National Advisory Committee for Aeronautics (NACA) - 743 Matching Results

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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.
Considerations of the Total Drag of Supersonic Airfoil Sections: 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.
Investigations on Reductions of Friction on Wings, in Particular by Means of Boundary Layer Suction: Memorandum presenting investigation on reductions of friction on wings, especially by means of boundary-layer suction. The report is broken up into several sections, including: causes of transition, laminar profiles with the transition taking place, laminar boundary-layer suction, investigation of the laminar pressure increase, investigation of the slot flow for laminar boundary-layer suction with single slots, tests about keeping a boundary layer for high Reynolds laminar with the aid of boundary-layer suction, and an investigation of a slightly-cambered laminar suction profile of 10.5-percent thickness.
A flight investigation to increase the safety of a light airplane: Report presenting information about a series of modifications incorporated into light airplanes to increase safety, including decreasing the wing incidence, increasing the wing washout, increasing the area and aspect ratio of the horizontal and vertical tails, moving the elevators out of propeller slipstreams, depressing the thrust axis, and limiting the rudder travel. The new inherent safety characteristics and effects on the airplane's performance are provided.
Effect of Centrifugal Force on the Elastic Curve of a Vibrating Cantilever Beam: Report presenting the results of a study to determine the effect of rotation on the dynamic-stress distribution in vibrating cantilever beams. Both theoretical and experimental results are obtained by means of stroboscopic photographs and strain gauges. Both types of results indicated that the introduction of centrifugal force had no effect on the maximum dynamic-stress locations in a vibrating cantilever beam fixed at the center of rotation within the investigated speed range.
Boundary-Induced Upwash for Yawed and Swept-Back Wings in Closed Circular Wind Tunnels: 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.
Data on Optimum Length, Shear Strength, and Tensile Strength of Age-Hardened 17S-T Machine-Countersunk Rivets in 75S-T Sheet: Report presenting a series of tensile-strength and shear-strength tests made on age-hardened 17S-T rivets machine-countersunk in 75S-T sheets. The results of the tests indicated that the joints can be made satisfactorily with regard to both flushness and strength if the ratio of buck to diameter is kept to a certain value.
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.
The streamline pattern in the vicinity of an oblique airfoil: "A method for determining the streamwise flow pattern of a nonviscous incompressible fluid about an oblique airfoil from the corresponding flow pattern about the airfoil in normal position is presented and illustrated in two examples. The method can be extended to account approximately for compressibility effects by applying the Prandtl-Glauert correction factor to the flow pattern that is normal to the leading edge of the airfoil. The method is expected to be useful in determining the shape of a fuselage or nacelle having a minimum of interference with the flow over a swept-back wing" (p. 1).
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.
Experimental and calculated characteristics of several NACA 44-series wings with aspect ratios of 8, 10, and 12 and taper ratios of 2.5 and 3.5: The aerodynamic characteristics of seven unswept tapered wings were determined by calculation from two-dimensional data and by wind-tunnel tests in order to demonstrate the accuracy of the calculations and to show some of the effects of aspect ratio, taper ratio, and root thickness-chord ratio. The characteristics were calculated by the usual application of the lifting-line theory which assumes linear section lift curves and also by an application of the theory which allows the use of nonlinear lift curves. A correction to the lift for the effect of chord was made by using the Jones edge-velocity factor. The wings had aspect ratios of 8, 10, and 12, taper ratios of 2.5 and 3.5, and NACA 44-series airfoils.
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.
Column and Plate Compressive Strengths of Aircraft Structural Materials: Extruded 0-1HTA Magnesium Alloy: 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.
An investigation of the aerodynamic characteristics of a rotating axial-flow blade grid: Report presenting the results of an experimental investigation of the aerodynamic characteristics of a rotating axial-flow blade grid with pressure-increasing effect. Several techniques of measurement were used, including pressure distribution measurements, pitot tubes, and hot wire wake surveys. Results regarding the lift and pressure drag of the blade sections, aerodynamic characteristics of the blade sections, profile drag, and static pressure are provided.
