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 Collection: National Advisory Committee for Aeronautics Collection
An investigation of supersonic store interference in the vicinity of a 22 deg swept wing fuselage configuration at Mach numbers of 1.61 and 2.01
Pressure tunnel investigation of supersonic store interference in vicinity of 22 deg swept wing fuselage configuration at mach numbers 1.61 and 2.01. digital.library.unt.edu/ark:/67531/metadc53117/
Transonic aerodynamic and trim characteristics of 1/15-scale models of the convair mx-1964 airplane with indented fuselage
No Description digital.library.unt.edu/ark:/67531/metadc53110/
A comparison of flight-measured carrier- approach speeds with values predicted by several different criteria for 41 fighter-type airplane configurations
Comparison of flight measured carrier-approach speeds with values predicted by several different criteria for 41 fighter aircraft configurations. digital.library.unt.edu/ark:/67531/metadc53118/
Chemical and physical properties of a boron-carbon-hydrogen fuel z-244 /naca 55z8/
No Description digital.library.unt.edu/ark:/67531/metadc53114/
Experimental Behavior of Pentaborane-Air Combustion Products During Expansion in a Convergent Divergent Nozzle
In order to evaluate the post combustion behavior of boric oxide, pentaborane-air mixtures, burned to completion at a combustor pressure of 3 atmospheres, were expanded through a 7.1-inch-long convergent-divergent nozzle having a 4-inch-diameter throat and an exit-to-throat area ratio of 1.68. The experimentally determined thrust performance was in good agreement with the ideal equilibrium performance at stagnation temperatures of 3300 deg R and lower. The boric oxide vapor at the combustor exit required about 400 F deg supercooling before any condensed phase was observed. For a given thrust, fuel consumption was as much as 20 percent greater than predicted from vapor-pressure data for combustor outlet temperatures i n the vicinity of 3600 deg R. A similar result could be expected in full-scale engines, since the test combustor provided an unusually long dwell time and a highly turbulent environment. During the expansion process, the vapor (when present) did not condense to the extent predicted for an equilibrium expansion process. Moreover, condensation was observed only i n the form of small, abrupt phase changes i n the subsonic flow near the throat. Friction, due to liquid boric oxide films on the nozzle surfaces, was negligible when the surface temperature was above 800 F. digital.library.unt.edu/ark:/67531/metadc53119/
Preliminary report on experimental investigation of engine dynamics and controls for a 48-inch ramjet engine
Experimental investigation of engine dynamics and controls for 48-inch ramjet engine in free jet facility at Mach number 2.76 and altitudes 68,000 to 82,000 feet. digital.library.unt.edu/ark:/67531/metadc53116/
Surge-inception study in a two-spool turbojet engine
No Description digital.library.unt.edu/ark:/67531/metadc53113/
Preliminary investigation of reflections of oblique waves from a porous wall
No Description digital.library.unt.edu/ark:/67531/metadc53288/
Comparison of various heat exchangers for liquid-metal nuclear turbojet over range of flight and operating conditions
No Description digital.library.unt.edu/ark:/67531/metadc53284/
Measurement and analysis of turbulent flow containing periodic flow fluctuations
No Description digital.library.unt.edu/ark:/67531/metadc53289/
Analysis of rocket, ramjet, and turbojet engines for supersonic propulsion of long-range missiles. 3: Ramjet engine performance
No Description digital.library.unt.edu/ark:/67531/metadc53286/
Some notes on the probable damage to an intercontinental-ballistic-missile warhead following puncture of the heat shield
No Description digital.library.unt.edu/ark:/67531/metadc53283/
Chemical and physical properties of modified Hi-Cal-2
No Description digital.library.unt.edu/ark:/67531/metadc53245/
Flight investigation of a liquid hydrogen fuel system
No Description digital.library.unt.edu/ark:/67531/metadc53242/
Design and performance of fuel control for aircraft hydrogen fuel system
No Description digital.library.unt.edu/ark:/67531/metadc53241/
An Oil-Stream Photomicrographic Aeroscope for Obtaining Cloud Liquid-Water Content and Droplet Size Distributions in Flight
An airborne cloud aeroscope by which droplet size, size distribution, and liquid-water content of clouds can be determined has been developed and tested in flight and in wind tunnels with water sprays. In this aeroscope the cloud droplets are continuously captured in a stream of oil, which Is then photographed by a photomicrographic camera. The droplet size and size distribution can be determined directly from the photographs. With the droplet size distribution known, the liquid-water content of the cloud can be computed from the geometry of the aeroscope, the airspeed, and the oil-flow rate. The aeroscope has the following features: Data are obtained semi-automatically, and permanent data are taken in the form of photographs. A single picture usually contains a sufficient number of droplets to establish the droplet size distribution. Cloud droplets are continuously captured in the stream of oil, but pictures are taken at Intervals. The aeroscope can be operated in icing and non-icing conditions. Because of mixing of oil in the instrument, the droplet-distribution patterns and liquid-water content values from a single picture are exponentially weighted average values over a path length of about 3/4 mile at 150 miles per hour. The liquid-water contents, volume-median diameters, and distribution patterns obtained on test flights and in the Lewis icing tunnel are similar to previously published data. digital.library.unt.edu/ark:/67531/metadc53544/
