From Summary: "These properties compare favorably with those of the strongest similar alloys previously investigated. However, compared with a 60Cr-25Fe-15Mo alloy, the three cobalt-chronium-nickel cast alloys are inferior. A correlation of NACA and OSRD (Project NRC-8) data is presented, showing the variation of rupture strengths with temperature in the range of 1350^o to 2000^o for alloys."
"In the present paper, under the same lineaeizing assumptions as are made in the derivation in reference 1 but with the explicit consideration and simplification of the form of the wake extending from the rear of the airfoil, the methods of Theodorsen (reference 2) have been extended to obtain the forces on the airfoil not only at a fixed angle of attack but also in arbitrary motion" (p. 1).
Note presenting the performance of the turbine component of a research jet engine investigated with cold air. The interaction and matching of the turbine with the eight-stage compressor were computed with the combination considered as a jet engine and overall performance of the engine was then determined. Results regarding the performance of the first stator ring, turbine performance, and turbine-compressor matching are provided.
Note presenting an analysis that was undertaken as part of an investigation of low-density fibrous core materials for sandwich construction. This particular investigation found that honeycomb structure exhibit promise as core materials because of their high strength-weight ratios. A formula has been derived that considerably reduced the amount of testing necessary to evaluate the effectiveness of the materials.
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."
Investigations were made to develop a simplified method for designing exhaust-pipe shrouds to provide desired or maximum cooling of exhaust installations. Analysis of heat exchange and pressure drop of an adequate exhaust-pipe shroud system requires equations for predicting design temperatures and pressure drop on cooling air side of system. Present experiments derive such equations for usual straight annular exhaust-pipe shroud systems for both parallel flow and counter flow. Equations and methods presented are believed to be applicable under certain conditions to the design of shrouds for tail pipes of jet engines.
From Introduction: "The present paper contains the development of a recurrence formula for the bolt loads for the simplified case of a symmetrical butt joint with bolts spaced evenly in line with the applied load. The method presented herein is based on the fundamental relationship which was developed in reference 1 between the loads on any two successive bolts. The present paper also gives the results of an experimental investigation conducted to substantiate further the adequacy of the elastic theory as well as to yield additional data on the critical bolt load and the behavior of long joints in the plastic range and at the ultimate load."
The feasibility of measuring the vibration in the buckets of a gas turbine under service conditions of speed and temperature was determined by use of a high temperature wire strain gauge cemented to a modified supercharger turbine bucket. A high-temperature wire strain gauge and the auxiliary mechanical and electrical equipment developed for the investigation are described.
Report presenting an investigation made of the angle-of-attack-type loading for an elliptical wing of aspect ratio 4.5 in an attempt to augment existing methods of prediction of finite span angle-of-attack hinge-moment parameters.
"In conjunction with assumptions concerning the proportion of time spent at various speeds, statistical gust data were used to determine gust load factors that could be exceeded a given number of times during the operational life of an airplane. The results indicated that present gust load factors might be considerably lowered in certain cases with a consequent decrease in structural weight. Modification of the present criterion, however, must await the accumulation of data not presently available" (p. 1).
From Introduction: "The development of the measuring apparatus and techniques is presented herein. The application of the analogy to flows through nozzles and about circular cylinders at subsonic velocities extending into supercritical range is also presented."
Report presenting a summary of the hydrodynamic qualities of interest in the normal operation of a seaplane, established over a period of years by model testing and by some knowledge of full-size operation. Results regarding longitudinal stability and control, landing stability, seaworthiness, performances, and lateral stability and control are provided.
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."
Report presenting testing to determine the bearing strength characteristics of some magnesium-alloy sand castings and the relation between those and more commonly determined tensile properties. The primary sand-cast magnesium alloys of interest for aircraft design are AM403, AM260, and AM265. Results of all of the tension, compression, and shear tests are provided in tables.
Note presenting a method for the calculation of bending stresses due to torsion in a tapered box beam. A special taper was assumed in which all flanges, if extended, would meet at a point. The results obtained by this method were compared with experimental data obtained from tests performed on a tapered box beam.
Report presenting a determination of the tunnel-induced velocities for yawed and swept-back airfoils in a closed circular wind tunnel. Calculations were performed for elemental horseshoe vortices with one tip of the bound vortex on the tunnel axis for a range of yaw angles and bound-vortex lengths.
Note presenting boundary-layer momentum equations for the three-dimensional flow of a fluid with variable density and viscosity in a form similar to the momentum equation for two-dimensional flow. The momentum equations can be reduced to the forms of the three-dimensional momentum equations that have been given recently by Prandtl for a fluid with constant density and viscosity.
"The present paper evaluates the shear buckling stresses of rectangular flat plates with simply supported edges more accurately than previous work on this problem. Both symmetric (odd number of buckles) and antisymmetric (even number of buckles) patterns were considered. A curve is presented from which the critical stresses may be obtained when the dimensions of the plate are known" (p. 1).
