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A numerical method for evaluating wave drag
"A numerical method for evaluating the Von Karman wave-drag equation has been developed and applied to the calculation of wave drag for several bodies of revolution. Results indicated good agreement with the exact solution. Sufficient accuracy of wave drag was obtained by using a simple numerical method to determine the second derivatives of the area distributions" (p. 1).
Date:
June 1958
Creator:
Cahn, Maurice S. & Olstad, Walter B.
System:
The UNT Digital Library
Some Linear Dynamics of Two-Spool Turbojet Engines
Note presenting general equations for the linear responses of inner- and outer-spool speed to change in turbine-inlet temperature and exhaust-nozzle area are derived and evaluated from hypothetical two-spool-engine characteristics at design speed. Experimental corroboration of analysis is also provided in the form of response to fuel flow, response to exhaust-nozzle area, and response to turbine-inlet temperature are provided.
Date:
June 1956
Creator:
Novik, David
System:
The UNT Digital Library
Aerodynamic loads on a leading-edge flap and a leading-edge slat on the NACA 64A010 airfoil section
From Summary: "The present report presents the chordwise distributions of pressure measured concurrently with the force and moment data of NACA TN 3007."
Date:
June 1954
Creator:
Kelly, John A. & McCullough, George B.
System:
The UNT Digital Library
Flutter analysis of rectangular wings of very low aspect ratio
Report presenting a flutter analysis for rectangular wings of very low aspect ratio with a constant thickness, which used slender-body aerodynamic theory and thin-plate theory. The results show that the variation of flutter speed and mode shape with aspect ratio. Approximation of the chordwise deflection shape by use of parabolic or cubic curves yields flutter speeds in fair agreement with those of the "exact" theory for a ratio of chord to semispan less than 3 with the cubic approximation giving almost exact results.
Date:
June 1958
Creator:
Fralich, Robert W. & Hedgepeth, John M.
System:
The UNT Digital Library
Further Investigation of Fatigue-Crack Propagation in Aluminum-Alloy Box Beams
Report presenting testing of twenty-one box beams constructed according to nine designs that were subjected to fatigue tests at one load level to study fatigue-crack propagation and accompanying stress redistribution. Six designs had stiffeners riveted to the skin, two had integrally stiffened covers, and one had stiffeners bonded to the skin. Results regarding crack initiation, crack propagation, and stresses are provided.
Date:
June 1958
Creator:
Hardrath, Herbert F. & Leybold, Herbert A.
System:
The UNT Digital Library
Propeller-noise charts for transport airplanes
Report presenting calculations of rotational-noise and vortex-noise levels at a distance of 300 feet for engine ratings of 1000 to 10,000 horsepower for a large number of propellers in static operation. The results are presented in chart and table form for rapid estimation of the noise levels and spectrums in a range of tip Mach numbers. Results regarding tip Mach number, number of blades, and power loading are provided.
Date:
June 1953
Creator:
Hubbard, Harvey H.
System:
The UNT Digital Library
Fundamental Study of Erosion Caused by Steep Pressure Waves
"A fundamental study of erosion caused by steep pressure waves has been carried out. It is believed that the study gives an insight to the possible causes of damage in high-speed sleeve bearings. In particular, the effect on annealed copper surfaces of steep-fronted pressure waves in oil has been studied, the general conclusion being that cavitation of the oil is the probable cause of damage" (p .1).
Date:
June 1954
Creator:
Rightmire, B. G. & Bonneville, J. M.
System:
The UNT Digital Library
Estimation of Compressible Boundary-Layer Growth Over Insulated Surfaces With Pressure Gradient
Note presenting the incompressible boundary-layer theory of Truckenbrodt extended using a modified Stewartson-type transformation to include compressible boundary-layer development over insulated surfaces. The method is applicable to two-dimensional and axisymmetric, laminar and turbulent boundary layer, and accounts for the pressure gradient along the wall for both compressible and incompressible flow. Some experimental measurements of the boundary layer on small axisymmetric bodies on the wall of a supersonic wind tunnel compared with theoretical predictions.
Date:
June 1957
Creator:
Englert, Gerald W.
System:
The UNT Digital Library
Thermodynamic study of a Roots compressor as a source of high-temperature air
Report presenting an analysis to ascertain the feasibility of using the device to produce high-temperature air. The production of high temperature is associated with the leakage of the hot outlet air through the tip clearance to the inlet and the subsequent mixing with the supply air. The calculated performance of the unit is very sensitive to the assumed value of Stanton number.
