UNT Libraries Government Documents Department - 1,423 Matching Results

Search Results

prev Results: 21 - 70 next
Equations, Tables, and Charts for Compressible Flow
"This report, which is a revision and extension of NACA-TN-1428, presents a compilation of equations, tables, and charts useful in the analysis of high-speed flow of a compressible fluid. The equations provide relations for continuous one-dimensional flow, normal and oblique shock waves, and Prandtl-Meyer expansions for both perfect and imperfect gases. The tables present useful dimensionless ratios for continuous one-dimensional flow and for normal shock waves as functions of Mach number for air considered as a perfect gas" (p. 613).
Aerodynamic Coefficients and Transformation Tables
From Introduction: "The following brief explanation with tables of equivalents in various systems of units, has been prepared in order to facilitate such transformation."
A Résumé of the Advances in Theoretical Aeronautics Made by Max M. Munk
"In order to apply profitably the mathematical methods of hydrodynamics to aeronautical problems, it is necessary to make simplifications in the physical conditions of the latter. In a valuable paper presented by Dr. Max M. Munk, of the National Advisory Committee for Aeronautics, Washington, to the Delft Conference in April, 1924, these necessary simplifying assumptions are discussed in detail. It is the purpose of the present paper to present in as simple a manner as possible some of the interesting results obtained by Dr. Munk's methods" (p. 93).
Determination of control-surface characteristics from NACA plain-flap and tab data
From Summary: "The data from previous NACA pressure-distribution investigations of plain flaps and tabs with sealed gaps have been analyzed and are presented in this paper in a form readily applicable to the problems of control-surface design. The experimentally determined variation of aerodynamic parameters with flap chord and tab chord are given in chart form and comparisons are made with the theory. With the aid of these charts and the theoretical relationships for a thin airfoil, the aerodynamic characteristics for control surfaces of any plan form with plain flaps and tabs with sealed gaps may be determined. A discussion of the basic equations of the thin-airfoil theory and the development of a number of additional equations that will be helpful in tail design are presented in the appendixes. The procedure for applying the data is described and a sample problem of horizontal tail design is included."
Determination of the Characteristics of Tapered Wings
This report presents tables and charts for use in determining the characteristics of tapered wings. Theoretical factors are given from which the following characteristics of tapered wings may be found: the span lift distribution, the induced-angle-of attack distribution, the lift-curve slope, the angle of zero lift, the induced drag, the aerodynamic-center position, and the pitching moment about the aerodynamic center.
The experimental and calculated characteristics of 22 tapered wings
From Summary: "The experimental and calculated aerodynamic characteristics of 22 tapered wings are compared, using tests made in the variable-density wind tunnel. The wings had aspect ratios from 6 to 12 and taper ratios from 1:6:1 and 5:1. The compared characteristics are the pitching moment, the aerodynamic-center position, the lift-curve slope, the maximum lift coefficient, and the curves of drag. The method of obtaining the calculated values is based on the use of wing theory and experimentally determined airfoil section data. In general, the experimental and calculated characteristics are in sufficiently good agreement that the method may be applied to many problems of airplane design."
Charts Relating the Compressive Buckling Stress of Longitudinally Supported Plates to the Effective Deflectional and Rotational Stiffness of the Supports
"A stability analysis is made of a long flat rectangular plate subjected to a uniform longitudinal compressive stress and supported along its longitudinal edges and along one or more longitudinal lines by elastic line supports. The elastic supports possess deflectional and rotational stiffness. Such configuration is an idealization of the compression cover skin and internal structure of a wing and tail surfaces" (p. 1).
A flight evaluation of the longitudinal stability characteristics associated with the pitch-up of a swept-wing airplane in maneuvering flight at transonic speeds
This report presents the results of flight measurements of longitudinal stability and control characteristics made on a swept-wing jet aircraft to determine the origin of the pitch-up encountered in maneuvering flight at transonic speeds. For this purpose measurements were made of elevator angle, tail angle of attack, and wing-fuselage pitching moments (obtained from measurements of the balancing tail loads).
