National Advisory Committee for Aeronautics (NACA) - 819 Matching Results
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- Achievement of Continuous Wall Curvature in Design of Two-Dimensional Symmetrical Supersonic Nozzles
- "Auxiliary boundary conditions are derived to assure continuity of wall curvature in applying the method of characteristics to the design of two-dimensional symmetrical supersonic nozzles. An illustrative example is included" (p. 1).
- Airfoil profiles for minimum pressure drag at supersonic velocities -- general analysis with application to linearized supersonic flow
- From Summary: "A theoretical investigation is made of the airfoil profile for minimum pressure drag at zero lift in supersonic flow. In the first part of the report a general method is developed for calculating the profile having the least pressure drag for a given auxiliary condition, such as a given structural requirement or a given thickness ratio. To illustrate the general method, the optimum airfoil, defined as the airfoil having minimum pressure drag for a given auxiliary condition, is calculated in a second part of the report using the equations of linearized supersonic flow."
- An Approximate Method of Calculating the Deformations of Wings Having Swept, M or W, A, and Swept-Tip Plan Forms
- "An approximate method of calculating the deformations of wings of uniform thickness having swept, M or W, Delta, and swept-tip plan forms is presented. The method employs an adjustment to the elementary beam theory to account for the effect of the triangular root portion of a swept wing on the deformation of the outboard section of the wing. To demonstrate the general applicability of the method, the modified elementary theory is applied to the more complex M or W, Delta, and swept-tip plan forms as well as to swept plan forms" (p. 1).
- Axisymmetric Supersonic Flow in Rotating Impellers
- "General equations are developed for isentropic, frictionless, axisymmetric flow in rotating impellers with blade thickness taken into account and with blade forces eliminated in favor of the blade-surface function. It is shown that the total energy of the gas relative to the rotating coordinate system is dependent on the stream function only, and that if the flow upstream of the impeller is vortex-free, a velocity potential exists which is a function of only the radial and axial distances in the impeller. The characteristic equations for supersonic flow are developed and used to investigate flows in several configurations in order to ascertain the effect of variations of the boundary conditions on the internal flow and the work input" (p. 1).
- Behavior of vortex system behind cruciform wings - motions of fully rolled-up vortices
- An investigation and analysis of the motions of four fully rolled-up vortices representing the vortex system trailing behind cruciform wings by theoretical and visual-flow methods. Equations are developed for the three-dimensional paths traced by the vortices behind a cruciform wing banked 45 degrees, and calculations are made of the distance behind the wing at which the upper two vortices pass through the lower two.
- Buckling of rectangular sandwich plates subjected to edgewise compression with loaded edges simply supported and unloaded edges clamped
- Report presenting the compressive stress for buckling for a rectangular flat sandwich plate with loaded edges simply supported and unloaded edges rigidly clamped. The true values of the buckling stress are estimated as the arithmetic means of these bounds and are presented in a diagram which covers the entire practical range of the geometric and mechanical quantities involved.
- The Calculated and Measured Performance Characteristics of a Heated-Wire Liquid-Water-Content Meter for Measuring Icing Severity
- "Ground tests have been made of an instrument which, when assembled in a more compact form for flight installation, could be used to obtain statistical flight data on the liquid-water content of icing clouds and to provide an indication of icing severity. The sensing element of the instrument consists of an electrically heated wire which is mounted in the air stream. The degree of cooling of the wire resulting from evaporation of the impinging water droplets is a measure of the liquid-water content of the cloud" (p. 1).
- Calculation of aerodynamic forces on a propeller in pitch or yaw
- An analysis was made to determine the applicability of existing propeller theory and the theory of oscillating airfoils to the problem of determining the magnitude of the forces on propellers in pitch or yaw. Strip calculations using compressible airfoil characteristics were first made as though steady-state conditions existed successively at several blade positions of the propeller blades during one revolution. A theory of oscillating airfoils in pulsating incompressible potential flow was then considered from which it was possible to determine factors which would modify the steady-state forces.