Date:
June 1957
Creator:
Cohen, Clarence B.; Woollett, Richard R. & Weston, Kenneth C.
System:
The UNT Digital Library
Experimental investigation of an impulse-type supersonic compressor rotor having a turning of 73 degrees at the mean radius
Report presenting testing of a 16-inch-diameter supersonic impulse rotor with guide vanes in Freon-12. Results regarding the overall performance and blade-element performance are provided.
Date:
June 1958
Creator:
Sterrett, James R.
System:
The UNT Digital Library
Effects of Rapid Heating on Strength of Airframe Components
Note presenting results of several experimental investigations which indicate the effects of rapid heating on the bending strength of multiweb beams and ring-stiffened cylinders. Thermal stresses are shown to reduce the bending load carried at buckling by both beams and cylinders.
Date:
June 1957
Creator:
Pride, Richard A.; Hall, John B., Jr. & Anderson, Melvin S.
System:
The UNT Digital Library
Two Factors Influencing Temperature Distributions and Thermal Stresses in Structures
"The influence of joint conductivity and internal radiation on temperature distribution and thermal stresses has been discussed. Joints of poor conductivity can occur in normal fabrication procedure and greatly alter temperature distributions and increase thermal stresses. On the other hand, internal radiation tends to make the temperature distributions more uniform and thereby relieves thermal stress" (p. 1).
Date:
June 1957
Creator:
Brooks, William A., Jr.; Griffith, George E. & Strass, H. Kurt
System:
The UNT Digital Library
The combinations of thermal and load stresses for the onset of permanent buckling in plates
A simple and practical method for evaluating the onset of permanent buckling in plates in the presence of combined thermal and compressive load stresses is outlined. A particular application of the method shows reasonable agreement with tests of 17-7 PH stainless-steel square tubes. The results indicate that the compressive load stress which the plate can support at the onset of permanent buckling is substantially reduced as the temperature difference of the plate and adjoining members increases.
Date:
June 1957
Creator:
Zender, George W. & Pride, Richard A.
System:
The UNT Digital Library
Adaptor for Measuring Principal Strains With Tuckerman Strain Gage
Report discussing an adapter which uses three Tuckerman optical strain gages to measure the displacement of the three vortices of an equilateral triangle along lines 120 degrees apart. These displacements are substituted in well-known equations in order to compute the magnitude and direction of the principal strains. Tests of the adaptor indicate that principal strains over a gage length of 1.42 inch may be measured with a systematic error not exceeding 4 percent and a mean observational error of the order of + or minus 0.000006. The maximum observed error in strain was of the order of 0.00006. The directions of principal strains for unidirectional stress were measured with the adaptor with an average error of the order of 1 degree.
Date:
June 1943
Creator:
McPherson, A. E.
System:
The UNT Digital Library
Effect of Transient Heating on Vibration Frequencies of Some Simple Wing Structures
"Thermal stresses, which may result from transient heating, can cause changes in the effective stiffness of wing structures. Some effects of this change in stiffness were investigated experimentally by radiantly heating three types of simple wing structures: a uniform plate, a solid double-wedge section, and a circular-arc multiweb-wing section. Changes in stiffness were determined by measuring the changes in natural frequency of vibration during transient heating. Some comparisons are made between theoretical calculations and the measured data" (p. 1).
Date:
June 1957
Creator:
Vosteen, Louis F.; McWithey, Robert R. & Thomson, Robert G.
System:
The UNT Digital Library
The Condensation Line of Air and the Heats of Vaporization of Oxygen and Nitrogen
"The condensation pressure of air was determined over the range of temperature from 60 to 85 K. The experimental results were slightly higher than the calculated values based on the ideal solution law. Heat of vaporization of oxygen was determined at four temperatures ranging from about 68 to 91 K and of nitrogen similarly at four temperatures ranging from 62 to 78 K" (p. 1).
Date:
June 1953
Creator:
Furukawa, George T. & McCoskey, Robert E.
System:
The UNT Digital Library
Normal-pressure tests of circular plates with clamped edges
A fixture is described for making normal-pressure tests of flat plates 5 inches in diameter in which particular care was taken to obtain rigid clamping at the edges. Results are given for 19 plates, ranging in thickness from 0.015 to 0.072 inch. The center deflections and the extreme-fiber stresses at low pressures were found to agree with theoretical values; the center deflections at high pressures were 4 to 12 percent greater than the theoretical values. Empirical curves are derived of the pressure for the beginning of permanent set as a function of the dimensions of the plate and the tensile properties of the material.