Comparison of performance of experimental and conventional cage designs and materials for 75-millimeter-bore cylindrical roller bearings at high speed
From Summary: "The results of two investigations, one to determine the relative merits of four experimental and two conventional design 75-millimeter-bore (size 215) cylindrical roller bearings and one to determine the relative merits of nodular iron and bronze as cage materials for this size and type of bearing, are presented in this report. Nine test bearings were operated over a range of dn values (product of bearing bore in mm and shaft speed in r.p.m) from 0.3 x 10(6) to 2.3 x 20(6), radial loads for 7 to 1613 pounds, and oil flows from 2 to 8 pounds per minute with a single-jet circulatory oil feed. Of the six bearings used to evaluate designs, four were experimental types with outer-race-riding cages and inner-race-guided rollers, and two were conventional types, one with outer-race-guided rollers and cage and one with inner-race-guided rollers and cage."
The development and application of high-critical-speed nose inlets
From Summary: "An analysis of the nose-inlet shapes developed in previous investigations to represent the optimum from the standpoint of critical speed has shown that marked similarity exists between the nondimensional profiles of inlets which have widely different proportions and critical speeds. With the nondimensional similarity of such profiles established, the large differences in the critical speeds of these nose inlets must be a function of their proportions. An investigation was undertaken in the Langley 8-foot high-speed tunnel to establish the effects of nose-inlet proportions on critical Mach number to develop a rational method for the design of high-critical-speed nose inlets to meet desired requirements."
Preliminary experiments to determine scale and slip-stream effects on a 1/24th size model of a JN4H biplane
This work was undertaken to obtain results on a small model of a complete airplane which might be used for comparison with corresponding tests made in full flight. Somewhat similar tests have been previously made at various other laboratories; but as certain discrepancies exist between corresponding tests in different tunnels, it has been deemed advisable to obtain a direct comparison for this particular installation. The present work covers tests on a one-twenty-fourth scale model at speeds varying from 6.7 m/sec. (15 m.p.h.) to 40.2 m/sec, (90 m.p.h.). A slip stream correction has been obtained by the use of a small belt-driven propeller mounted in front of the model, and force coefficients thus obtained are compared with the measurements of the same forces made in full flight on a geometrically similar airplane. This report gives lift, drag, and longitudinal moment values obtained in tests of a particularly accurate model over a wide range of speeds. A measure of the slip stream corrections on lift and drag forces was obtained by the use of a power-driven model propeller. Measurements were also made of forces and longitudinal moments for all angles from 0 degree to 360 degrees.
The resistance of spheres in wind tunnels and in air
From Summary: "A satisfactory confirmation of Reynolds law has been accomplished, the effect of means of support determined, the range of experiment greatly extended by work in the new variable density wind tunnel, and the effects of turbulence investigated by work in the tunnels and by towing and dropping tests in free air. It is concluded that the erratic nature of most of the previous work is due to support interference and differing turbulence conditions. While the question of support has been investigated thoroughly, a systematic and comprehensive study of the effects of scale and quality of turbulence will be necessary to complete the problem, as this phase was given only general treatment."
The Distribution of Lift Over Wing Tips and Ailerons
"This investigation was carried out in the 5-foot wind tunnel of the Langley Memorial Aeronautical Laboratory for the purpose of obtaining more complete information on the distribution of lift between the ends of wing spars, the stresses in ailerons, and the general subject of airflow near the tip of a wing. It includes one series of tests on four models without ailerons, having square, elliptical, and raked tips respectively, and a second series of positively and negatively raked wings with ailerons adjusted to different settings. The results show that negatively raked tips give a more uniform distribution of air pressure than any of the other three arrangements, because the tip vortex does not disturb the flow at the trailing edge" (p. 105).
A simplified theoretical method of determining the characteristics of a lifting rotor in forward flight
Theoretical derived expressions for the flapping, the thrust, the torque, and the profile drag-lift ratio of nonfeathering rotor with hinged, rectangular, linearly twisted blades are given as simple functions of the inflow velocity and the blade pitch. Representative values of the coefficients of each of the terms in these expressions are tabulated for a series of specified values of the tip-speed ratio. Analysis indicates that the tabulated values can be used to calculate, with reasonable accuracy, the characteristics of any rotor of conventional design.