Investigation of the Aileron and tab of a spring-tab lateral-control system in the Langley 19-foot pressure tunnel: Report presenting tests of a partial-span model of a large bomber-type airplane, which were conducted to provide data on the aerodynamic characteristics of the aileron-tab arrangement and of the wing. Testing occurred to determine the rolling-moment, yawing-moment, and hinge-moment characteristics of the aileron and tab and the effect of midchord wing slots on the characteristics of the wing and aileron and tab. Results regarding the aerodynamic and stalling characteristics of the wing and aerodynamic characteristics of the aileron and tab are provided.
Notes and Tables for Use in the Analysis of Supersonic Flow: Paper presenting a compilation of formulas, tables, and curves that have been found to be useful in the analysis of supersonic wind-tunnel data.
Foaming Volume and Foam Stability: "A method of measuring foaming volume is described and investigated to establish the critical factors in its operation. Data on foaming volumes and foam stabilities are given for a series of hydrocarbons and for a range of concentrations of aqueous ethylene-glycol solutions. It is shown that the amount of foam formed depends on the machinery of its production as well as on properties of the liquid, whereas the stability of the foam produced, within specified mechanical limitations, is primarily a function of the liquid" (p. 1).
Flight Measurements of the Lateral Control Characteristics of Narrow-Chord Ailerons on the Trailing Edge of a Full-Span Slotted Flap: Note presenting results of flight tests made to determine the effect of flap deflection on the lateral control characteristics of a modified Brewster F2A-2 airplane equipped with partial-span narrow-chord ailerons on the trailing edge of a full-span NACA slotted flap. The results indicated that the effectiveness of the ailerons was greatly reduced at flap deflections greater than about 20 degrees.
A Comparison of the Lateral Motion Calculated for Tailless and Conventional Airplanes: 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.
Two-dimensional wind-tunnel investigation of a 10.7-percent-thick symmetrical tail section with a 0.40 airfoil-chord control surface and a 0.20 control-surface-chord tab: Report presenting an investigation of a 10.7-percent-thick symmetrical tail section equipped with a flat-side airfoil-chord flap with a flap-chord overhang and a plain flap-chord tab. Airfoil lift, drag, pitching-moment, and flap and tab hinge-moment characteristics were determined at various flap and tab deflections.
Tentative Tables for the Properties of the Upper Atmosphere: Note presenting three temperature-height relationships and one composition-height relationship developed by the NACA and tables based on them for pertinent properties of the upper atmosphere. Two sets of tables based on the adopted tentative standard specifications for the upper atmosphere are presented.
Experimental Investigation of the Stress Distribution Around Reinforced Circular Cut-Outs in Skin Stringer Panels Under Axial Loads: Note presenting results of strain surveys around four reinforced circular cut-outs successively made in an axially loaded skin-stringer tension panel. Curves are presented which show the distribution of stringer and shear stresses in the panel and bending stresses in the reinforcing rings.
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."
Frequency-Response Method for Determination of Dynamic Stability Characteristics of Airplanes With Automatic Controls: Note presenting a frequency-response method for determining the critical control-gearing and hunting oscillations of airplanes with automatic pilots. The method is graphical and has several advantages over the standard numerical procedure based on Routh's discriminant. Several examples are worked out to illustrate the application of the frequency-response method in determining the effect of automatic-pilot lag or lead on critical control gearing and in determining the amplitude and frequency of hunting.
Investigations of Free Turbulent Mixing: Note presenting a discussion of the integral relations for flow of the boundary-layer type. It is shown that the characteristic laws of spread of jets, wakes, and so forth, can be obtained directly for the laminar case and, with the help of dimensional reasoning, for the turbulent case as well. Measurements of the mean velocity, the intensity and scale of the turbulent fluctuations, and of the turbulent shear in a two-dimensional mixing zone are presented.
Performance of axial-flow fan and compressor blades designed for high loadings: Report presenting an investigation to determine the effects of loading on the performance of axial-flow fan and compressor blades in a test blower. Results regarding verification of the two-dimensional design data and effects of blade roughness are provided.
