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Summary and Analysis of Data on Damping in Yaw and Pitch for a Numbers of Airplane Models

Description: Note presenting damping data obtained from free-flight-tunnel tests of 13 models; the results are analyzed and compared with calculated results. The contributions of the wing, flaps, fuselage, tail surfaces, and power to the damping in pitch and yaw were studied. For complete models, fairly good agreement was obtained between experimental and calculated values for power-off, flaps-neutral conditions.
Date: May 1946
Creator: Cotter, William E., Jr.
Partner: UNT Libraries Government Documents Department

The Measurement of the Damping in Roll on a JN4h in Flight

Description: "This investigation was carried out by the National Advisory Committee for Aeronautics for the purpose of measuring the value of L sub P in flight. The method consisted in flying with heavy weights on each wing tip, suddenly releasing one of them, and allowing the airplane to roll up to 90 degrees with controls held in neutral while a record was being taken of the airspeed, and angular velocity about the X axis. The results are of interest as they show that the damping found in the wind tunnel by the method of small oscillations is in general 40 per cent higher than the damping in flight" (p. 201).
Date: 1924
Creator: Norton, F. H.
Partner: UNT Libraries Government Documents Department

Investigation of the Structural Damping of a Full-Scale Airplane Wing

Description: "An investigation to determine the structural damping characteristics of a full-scale airplane wing was conducted by the shock-excitation method wherein the wing was loaded to a predetermined deflection and the load suddenly released. The test specimen vibrated at its fundamental bending frequency of 1.69 cycles per second. Only the first 2 or 3 cycles showed any indication of a higher frequency being superimposed upon the fundamental bending frequency. The damping was found to increase from about 0.002 to critical at an amplitude of vibration of plus and minus 0.05 inch to approximately 0.006 of critical at an amplitude of + or - 5 inches" (p. 1).
Date: February 1952
Creator: Fearnow, Dwight O.
Partner: UNT Libraries Government Documents Department

Damping Coefficients Due to Tail Surfaces in Aircraft

Description: "The object of the investigation described in this report was to compare the damping coefficients of an airfoil as calculated from a knowledge of the static characteristics of the section with those obtained experimentally with an oscillation. The damping coefficients as obtained, according to the conventional notation, can be considered either as due to pitching or as due to yawing, the oscillation in these experiments being so arranged that the surfaces oscillate about a vertical axis. This is in reality the case when the influence is yawing about the standard Z-axis, but it can also be considered as a pitching motion when the model is so rigged that its standard Y-axis becomes vertical" (p. 118).
Date: January 1, 1923
Creator: Chu, Lynn
Partner: UNT Libraries Government Documents Department

Damping in Pitch of Low-Aspect-Ratio Wings at Subsonic and Supersonic Speeds

Description: Memorandum presenting the application of the concept of indicial functions to the analysis of the aerodynamic phenomena associated with the short-period pitching mode of wings in subsonic and supersonic flight. Simple physical relationships are pointed out and are used to study the effect on the rotary-damping-moment coefficient of changes in center-of-gravity position, Mach number, aspect ratio, plan form, frequency, and thickness.
Date: April 8, 1953
Creator: Tobak, Murray
Partner: UNT Libraries Government Documents Department

Investigation of the Structural Damping of a Full-Scale Airplane Wing

Description: "An investigation to determine the structural damping characteristics of a full-scale airplane wing was conducted by the shock-excitation method wherein the wing was loaded to a predetermined deflection and the load suddenly released. The test specimen vibrated at its fundamental bending frequency of 1.69 cycles per second. Only the first 2 or 3 cycles showed any indication of a higher frequency being superimposed upon the fundamental bending frequency" (p. 1).
Date: March 9, 1951
Creator: Fearnow, Dwight O.
Partner: UNT Libraries Government Documents Department

Combined Effect of Damping Screens and Streams Convergence on Turbulence

Description: Note presenting an analysis of the combined effect of a series of damping screens followed by an axisymmetric-stream convergence on the mean-square fluctuation-velocity intensities, scales, correlations, and one-dimensional spectra of a turbulence field convected by a main stream. Numerical results for the statistical quantities describing the turbulence field downstream of a screen-contraction configuration are obtained for the case of upstream isotropic turbulence.
Date: January 1953
Creator: Tucker, Maurice
Partner: UNT Libraries Government Documents Department

Preliminary Investigation of Helmholtz Resonators for Damping Pressure Fluctuations in 3.6-Inch Ram Jet at Mach Number 1.90

