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Reciprocity relations in aerodynamics
From Introduction: "The purpose of the present paper is twofold. First, a close connection will be established between reverse-flow theorems in subsonic and supersonic, steady-state wing theory and known reciprocity relations between two solutions of the equation the flow field."
Date:
May 1952
Creator:
Heaslet, Max A. & Spreiter, John R.
System:
The UNT Digital Library
Spin Tests of Two Models of a Low-Wing Monoplane to Investigate Scale Effect in the Model Test Range
Note presenting testing performed on scale models of a modern low-wing monoplane in the 15-foot free-spinning wind tunnel. Results are presented in the form of charts that afford a direct comparison between the spins of the two models for a number of different conditions. The results indicate that, within the range of Reynolds numbers used in the present investigation, such factors as difficulty of ballasting and testing are more important in determining proper model size than the changes in scale effect likely to result from the use of different sizes of models.
Date:
May 1941
Creator:
Donlan, Charles J.
System:
The UNT Digital Library
A Dynamic-Model Study of the Effect of Added Weights and Other Structural Variations on the Blade Bending Strains of an Experimental Two-Blade Jet-Driven Helicopter in Hovering and Forward Flight
Report presenting an investigation of the blades of an experimental two-blade jet-driven helicopter when subject to a condition of near resonance between the frequencies of the first elastic bending mode of the blades and third harmonic component of the aerodynamic loading that results in high bending strains in normal flight conditions. Various changes in design configuration on the blade bending strains were explored. Results regarding the preliminary studies, effects of variation in flight conditions and blade configuration, and harmonic analysis are provided.
Date:
May 1955
Creator:
McCarty, John Locke & Brooks, George W.
System:
The UNT Digital Library
Some effects of tail height and wing plan form on the static longitudinal stability characteristics of a small-scale model at high subsonic speeds
Report presenting an investigation in the high-speed 7- by 10-foot tunnel to determine some effects of tail height and wing plan form on the static longitudinal stability characteristics of a complete, small-scale model at high subsonic speeds. It had both a low-tail and high-tail position. Results regarding the lift and drag characteristics and longitudinal stability characteristics are provided.
Date:
May 1957
Creator:
Few, Albert G., Jr. & King, Thomas J., Jr.
System:
The UNT Digital Library
Cascade investigation of a related series of 6-percent-thick guide-vane profiles and design charts
Report presenting a description of a new blade series designed to operate at near choking inlet Mach numbers and to have near maximum critical Mach numbers by employing high aerodynamic loading of the profiles in the leading-edge region. Results regarding aerodynamic characteristics and prediction of high-speed performance are provided.
Date:
May 1957
Creator:
Dunavant, James C.
System:
The UNT Digital Library
Heat-Loss Characteristics of Hot-Wire Anemometers at Various Densities in Transonic and Supersonic Flow
Note presenting an experimental investigation of the heat-loss characteristics of heated fine wires suitable for use as anemometers in turbulence research. The effects of each of the several variables on the heat-loss characteristics of both normally oriented and swept wires were measured. The temperature-loading effects were found to cause large sensitivity differences between constant-temperature and constant-current operation.
Date:
May 1955
Creator:
Spangenberg, W. G.
System:
The UNT Digital Library
Charts for the analysis of flow in a whirling duct
From Summary: "Charts are developed for the analysis of flow in a whirling constant-diameter duct. These charts permit the determination of the duct-exit Mach number, or the Mach number at any point along the duct, for practical ranges of duct-inlet Mach number, duct-tip Mach number, friction factor, ratio of ambient temperature to duct-flow total temperature, ratio of duct-tip radius to duct hydraulic diameter, and heat conductivity through the duct wall and surrounding material. The method of using the charts is illustrated through the computation of a sample problem."
Date:
May 1957
Creator:
Makofski, Robert A.
System:
The UNT Digital Library
Lift and moment responses to penetration of sharp-edged traveling gusts, with application to penetration of weak blast waves
Report presenting calculations of the lift and moment responses to penetration of sharp-edged traveling gusts for wings in incompressible and supersonic two-dimensional flow, for wide delta and rectangular wings in supersonic flow, and for very narrow delta wings. The results of the calculations indicate that the forward speed of the gusts has a large effect on the lift- and moment-response functions.
Date:
May 1957
Creator:
Drischler, Joseph A. & Diederich, Franklin W.
