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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

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

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

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

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

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

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

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

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

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

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

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

Chromaticity measurement via the fourier spectrum of transverse oscillations

Description: Turn-by-turn data from a single BPM includes information on the chromaticity in sidebands displaced above and below the betatron frequency by an amount of the synchrotron frequency. It may be necessary to induce small amplitude synchrotron oscillation by giving the beam a small kick. Power spectrum of the BPM data gives clear chromatic sidebands, and they can be applied to the chromaticity measurement in the Fermilab Booster.
Date: August 13, 2004
Creator: Yang, Xi
Partner: UNT Libraries Government Documents Department


Description: The density oscillations of warm particle bunches is investigated theoretically. Two different mathematical approaches are employed to derive the basic equation describing density oscillations; one is a fluid approach and the second is a more general Green1s function formulation. The motion is analyzed in first order perturbation theory where it is shown, under the assumption of no degeneracy, that there are only stable oscillations. Second order perturbation theory gives damping of the motion. The perturbation theory is examined and a criterion is exhibited for its proper use. Thus, when the resistivity is small enough (but nonzero) then the motion is stable, but when the resistivity is large then the motion is essentially unstable with a growth rate which is that of an unbunched beam. The criterion is approximately evaluated using a model for a bunched beam.
Date: November 1, 1982
Creator: Channell, P.J.; Sessler, A.M. & Wurtele, J.S.
Partner: UNT Libraries Government Documents Department

Some effects of roll rate on the longitudinal stability characteristics of a cruciform missile configuration as determined from flight test for a Mach number range of 1.1. to 1.8

Description: Report presenting flight testing of a model of a cruciform missile configuration with a low-aspect-ratio wing equipped with flap-type controls in order to determine the stability and control characteristics while rolling at about 5 radians per second. Results indicated that if the ratio of roll rate to natural circular frequency in pitch is not greater than about 0.3, the motion following a step disturbance in pitch essentially remains in a plane in space. Results regarding time histories, normal force due to angle of attack, pitching moment due to angle of attack, damping, and control effectiveness are provided.
Date: June 19, 1956
Creator: Lundstrom, Reginald R. & Baber, Hal T., Jr.
Partner: UNT Libraries Government Documents Department

Correlation of experimental and calculated effects of product of inertia on lateral stability

Description: Report presenting a correlation of the experimental and calculated effects of the product of inertia on the stability of lateral oscillations of airplanes. The experimental and calculated boundaries were in good agreement with one another, but neglecting the product of inertia led to wide discrepancies. Results regarding stability and its influence on general flight behavior are provided.
Date: July 1947
Creator: McKinney, Marion O., Jr. & Drake, Hubert M.
Partner: UNT Libraries Government Documents Department

Investigations of Lateral Stability of a Glide Bomb Using Automatic Control Having No Time Lag

Description: The investigation of the lateral stability of an automatically controlled glide bomb led also to the attempt of clarifying the influence of a phugoid oscillation or of any general longitudinal oscillation on the lateral stability of a glide bomb. Under the assumption that its period of oscillation considerably exceeds the rolling and yawing oscillation and that c(sub a) is, at least in sections, practically constant, the result of this test is quite simple. It becomes clear that the influence of the phugoid oscillation may be replaced by suitable variation of the rolling-yawing moment on a rectilinear flight path instead of the phugoid oscillation. If the flying weight of the glide bomb of unchanged dimensions is increased, an increase of the flight velocity will be more favorable than an increase of the lift coefficient. The arrangement of the control permits lateral stability to be achieved in every case; a minimum rolling moment due to sideslip proves of great help.
Date: August 1950
Creator: Sponder, E. W.
Partner: UNT Libraries Government Documents Department

Determination of lateral-stability derivatives and transfer-function coefficients from frequency-response data for lateral motions

Description: A method is presented for determining the lateral-stability derivatives, transfer-function coefficients, and the modes for lateral motion from frequency-response data for a rigid aircraft. The method is based on the application of the vector technique to the equations of lateral motion, so that the three equations of lateral motion can be separated into six equations. The method of least squares is then applied to the data for each of these equations to yield the coefficients of the equations of lateral motion from which the lateral-stability derivatives and lateral transfer-function coefficients are computed. Two numerical examples are given to demonstrate the use of the method.
Date: 1955
Creator: Donegan, James J.; Robinson, Samuel W., Jr. & Gates, Ordway B., Jr.
Partner: UNT Libraries Government Documents Department

Theoretical and experimental investigation of the effect of tunnel walls on the forces on an oscillating airfoil in two-dimensional subsonic compressible flow

Description: This report presents a theoretical and experimental investigation of the effect of wind-tunnel walls on the air forces on an oscillating wing in two-dimensional subsonic compressible flow. A method of solving an integral equation which relates the downwash on a wing to the unknown loading is given, and some comparisons are made between the theoretical results and the experimental results. A resonance condition, which was predicted by theory in a previous report (NACA report 1150), is shown experimentally to exist. In addition, application of the analysis is made to a number of examples in order to illustrate the influence of walls due to variations in frequency of oscillation, Mach number , and ratio of tunnel height to wing semichord.
Date: 1956
Creator: Runyan, Harry L.; Woolston, Donald S. & Rainey, A. Gerald
Partner: UNT Libraries Government Documents Department

Correlation of predicted and experimental lateral oscillation characteristics for several airplanes

Description: Report presenting an investigation of the accuracy of a currently used method for predicting the dynamic lateral oscillatory characteristics of airplanes. The study involved the comparison of controls-fixed flight-test data from several current fighter-type jet airplanes with the calculated values of period and damping for the airplanes.
Date: December 15, 1952
Creator: Heinle, Donovan R. & McNeill, Walter E.
Partner: UNT Libraries Government Documents Department