Description: Memorandum presenting an investigation conducted at Mach number 1.90 to determine if Helmholtz resonators can be used in a typical ramjet configuration to damp pressure pulsations associated with shock oscillations. Only one of the two resonators was found to effectively damp pressure pulsations that occurred when the ram jet was operating in the vicinity of its peak pressure recovery. Neither was found to effectively damp pressure pulsations over the entire range of ramjet operating conditions.
Date: May 22, 1951
Creator: Fox, Jerome L.
Partner: UNT Libraries Government Documents Department

The damping due to roll of triangular, trapezoidal, and related plan forms in supersonic flow

Description: Report presenting solutions obtained for the damping in roll of triangular, trapezoidal, rectangular, and two swept-back plan forms. The results indicate that as the aspect ratio is increased, the limiting value of the damping in roll for trapezoidal and rectangular plan forms is equal to the value for two-dimensional flow which is twice the limiting value for triangular plan forms.
Date: March 1948
Creator: Jones, Arthur L. & Alksne, Alberta
Partner: UNT Libraries Government Documents Department

Results of an experimental investigation of small viscous dampers

Description: Report presenting the results of an experimental investigation of several small viscous dampers. The characteristics of the dampers are presented in the form of the magnitudes of the damping forces and spring forces as a function of the maximum velocity of the piston. The results indicated that the temperature has a large effect on the force produced by the dampers and demonstrated the necessity for consideration of the heat generated and dissipated as a result of work done by the dampers.
Date: June 1958
Creator: Silveira, Milton A.; Maglieri, Domenic J. & Brooks, George W.
Partner: UNT Libraries Government Documents Department

An experimental investigation at subsonic and supersonic speeds of the torsional damping characteristics of a constant-chord control surface of an aspect ratio 2 triangular wing

Description: Report presenting the results of a wind-tunnel investigation of the torsional damping characteristics of a constant-chord control surface. The results indicated that the damping coefficient at supersonic speeds was near zero with a tendency toward instability at low supersonic Mach numbers. Results regarding theory, damping moments, and restoring moments are provided.
Date: July 2, 1953
Creator: Reese, David E., Jr.
Partner: UNT Libraries Government Documents Department

Damping characteristics of dashpots

Description: An investigation of the damping characteristics of dashpots was carried out combining theory and experiment. Laminar flow was assumed and three equations for the steady velocity of a piston moving in a cylinder filled with liquid were derived. In the first equation, the piston was assumed coaxial in the cylinder and, in the second equation, the piston was assumed eccentric in the cylinder with an element of the piston in contact with the cylinder wall. The third equation is for a piston of circular cross section in an elliptical cylinder. Experiments showed that the piston is normally eccentric in the cylinder. The pistons tested were 1.25 and 2 inches in diameter 0.062 to 1.00 inch long, and the clearances varied from 1.36 to 5.16 x 10 to the 3rd power inch. The difference in pressure on the two sides of the piston varied from about 2 to 55 pounds per square inch. The piston velocities for each assembly were measured with damping liquids of three different viscosities. At high piston velocities, when turbulent flow exists, the observed velocities were much lower than the velocities calculated on the basis of laminar flow. Results for a wide range of Reynolds numbers are presented in graphical form.
Date: October 1941
Creator: Peterson, John B.
Partner: UNT Libraries Government Documents Department

Free-flight tests of 45 degree swept wings of aspect ratio 3.15 and taper ratio 0.54 to measure wing damping of the first bending mode and to investigate the possibility of flutter at transonic speeds

Description: Report presenting free-flight tests made on two pairs of wings of aspect ratio 3.15, taper ratio 0.54, and 45 degrees sweepback in the transonic speed range to measure wing damping and to investigate the possibility of flutter. Results regarding the flight test and analysis and discussion are provided.
Date: October 12, 1954
Creator: O'Kelly, Burke R.; Lundstrom, Reginald R. & Lauten, William T., Jr.
Partner: UNT Libraries Government Documents Department

Dynamic lateral behavior of high-performance aircraft

Description: Report presenting a study of several proposed high-performance aircraft to define some problem areas in dynamic lateral behavior of high-speed aircraft which require specific attention. Aileron control problems and Dutch roll characteristics with and without artificial damping were explored in depth.
Date: August 6, 1958
Creator: Moul, Martin T. & Paulson, John W.
Partner: UNT Libraries Government Documents Department

Estimation of the damping in roll of supersonic-leading-edge wing-body combinations

Description: From Summary: "A description is given of a linear-theory method for the estimation of the damping in roll of supersonic-leading-edge wings mounted on cylindrical bodies. The error resulting from an approximation essential to the method is shown to be small. The damping in roll is calculated for configurations having rectangular and triangular wings; for most of the range of variables the net effect of the body is to decrease the damping in roll."
Date: July 1950
Creator: Tucker, Warren A. & Piland, Robert O.
Partner: UNT Libraries Government Documents Department

