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Free Oscillations of an Atmosphere in Which Temperature Increases Linearly With Height

Description: Note presenting the concept that when the temperature in the atmosphere increases linearly with height, the speed of propagation of long waves does not approach a limit with increasing wave length, as in the case of an atmosphere in which the temperature at great heights is assumed to be constant or decreasing, but increases linearly with the period.
Date: October 1950
Creator: Pekeris, C. L.
Partner: UNT Libraries Government Documents Department

Stability of Systems Containing a Heat Source - The Rayleigh Criterion

Description: "The stability of systems containing a heat source is examined from the energy point of view. Rayleigh's criterion is derived. In the case of a flame, it is found that Rayleigh's criterion must be modified slightly if the specific-heat ratios of the burned and unburned gases are different" (p. 1).
Date: June 26, 1956
Creator: Chu, Boa-Teh
Partner: UNT Libraries Government Documents Department

Laminar-boundary-layer oscillations and transition on a flat plate

Description: Report presenting an investigation of oscillations in the laminar boundary layer on a flat plate and their relation to transition to turbulent flow. The characteristics of boundary-layer oscillations were studied most successfully when the oscillations were artificially produced by a vibrating ribbon placed in the boundary layer near the surface. A review of theory regarding laminar-boundary-layer oscillations is provided.
Date: April 1943
Creator: Schubauer, G. B. & Skramstad, H. K.
Partner: UNT Libraries Government Documents Department

On the Kernel function of the integral equation relating the lift and downwash distributions of oscillating finite wings in subsonic flow

Description: This report treats the Kernel function of an integral equation that relates a known prescribed downwash distribution to an unknown lift distribution for a harmonically oscillating finite wing in compressible subsonic flow. The Kernel function is reduced to a form that can be accurately evaluated by separating the Kernel function into two parts: a part in which the singularities are isolated and analytically expressed and a nonsingular part which may be tabulated. The form of the Kernel function for the sonic case (Mach number 1) is treated separately. In addition, results for the special cases of Mach number of 0 (incompressible case) and frequency of 0 (steady case) are given. The derivation of the integral equation which involves this Kernel function is reproduced as an appendix. Another appendix gives the reduction of the form of the Kernel function obtained herein for the three-dimensional case to a known result of Possio for two-dimensional flow. A third appendix contains some remarks on the evaluation of the Kernel function, and a fourth appendix presents an alternate form of expression for the Kernel function.
Date: 1955
Creator: Watkins, Charles E.; Runyan, Harry L. & Woolston, Donald S.
Partner: UNT Libraries Government Documents Department

Calculated lateral frequency response and lateral oscillatory characteristics for several high-speed airplanes in various flight conditions

Description: From Summary: "Calculations have been made to determine the effects of Mach number and altitude on the lateral frequency response, the lateral response to a lateral sinusoidal gust distribution, and the period and damping of the lateral oscillation for the North American F-86A, Grumman F9F-2, Republic F-84, Douglas D-558-II, and Bell X-1 airplanes without autopilots. Aeroelastic and unsteady lift effects have not been included in the calculations and may have a large effect on the results for certain flight conditions. The results of the investigation are presented, without analysis, for reference purposes."
Date: December 10, 1953
Creator: Jaquet, Byron M.
Partner: UNT Libraries Government Documents Department

Effect of ram-jet pressure pulsations on supersonic-diffuser performance

Description: Experimental study of effects of combustion roughness and controlled mechanical oscillations on diffuser operation was conducted on an 8-inch ram jet at Mach number 1.87. Within experimental accuracy, the optimum mean combustion-chamber static pressure occurred when the maximum instantaneous static pressure equalled the optimum steady-flow value and the corresponding decrement in optimum mean static pressure was equal to one-half the total amplitude of the pressure pulsations. A marked attenuation of amplitude of cold-buzz pressure fluctuations was effected over limited range of subcritical diffuser operation by means of properly tuned rotating disk located in combustion chamber.
Date: November 20, 1950
Creator: Connors, James F.
Partner: UNT Libraries Government Documents Department

Experimental investigation of the effect of an oscillating airstream (Katzmayr effect) on the characteristics of airfoils