"A simple approximate method is given for the calculation of isentropic irrotational flows past symmetrical airfoils, including mixed subsonic-supersonic flows. The method is based on the choice of suitable values for the streamline curvature in the flow field and the subsequent integration of the equations of motion. The method yields limiting solutions for potential flow. The effect of circulation is considered" (p. 1).
Note presenting a verification of previously derived equations for calculating the rate of heat transfer from airfoils in icing conditions, which have come about as a result of an investigation of the meteorological conditions conducive to the formation of ice on aircraft and a study of the process of airfoil thermal ice prevention. The results indicated that knowledge of these components has increased to a point where the design of heated wings on a fundamental, wet-air basis can now be undertaken with reasonable certainty.
Flight tests were made in natural icing conditions with two 8-ft-chord heated airfoils of different sections. Measurements of meteorological variables conducive to ice formation were made simultaneously with the procurement of airfoil thermal data. The extent of knowledge on the meteorology of icing, the impingement of water drops on airfoil surfaces, and the processes of heat transfer and evaporation from a wetted airfoil surface have been increased to a point where the design of heated wings on a fundamental, wet-air basis now can be undertaken with reasonable certainty.
Report presenting calculations of the supersonic wave drag at zero lift for a series of wings with thin symmetrical biconvex sections with untapered plan forms and various angles of sweepback and aspect ratios.
Note presenting a study of run-in and scuffed steel, chrome-plate, and cast-iron surfaces. X-ray and electronic diffraction techniques, micro-hardness determinations, and microscopy were used. The surface changes varied and wer efound to include three classes: chemical reaction, hardening, and crystallite-size alteration.
Solutions of the Hugoniot shock equations and Meyer expansion equations are plotted in such a manner as to permit the pressure distribution, the local Mach number, and the angles of shock waves on arbitrary sharp-nose airfoils at supersonic speeds to be obtained directly. (author).
Report presenting charts with coefficients for the stress analysis of a reinforced circular cylinder. They allow for the rapid determination of sheer flows and direct stresses in the sheet of a cylinder as well as the shear forces, axial forces, and bending moments in the rings. Separate charts are also given for three basic ring loadings.
Report presenting a set of charts for the convenient determination of flow conditions behind a shock wave and at the surface of inclined planes and axially symmetric cones located in a uniform frictionless supersonic air stream. Shock angle, static-pressure coefficient, static-pressure ratio, total-pressure ratio, Mach number ratio, and velocity ratio for two-dimensional and conical flow fields are plotted for a range of free-stream Mach numbers.
Report presenting a method for the calculation of the buckling stress of a multiweb wing in bending as well as design charts based on this method for the minimum-weight design of 24S-T aluminum alloy sheets, extruded 75S-T aluminum alloy, and extruded 0-1HTA magnesium alloy. An example of the use of the charts is also provided.
"In order to facilitate solutions of the general problem of helicopter selection, the aerodynamic performance of rotors is presented in the form of charts showing relations between primary design and performance variables. By the use of conventional helicopter theory, certain variables are plotted and other variables are considered fixed. Charts constructed in such a manner show typical results, trends, and limits of helicopter performance" (p. 1).
Report presenting an analysis of wind-tunnel data on the hinge-moment characteristics of control-surface tabs. Results regarding the correlation of section data, correlation of finite-span data, and effect of Mach number are provided.
Report presenting the aerodynamic characteristics of 19 isolated tail surfaces, which have been determined by wind tunnel tests. Testing was also made of rectangular airfoils of various aspect ratios with and without double end plates of various shapes. The analysis indicated that the slope of the lift curve could be predicted within 10 percent for all models by use of lifting-surface-theory equations.
Presented here are the summary charts of the collapsed results of general tank tests of about 100 flying boat hull models. These summary charts are intended to be used as an engineering tool to enable a flying boat designer to grasp more quickly the significance of various hull form parameters as they influence his particular airplane. The form in which the charts are prepared is discussed in some detail in order to make them clearer to the designer. This is a data report, and no attempt has been made to produce conclusions or correlations of the usual sort. However, some generalizations are put forward on the various methods in which summary charts may be used.
Column and plate compressive strengths of extruded 0-1HTA magnesium alloy were determined both within and beyond the elastic range from tests of flat end H-section columns and from local instability tests of H-, Z-, and channel section columns. These tests are part of an extensive research investigation to provide data on the structural strength of various aircraft materials. The results are presented in the form of curves and charts that are suitable for use in the design and analysis of aircraft structures.
Report presenting an investigation of the effect of diffuser performance of the passage curvature of two vaneless diffusers designed with a 6 degree equivalent-cone divergence angle along a logarithmic-spiral path in combination with two mixed-flow impellers. The peak of overall adiabatic efficiency is compared with the corresponding diffuser efficiency. Results regarding the variation of diffuser efficiency with load-coefficient parameter and peak overall adiabatic efficiencies and corresponding diffuser efficiencies of the two compressors are provided.