- Calculations on the forces and moments for an oscillating wing-aileron combination in two-dimensional potential flow at sonic speed
- Report presenting the use of linearized theory for compressible unsteady flow to obtain the velocity potential and lift and moment for a thin, harmonically oscillating, two-dimensional wing-aileron combination moving at sonic speed.
- Comparison of High-Speed Operating Characteristics of Size 215 Cylindrical-Roller Bearings as Determined in Turbojet Engine and in Laboratory Test Rig
- A comparison of the operating characteristics of 75-millimeter-bore (size 215) cylindrical-roller one-piece inner-race-riding cage-type bearings was made by means of a laboratory test rig and a turbojet engine. Cooling correlation parameters were determined by means of dimensional analysis, and the generalized results for both the inner- and the outer-race bearing operating temperatures are computed for the laboratory test rig and the turbojet engine. A method is given that enables the designer to predict the inner- and outer-race turbine roller-bearing temperatures from single curves, regardless of variations in speed, load, oil flow, oil inlet temperature, oil inlet viscosity, oil-jet diameter, or any combination of these parameters.
- Compressive buckling of simply supported curved plates and cylinders of sandwich construction
- From Summary: "Theoretical solutions are presented for the buckling in uniform axial compression of two types of simply supported curved sandwich plates: the corrugated-core type and the isotropic-core type. The solutions are obtained from a theory for orthotropic curved plates in which deflections due to shear are taken into account. Results are given in the form of equations and curves."
- Concerning the Flow About Ring-Shaped Cowlings of Finite Thickness: Part 1
- "It is shown how one may obtain, in a simple manner, the forms of ring-shaped bodies from existing tables of functions according to the customary method of superposition of flow due to singularities and parallel flow. A number of examples of the forms and pressure distributions of annular source bodies with and without hub body are given, and the inlet conditions of such ring-shaped cowlings are investigated. Furthermore, the annular bodies of finite length are indicated that correspond to Joukowsky profiles for the two-dimensional case" (p. 1).
- Design of two-dimensional channels with prescribed velocity distribution along the channel walls 1: relaxation solutions
- Report presenting a general method of design is developed for two-dimensional unbranched channels with prescribed velocities as a function of arc length along the channel walls. The method is developed for both incompressible and compressible, irrational, nonviscous flow. Five numerical examples are given including three elbow designs with the same prescribed velocity as a function of arc length along the channel walls but with incompressible, linearized compressible, and compressible flow.
- Detailed Computational Procedure for Design of Cascade Blades With Prescribed Velocity Distributions in Compressible Potential Flows
- "A detailed step-by-step computational outline is presented for the design of two-dimensional cascade blades having a prescribed velocity distribution on the blade in a potential flow of the usual compressible fluid. The outline is based on the assumption that the magnitude of the velocity in the flow of the usual compressible nonviscous fluid is proportional to the magnitude of the velocity in the flow of a compressible nonviscous fluid with linear pressure-volume relation" (p. 1).
- Direct Measurements of Skin Friction
- Note presenting a device developed to measure local skin friction on a flat plate by measuring the force exerted upon a very small movable part of the surface of a flat plate. The device is applied to both low-speed and high-speed measurements. The paper describes the design and construction of the device and the results of the measurements.
- Ditching Investigation of a 1/12-Scale Model of the Douglas F3D-2 Airplane, TED No. NACA DE 381
- "An investigation of a 1/12- scale dynamically similar model of the Douglas F3D-2 airplane was made in calm water to observe the ditching behavior and to determine the safest procedure for making an emergency water landing. Various conditions of damage were simulated to determine the behavior which probably would occur in a full-scale ditching. The behavior of the model was determined from motion-picture records, time- history acceleration records, and visual observations" (p. 1).