Description: A series of experiments were conducted related to the action of an airstream oscillating vertically on supporting surfaces. The object of the experiments was to verify the very interesting results of Mr. Katzmayr, Director of the Vienna Aerodynamics Laboratory, and, if possible, to obtain more complete data on the effect of the amplitude and velocity of the oscillations of the airstream. The results obtained by Mr. Katzmayr are briefly summarized. The conduct of the numerous experiments to verify his results are described in detail. Experimental results are given in tabular and graphical form.
Date: September 1924
Creator: Toussaint; Kerneis & Girault
Partner: UNT Libraries Government Documents Department

Single-degree-of-freedom-flutter calculations for a wing in subsonic potential flow and comparison with an experiment

Description: The effect of Mach number and structural damping on single-degree-of-freedom pitching of a wing is presented. Some experimental results are compared with theory and good agreement is found for certain ranges of an inertia parameter.
Date: 1952
Creator: Runyan, Harry L.
Partner: UNT Libraries Government Documents Department

Theoretical analysis of oscillations of a towed cable

Description: Report presenting a theoretical study of the oscillations of a towed cable, which indicated that oscillations traveling downwind along the cable are amplified by aerodynamic forces when the airspeed is greater than the speed of propagation of waves along the cable. The theory provides a possible explanation for the violent motions of towed airspeed heads which appear above a certain speed.
Date: 1949
Creator: Phillips, William H.
Partner: UNT Libraries Government Documents Department

Effects of blade plan form on free-space oscillating pressures near propellers at flight Mach numbers to 0.72

Description: Report presenting a series of measurements made on the oscillating pressures near a tapered-blade-plan-form propeller at flight Mach numbers up to 0.72. Flight Mach number, power, and engine speed were controlled in an attempt to duplicate the conditions of a previous flight investigation. Results regarding effects of flight Mach number, effect of engine speed, and effects of engine power are provided.
Date: August 1957
Creator: Kurbjun, Max C.
Partner: UNT Libraries Government Documents Department

Measurement of aerodynamic forces for various mean angles of attack on an airfoil oscillating in pitch and on two finite-span wings oscillating in bending with emphasis on damping in the stall

Description: "The oscillating air forces on a two-dimensional wing oscillating in pitch about the midchord have been measured at various mean angles of attack and at Mach numbers of 0.35 and 0.7. The magnitudes of normal-force and pitching-moment coefficients were much higher at high angles of attack than at low angles of attack for some conditions. Large regions of negative damping in pitch were found, and it was shown that the effect of increasing the Mach number 0.35 to 0.7 was to decrease the initial angle of attack at which negative damping occurred" (p. 521).
Date: January 21, 1956
Creator: Rainey, A. Gerald
Partner: UNT Libraries Government Documents Department

Measurement of aerodynamic forces for various mean angles of attack on an airfoil oscillating in pitch and on two finite-span wings oscillating in bending with emphasis on damping in the stall

Description: Report presenting measurements of the oscillating air forces on a two-dimensional wing oscillating in pitch about the midchord that have been measured at various mean angles of attack and at two different Mach numbers. The magnitudes of normal-force and pitching-moment coefficients were found to be much higher at large angles of attack than at low angles of attack for some conditions. Results regarding the effects at low angles of attack, high angles of attack, and a description of finite-span wings oscillating in first bending mode are provided.
Date: May 1956
Creator: Rainey, A. Gerald
Partner: UNT Libraries Government Documents Department

Velocity potential and air forces associated with a triangular wing in supersonic flow, with subsonic leading edges, and deforming harmonically according to a general quadratic equation

Description: Report presenting the velocity potential for a triangular wing with subsonic leading edges experiencing harmonic deformations in supersonic flow. The oscillations considered are such that the amplitude of wing distortion can be represented by a general quadratic expression for a surface.
Date: September 1953
Creator: Watkins, Charles E. & Berman, Julian H.
Partner: UNT Libraries Government Documents Department

A method for studying the hunting oscillations of and airplane with a simple type of automatic control

Description: Report presenting a method for predicting the amplitude and frequency, under certain simplifying conditions, of the hunting oscillations of an automatically controlled aircraft with lag in the control system or in response of the aircraft to the controls. Formulas are given expressing the response to a variation of signal in terms of response to a unit signal.
Date: May 1944
Creator: Jones, Robert T.
Partner: UNT Libraries Government Documents Department