Note presenting analytical comparisons of weights and volumes for flat-plate heat exchangers with the same calculated thermal output and friction pressure drop for three different fin configurations, including no fins, fins in both the air and exhaust gas passages, and fins in the air passages only. Two different heat exchangers were used and compared with predicted weights and volumes.
Note presenting an investigation to compare the 14S-T with 24S-T in extruded stiffeners for stiffened flat sheet panels. The tests were made with stiffened flat sheet panels with three hat-shape stiffeners. Data is provided on the strength of the two alloys as well as the effect of sheet thickness on relative stiffener strengths.
Report presenting an investigation in the stability tunnel on two semispan swept-wing models to determine experimentally the span-load distributions and to compare the experimental and theoretical results. Lift, drag, pitching moment, and stalling characteristics are provided.
Note presenting an investigation to compare the crystal structure of the predominant phase at temperatures of 1200, 1500, and 1800 degrees Fahrenheit in 10 wrought heat-resisting alloys with crystal structure observed at room temperature. The alloys investigated included S-816, S-590, Hastelloy B, 19-9 W-Mo, N-155, 16-25-6, K-42-B, Inconel X, Nimonic 80, and type 347 stainless steel.
Report presenting a comparison of the maximum amount of transverse righting moment at rest provided by auxiliary floats or stub wings for 25 seaplanes and the minimum righting moment required by certain design specifications. Large differences were found to exist between the specifications and 25 designs studied.
Report presenting a flight investigation of a scout-bomber airplane with 4.7 degrees and 10 degree geometric dihedral in the wing outer panels in order to obtain flight test results pertaining to the upper limit of the wing-dihedral angle for satisfactory handling qualities. No unusual or undesirable lateral control characteristics were observed with the combinations of stability parameters obtained with the two dihedral angles used.
Report presenting measurements of sound pressures for static conditions for two-blade, four-blade, and seven-blade propellers over a range of tip Mach numbers. Results regarding sound pressures and loudness are provided.
Report presenting an analysis of wind-tunnel data for two types of lateral-control system for large airplanes in order to determine the control-force characteristics and rolling effectiveness of each system. The two types of control systems explored are a spring-tab aileron and a combination spoiler and guide or pilot-aileron arrangement.
Theoretical analysts of lateral dynamic motion of tailless and conventional airplanes was made for fighter and heavy transport. Their reactions to a lateral gust and control power required by each for simple maneuvers were determined and compared. Both types of airplanes require almost identical aileron control power to perform a given maneuver; tailless airplane requires about 1-2 to 1-3 directional control power of conventional airplane. Tailless airplane also shows greatest displacement for a given disturbance and has least damping in oscillatory mode.
Report presenting the application of three methods for calculating span load distribution for five swept wings. The methods were examined to establish their relative accuracy and ease of application. While the Weissinger and Falkner methods were more useful for certain circumstances, there were no advantages noted with the Mutterperl method.
Note presenting comparisons of theoretical and experimental airfoil lift coefficients and pressure distributions made for two cascades of entrance vanes and three cascades of blower blades with NACA 6-series airfoils, and for one cascade of turbine blades. Results regarding the entrance vanes, blower blades, turbine blades, and possibilities of three-dimensional effects are provided.
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.
Report presenting results for a part of a test program on 24S-T aluminum-alloy flat compression panels with longitudinal formed hat-section stiffeners. This particular part of the program is concerned with panels in which the thickness of the stiffener material is equal to the thickness of the skin. Results regarding the hat-stiffened panels and a comparison of hat-stiffened and Z-stiffened panels are provided.
The results of calculations of the viscous and pressure drags of some two-dimensional supersonic airfoils at zero lift are presented. The results indicate that inclusion of viscous drag alters many previous results regarding the desirability of certain airfoil shapes for securing low drags at supersonic speeds. At certain Reynolds and Mach numbers, for instance, a circular-arc airfoil may theoretically have less drag than the previously advocated symmetrical wedge-shape profile; although under different conditions, the circular-arc airfoil may have a higher drag.
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.
Note presenting the rolling moments of one tapered wing and two geometrically similar wings in rolling flow with the wing stationary and in straight flow with forced rotation of the wing to obtain a correlation between the two methods of testing and to determine the rolling characteristics of the wings. The results showed that for unswept wings the rolling characteristics obtained by rotation of the air agreed with those obtained by forced rotation of the wing.
Note presenting an investigation of the buckling of a simply supported rectangular flat plate under combinations of shear and direct stress by means of an energy method. The critical combinations of stress for several length-width ratios were determined to an accuracy of about 1 percent in conjunction with a modified matrix iteration method. Results regarding the shear and longitudinal stress and shear and transverse stress are provided.
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