Experimental Verification of Two Methods for Computing the Take-Off Ground Run of Propeller-Driven Aircraft: Note presenting a comparison between the measured take-off ground run of an airplane equipped with seven different propeller-engine gear-ratio combinations and the computed distances by two different methods. Results indicated that the values of ground run calculated by Diehl's approximate method checked experimental values with 7 percent but were in error as much as 10 to 15 percent under certain conditions. Improved methods of thrust computation may be required in order to avoid large errors and before any more rigorous methods can be substituted for Diehl's method.
Effect of brake forming in various tempers on the strength of Alclad 75S-T aluminum-alloy sheet: Results are presented of tests to determine the effect of brake forming in various tempers on the strength of Alclad 75S-T aluminum alloy sheet in the direction parallel to the brake. The tensile and compressive strengths of Alclad 75S-T sheet, formed in the O and W tempers, were either increased or little affected compared with those of similarly treated unformed material. When Alclad 75S-T sheet 'as received' was formed, however, the tensile yield stress was reduced about 7 percent for the with-grain direction and 1 percent for the cross-grain direction, whereas the tensile ultimate and compressive yield stresses were increased somewhat. The elongation was always slightly reduced as a result of forming.
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.
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."
Interference of Wing and Fuselage From Tests of 30 Combinations With Triangular and Elliptical Fuselages in the NACA Variable-Density Tunnel: Note presenting tests of 12 wing-fuselage combinations employing triangular and 18 employing elliptical fuselages made in the NACA variable-density tunnel as part of a program to investigate at large values of Reynolds number the aerodynamic effects of wing-fuselage interference. The parameters of combination covered in the investigation were the vertical position of the wing with respect to the fuselage axis, wing shape, and wing-fuselage juncture shape.
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.
Preliminary Analysis of NACA Measurements of Atmospheric Turbulence Within a Thunderstorm - U.S. Weather Bureau Thunderstorm Project: "A general description of the field operations of the U.S. Weather Bureau thunderstorm project conducted in the vicinity of Orlando, Florida during the summer month of 1946 is given. The participation of NACA in this project is described and measurements of atmospheric turbulence taken by NACA are presented for one of the flights. The results indicate that some regions of thunderstorms may present no great hazard to flight, while exceptionally severe conditions of atmospheric turbulence may occur in other regions, or even in the same region, at about the same time" (p. 1).
In-line aircraft-engine bearing loads 3: main-bearing loads: Report presenting the application of dimensional analysis to the computation of the main bearing of a V-type in-line aircraft engine. Two crankshafts have been considered, one designed for higher operating speed than the other. Two types of engines are considered: one for regular V-type engines and one for production V-type engines.
Meteorological Conditions Associated With Flight Measurements of Atmospheric Turbulence: "The results obtained from a series of flight measurements of atmospheric turbulence within convective-type clouds and from meteorological soundings are presented together with descriptions of the flights and concurrent weather conditions. These results are presented to provide a background of experience for the forecaster and pilot by illustrating the turbulence conditions as indicated by effective gust velocities in convective-type clouds under spring and summer weather conditions along the eastern coast of the United States" (p. 1).
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.
A Lifting-Surface-Theory Solution and Tests of an Elliptic Tail Surface of Aspect Ratio 3 with a 0.5-Chord 0.85-Span Elevator: Note presenting an electromagnetic-analogy model of the vortex load, estimated from lifting-line theory with an arbitrary fairing near the elevator tip, on a thin elliptic horizontal tail surface of aspect ratio 3 with a 0.5-chord 0.85-span plain elevator was constructed and tested. A comparison of the aspect-ratio corrections for the partial-span elevators was made with those previously presented for full-span elevators. Wind-tunnel results for a tail surface of the some plan form are presented.
Measurements of the Pressure Distribution on the Horizontal Tail Surface of a Typical Propeller-Driven Pursuit Airplane in Flight 2: The Effect of Angle of Sideslip and Propeller Operation: Report presenting measurements in sideslipping flight of the pressure distribution over the horizontal tail surface of a tractor-propeller-driven pursuit airplane to determine the effects of angle of sideslip and propeller operation on the tail-load distribution. Results regarding the reduction of data, effect of sideslip and power on tail loads, effect of sideslip and power on tail moments, and a comparison of the calculated loading with experimental results.