A study of the torque equilibrium of an autogiro rotor
From Summary: "Two improvements have been made in the method developed in NACA Reports nos. 487 and 591 for the estimation of the inflow velocity required to overcome a given decelerating torque in an autogiro rotor. At low tip-speed ratios, where the assumptions necessary for the analytical integrations of the earlier papers are valid, the expressions therein derived are greatly simplified by combining and eliminating terms with a view of minimizing the numerical computations required. At high tip-speed ratios, by means of charts based on graphical integrations, errors inherent in the assumptions associated with the analytical method are largely eliminated."
Spinning characteristics of the XN2Y-1 airplane obtained from the spinning balance and compared with results from the spinning tunnel and from flight tests
Report presents the results of tests of a 1/10-scale model of the XN2Y-1 airplane tested in the NACA 5-foot vertical wind tunnel in which the six components of forces and moments were measured. The model was tested in 17 attitudes in which the full-scale airplane had been observed to spin, in order to determine the effects of scale, tunnel, and interference. In addition, a series of tests was made to cover the range of angles of attack, angles of sideslip, rates of rotation, and control setting likely to be encountered by a spinning airplane. The data were used to estimate the probable attitudes in steady spins of an airplane in flight and of a model in the free-spinning tunnel. The estimated attitudes of steady spin were compared with attitudes measured in flight and in the spinning tunnel. The results indicate that corrections for certain scale and tunnel effects are necessary to estimate full-scale spinning attitudes from model results.
The Aerodynamic Forces and Moments Exerted on a Spinning Model of the NY-1 Airplane as Measured by the Spinning Balance
From Summary: "A preliminary investigation of the effects of changes in the elevator and rudder settings and of small changes in attitude upon the aerodynamic forces and moments exerted upon a spinning airplane was undertaken with the spinning balance in the 5-foot vertical tunnel of the National Advisory Committee for Aeronautics. The tests were made on a 1/12-scale model of the "NY-1" airplane. Data by which to fix the attitude, the radius of spin, and the rotational and air velocities were taken from recorded spins of the full-scale airplane."
Spinning characteristics of wings 1: rectangular Clark Y monoplane wing
"A series of wind tunnel tests of a rectangular Clark Y wing was made with the NACA spinning balance as part of a general program of research on airplane spinning. All six components of the aerodynamic force and moment were measured throughout the range of angles of attack, angles of sideslip, and values omega b/2v likely to be attained by a spinning airplane; the results were reduced to coefficient form. It is concluded that a conventional monoplane with a rectangular Clark y wing can be made to attain spinning equilibrium throughout a wide range of angles of attack but that provision of a yawing moment coefficient of -0.02 (against the spin) by the tail, fuselage, and interferences will insure against attainment of equilibrium in a steady spin" (p. 231).
Wind-Tunnel Tests on Airfoil Boundary Layer Control Using a Backward-Opening Slot (1931)
"This report presents the results of an investigation to determine the effect of boundary layer control on the lift and drag of an airfoil. Boundary layer control was accomplished by means of a backward-opening slot in the upper surface of the hollow airfoil. Air was caused to flow through this slot by a pressure which was maintained inside the airfoil by a blower. Various slot locations, slot openings, and wing pressures were used" (p. 3).
Flight Investigation at High Speeds of the Drag of Three Airfoils and a Circular Cylinder Representing Full-Scale Propeller Shanks
"Tests have been made at high speeds to determine the drag of models, simulating propeller shanks, in the form of a circular cylinder and three airfoils, the NACA 16-025, the NACA 16-040, and the NACA 16-040 with the rear 25 percent chord cut off. All the models had a maximum thickness of 4 1/2 inches to conform with average propeller-shank dimensions and a span of 20 1/4 inches. For the tests the models were supported perpendicular to the lower surface of the wing of an XP-51 airplane (p. 277).
