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Some Recent Contributions to the Study of Transition and Turbulent Boundary Layers
Report presenting a paper in two parts about transition and turbulent boundary layers. The first part reviews the current problem of the instability of laminar boundary layers. The second part reviews the current state of knowledge of the mechanics of turbulent boundary layers and of the methods now being used for fundamental studies of the turbulent fluctuations in turbulent boundary layers.
Date:
April 1947
Creator:
Dryden, Hugh L.
System:
The UNT Digital Library
Quantitative Study of Variations in Concentration of Glycerol and Aerosol OT on Foaming Volume of Oil at Room Temperature
"The amount of foam that can be formed in the presence of certain pure chemical agents was investigated by a new method. The effect of variations in concentration and proportion of Aerosol OT and glycerol was studied and the effects of various other mixtures have been given for comparison. Both Gulf Agent and Aerosol-OT - glycerol mixtures, when present in comparable amounts, prohibited the formation of the normal volumes of foam to the same extent and in the optimum cases reduced it to only one-tenth of its normal value" (p. 1).
Date:
April 1949
Creator:
McBain, J. W. & Ross, Sydney
System:
The UNT Digital Library
Effect of Various Compounds in Use With Airplane Engines Upon Foaming of Aircraft Lubricating Oil
Report presenting an investigation of aircraft lubricating oil that is contaminated with various materials used in connection with airplane engines or contained in the fuel. Over 60 of the materials have been tested to determine their influence on the foaming of an aircraft lubricating oil. All but 13 of the compounds were found to have a small or negligible effect, but the other 13 were found to be strong foaming agents.
Date:
April 1949
Creator:
McBain, J. W. & Woods, W. W.
System:
The UNT Digital Library
Flight Measurements of Helicopter Blade Motion With a Comparison Between Theoretical and Experimental Results
Note presenting photographic records of the behavior of a blade in flight as obtained with a conventional single-rotor helicopter. The results of the measurements of flapping motion, in-plane motion, and blade distortions are presented for selected conditions of flight at tip-speed ratios ranging from 0.12 to 0.25. Plots of blade twisting and blade bending in the plane of flapping are presented for a sample case.
Date:
April 1947
Creator:
Myers, Garry C., Jr.
System:
The UNT Digital Library
Flight Tests of a Helicopter in Autorotation, Including a Comparison With Theory
Note presenting the results of glide performance tests conducted on a test helicopter with its original production blades in the autorotation condition. The data was reduced to coefficient form, and performance at standard sea-level conditions were calculated.
Date:
April 1947
Creator:
Gessow, Alfred & Myers, Garry C., Jr.
System:
The UNT Digital Library
Investigation of Effects of Surface Temperature and Single Roughness Elements on Boundary-Layer Transition
Note presenting an investigation of the laminar boundary layer and the position of the transition point on a heated flat plate. The Reynolds number of transition was found to decrease as the temperature of the plate is increased. Results regarding the effect of surface temperature, effect of roughness elements, mean-velocity profile near a heated wall, instability of inflection-point profiles, and laminar separation and transition are provided.
Date:
April 1947
Creator:
Liepmann, Hans W. & Fila, Gertrude H.
System:
The UNT Digital Library
A method for the determination of air infiltration rates in airplane cabins
From Summary: "A method for the experimental determination of the rate of infiltration of air into aircraft cabins during flight has been developed and tested. This method consists of releasing a quantity of gas in the cabin and calculating the infiltration rate from the measured rate of change of the gas concentration. The results of the flight tests indicate that after the infiltration rate is established at one altitude and airspeed, the infiltration rates at other altitudes and airspeeds can be calculated."
Date:
April 1946
Creator:
Stalder, Jackson R. & Zeiller, E. Lewis
System:
The UNT Digital Library
Comparison between predicted and observed performance of gas-turbine stator blade designed for free-vortex flow
Report presenting a comparison between the calculated design performance of a gas-turbine stator blade and its performance in a sector of an annular cascade tunnel. The gas velocities on the blade surface were computed by the stress filament method and compared with experimental values, with which they agreed satisfactorily. Results regarding discharge angle, vane-surface-velocity distribution, tangential- and axial-velocity distribution, and radial-equilibrium consideration are provided.