System:
The UNT Digital Library
On flow of electrically conducting fluids over a flat plate in the presence of a transverse magnetic field
Report presenting a study of the use of a magnetic field to control the motion of electrically conducting fluids. Results indicated that the skin friction and heat-transfer rate are reduced when the transverse magnetic field is fixed relative to the plate and increased when fixed relative to the fluid.
Date:
May 1957
Creator:
Rossow, Vernon J.
System:
The UNT Digital Library
An approximate analytical method for studying entry into planetary atmospheres
Report presenting a single, ordinary, nonlinear differential equation of second order that can be used for determining entry into an exponential planetary atmosphere. The reduced equation includes various terms, some of which represent the gravity force, the centrifugal acceleration, and the lift force. A number of solutions for lifting and nonlifting vehicles entering at various initial angles are obtained from the complete nonlinear equation.
Date:
May 1958
Creator:
Chapman, Dean R.
System:
The UNT Digital Library
Summary of experimental heat-transfer measurements in turbulent flow for a Mach number range from 0.87 to 5.05
Report presenting heat-transfer measurements made in turbulent flow at a variety of Mach and Reynolds numbers through the use of an axially symmetric annular nozzle consisting of an inner shaped center body and an outer cylindrical sleeve. The results are presented as Stanton number and recovery factor as a function of Reynolds number. Stanton number was found to decrease with an increase in Reynolds number and usually decreases with an increase in Mach number.
Date:
May 1958
Creator:
Brevoort, Maurice J. & Arabian, Barbara D.
System:
The UNT Digital Library
An experimental investigation of wake effects on hydro-skis
Report presenting an experimental investigation to determine the effects of planing in a wake on the forces of a planing surface and to locate desirable positions in the wake with regard to the lift and lift-drag ratio of the planing surface. Two combinations of hydro-skis were tested: one with two in tandem and one with three arranged with one hydro-ski in the front and two in the back. Results indicated that the rear hydro-ski in tandem arrangement could have large increases in lift coefficient and small improvements in lift-drag ratio compared with the regular configuration.
Date:
May 1958
Creator:
McBride, Ellis E. & Fisher, Lloyd J.
System:
The UNT Digital Library
Flight Investigation of Effects of Retreating-Blade Stall on Bending and Torsional Moments Encountered by a Helicopter Rotor Blade
Note presenting flight tests conducted with a medium-size single-rotor helicopter, one blade of which was equipped with strain gages, to determine the effects of retreating-blade stall on the rotor blade bending and torsional moments during high-speed flight and pull-up maneuvers. The results indicate that retreating-blade stall has a substantial effect on the periodic rotor blade moments. Results regarding the effect of stall in steady forward flight and effect of stall in pull-up maneuvers are provided.
Date:
May 1958
Creator:
Ludi, LeRoy H.
System:
The UNT Digital Library
Nonuniformities in Shock-Tube Flow Due to Unsteady-Boundary-Layer Action
Note presenting an evaluation of the boundary layer along the walls of a shock tube, which induces pressure and velocity gradients within the core of potential flow.
Date:
May 1957
Creator:
Mirels, Harold & Braun, W. H.
System:
The UNT Digital Library
Study of ground-reaction forces measured during landing impacts of a large airplane
Report presenting the results of tests conducted on a large bomber-type airplane to determine the ground-reaction forces imposed on the main landing gear under actual landing conditions. The vertical force on the landing gear truck at which the oleopneumatic shock strut began to compress varied over a wide range. Results regarding vertical forces, drag forces, and side forces are provided.
Date:
May 1958
Creator:
Hall, Albert W.; Sawyer, Richard H. & McKay, James M.
System:
The UNT Digital Library
Appraisal of the Hazards of Friction-Spark Ignition of Aircraft Crash Fires
Note presenting a study to determine if common aircraft metals produce friction sparks capable of igniting combustibles that might be spilled in an airplane crash. Samples of aluminum, titanium, magnesium, chrome-molybdenum steel, and stainless steel were dragged over concrete and asphalt runways while a combustible mixture of gasoline, JP-4 fuel, kerosene, or preheated oil was sprayed around the sample.
Date:
May 1957
Creator:
Campbell, John A.