Study of effects of sweep on the flutter of cantilever wings
An experimental and analytical investigation of the flutter of sweptback cantilever wings is reported. The experiments employed groups of wings swept back by rotating and by shearing. The angle of sweep range from 0 degree to 60 degrees and Mach numbers extended to approximately 0.85. A theoretical analysis of the air forces on an oscillating swept wing of high length-chord ratio is developed, and the approximations inherent in the assumptions are discussed. Comparison with experiment indicates that the analysis developed in the present report is satisfactory for giving the main effects of sweep, at least for nearly uniform cantilever wings of high and moderate length-chord ratios.
Estimation of F-3 and F-4 knock-limited performance ratings for ternary and quaternary blends containing triptane or other high-antiknock aviation-fuel blending agents
Charts are presented that permit the estimation of F-3 and F-4 knock-limited performance ratings for certain ternary and quaternary fuel blends. Ratings for various ternary and quaternary blends estimated from these charts compare favorably with experimental F-3 and F-4 ratings. Because of the unusual behavior of some of the aromatic blends in the F-3 engine, the charts for aromatic-paraffinic blends are probably less accurate than the charts for purely paraffinic blends.
NACA investigation of fuel performance in piston-type engines
This report is a compilation of many of the pertinent research data acquired by the National Advisory Committee for Aeronautics on fuel performance in piston engines. The original data for this compilation are contained in many separate NACA reports which have in the present report been assembled in logical chapters that summarize the main conclusions of the various investigations. Complete details of each investigation are not included in this summary; however, such details may be found, in the original reports cited at the end of each chapter.
Basic considerations in the combustion of hydrocarbon fuels with air
Basic combustion research is collected, collated, and interpreted as it applies to flight propulsion. The following fundamental processes are treated in separate chapters: atomization and evaporation of liquid fuels, flow and mixing processes in combustion chambers, ignition and flammability of hydrocarbon fuels, laminar flame propagation, turbulent flames, flame stabilization, diffusion flames, oscillations in combustors, and smoke and coke formation in the combustion of hydrocarbon-air mixtures. Theoretical background, basic experimental data, and practical significance to flight propulsion are presented.
A Simplified Method of Elastic-Stability Analysis for Thin Cylindrical Shells
"This paper develops a new method for determining the buckling stresses of cylindrical shells under various loading conditions. In part I, the equation for the equilibrium of cylindrical shells introduced by Donnell in NACA report no. 479 to find the critical stresses of cylinders in torsion is applied to find critical stresses for cylinders with simply supported edges under other loading conditions. In part II, a modified form of Donnell's equation for the equilibrium of thin cylindrical shells is derived which is equivalent to Donnell's equation but has certain advantages in physical interpretation and in ease of solution, particularly in the case of shells having clamped edges" (p. 285).
Critical combinations of shear and transverse direct stress for an infinitely long flat plate with edges elastically restrained against rotation
An exact solution and a closely concurring approximate energy solution are given for the buckling of an infinitely long flat plate under combined shear and transverse direct stress with edges elastically restrained against rotation. It was found that an appreciable fraction of the critical stress in pure shear may be applied to the plate without any reduction in the transverse compressive stress necessary to produce buckling. An interaction formula in general use was shown to be decidedly conservative for the range in which it is supposed to apply.
Critical Stress of Thin-Walled Cylinders in Axial Compression
Empirical design curves are presented for the critical stress of thin-wall cylinders loaded in axial compression. These curves are plotted in terms of the nondimensional parameters of small-deflection theory and are compared with theoretical curves derived for the buckling of cylinders with simply supported and clamped edges. An empirical equation is given for the buckling of cylinders having a length-radius ratio greater than about 0.75.
The Decay of a Simple Eddy
The principal result obtained in this report is a generalization of Taylor's formula for a simple eddy. The discussion of the properties of the eddy indicates that there is a slight analogy between the theory of eddies in a viscous fluid and the quantum theory of radiation. Another exact solution of the equations of motion of viscous fluid yields a result which reminds one of the well-known condition for instability in the case of a horizontally stratified atmosphere.