A summary of meteorological conditions associated with aircraft icing and a proposed method of selecting design criterions for ice-protection equipment
No Description digital.library.unt.edu/ark:/67531/metadc53549/
Pressure Distribution on Joukowski Wings
The hydrodynamics and mathematical models as applied to the potential flow about a Joukowski wing are presented. digital.library.unt.edu/ark:/67531/metadc53400/
Elements of the Wing Section Theory and of the Wing Theory
Results are presented of the theory of wings and of wing sections which are of immediate practical value. They are proven and demonstrated by the use of the simple conceptions of kinetic energy and momentum only. digital.library.unt.edu/ark:/67531/metadc53404/
Flow and Force Equations for a Body Revolving in a Fluid
A general method for finding the steady flow velocity relative to a body in plane curvilinear motion, whence the pressure is found by Bernoulli's energy principle is described. Integration of the pressure supplies basic formulas for the zonal forces and moments on the revolving body. The application of the steady flow method for calculating the velocity and pressure at all points of the flow inside and outside an ellipsoid and some of its limiting forms is presented and graphs those quantities for the latter forms. In some useful cases experimental pressures are plotted for comparison with theoretical. The pressure, and thence the zonal force and moment, on hulls in plane curvilinear flight are calculated. General equations for the resultant fluid forces and moments on trisymmetrical bodies moving through a perfect fluid are derived. Formulas for potential coefficients and inertia coefficients for an ellipsoid and its limiting forms are presented. digital.library.unt.edu/ark:/67531/metadc53409/
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 case of rotation of an airship hull is investigated and a coefficient is defined with the same advantages as the corresponding coefficient for rectilinear motion. digital.library.unt.edu/ark:/67531/metadc53406/
The Aerodynamic Forces on Airship Hulls
The new method for making computations in connection with the study of rigid airships, which was used in the investigation of Navy's ZR-1 by the special subcommittee of the National Advisory Committee for Aeronautics appointed for this purpose is presented. The general theory of the air forces on airship hulls of the type mentioned is described and an attempt was made to develop the results from the very fundamentals of mechanics. digital.library.unt.edu/ark:/67531/metadc53403/
Experience with geared propeller drives for aviation engines
I. The development of the gear wheels: (a) bending stresses; (b) compressive stresses; (c) heating; (d) precision of manufacture. II. General arrangement of the gearing. III. Vibration in the shaft transmission. An overview is given of experience with geared propeller drives for aviation engines. The development of gear wheels is discussed with emphasis upon bending stresses, compressive stresses, heating, and precision in manufacturing. With respect to the general arrangement of gear drives for airplanes, some principal rules of mechanical engineering that apply with special force are noted. The primary vibrations in the shaft transmission are discussed. With respect to vibration, various methods for computing vibration frequency and the influence of elastic couplings are discussed. digital.library.unt.edu/ark:/67531/metadc53702/
Tests of the Daimler D-IVa engine at a high altitude test bench
Reports of tests of a Daimler IVa engine at the test-bench at Friedrichshafen, show that the decrease of power of that engine, at high altitudes, was established, and that the manner of its working when air is supplied at a certain pressure was explained. These tests were preparatory to the installation of compressors in giant aircraft for the purpose of maintaining constant power at high altitudes. digital.library.unt.edu/ark:/67531/metadc53701/
Italian and French experiments on wind tunnels
Given here are the results of experiments conducted by Colonel Costanzi of the Italian Army to determine the influence of the surrounding building in which a wind tunnel was installed on the efficiency of the installation, and how the efficiency of the installation was affected by the design of the tunnel. Also given are the results of a series of experiments by Eiffel on 34 models of tunnels of different dimensions. This series of experiments was started in order to find out if, by changing the shape of the nozzle or of the diffuser of the large tunnel at Auteuil, the efficiency of the installation could be improved. digital.library.unt.edu/ark:/67531/metadc53707/
Relation of rib spacing to stress in wing planes