- Effects of compressibility on the performance of two full-scale helicopter rotors
- Report presents the results of an investigation conducted on the Langley helicopter test tower to determine experimentally the effects of compressibility on the performance and blade pitching moments of two full-scale helicopter rotors. Two sets of rotor blades were tested which differed only in that the blades of one set incorporated -8 degrees of linear twist, whereas the blades of the other set were untwisted. The tests covered a range of tip speeds from 350 to 770 feet per second and a range of pitch angles from 0 degrees to the limit imposed by extreme vibration.
- The effects of Reynolds number on the application of NACA 16-series airfoil characteristics to propeller design
- Report presenting an analysis of airfoil data from several NACA 16-series propeller airfoils from tests of 5-inch chord models in the 24-inch high-speed tunnel and 12-inch-chord models in the 8-foot high-speed tunnel. Results indicated that differences of less than 1 percent in propeller efficiency at or near the design condition will be involved in applying data from 5-inch-chord and 12-inch-chord airfoil tests to full-scale propeller design.
- Electrical Pressure Integrator
- Note presenting the design of an instrument utilizing Wheatstone bridge type of pressure sensing units that is capable of integration of airfoil pressures into a quantity representative of the normal force and pitching moment acting on the airfoil. Flight and wind-tunnel versions of the instrument are briefly described along with samples of test data obtained from them.
- Equal-Strength Design of Tension-Field Webs and Uprights
- Note presenting a method for proportioning thin-web beams to attain equal strength of web and uprights which may in turn be employed toward optimum design of these components. Improved empirical formulas for this purpose are developed the results checked by experimental loading of six beams.
- Estimate of Slip Effect on Compressible Laminar-Boundary-Layer Skin Friction
- Note presenting a consideration of Rayleigh's problem for a compressible viscous gas, subject to slip at the wall. Expressions for slip velocity and skin friction are derived with the gas temperature at the wall and the product of viscosity times density assumed constant, or nearly so. The results of the solution are interpreted to define the border region between continuum and slip flow and to estimate the effect of slip.
- Experimental Aerodynamic Derivatives of a Sinusoidally Oscillating Airfoil in Two-Dimensional Flow
- "Experimental measurements of the aerodynamic reactions on a symmetrical airfoil oscillating harmonically in a two-dimensional flow are presented and analyzed. Harmonic motions include pure pitch and pure translation, for several amplitudes and superimposed on an initial angle of attack, as well as combined pitch and translation. The apparatus and testing program are described briefly and the necessary theoretical background is presented" (p. 1).
- Experimental Determination of the Effect of Horizontal-Tail Size, Tail Length, and Vertical Location on Low-Speed Static Longitudinal Stability and Damping Pitch of a Model Having 45 Degree Sweptback Wing and Tail Surfaces
- Report presents the results of an investigation conducted in the Langley stability tunnel to determine the effects of horizontal tails of various sizes and at various tail lengths (when loaded on the fuselage center line) and also the effects of vertical location of the horizontal tail relative to the wing on the low-speed static longitudinal stability and on the steady-state rotary damping in pitch for a complete-model configuration. The wing and tail surfaces had the quarter-chord lines swept back 45 degrees and had aspect ratios of 4.
- Experimental Determination of Time Constants and Nusselt Numbers for Bare-Wire Thermocouples in High-Velocity Air Streams and Analytic Approximation of Conduction and Radiation Errors
- Report presenting the results of experiments conducted to determine time constants of several bare-wire thermocouples mounted in cross flow to an air stream. Four pairs of common thermocouple materials with three different wire diameters were used. Results regarding the time constants, Nusselt numbers, effective gas temperature, and some numerical calculations are provided.
- An Experimental Investigation of Transonic Flow Past Two-Dimensional Wedge and Circular-Arc Sections Using a Mach-Zehnder Interferometer
- Report presents the results of interferometer measurements of the flow field near two-dimensional wedge and circular-arc sections of zero angle of attack at high-subsonic and low-supersonic velocities. Both subsonic flow with local supersonic zone and supersonic flow with detached shock wave have been investigated. Pressure distributions and drag coefficients as a function of Mach number have been obtained.