Diagrams of Airplane Stability
In this report a study is made of the effect on longitudinal and lateral oscillations of an airplane of simultaneous variations in two resistance derivatives while the remainder of the derivatives are constant. The results are represented by diagrams in which the two variable resistance derivatives are used as coordinates, and curves are plotted along which the modulus of decay of a long oscillation has a constant value. The same type of analysis is also carried out for the stability of the parachute.
The Inertia Coefficients of an Airship in a Frictionless Fluid
The apparent inertia of an airship hull is examined. The exact solution of the aerodynamical problem is studied for hulls of various shapes with special attention given to the case of an ellipsoidal hull. So that the results for the ellipsoidal hull may be readily adapted to other cases, they are expressed in terms of the area and perimeter of the largest cross section perpendicular to the direction of motion by means of a formula involving a coefficient kappa which varies only slowly when the shape of the hull is changed, being 0.637 for a circular or elliptic disk, 0.5 for a sphere, and about 0.25 for a spheroid of fineness ratio.
The Inertial Coefficients of an Airship in a Frictionless Fluid
This report deals with the investigation of the apparent inertia of an airship hull. The exact solution of the aerodynamical problem has been studied for hulls of various shapes and special attention has been given to the case of an ellipsoidal hull. In order that the results for this last case may be readily adapted to other cases, they are expressed in terms of the area and perimeter of the largest cross section perpendicular to the direction motion by means of a formula involving a coefficient K which varies only slowly when the shape of the hull is changed, being 0.637 for a circular or elliptic disk, 0.5 for a sphere, and about 0.25 for a spheroid of fineness ratio 7.
Stability of the Parachute and Helicopter
This report deals with an extension of the theory of stability in oscillation to the case of aircraft following a vertical trajectory, and particularly to the oscillations of parachutes.
The NACA Impact Basin and Water Landing Tests of a Float Model at Various Velocities and Weights
"The first data obtained in the United States under the controlled testing conditions necessary for establishing relationships among the numerous parameters involved when a float having both horizontal and vertical velocity contacts a water surface are presented. The data were obtained at the NACA impact basin. The report is confined to a presentation of the relationship between resultant velocity and impact normal acceleration for various float weights when all other parameters are constant" (p. 411).
A wind-tunnel test technique for measuring the dynamic rotary stability derivatives at subsonic and supersonic speeds
"A method is described for measuring the dynamic stability derivatives of a model airplane in a wind tunnel. The characteristic features of this system are that single-degree-of-freedom oscillations were used to obtain combinations of rolling, yawing and pitching motions; that the oscillations were excited and controlled by velocity feedback which permitted operation under conditions unfavorable for more conventional types of oscillatory testing; and that data processing was greatly simplified by using analog computer elements in the strain-gage circuitry. A small number of experimental data are included to illustrate the general scope of results obtainable with this system" (p. 1).
Differential Pressures on a Pitot-Venturi and a Pitot-Static Nozzle Over 360 Degrees Pitch and Yaw
"Measurements of the differential pressures on two navy air-speed nozzles, consisting of a Zahm type Pitot-Venturi tube and a SQ-16 two-pronged Pitot-static tube, in a tunnel air stream of fixed speed at various angles of pitch and yaw between 0 degrees and plus or minus 180 degrees. This shows for a range over -20 degrees to +20 degrees pitch and yaw, indicated air speeds varying very slightly over 2 per cent for the Zahm type and a maximum of about 5 per cent for the SQ-16 type from the calibrated speed at 0 degree. For both types of air-speed nozzle the indicated air speed increases slightly as the tubes are pitched or yawed several degrees from their normal 0 degrees altitude, attains a maximum around plus or minus 15 degrees to 25 degrees, declines rapidly therefrom as plus or minus 40 degrees is passed, to zero in the vicinity of plus or minus 70 degrees to 100 degrees, and thence fluctuates irregular from thereabouts to plus or minus 180 degrees" (p. 223).
