of 21/2 percent of the airfoil chord, was found to give approximately 50 percent reduction in the hinge moment caused by a given deflection of the flap and 80 percent reduction in the hinge moment due to the angle of attack of this airfoil for a wide range of angles. Elliptical trailing edge shapes were also tried but were found to be somewhat less effective.

Jones, R. T.↗
NASA NTRS1976

Determination of optimum planforms for control surfaces

A theoretical analysis is made to determine the optimum chord distribution, location, and extent of control surfaces, with the ratio of hinge moment to effectiveness as the criterion. Expressions for the effectiveness - for ailerons, the rolling moment, and for tail surfaces, the change of lift on the tail due to deflection of the surface-were derived from lifting line theory. Solutions found for a range of airfoil planforms indicate that, regardless of the characteristics of the tail surface, the chord of the rudder or the elevator should be very nearly constant over its span. The optimum ailerons are also of a characteristics shape, varying little with the planform of the wing.

Jones, R. T.↗
NASA NTRS1976

Emergency measures for increasing the range of fighter airplanes

An analysis was made to show the relative effectiveness of streamline external fuel tanks, a fuel tank in the form of a wing mounted in a biplane position, and auxiliary wing panels attached at the wing tips to increase the span as temporary means for increasing the range of a fighter-type airplane. Figures and charts for the various devices considered show the results of calculations of range, duration of flight, and take-off distance for both land base and carrier operation. The results indicated that the wing tip extensions were the most promising of the devices considered.

Jones, R. T.↗
NASA NTRS1976

Effect of hinge-moment parameters on elevator stick forces in rapid maneuvers

The importance of the stick force per unit normal acceleration as a criterion of longitudinal stability and the critical dependence of this gradient on elevator hinge moment parameters are investigated with special reference to transient effects for maneuvers of short duration. The analysis shows that different combinations of elevator parameters, which give the same stick force per unit acceleration in turns, give widely different force variations during the entries into and recoveries from steady turns and during maneuvers of short duration such as abrupt pull-ups. The stick force per unit acceleration is greater for abrupt than for gradual control movements.

Jones, R. T.↗