- Flight investigation of a mechanical feel device in an irreversible elevator control system of a large airplane
- Report presents the results of measurements of the longitudinal stability and control characteristics of a large airplane using a mechanical feel device in combination with a booster incorporated in the elevator-control system. Tests were made to investigate the feasibility of eliminating the aerodynamic control forces through use of a booster and of providing control-feel forces mechanically. The feel device consisted of a centering spring which restrained the control stick through a linkage which was changed as a function of the dynamic pressure. Provisions were made for trimming and for manual adjustment of the force gradient. The system was designed to approximate the control-force characteristics that would result with a conventional elevator control with linear hinge-moment characteristics.
- Free-Spinning-Tunnel Investigation of a 1/24-Scale Model of the Grumman F9F-6 Airplane: TED No. NACA DE 364
- From Summary: "An investigation of a 1/24-scale model of the Grumman F9F-6 airplane has been conducted in the Langley 20-foot free-spinning tunnel. The erect and inverted spin and recovery characteristics of the model were determined for the normal flight loading with the model in the clean condition. The effect of loading variations was investigated briefly. Spin-recovery parachute tests were also performed."
- Fundamental effects of cold-work on some cobalt-chromium-nickel-iron base creep-resistant alloys
- Report presenting an investigation of the influence of cold-working on the creep properties of an alloy containing 20 percent cobalt, 20 percent chromium, 20 percent nickel, and balance iron and on the same alloy modified by small additions of tungsten alone or tungsten, molybdenum, and columbium in combination. The effects of cold-working were the same on all alloys studied. Results regarding the amount of cold reduction for maximum creep resistance, diffraction lines, stress relaxation properties, and properties of similarity across all alloys are provided.
- General Consideration of Problems in Compressible Flow Using the Hodograph Method
- Report presenting an investigation of the hodograph method as it is applied in general to the problem of compressible flow.
- A General Theory of Three-Dimensional Flow in Subsonic and Supersonic Turbomachines of Axial-, Radial-, and Mixed-Flow Types
- Note presenting a general theory of steady three-dimensional flow of a nonviscous fluid in subsonic and supersonic turbomachines with arbitrary hub and casing shapes and a finite number of blades. The equations obtained to describe the fluid flow on these stream surfaces show clearly the several approximations involved in ordinary two-dimensional treatments.
- Hydrodynamic Characteristics of a Low-Drag, Planing-Tail Flying Boat Hull
- Note presenting the hydrodynamic characteristics of a flying boat incorporating a low-drag, planing-tail hull as determined from model tests made in tank no. 2 and compared with tests of the same flying boat incorporating a conventional type of hull. The planing-tail model had a greater range of elevator deflection and center-of-gravity location for stable take-offs than did the conventional model.
- An Impulse-Momentum Method for Calculating Landing-Gear Contact Conditions in Eccentric Landings
- "An impulse-momentum method for determining impact conditions for landing gears in eccentric landings is presented. The analysis is primarily concerned with the determination of contact velocities for impacts subsequent to initial touchdown in eccentric landings and with the determination of the effective mass acting on each landing gear. These parameters determine the energy-absorption requirements for the landing gear and, in conjunction with the particular characteristics of the landing gear, govern the magnitude of the ground loads" (p. 1).
- Investigation of hydrocarbon ignition
- From Summary: "Accurate spotaneous ignition temperatures have been determined for some 50 pure organic compounds. The effects of a wide variety of additives and of eight selected metals on the spontaneous-ignition-temperature values of representatives of this group also have been observed. Results are correlated with chemical structure and with antiknock characteristics where known; more fundamental aspects of the possible chain-breaking and chain-branching reactions involved are also considered."
- Investigation of Laminar Boundary Layer in Compressible Fluids Using the Crocco Method
- Note presenting the use of the Crocco method to solve the simultaneous differential equations of momentum and energy involved in the flow of air in a thin laminar boundary layer on a flat plate. The Crocco method was used because it gave accurate results for arbitrary Prandtl number near unity. Variations of shear, velocity, temperature, and Mach number across the boundary layer are included.