Some factors affecting the reproducibility of penetration and the cut-off of oil sprays for fuel-injection engines
This investigation was undertaken at the Langley Memorial Aeronautical Laboratory in connection with a general research on fuel-injection for aircraft. The purpose of the investigation was to determine the factors controlling the reproducibility of spray penetration and secondary discharges after cut-off. The development of single sprays from automatic injection valves was recorded by means of special high-speed photographic apparatus capable of taking 25 consecutive pictures of the moving spray at a rate of 4,000 per second. The effect of two types of injection valves, injection-valve tube length, initial pressure in the injection-valve tube, speed of the injection control mechanism, and time of spray cut-off, on the reproducibility of spray penetration, and on secondary discharges were investigated. It was found that neither type of injection valve materially affected spray reproducibility. The initial pressure in the injection-valve tube controlled the reproducibility of spray penetrations. An increase in the initial pressure or in the length of the injection-valve tube slightly increased the spray penetration within the limits of this investigation. The speed of the injection-control mechanism did not affect the penetration. Analysis of the results indicates that secondary discharges were caused in this apparatus by pressure waves initiated by the rapid opening of the cut-off valve. The secondary discharges were eliminated in this investigation by increasing the length of the injection-valve tube. (author).
The N.A.C.A. photographic apparatus for studying fuel sprays from oil engine injection valves and test results from several researches
"Apparatus for recording photographically the start, growth, and cut-off of oil sprays from injection valves has been developed at the Langley Memorial Aeronautical Laboratory. The apparatus consists of a high-tension transformer by means of which a bank of condensers is charged to a high voltage. The controlled discharge of these condensers in sequence, at a rate of several thousand per second, produces electric sparks of sufficient intensity to illuminate the moving spray for photographing. The sprays are injected from various types of valves into a chamber containing gases at pressures up to 600 pounds per square inch" (p. 361).
Wind-tunnel investigation of air inlet and outlet openings on a streamline body
In connection with the general problem of providing air flow to an aircraft power plant located within a fuselage, an investigation was conducted in the Langley 8-foot high-speed tunnel to determine the effect on external drag and pressure distribution of air inlet openings located at the nose of a streamline body. Air outlet openings located at the tail and at the 21-percent and 63-percent stations of the body were also investigated. Boundary layer transition measurements were made and correlated with the force and the pressure data. Individual openings were investigated with the aid of a blower and then practicable combinations of inlet and outlet openings were tested. Various modifications to the internal duct shape near the inlet opening and the aerodynamic effects of a simulated gun in the duct were also studied. The results of the tests suggested that outlet openings should be designed so that the static pressure of the internal flow at the outlet would be the same as the static pressure of the external flow in the vicinity of the opening.
Analysis of Heat and Compressibility Effects in Internal Flow Systems and High-Speed Tests of a Ram-Jet System
Report discussing an analysis has been made by the NACA of the effects of heat and compressibility in the flow through the internal systems of aircraft along with equations and charts are developed whereby the flow characteristics at key stations in a typical internal system may be readily obtained.
High-Speed Tests of a Model Twin-Engine Low-Wing Transport Airplane
Report presents the results of force tests made of a 1/8-scale model of a twin-engine low-wing transport airplane in the NACA 8-foot high-speed tunnel to investigate compressibility and interference effects of speeds up to 450 miles per hour. In addition to tests of the standard arrangement of the model, tests were made with several modifications designed to reduce the drag and to increase the critical speed.
Aircraft speed instruments
From Summary: "This report presents a concise survey of the measurement of air speed and ground speed on board aircraft. Special attention is paid to the Pitot-static air-speed meter which is the standard in the United States for airplanes. A bibliography on air-speed measurement concludes the report."
Astronomical Methods in Aerial Navigation
The astronomical method of determining position is universally used in marine navigation and may also be of service in aerial navigation. The practical application of the method, however, must be modified and adapted to conform to the requirements of aviation. Much of this work of adaptation has already been accomplished, but being scattered through various technical journals in a number of languages, is not readily available. This report is for the purpose of collecting under one cover such previous work as appears to be of value to the aerial navigator, comparing instruments and methods, indicating the best practice, and suggesting future developments.