System:
The UNT Digital Library
Origin and Prevention of Crash Fires in Turbojet Aircraft
The manner in which the jet engine may start a crash fire was explored in test-stand and full-scale crash studies. On the basis of these studies, a method was devised for inserting and cooling the engine parts that may serve as ignition sources in crash. This method was tried successfully in full-scale crashes of jet-powered airplanes carrying engines in pod nacelles and engines buried within the airplane structure.
Date:
May 1957
Creator:
Pinkel, I. Irving; Weiss, Solomon; Preston, G. Merritt & Pesman, Gerard J.
System:
The UNT Digital Library
Theoretical and Experimental Investigation of Random Gust Loads Part 1: Aerodynamic Transfer Function of a Simple Wing Configuration in Incompressible Flow
Sinusoidally oscillating downwash and lift produced on a simple rigid airfoil were measured and compared with calculated values. Statistically stationary random downwash and the corresponding lift on a simple rigid airfoil were also measured and the transfer functions between their power spectra determined. The random experimental values are compared with theoretically approximated values. Limitations of the experimental technique and the need for more extensive experimental data are discussed.
Date:
May 1957
Creator:
Hakkinen, Raimo J. & Richardson, A. S., Jr.
System:
The UNT Digital Library
Theoretical and Experimental Investigation of Random Gust Loads Part 2: Theoretical Formulation of Atmospheric Gust Response Problem
Note presenting equations of motion derived for the dynamic response of an aircraft to random atmospheric gust loads. The equations include the degrees of freedom of plunging, pitching, rolling, and an arbitrary number of elastic normal modes. Results for simplified cases show that unsteady aerodynamic theory is not important for increasingly large values of the turbulence scale compared with values of the wing chord.
Date:
May 1957
Creator:
Richardson, A. S., Jr.
System:
The UNT Digital Library
A variational theorem for creep with applications to plates and columns
From Summary: "A variational theorem is presented for a body undergoing creep. Solutions to problems of creep bending and creep collapse of plates, columns, beams, and shells can be obtained by means of the direct methods of the calculus of variations in conjunction with the stated theorem. The application of the theorem is illustrated for plates and columns by the solution of two sample problems."
Date:
May 1957
Creator:
Sanders, J. Lyell, Jr.; McComb, Harvey G., Jr. & Schlechte, Floyd R.
System:
The UNT Digital Library
Experimental Influence Coefficients and Vibration Modes of a Built-Up 45 Degree Delta-Wing Specimen
Note presenting experimental influence coefficients and vibration modes and frequencies of a built-up 45 degrees delta-wing specimen. The symmetrical and antisymmetrical static influence coefficients were obtained on a three-point support.
Date:
May 1957
Creator:
Kordes, Eldon E.; Kruszewski, Edwin T. & Weidman, Deene J.
System:
The UNT Digital Library
A phenomenological relation between stress, strain rate, and temperature for metals at elevated temperatures
Report presenting a phenomenological relation between stress, strain rate, and temperature to account for the behavior of polycrystalline metals above the equicohesive temperature. This is because the behavior of metals at elevated temperatures is constantly becoming a more important problem. The validity of the relation suggested in the equation appears to be accurate for 7075-T6 aluminum alloy.
Date:
May 1957
Creator:
Stowell, Elbridge Z.
System:
The UNT Digital Library
Least-Work Analysis of the Problem of Shear Lag in Box Beams
The distribution of stress in the cover sheets of thin-wall box beams is analyzed, with regard to the effect of shear deformation in the cover sheets, by the method of least work. Explicit results are obtained for a number of representative cases that show the influence of the following factors on the stress patterns. General conclusions are drawn from the results obtained. Among them the most important one appears to be the fact that the shear-lag effect depends primarily on several tow qualities.
Date:
May 1943
Creator:
Hildebrand, Francis B. & Reissner, Eric
System:
The UNT Digital Library
Effect of standing transverse acoustic oscillations on fuel-oxidant mixing in cylindrical combustion chambers
Vapor fuel-oxidant mixing is analyzed for standing transverse acoustic fields simulating those existing in screeching or screaming combustors. The additional mixing due to the acoustic field is shown to be a function of sound pressure and frequency, stream velocity, and turbulence. The effects of these parameters are shown graphically for a realistic range of combustor conditions. The fuel-oxidant ratio at various combustor stations is shown to have a cyclic fluctuation which is in phase with the pressure fluctuations. Possible mechanisms contributing to screech and scream are discussed.
Date:
May 1957
Creator:
Mickelsen, William R.
System:
The UNT Digital Library