- An Iterative Transformation Procedure for Numerical Solution of Flutter and Similar Characteristics-Value Problems
- "An iterative transformation procedure suggested by H. Wielandt for numerical solution of flutter and similar characteristic-value problems is presented. Application of this procedure to ordinary natural-vibration problems and to flutter problems is shown by numerical examples. Comparisons of computed results with experimental values and with results obtained by other methods of analysis are made" (p. 1).
- Landing characteristics in waves of three dynamic models of flying boats
- Powered models of three different flying boats were landed in oncoming waves of various heights and lengths. The effects of varying the trim at landing, the deceleration after landing, and the size of the waves were determined. Data are presented on the motions and accelerations obtained during landings in rough water.
- On a Solution of the Nonlinear Differential Equation for Transonic Flow Past a Wave-Shaped Wall
- "The Prandtl-Busemann small-perturbation method is utilized to obtain the flow of a compressible fluid past an infinitely long wave-shaped wall. When the essential assumption for transonic flow (that all Mach numbers in the region of flow are nearly unity) is introduced, the expression for the velocity potential takes the form of a power series in the transonic similarity parameter. On the basis of this form of the solution, an attempt is made to solve the nonlinear differential equation for transonic flow past the wavy wall" (p. 1).
- One-dimensional compressible flow in vaneless diffusers of radial- and mixed-flow centrifugal compressors, including effects of friction, heat transfer and area change
- Report presenting an analysis method and a design method for one-dimensional, compressible flow with friction, heat transfer, and area change in vaneless diffusers with arbitrary profiles in the axial-radial plane. The effects of mixing losses due to nonuniform flow conditions at the impeller discharge are not considered.
- Orientation of orifices on bodies of revolution for determination of stream static pressure at supersonic speeds
- Report presenting experimental data obtained in the 4- by 4-foot supersonic tunnel for a parabolic body of revolution of large fineness ratio at mach number 1.59, which are analyzed in order to locate positions at which static-pressure orifices will indicate a constant static pressure independent of the pitch-yaw attitude of the body.
- Preliminary Investigation of a New Type of Supersonic Inlet
- "A supersonic inlet with supersonic deceleration of the flow entirely outside of the inlet is considered a particular arrangement with fixed geometry having a central body with a circular annular intake is analyzed, and it is shown theoretically that this arrangement gives high pressure recovery for a large range of Mach number and mass flow and, therefore, is practical for use on supersonic airplanes and missiles. Experimental results confirming the theoretical analysis give pressure recoveries which vary from 95 percent for Mach number 1.33 to 86 percent for number 2.00. These results were originally presented in a classified document of the NACA in 1946" (p. 1).
- Preliminary Results Obtained from Flight Test of a 1/7-Scale Rocket-Powered Model of the Grumman XF10F Airplane Configuration in the Swept-Wing Condition, TED No. NACA DE 354
- "A flight investigation of a 1/7-scale rocket-powered model of the XF10F Grumman XF10F airplane in the swept-wing configuration has been made. The purpose of this test was to determine the static longitudinal stability, damping in pitch, and longitudinal control effectiveness of the airplane with the center of gravity at 20 percent of the wing mean aerodynamic chord. Only a small amount of data was obtained from the test because, immediately after booster separation at a Mach number of 0.88, the configuration was directionally unstable and diverged in sideslip" (p. 1).
- Single-degree-of-freedom-flutter calculations for a wing in subsonic potential flow and comparison with an experiment
- The effect of Mach number and structural damping on single-degree-of-freedom pitching of a wing is presented. Some experimental results are compared with theory and good agreement is found for certain ranges of an inertia parameter.