Test of single-stage axial-flow fan
"A single-stage axial fan was built and tested in the shop of the propeller-research tunnel of the NACA. The fan comprised a simple 24-blade rotor having a diameter of 21 inches and a solidity of 0.86 and a set of 37 contravanes having a solidity of 1.33. The rotor was driven by a 25-horsepower motor capable of rotating at a speed of 3600 r.p.m. The fan was tested for volume, pressure, and efficiency over a range of delivery pressures and volumes for a wide range of contravane and blade-angle settings" (p. 49).
Knock-limited performance of several internal coolants
The effect of internal cooling on the knock-limited performance of an-f-28 fuel was investigated in a CFR engine, and the following internal coolants were used: (1) water, (2), methyl alcohol-water mixture, (3) ammonia-methyl alcohol-water mixture, (4) monomethylamine-water mixture, (5) dimethylamine-water mixture, and (6) trimethylamine-water mixture. Tests were run at inlet-air temperatures of 150 degrees and 250 degrees F. to indicate the temperature sensitivity of the internal-coolant solutions.
Photographic investigation of combustion in a two-dimensional transparent rocket engine
Motion pictures at camera speeds up to 3000 frames per second were taken of the combustion of liquid oxygen and gasoline in a 100-pound thrust rocket engine. The effect of seven methods of propellant injection on the uniformity of combustion was investigated. The flame front was generally found to extend to the injector faces and all the injection systems showed considerable nonuniformity of combustion. Pressure vibration records indicated combustion vibrations that corresponded to resonant-chamber frequencies.
An Investigation of Backflow Phenomenon in Centrifugal Compressors
Report presents the results of an investigation conducted to determine the nature and the extent of the reversal of flow, which occurs at the inlet of centrifugal compressors over a considerable portion of the operating range. Qualitative studies of this flow reversal were made by lampblack patterns taken on a mixed-flow-type impeller and by tuft studies made on a conventional centrifugal compressor. Quantitative studies were made on a compressor specially designed to enable survey of angularity of flow, static and total pressures, and temperatures to be taken very close to the impeller front housing.
An empirically derived basis for calculating the area, rate, and distribution of water-drop impingement on airfoils
From Summary: "An empirically derived basis for predicting the area, rate, and distribution of water-drop impingement on airfoils of arbitrary section is presented. The concepts involved represent an initial step toward the development of a calculation technique which is generally applicable to the design of thermal ice-prevention equipment for airplane wing and tail surfaces. It is shown that sufficiently accurate estimates, for the purpose of heated-wing design, can be obtained by a few numerical computations once the velocity distribution over the airfoil has been determined. The calculation technique presented is based on results of extensive water-drop trajectory computations for five airfoil cases which consisted of 15-percent-thick airfoils encompassing a moderate lift-coefficient range."
Exploratory investigation of boundary-layer transition on a hollow cylinder at a Mach number of 6.9
Report presenting an investigation of the Reynolds number for transition on the outside of a hollow cylinder with heat transfer from the boundary layer to the wall at Mach number 6.9. At a given Mach number, it appears that the Reynolds number based on leading-edge thickness is an important parameter in comparisons of flat-plate transition data from various installations.
Determination of the Profile Drag of an Airplane Wing in Flight at High Reynolds Numbers
Report presenting flight tests to determine the profile-drag coefficients of a portion of the original wing surface of an all-metal airplane and a portion of the wing made aerodynamically smooth and more nearly fair than the original section. Tests were also carried out to determine the point of transition from laminar to turbulent boundary layer and to determine the velocity distribution along the upper surface of the wing.
Determination of the Profile Drag of an Airplane Wing in Flight at High Reynolds Numbers
"Flight tests were made to determine the profile-drag coefficients of a portion of the original wing surface of an all-metal airplane and of a portion of the wing made aerodynamically smooth and more nearly fair than the original section. The wing section was approximately the NACA 2414.5. The tests were carried out over a range of airplane speeds giving a maximum Reynolds number of 15,000,000. Tests were also carried out to locate the point of transition from laminar to turbulent boundary layer and to determine the velocity distribution along the upper surface of the wing" (p. 483).
Back to Top of Screen