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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

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

Low-speed tests of a free-to-yaw model in two wind tunnels of different turbulence

Description: Report presenting tests at low speeds in the low turbulence pressure tunnel and the stability tunnel in order to determine the extent of any resulting oscillations of a model mounted with freedom in yaw and to demonstrate the extent to which directional fluctuations in an air stream can be responsible for the oscillations.
Date: February 26, 1952
Creator: Cahill, Jones F. & Bird, John D.
Partner: UNT Libraries Government Documents Department

Photographic study of rotary screaming and other oscillations in a rocket engine

Description: Report presenting an investigation of combustion oscillations using white fuming nitric acid and a hydrocarbon fuel in a 1000-pound-thrust rocket engine. Results regarding rotary oscillation shown by 40,000-frame-per-second photographs, oscillations recorded by streak photography, ion gap traces, pressure measurements, and plastic chamber erosion are provided.
Date: May 25, 1954
Creator: Male, Theodore; Kerslake, William R. & Tischler, Adelbert O.
Partner: UNT Libraries Government Documents Department

Dynamic stability of vehicles traversing ascending or descending paths through the atmosphere

Description: From Summary: "An analysis is given of the oscillatory motions of vehicles which traverse ascending and descending paths through the atmosphere at high speed. The specific case of a skip path is examined in detail, and this leads to a form of solution for the oscillatory motion which should recur over any trajectory. The distinguishing feature of this form is the appearance of the Bessel rather than the trigonometric function as the characteristic mode of oscillation."
Date: July 1958
Creator: Tobak, Murray & Allen, H. Julian
Partner: UNT Libraries Government Documents Department

Low-speed study of the effects of frequency on the stability derivatives of wings oscillating in yaw with particular reference to high angle of attack conditions

Description: Report presenting a low-speed investigation in the free-flight tunnel to provide basic information regarding the effect of frequency on wings oscillating in yaw. The investigation consisted of both free-oscillation tests and forced-oscillation tests of a 60 delta wing, a 45 degree sweptback wing of aspect ratio 2.61, and an unswept wing of aspect ratio 3 over a range of angles of attack. Results regarding the static force test results, directional stability, cross derivative, effective dihedral, and flow separation are provided.
Date: November 1, 1955
Creator: Campbell, John P.; Johnson, Joseph L., Jr. & Hewes, Donald E.
Partner: UNT Libraries Government Documents Department

The question of spontaneous wing oscillations: determination of critical velocity through flight-oscillation tests

Description: Determination of the spontaneous oscillations of a wing or tail unit entail many difficulties, both the mathematical determination and the determination by static wing oscillation tests being far from successful and flight tests involving very great risks. The present paper gives a method developed at the Junkers Airplane Company by which the critical velocity with respect to spontaneous oscillations of increasing amplitude can be ascertained in flight tests without undue risks, the oscillation of the surface being obtained in the tests by the application of an external force.
Date: October 1936
Creator: Schlippe, B. V.
Partner: UNT Libraries Government Documents Department

An experimental investigation of the hinge-moment characteristics of a constant-chord control surface oscillating at high frequency

Description: From Summary: "The results of an experimental investigation of the hinge-moment characteristics of a constant-chord control surface oscillating at high frequency is presented. The control surface was mounted on an aspect-ratio-2 triangular wing. The aerodynamic restoring-moment coefficient and damping-moment coefficient were determined at a frequency of 260 cycles per second for a Mach number range of 0.6 to 0.8 and 1.3 to 1.9 at angles of attack of 5 degrees and 10 degrees. The test results showed linear theory to be a reliable guide to the prediction of the trend of the restoring-moment coefficient with Mach number for the supersonic speed range of the investigation but overestimated the magnitude of the coefficient."
Date: December 28, 1955
Creator: Reese, David E., Jr. & Carlson, William C. A.
Partner: UNT Libraries Government Documents Department

Method for calculating the aerodynamic loading on an oscillating finite wing in subsonic and sonic flow

Description: Report presenting a method for determining the air forces on an oscillating finite wing of general plan form in subsonic flow, including the limiting case of sonic flow. The method is applied to rectangular and delta wings and is compared to existing theory.
Date: August 1956
Creator: Runyan, Harry L. & Woolston, Donald S.
Partner: UNT Libraries Government Documents Department

Diagrams of airplane stability

Description: In this report a study is made of the effect on longitudinal and lateral oscillations of an airplane of simultaneous variations in two resistance derivatives while the remainder of the derivatives are constant. The results are represented by diagrams in which the two variable resistance derivatives are used as coordinates, and curves are plotted along which the modulus of decay of a long oscillation has a constant value. The same type of analysis is also carried out for the stability of the parachute. In discussing the stability of the helicopter it is concluded that the gyroscopic effect on stability will be greater than in the case of the airplane.
Date: 1921
Creator: Batemen, H.
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