Date:
April 1949
Creator:
Huppert, M. C. & MacGregor, Charles
System:
The UNT Digital Library
An analysis of the factors that affect the exhaust process of a four-stroke-cycle reciprocating engine
From Introduction: "An investigation was made to determine the relative significance of the factors that affect the exhaust process; the effects that an exhaust-process change has on cylinder charging were given special attention. Differential equations of this nature have been developed by Kemble (reference 1) but the forms of these equations are such that general conclusions regarding the various factors affecting the exhaust process cannot be determined."
Date:
April 1947
Creator:
Stanitz, John D.
System:
The UNT Digital Library
Plastic buckling of simply supported compressed plates
Report presenting an investigation to ascertain the validity of various theories for the plastic buckling of compressed simply supported plates by means of local-instability tests of drawn square tubes of 14S-T6 aluminum alloy. The results obtained were in excellent agreement with Stowell's unified theory for the plastic buckling of columns and plates.
Date:
April 1949
Creator:
Pride, Richard A. & Heimerl, George J.
System:
The UNT Digital Library
A spectrophotometric method for identification and estimation of alkylnaphthalenic-type hydrocarbons in kerosene
Report presenting a spectrophotometric method for identifying and estimating approximate amounts of naphthalenic-type hydrocarbons, which is suitable for finding differences in the naphthalenic content of kerosene fractions in petroleum.
Date:
April 1947
Creator:
Cleaves, Alden P. & Carver, Mildred S.
System:
The UNT Digital Library
Axial-flow fan and compressor blade design data on 52.5 degrees stagger and further verification of cascade data by rotor tests
From Summary: "Previous tests of blower-blade sections have been extended by a series of tests at 52.5 degrees stagger. The results of these tests have been combined with the earlier test results and are presented in new blade design charts which supersede those previously presented. An investigation in a test blower over a range of stagger from 44 degrees to 65 degrees has shown that for blades at a solidity of 1.0, the two-dimensional cascade data predict the turning angle to within 1/2 degrees."
Date:
April 1947
Creator:
Bogdonoff, Seymour M. & Hess, Eugene E.
System:
The UNT Digital Library
Effect of the tunnel-wall boundary layer on test results of a wing protruding from a tunnel wall
Report presenting two-dimensional span-loading tests of a two-foot-chord NACA 65(sub 1)-012 airfoil model in the stability tunnel to determine tunnel-wall boundary-layer effects. Testing indicated that a small loss in average load may be expected. Results regarding tunnel-wall velocity profiles, pressure distributions, spanwise surveys, and force and moment coefficients are provided.
Date:
April 1947
Creator:
Mendelsohn, Robert A. & Polhamus, Josephine F.
System:
The UNT Digital Library
Effect of Variables in Welding Technique on the Strength of Direct-Current Metal-Arc-Welded Joints in Aircraft Steel 2 - Repeated-Stress Tests of Joints in SAE 4130 Seamless Steel Tubing
"A series of tests were made for the purposes of establishing the effects of several variables in welding technique on the fatigue strength of arc-welded joints in SAE 4130 seamless steel tubing. The variables included type of electrode, speed of welding, current, position, amount of preheat, and other factors which in turn controlled the weld contour, penetration, and depth of the heat-affected zone. A range of joint design was also investigated" (p. 1).
Date:
April 1948
Creator:
Voldrich, C. B. & Armstrong, E. T.
System:
The UNT Digital Library
Compressive-Strength Comparisons of Panels Having Aluminum-Alloy Sheet and Stiffeners With Panels Having Magnesium-Alloy Sheet and Aluminum Alloy Stiffeners
Report presenting comparisons of 24S-T aluminum-alloy flat compression panels with longitudinal Z-section stiffeners and panels with flat FS-1E magnesium-alloy sheet and longitudinal 24S-T aluminum-alloy Z-section stiffeners. The use of the composite magnesium-alloy, aluminum-alloy construction permits wider stiffener spacing with little to not loss in structural efficiency or stress for local buckling. Results regarding stiffener spacing, proportions, and consideration of the different material constructions are provided.
Date:
April 1947
Creator:
Dow, Norris F.; Hickman, William A. & McCracken, Howard L.
System:
The UNT Digital Library
Critical shear stress of infinitely long, simply supported plate with transverse stiffeners
From Summary: "A theoretical solution is given for the critical shear stress of an infinitely long, simply supported, flat plate with identical, equally spaced, transverse stiffeners of zero torsional stiffness. Results are obtained by means of the Lagrangian multiplier method and are presented in the form of design charts. Experimental results are included and are found to be in good agreement with the theoretical results."
Date:
April 1949
Creator:
Stein, Manuel & Fralich, Robert W.