A method for studying the hunting oscillations of an airplane with a simple type of automatic control

Description: "A method is presented for predicting the amplitude and frequency, under certain simplifying conditions, of the hunting oscillations of an automatically controlled aircraft with lag in the control system or in the response of the aircraft to the controls. If the steering device is actuated by a simple right-left type of signal, the series of alternating fixed-amplified signals occurring during the hunting may ordinarily be represented by a "square wave." Formulas are given expressing the response to such a variations of signal in terms of the response to a unit signal" (p. 487).
Date: May 5, 1944
Creator: Jones, Robert T.
Partner: UNT Libraries Government Documents Department

The effect of longitudinal moment of inertia upon dynamic stability

Description: "Free flight tests were carried out to show whether the longitudinal oscillations of a standard S.E.5A airplane are noticeably affected if its longitudinal moment of inertia is increased. These oscillations were taken by means of a self-recording instrument, the airplane having first its ordinary moment of inertia and then one increased by 14 percent. The period of oscillation was slightly longer after the increase of the moment of inertia, but the damping was not affected" (p. 1).
Date: October 1922
Creator: Norton, F. H. & Carroll, T.
Partner: UNT Libraries Government Documents Department

Some effects of aspect ratio and tail length on the contribution of a vertical tail to unsteady lateral damping and directional stability of a model oscillating continuously in yaw

Description: Report presenting a fuselage-vertical-tail combination with tails of two aspect ratios, each of which was tested at four tail lengths, and oscillated in yaw through a range of reduced-frequency parameter corresponding to the lateral motions of airplanes. Three phase angles were measured with the tail in the presence of the fuselage.
Date: January 1954
Creator: Fisher, Lewis R.
Partner: UNT Libraries Government Documents Department

A wind-tunnel test technique for measuring the dynamic rotary stability derivatives at subsonic and supersonic speeds

Description: "A method is described for measuring the dynamic stability derivatives of a model airplane in a wind tunnel. The characteristic features of this system are that single-degree-of-freedom oscillations were used to obtain combinations of rolling, yawing and pitching motions; that the oscillations were excited and controlled by velocity feedback which permitted operation under conditions unfavorable for more conventional types of oscillatory testing; and that data processing was greatly simplified by using analog computer elements in the strain-gage circuitry. A small number of experimental data are included to illustrate the general scope of results obtainable with this system" (p. 1).
Date: September 20, 1954
Creator: Beam, Benjamin H.
Partner: UNT Libraries Government Documents Department

A system for measuring the dynamic lateral stability derivatives in high-speed wind tunnels

Description: Report presenting a description of a two-degree-of-freedom system that forces rolling oscillations. Details of the system, the theory, and the method of operation are discussed. Results indicated that the quantities related to the primary mode of operation of the system could be obtained satisfactorily.
Date: December 1954
Creator: Lessing, Henry C.; Fryer, Thomas B. & Mead, Merrill H.
Partner: UNT Libraries Government Documents Department

Note on flutter of a 60 degree delta wing encountered at low-supersonic speeds during the flight of a rocket-propelled model

Description: From Summary: "An analysis of the flight time history of a rocket-propelled model of a 60 degree delta-wing airplane configuration, fired for the purpose of obtaining zero-lift drag data, indicated wing flutter and subsequent failure at low-supersonic Mach numbers. This flutter occurred during the unpowered decelerating portion of the flight. The behavior of the model during flight is discussed and the mass and stiffness characteristics of a duplicate wing are presented."
Date: May 14, 1951
Creator: Lauten, William T., Jr. & Mitcham, Grady L.
Partner: UNT Libraries Government Documents Department

Some calculations of the lateral response of two airplanes to atmospheric turbulence with relation to the lateral snaking problem

Description: Report presenting calculations of the lateral response to representative time histories of atmospheric turbulence for two airplanes with widely different dynamic properties and explanations for their differences in behavior. The results indicate that atmospheric turbulence can cause and maintain a lateral hunting oscillation of a plane, which can be fairly regular and more pronounced for lightly damped airplanes. This may explain some of the cases of airplane snaking that have not been explained by other causes.
Date: May 1955
Creator: Bird, John D.
Partner: UNT Libraries Government Documents Department