Date:
June 1942
Creator:
McPherson, Albert E.; Ramberg, Walter & Levy, Samuel
System:
The UNT Digital Library
Physical Properties of Concentrated Nitric Acid
Note presenting a review of the data existing in the literature and experimental measurements made in order to obtain the physical properties of white fuming nitric acid. The main object of the investigation was to obtain reliable values of the thermal properties of concentrated nitric acid for use in correlating the data obtained in heat-transfer research and in fluid-friction-characteristics investigations.
Date:
June 1953
Creator:
Sibbitt, W. L.; St. Clair, C. R.; Bump, T. R.; Pagerey, P. F.; Kern, J. P. & Fyfe, D. W.
System:
The UNT Digital Library
Loads implications of gust-alleviation systems
A brief review is presented of the basic methods of gust alleviation. Some results obtained in flight tests of a gust-alleviation system are included.
Date:
June 1957
Creator:
Phillips, William H.
System:
The UNT Digital Library
Investigation of a Short-Annular-Diffuser Configuration Utilizing Suction as a Means of Boundary-Layer Control
Note presenting an investigation of a straight outer-wall annular diffuser with a center-body length of one-half the outer-body diameter and an area ratio of 1.9:1 for mean inlet flow angles of 0 and 19.5 degrees in order to determine the effect of area suction applied on the inner wall. The entrance shape, number, and location of the openings through which the air was removed were varied. Results regarding inlet flow conditions, visual-flow observations with axial flow, performance with axial flow, and performance with whirling flow are provided.
Date:
June 1957
Creator:
Wilbur, Stafford W. & Higginbotham, James T.
System:
The UNT Digital Library
Some Considerations of Hysteresis Effects on Tire Motion and Wheel Shimmy
"A theoretical study is made of the influence of tire hysteresis effects on the rolling motion and wheel shimmy of landing gears. The results of this study indicate that hysteresis forces and moments have a noticeable secondary influence on the landing-gear rolling behavior. Comparisons of the available experimental data with the corresponding theoretical predictions provide a fair confirmation of the theory" (p. 1).
Date:
June 1957
Creator:
Smiley, Robert F.
System:
The UNT Digital Library
Influence of crucible materials on high-temperature properties of vacuum-melted nickel-chromium-cobalt alloy
A study of the effect of induction-vacuum-melting procedure on the high-temperature properties of a titanium-and-aluminum-hardened nickel-base alloy revealed that a major variable was the type of ceramic used as a crucible. Reactions between the melt and magnesia or zirconia crucibles apparently increased high-temperature properties by introducing small amounts of boron or zirconium into the melts. Heats melted in alumina crucibles had relatively low rupture life and ductility at 1,600 F and cracked during hot-working as a result of deriving no boron or zirconium from the crucible.
Date:
June 1957
Creator:
Decker, R. F.; Rowe, John P. & Freeman, J. W.
System:
The UNT Digital Library
Investigation at low speeds of deflectors and spoilers as gust alleviators on a model of the Bell X-5 airplane with 35 degree swept wings and on a high-aspect-ratio 35 degree swept-wing-fuselage model
Results of an investigation at low speeds to determine the gust-alleviation capabilities (reduction in lift-curve slope) of spoilers and deflectors on a 35 degree swept-wing model of high aspect ratio and on a 1/4-scale model of the X-5 airplane with 35 degree swept wings indicate that deflector and spoiler-deflector types of controls can be designed to provide considerable gust alleviation for a swept-wing airplane while still maintaining stability and control.
Date:
June 1957
Creator:
Croom, Delwin R. & Huffman, Jarrett K.
System:
The UNT Digital Library
The Exact Solution of Shear-Lag Problems in Flat Panels and Box Beams Assumed Rigid in the Transverse Direction
"A mathematical procedure is herein developed for obtaining exact solutions of shear-lag problems in flat panels and box beams: the method is based on the assumption that the amount of stretching of the sheets in the direction perpendicular to the direction of essential normal stresses is negligible. Explicit solutions, including the treatment of cut-outs, are given for several cases and numerical results are presented in graphic and tabular form. The general theory is presented in a from which further solutions can be readily obtained" (p. 1).
Date:
June 1943
Creator:
Hildebrand, Francis B.
System:
The UNT Digital Library