Investigation of damping liquids for aircraft instruments

Description: "This report covers the results of an investigation carried on at the Bureau of Standards under a research authorization from, and with the financial assistance of, the National Advisory Committee for Aeronautics. The choice of a damping liquid for aircraft instruments is difficult owing to the range of temperature at which aircraft operate. Temperature changes affect the viscosity tremendously. The investigation was undertaken with the object of finding liquids of various viscosities otherwise suitable which had a minimum change in viscosity with temperature" (p. 405).
Date: May 16, 1928
Creator: Keulegan, G. H.
Partner: UNT Libraries Government Documents Department

Aerodynamic Characteristics of Damping Screens

Description: From Summary: "The experimental investigation of damping screens described herein was undertaken primarily to test theories of the effects of damping screens and to obtain information on the performance of screens in oblique flow. The characteristics investigated include the damping of longitudinal and lateral components of turbulence, the effect of screens on scale, the conditions for the production of turbulence and eddies by screens, and the damping of spatial variations of mean speed."
Date: January 1950
Creator: Schubauer, G. B.; Spangenberg, W. G. & Klebanoff, P. S.
Partner: UNT Libraries Government Documents Department

Experimental damping in pitch of 45 degree triangular wings

Description: Report presenting the results of an experimental wind-tunnel investigation of the damping in pitch of two triangular wings having leading edges swept back 45 degrees are presented. The wings differed only in airfoil section. Results regarding the damping coefficients, aeroelastic effects at supersonic speeds, Reynolds number effects, and application of the results to the prediction of the dynamic behavior of full-scale aircraft are provided.
Date: December 1, 1950
Creator: Tobak, Murray; Reese, David E., Jr. & Beam, Benjamin H.
Partner: UNT Libraries Government Documents Department

Theoretical Damping in Roll and Rolling Moment Due to Differential Wing Incidence for Slender Cruciform Wings and Wing-Body Combinations

Description: "A method of analysis based on slender-wing theory is developed to investigate the characteristics in roll of slender cruciform wings and wing-body combinations. The method makes use of the conformal mapping processes of classical hydrodynamics which transform the region outside a circle and the region outside an arbitrary arrangement of line segments intersecting at the origin. The method of analysis may be utilized to solve other slender cruciform wing-body problems involving arbitrarily assigned boundary conditions" (p. 1).
Date: 1952
Creator: Adams, Gaynor J. & Dugan, Duane W.
Partner: UNT Libraries Government Documents Department

A Theoretical Analysis of a Simple Aerodynamic Device to Improve the Longitudinal Damping of a Cruciform Missile Configuration at Supersonic Speeds

Description: Memorandum presenting a theoretical analysis of a cruciform missile configuration equipped with floating controls to determine if such controls can be utilized to improve the airframe transient response characteristics.The investigation covers either forward or aft locations of the floating controls at supersonic speeds. The results indicate that a substantial increase in airframe damping can be obtained through a proper selection of hinge-moment coefficients and through the use of a fixed-rate viscous damper attached to the floating-control surfaces.
Date: October 27, 1955
Creator: Clements, James E.
Partner: UNT Libraries Government Documents Department

Damping in Roll of Straight and 45 Degree Swept Wings of Various Taper Ratios Determined at High Subsonic, Transonic, and Supersonic Speeds With Rocket-Powered Models

Description: Report presenting rocket-powered flight testing to determine the damping in roll of several wings of 0 degree and 45 degree quarter-chord-line sweep with various taper ratios for a range of Mach numbers. Damping in roll decreased with decreasing taper ratio at roughly the same rate for swept and unswept wings and also decreased by sweeping the quarter-chord line. The experimental results were also consistently lower than what was predicted by theory.
Date: October 10, 1951
Creator: Sanders, E. Claude, Jr.
Partner: UNT Libraries Government Documents Department

Damping in Roll of Rocket-Powered Test Vehicles Having Swept, Tapered Wings of Low Aspect Ratio

Description: "Flight tests of rocket-powered models have been conducted to determine the damping in roll of a group of swept, tapered wings designed for flight in the transonic speed region. The Mach number range of these tests was from approximately 0.7 to 1.4. The experimental damping in roll for all configurations was less than predicted by linearized theory throughout the Mach umber range of these tests. The only wing in this group that experienced an appreciable transonic lateral trim change was the one with a 7-percent-thick circular-arc airfoil section" (p. 1).
Date: October 8, 1951
Creator: Sanders, E. Claude, Jr. & Edmondson, James L.
Partner: UNT Libraries Government Documents Department