The stress relations to the fabric and the rib consequent upon a change of spacing between ribs in a wing plane are discussed. Considering the wing plane as a static structure, and ignoring the question of aerodynamic efficiency, it appears that the unit stress in the rib and fabric will remain constant for constant p if the linear dimensions of both rib and fabric are increased alike, viz., if wing and fabric remain geometrically similar. Since the bulge and the structural dimensions remain geometrically similar, the whole distended plane remains so, and hence should have the same pressure distribution and efficiency. If therefore the Burgess rule of making the rib spacing always one-fifth of the chord of the plane be valid, it must be valid for all others that are mechanically similar in structure and covering. digital.library.unt.edu/ark:/67531/metadc53685/
The column strength of aluminum alloy 75S-T extruded shapes
Because the tensile strength and tensile yield strength of alloy 75S-T are appreciably higher than those of the materials used in the tests leading to the use of the straight-line column curve, it appeared advisable to establish the curve of column strength by test rather than by extrapolation of relations determined empirically in the earlier tests. The object of this investigation was to determine the curve of column strength for extruded aluminum alloy 75S-T. In addition to three extruded shapes, a rolled-and-drawn round rod was included. Specimens of various lengths covering the range of effective slenderness ratios up to about 100 were tested. digital.library.unt.edu/ark:/67531/metadc53682/
Soaring flight in Guinea
The term soaring is applied here to the flight of certain large birds which maneuver in the air without moving their wings. The author explains the methods of his research and here gives approximate figures for the soaring flight of the Egyptian Vulture and the African White backed Vulture. Figures are given in tabular form for relative air speed per foot per second, air velocity per foot per second, lift/drag ratio, and selected coefficients. The author argues that although the figures given were taken from a very limited series of observations, they have nevertheless thrown some light on the use by birds of the internal energy of the air. digital.library.unt.edu/ark:/67531/metadc53687/
Stress analysis of columns and beam columns by the photoelastic method
Principles of similarity and other factors in the design of models for photoelastic testing are discussed. Some approximate theoretical equations, useful in the analysis of results obtained from photoelastic tests are derived. Examples of the use of photoelastic techniques and the analysis of results as applied to uniform and tapered beam columns, circular rings, and statically indeterminate frames, are given. It is concluded that this method is an effective tool for the analysis of structures in which column action is present, particularly in tapered beam columns, and in statically indeterminate structures in which the distribution of loads in the structures is influenced by bending moments due to axial loads in one or more members. digital.library.unt.edu/ark:/67531/metadc53680/
The effect of longitudinal moment of inertia upon dynamic stability
Free flight tests were carried out to show whether the longitudinal oscillations of a standard S.E.5A airplane are noticeably affected if its longitudinal moment of inertia is increased. These oscillations were taken by means of a self-recording instrument, the airplane having first its ordinary moment of inertia and then one increased by 14 percent. The period of oscillation was slightly longer after the increase of the moment of inertia, but the damping was not affected. Presented here are test results from an investigation to determine the relative performance of a single-cylinder, high-speed, compression-ignition engine when using fuel injection valve nozzles with different numbers, sizes, and directions of round orifices. A spring loaded, automatic injection valve was used. It was centrally located at the top of a vertical disk-type combustion chamber formed between horizontally opposed inlet and exhaust valves of a 5-inch by 7-inch engine. A series of fuel injection valve nozzles with different arrangements of round orifices were tested, starting with orifices so small that impingement on the combustion chamber walls was impossible and increasing beyond the start of impingement. a :A table and curves are presented showing the performance of the engine with different nozzles. The test results are discussed, and some probable reasons given for the variation in performance with different nozzles on the basis of spray distribution. digital.library.unt.edu/ark:/67531/metadc53688/
Airplane performance as influenced by the use of a supercharged engine
The question of the influence of a supercharged engine on airplane performance is treated here in a first approximation, but one that gives an exact idea of the advantage of supercharging. Considered here is an airplane that climbs first with an ordinary engine, not supercharged, and afterwards climbs with a supercharged engine. The aim is to find the difference of the ceilings reached in the two cases. In the case of our figure, the ceiling from 25,000 feet is increased to 37,000 feet, the supercharging maintaining the power only up to 20,000 feet. This makes, in comparison with an engine without supercharging, an increase of about 50 percent. digital.library.unt.edu/ark:/67531/metadc53684/