- Some effects of varying the damping in pitch and roll on the flying qualities of a small single-rotor helicopter
- Report presenting flight-test measurements and pilots' opinions of the longitudinal flying qualities and lateral control characteristics of a small single-rotor helicopter. The damping of the helicopter in pitch and roll was varied by means of a rate-sensitive automatic-control device from the device inoperable to nearly three times that amount. Results regarding the determination of damping, pull-up time histories, time for curve of acceleration to become concave downward in pull-ups, longitudinal oscillations, and lateral control are provided.
- Stresses in a Two-Bay Noncircular Cylinder Under Transverse Loads
- A method, taking into account the effects of flexibility and based on a general eighth-order differential equation, is presented for finding the stresses in a two-bay, noncircular cylinder the cross section of which can be composed of circular arcs. Numerical examples are given for two cases of ring flexibility for a cylinder of doubly symmetrical (essentially elliptic) cross section, subjected to concentrated radial, moment, and tangential loads. The results paralleled those already obtained for shells with circular rings.
- A Study of Poisson's Ratio in the Yield Region
- "In the yield region of the stress-strain curve the variation in Poisson's ratio from the elastic to the plastic value is most pronounced. This variation was studied experimentally by a systematic series of tests on several aluminum alloys. The tests were conducted under simple tensile and compressive loading along three orthogonal axes" (p. 1).
- A Theoretical Analysis of the Effects of Fuel Motion on Airplane Dynamics
- "The general equations of motion for an airplane with a number of spherical fuel tanks are derived. The motion of the fuel is approximated by the motion of solid pendulums. The same type of derivation and equations are shown to apply to any type of fuel tank where the motion of the fuel may be represented in terms of undamped harmonic oscillators. Motions are calculated for a present-day high-speed airplane and a free-flying airplane model with two spherical tanks in the symmetry plane" (p. 1).
- Theoretical Damping in Roll and Rolling Moment Due to Differential Wing Incidence for Slender Cruciform Wings and Wing-Body Combinations
- "A method of analysis based on slender-wing theory is developed to investigate the characteristics in roll of slender cruciform wings and wing-body combinations. The method makes use of the conformal mapping processes of classical hydrodynamics which transform the region outside a circle and the region outside an arbitrary arrangement of line segments intersecting at the origin. The method of analysis may be utilized to solve other slender cruciform wing-body problems involving arbitrarily assigned boundary conditions" (p. 1).
- Thirty-Seventh Annual Report of the National Advisory Committee for Aeronautics: Administrative Report Including Technical Report Nos. 1003 to 1058
- "In accordance with the act of Congress, approved March 3,1915 (U.S. C. title 50, sec. 151), which established the National Advisory Committee for Aeronautics the Committee submits its thirty-seventh annual report for the fiscal year 1951. The United States is engaged in expanding military aviation to levels never before reached except in the midst of a major war. In Korea, our military aircraft are engaged in combat with airplanes of an unfriendly nation evidently able to build military aircraft of increasing capabilities. In this environment, the NACA is responsible for conducting an adequate program of scientific research to open the way for the design of aircraft and missile of superior performance" (p. VII).
- Transonic flow past a wedge profile with detached bow wave
- "A theoretical study has been made of the aerodynamic characteristics at zero angle of attack of a thin, doubly symmetrical double-wedge profile in the range of supersonic flight speed in which the bow wave is detached. The analysis utilizes the equations of the transonic small-disturbance theory and involves no assumptions beyond those implicit in this theory. The mixed flow about the front half of the profile is calculated by relaxation solution of boundary conditions along the shock polar and sonic line" (p. 1).
- Wind-Tunnel Investigation of the Contribution of a Vertical Tail to the Directional Stability of a Fighter-Type Airplane
- Contributions of vertical tail and fuselage to directional stability are determined from pressure distributions measured over wide ranges of angle of attack and angle of yaw with stabilizer in each of three vertical positions, with stabilizer removed and with both stabilizer and vertical tail removed. Results point out inadequacies of current design methods and show that more accurate methods must treat separately contributions of vertical tail, fuselage area above stabilizer, and fuselage area below stabilizer.