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.
Flight investigation of the effects on airplane static longitudinal stability of a bungee and engine-tilt modifications: Report presenting flight tests to evaluate an elevator stick-force bungee and engine tilt as methods of improving the longitudinal-control characteristics of an existing airplane. The stick-force bungee was found to be the simplest and most effective modification.
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.
The Effect of Changing the Ratio of Exhaust-Valve Flow Capacity to Inlet-Valve Flow Capacity on Volumetric Efficiency and Output of a Single-Cylinder Engine: Report presenting a series of tests with a single-cylinder engine in order to determine the effect on volumetric efficiency and on engine performance of changing the ratio of exhaust-valve flow capacity to inlet-valve flow capacity when operating with exhaust pressure equal to inlet pressure.
Effect of changing manifold pressure, exhaust pressure, and valve timing on the air capacity and output of a four-stroke engine operated with inlet valves of various diameters and lifts: Report presenting a series of tests made with a CFR engine to determine the effect of inlet-valve capacity, inlet and exhaust pressure, and valve timing on the volumetric efficiency at various speeds. Three combinations of inlet and exhaust pressures and seven valve-timing arrangements were used.
Hinge-moment characteristics of balanced elevator and rudder for a specific tail configuration on a fuselage in spinning attitudes: Report presenting the results of an investigation of a specific tail configuration in the 15-foot free-spinning tunnel in order to supplement the existing published data on hinge moments of elevators and rudders in spins. Hinge-moment measurements are presented for a balanced elevator equipped with trim tabs and for a balanced rudder. Results regarding elevator hinge moments, rudder hinge moments, and application of hinge-moment data are provided.
Effect of exhaust pressure on the performance of a 12-cylinder liquid-cooled engine: Report presenting a dynamometer-stand investigation to determine the effect of exhaust pressure on the performance of a 12-cylinder liquid-cooled aircraft engine equipped with a conventional exhaust collector. The results are presented in the form of curves that show the effect of exhaust pressure on engine power, charge-air flow, volumetric efficiency, inlet-manifold mixture temperature, exhaust-gas temperature, cylinder-head temperature, and heat rejected to the coolant.
Theoretical and experimental data for a number of NACA 6A-series airfoil sections: Report presenting theoretical and experimental data for NACA 6A-series basic thickness airfoils, which were designed to eliminate the trailing-edge cusp present in NACA 6-series sections. Results indicated that the section minimum-drag and maximum-lift characteristics of the 6-series and 6A-series airfoil sections are essentially the same. Drag, lift, pitching-moment characteristics, and aerodynamic center are also provided.
Effect of Geometric Dihedral on the Aerodynamic Characteristics of Two Isolated Vee-Tail Surfaces: Note presenting force tests of two isolated vee-tail surfaces with various amounts of dihedral made to provide an experimental verification of a simplified vee-tail theory and the results are presented which were found to be in good agreement with calculations of previous reports. Plots of the basic test data and summaries of the data in the form of plots of the variation of static-stability derivatives and control-effectiveness parameters with dihedral angle are included.
Correlation of Experimental and Calculated Effects of Product of Inertia on Lateral Stability: 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.
Charts for the Determination of Supersonic Air Flow Against Inclined Planes and Axially Symmetric Cones: 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.
Experimental Studies of the Knock-Limited Blending Characteristics of Aviation Fuels 2: Investigation of Leaded Paraffinic Fuels in an Air-Cooled Cylinder: Note presenting the relation between knock limit and blend composition of selected aviation fuel components individually blended with virgin base and with alkylate as determined in a full-scale air-cooled aircraft-engine cylinder. Results regarding mixture-response curves, relation of knock limit to blend composition, and correlation of knock ratings are provided.

National Advisory Committee for Aeronautics (NACA) - 743 Matching Results

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