Notes on the design of supercharged and overdimensioned aircraft engines
No Description digital.library.unt.edu/ark:/67531/metadc53689/
Static testing and proposed standard specifications
Static tests fall into two groups, the first of which is designed to load all members of the structure approximately in accordance with the worst loads which they carry in flight, while the second is directed to the testing of specific members which are suspected of weakness and which are difficult to analyze mathematically. The nature of the loading in the second type is different for every different test, but the purpose of the first is defined clearly enough to permit the adoption of some standard set of loading specifications, at least for airplanes of normal design. Here, an attempt is made to carry through an analysis leading to such a standard, the goal being the determination of a load which will simultaneously impose on every member of the airplane structure a stress equal to the worst it will carry in flight. digital.library.unt.edu/ark:/67531/metadc53686/
Notes on longitudinal stability and balance
No Description digital.library.unt.edu/ark:/67531/metadc53683/
Remarks on the Pressure Distribution over the Surface of an Ellipsoid, Moving Translationally Through a Perfect Fluid
The pressure distribution over ellipsoids when in translatory motion through a perfect fluid is calculated. A method to determine the magnitude of the velocity and of the pressure at each point of the surface of an ellipsoid of rotation is described. digital.library.unt.edu/ark:/67531/metadc53405/
The Minimum Induced Drag of Aerofoils
Equations are derived to demonstrate which distribution of lifting elements result in a minimum amount of aerodynamic drag. The lifting elements were arranged (1) in one line, (2) parallel lying in a transverse plane, and (3) in any direction in a transverse plane. It was shown that the distribution of lift which causes the least drag is reduced to the solution of the problem for systems of airfoils which are situated in a plane perpendicular to the direction of flight. digital.library.unt.edu/ark:/67531/metadc53402/
Graphic Construction of Joukowski Wings
A plot of the cross sectional outline of a Joukowski wing is presented. digital.library.unt.edu/ark:/67531/metadc53401/
Flow and Drag Formulas for Simple Quadrics
The pressure distribution and resistance found by theory and experiment for simple quadrics fixed in an infinite uniform stream of practically incompressible fluid are calculated. The experimental values pertain to air and some liquids, especially water; the theoretical refer sometimes to perfect, again to viscid fluids. Formulas for the velocity at all points of the flow field are given. Pressure and pressure drag are discussed for a sphere, a round cylinder, the elliptic cylinder, the prolate and oblate spheroid, and the circular disk. The velocity and pressure in an oblique flow are examined. digital.library.unt.edu/ark:/67531/metadc53407/
A Procedure for the Design of Air-Heated Ice-Prevention Systems
A procedure proposed for use in the design of air-heated systems for the continuous prevention of ice formation on airplane components is set forth. Required heat-transfer and air-pressure-loss equations are presented, and methods of selecting appropriate meteorological conditions for flight over specified geographical areas and for the calculation of water-drop-impingement characteristics are suggested. In order to facilitate the design, a simple electrical analogue was devised which solves the complex heat-transfer relationships existing in the thermal-system analysis. The analogue is described and an illustration of its application to design is given. digital.library.unt.edu/ark:/67531/metadc53433/
Langley Field wind tunnel apparatus
No Description digital.library.unt.edu/ark:/67531/metadc53825/
Air resistance measurements on actual airplane parts
For the calculation of the parasite resistance of an airplane, a knowledge of the resistance of the individual structural and accessory parts is necessary. The most reliable basis for this is given by tests with actual airplane parts at airspeeds which occur in practice. The data given here relate to the landing gear of a Siemanms-Schuckert DI airplane; the landing gear of a 'Luftfahrzeug-Gesellschaft' airplane (type Roland Dlla); landing gear of a 'Flugzeugbau Friedrichshafen' G airplane; a machine gun, and the exhaust manifold of a 269 HP engine. digital.library.unt.edu/ark:/67531/metadc53822/
A preliminary investigation of a new method for testing aerofoils in free flight
This report is a description of a new method of testing aerofoils in free flight devised by the National Advisory Committee for Aeronautics. The method consists in lowering below a flying airplane a large inverted aerofoil on three small steel wires in such a way that the lift on the aerofoil always keeps the wires tight. The resultant force is measured by the tension in the wires, and the direction of the resultant by the amount the wing trails backwards. A test was made on an aerofoil of the N.A.C.A. #64 section, 6 ft. in span and the results are compared with a similar section tested in the wind tunnel. This investigation indicates that by the use of suitable recording apparatus aerofoils may be accurately and conveniently tested at a Reynolds number, a velocity and a degree of turbulence, comparable with that on the full-sized airplane. Satisfactory experiments were also made in trailing a sphere and a streamlined body on single wires. digital.library.unt.edu/ark:/67531/metadc53821/