System:
The UNT Digital Library
Reinforced Circular Cutouts in Plane Sheets
Note presenting an attempt to design the reinforcement of a cutout in a plane sheet in such a way that it is as nearly as possible equivalent to the part of the structure which has been cut out. A perfect equivalence would mean that the stresses and displacements of the structure remain the same as those which would have appeared without the cutout.
Date:
April 1949
Creator:
Reissner, H. & Morduchow, M.
System:
The UNT Digital Library
Effect of Increase in Afterbody Length on the Hydrodynamic Qualities of a Flying-Boat Hull of High Length-Beam Ratio
Report presenting an investigation to determine the effects of increased afterbody length on the hydrodynamic qualities of a model of a flying boat with a hull with a length-beam ratio of 15. Results regarding longitudinal stability, spray characteristics, excess thrust for take-off, landings in waves, and a summary chart are provided.
Date:
April 1949
Creator:
Kapryan, Walter J. & Clement, Eugene P.
System:
The UNT Digital Library
A Metallurgical Investigation of Large Forged Discs of Low-Carbon N-155 Alloy
Research was undertaken to ascertain the properties of better wrought heat resisting alloys in the form of large discs required for gas turbine rotors. The properties of large discs of low carbon N-155 alloy in both the as-forged and water-quenched and aged conditions were determined by means of stress-rupture and creep tests for time periods up to about 2000 hours at 1200, 1350, and 1500 F. Short-time tensile test, impact test, and time-total deformation characteristics are included.
Date:
April 1947
Creator:
Cross, Howard C. & Freeman, J. W.
System:
The UNT Digital Library
Effect of Catalysts and pH Strength of Resin-Bonded Plywood
Report presenting the effects of various catalysts used to cure resinous adhesives on the strength properties of plywood, especially in regard to the degree of solidity developed by the catalysts in the resin film and the plywood. Six resins were tested with birch wood, which is the most commonly used wood in aircraft construction.
Date:
April 1947
Creator:
Kline, G. M.; Reinhart, F. W.; Rinker, R. C. & De Lollis, N. J.
System:
The UNT Digital Library
Stress and distortion measurements in a 45 degree swept box beam subjected to antisymmetrical bending and torsion
Report presenting an untapered aluminum-alloy box beam representing the main structural component of a full-span, two-spar, 45 degree swept wing with a carry-through section subjected to antisymmetrical tip bending and twisting loads such that stresses were kept below the proportional limit. Results regarding stresses due to antisymmetrical bending, stresses due to antisymmetrical torsion, distortions due to antisymmetrical bending, and distortions due to antisymmetrical torsion are provided.
Date:
April 1950
Creator:
Zender, George W. & Heldenfels, Richard R.
System:
The UNT Digital Library
On the Continuation of a Potential Gas Flow Across the Sonic Line
"Simple, sufficient conditions are given under which a two-dimensional steady compressible flow can be continued across the line of Mach number 1 as a continuous supersonic flow. Methods for the actual computation of the flow are described. The problem is of importance in the theory of transonic flows past airfoils" (p. 1).
Date:
April 1950
Creator:
Bers, Lipman
System:
The UNT Digital Library
Method of Experimentally Determining Radial Distributions of Velocity Through Axial-Flow Compressor
Note presenting a method by which the energy and continuity relations are simultaneously solved to express the velocity distributions downstream of any compressor blade row in terms of outlet total temperature, total pressure, and relative flow angle. The method is intended for use in units in which only a limited amount of experimental data can be obtained.
Date:
April 1950
Creator:
Finger, Harold B.
System:
The UNT Digital Library
Effect of tail surfaces on the base drag of a body of revolution at Mach numbers of 1.5 and 2.0
"Wind-tunnel tests were performed at Mach numbers of 1.5 and 2.0 to investigate the influence of tail surfaces on the base drag of a body of revolution without boattailing and having a turbulent boundary layer. The tail surfaces were of rectangular plan form of aspect ratio 2.33 and has symmetrical, circular-arc airfoil section. The results of the investigation showed that the addition of these tail surfaces with the trailing edges at or near the body base incurred a large increase in the base-drag coefficient. For a cruciform tail having a 10-percent-thick airfoil section, this increase was about 70 percent at a Mach number of 1.5 and 35 percent at a Mach number of 2.0" (p. 1).
Date:
April 1951
Creator:
Spahr, J. Richard & Dickey, Robert R.
System:
The UNT Digital Library