Variation in the number of revolutions of air propellers
No Description digital.library.unt.edu/ark:/67531/metadc53827/
Experiments with fabrics for covering airplane wings, to determine effect of method of installation
No Description digital.library.unt.edu/ark:/67531/metadc53820/
Notes on the construction and testing of model airplanes
Here, it is shown that the construction of an airplane model can and should be simplified in order to obtain the most reliable test data. General requirements for model construction are given, keeping in mind that the general purpose of wind tunnel tests on a model airplane is to obtain the aerodynamic characteristics, the static balance, and the efficiency of controls for the particular combination of wings, tail surfaces, fuselage, and landing gear employed in the design. These parts must be exact scale reproductions. Any appreciable variation from scale reproduction must be in the remaining parts of the model, i.e., struts, wires, fittings, control horns, radiators, engines, and the various attachments found exposed to the wind in special airplanes. Interplane bracing is discussed in some detail. digital.library.unt.edu/ark:/67531/metadc53828/
Reduction in efficiency of propellers due to slipstream
In the slipstream behind a propeller there is a considerable amount of kinetic energy which has been imparted to it by the engine without producing any corresponding propeller thrust. The increased absorption of power reduces the propeller efficiency. Attention has been previously directed to this question by Bendemann and Madelung and other writers. Their contribution serves to verify a simple method of calculating the reduction in the propeller efficiency due to the slip stream. That method of calculation is given here. Explanations and examples are given for as single propeller and for two propellers mounted in tandem. digital.library.unt.edu/ark:/67531/metadc53824/
Compressive strength of tapered airplane struts
No Description digital.library.unt.edu/ark:/67531/metadc53829/
The N.A.C.A. recording tachometer and angle of attack recorder
This note contains photos and descriptions of airplane flight apparatus for use in conjunction with a recording galvanometer. In measuring the angle of attack a variable resistance is used, being controlled by a vane in the airstream. Thus it is only necessary to measure the change of resistance. digital.library.unt.edu/ark:/67531/metadc53826/
A Simple Method of Estimating the Subsonic Lift and Damping in Roll of Sweptback Wings
A method of modifying existing correction factors of lifting-surface theory to account approximately for the effects of sweep was derived, and these factors were applied to existing lifting-line theories for the lift and damping in roll of swept wings. Despite the simplicity of the resulting formulas the agreement with experimental data for low speeds is very good. The equation for lift is expressed entirely in terms of the geometric characteristics of the wing and the section-lift-curve; the necessity for any charts is thereby eliminated. The equation for the damping in roll, however, requires a chart for the determination of the effective lateral center of pressure for rolling moment due to rolling. If the Glauert-Prandtl transformation is used, the formulas obtained can be applied to swept wings at subsonic speeds below the critical speed. digital.library.unt.edu/ark:/67531/metadc53591/
Empirical relation between induced velocity, thrust, and rate of descent of a helicopter rotor as determined by wind-tunnel tests on four model rotors
The empirical relation between the induced velocity, thrust, and rate of vertical descent of a helicopter rotor was calculated from wind tunnel force tests on four model rotors by the application of blade-element theory to the measured values of the thrust, torque, blade angle, and equivalent free-stream rate of descent. The model tests covered the useful range of C(sub t)/sigma(sub e) (where C(sub t) is the thrust coefficient and sigma(sub e) is the effective solidity) and the range of vertical descent from hovering to descent velocities slightly greater than those for autorotation. The three bladed models, each of which had an effective solidity of 0.05 and NACA 0015 blade airfoil sections, were as follows: (1) constant-chord, untwisted blades of 3-ft radius; (2) untwisted blades of 3-ft radius having a 3/1 taper; (3) constant-chord blades of 3-ft radius having a linear twist of 12 degrees (washout) from axis of rotation to tip; and (4) constant-chord, untwisted blades of 2-ft radius. Because of the incorporation of a correction for blade dynamic twist and the use of a method of measuring the approximate equivalent free-stream velocity, it is believed that the data obtained from this program are more applicable to free-flight calculations than the data from previous model tests. digital.library.unt.edu/ark:/67531/metadc53597/