From Summary: "These properties compare favorably with those of the strongest similar alloys previously investigated. However, compared with a 60Cr-25Fe-15Mo alloy, the three cobalt-chronium-nickel cast alloys are inferior. A correlation of NACA and OSRD (Project NRC-8) data is presented, showing the variation of rupture strengths with temperature in the range of 1350^o to 2000^o for alloys."
Report discussing an adapter which uses three Tuckerman optical strain gages to measure the displacement of the three vortices of an equilateral triangle along lines 120 degrees apart. These displacements are substituted in well-known equations in order to compute the magnitude and direction of the principal strains. Tests of the adaptor indicate that principal strains over a gage length of 1.42 inch may be measured with a systematic error not exceeding 4 percent and a mean observational error of the order of + or minus 0.000006. The maximum observed error in strain was of the order of 0.00006. The directions of principal strains for unidirectional stress were measured with the adaptor with an average error of the order of 1 degree.
Report presenting an investigation of the two-dimensional aerodynamic characteristics of 15 NACA airfoils at four Reynolds numbers. The results indicate that the drag coefficient at the design lift coefficient and the maximum lift coefficient are the most important aerodynamic characteristics and are most affected by Reynolds number changes.
Report presenting theoretical pressure distributions and experimental aerodynamic characteristics at low speeds for a group of NACA four-digit series airfoil sections. Results regarding lift, drag, and pitching moment are provided.
Report presenting an investigation in the two-dimensional low-turbulence pressure tunnel to determine the aerodynamic characteristics of the NACA 8-H-12 airfoil section at four Reynolds numbers. The section lift, drag, and pitching-moment characteristics are presented for smooth and rough surface conditions. Generally, no unusual scale effects are present for either condition.
From Summary: "Two topics of interest to persons attempting to apply the heat method of preventing ice formation on aircraft are considered. Surfaces moving through air at high speed are shown, both theoretically and experimentally, to be subject to important aerodynamic heating effects that will materially reduce the heat required to prevent ice. Numerical calculations of the path of water drops in an air stream around a circular cylinder are given. From these calculations, information is obtained on the percentage of the swept area cleared of drops."
From Introduction: "Although the aerodynamic characteristics of the components of such configurations may be well known, the mutual interference resulting from combining the wings, as well as the wings and body, may be so great that is desirable to study the aerodynamic properties of the complete configurations. Two methods of handling this problem are presented in this report. The first method is essentially an extension of the theory for slender wing-body combinations of reference 1 to determine the load distribution, forces, and moments exerted on slender cruciform-wing and body combinations inclined simultaneously at small angles in pitch and yaw. "
From Introduction: "In an incomprehensible medium, the mutual interference of a fuselage and wing of high-aspect ratio (to which lifting-line theory is applicable) has been treated by Lennertz, Wiselsberger, Pepper, and Multhopp in reference 1, 2, 3, and 4. It is the purpose of this note to treat the effect of on the aerodynamic loading of the mutual interference between a low-aspect-ratio pointed wing and a fuselage consisting of a slender body of revolution."
Report presenting an investigation to determine the aerodynamic characteristics of a group of NACA 16-series airfoils related in camber and thickness over a range of Mach numbers. All of the currently available force-test data for NACA 16-series airfoils obtained under the same test conditions in the 24-inch high-speed tunnel are presented.
From Introduction: "This paper deals only with the aerodynamics of the fan proper and demonstrates the manner in which the radial distribution of axial velocity of fluid through a fan is governed by geometry of the fan itself."
From Introduction: "In order to afford a means of comparison and to obtain a clear understanding of the results, a study of the effects of normal angular deflections of the ailerons, with and against the spin, was included in the investigation. Ailerons deflected with the spin means that the ailerons are deflected with right aileron up and left aileron down in a right spin. The results of the investigation are discussed in this paper."
"In the present paper, under the same lineaeizing assumptions as are made in the derivation in reference 1 but with the explicit consideration and simplification of the form of the wake extending from the rear of the airfoil, the methods of Theodorsen (reference 2) have been extended to obtain the forces on the airfoil not only at a fixed angle of attack but also in arbitrary motion" (p. 1).
"Several methods (references 1 and 2) based on gas-dynamic principles are available for reducing such measurements. The results obtained by these methods are subject to the limitation of the gas-dynamic theory which is that the mean free path of the molecules between impacts, is small with respect to the measuring device. Inasmuch as no information on the subject is to present known to be available, the purpose of the present paper is to present a method based on the concept of free-molecule theory for use in connection with this problem" (p. 1).
From Summary: "This paper describes a method for the determination of drop size and free water in clouds, based on the interpretation of an artificially created rainbow. Details of the design and operation of an optical instrument employing this method are presented."
From Summary: "An analysis is presented of the characteristics of gas-filled bellows for sensing gas density to delineate the factors that affect the accuracy of this type of bellows."
From Introduction: "A collection balanced-aileron test data is given in reference 1. Reference 2 presents a collection of data applicable to the design of tail surfaces. The results of analyses of data for control surfaces with internal balances, plain-overhang and Frise balances, beveled trailing edges, and unshielded horn balances have already been published in references 3 to 6."
From Summary: "This paper deals with the single problem if circular shell-supported frames subjected to concentrated loadings. A mathematical attack is developed and presented in the form of nondimensional-coefficient curves."
"An investigation was made to determine the effect of mixture strength and of normal as well as optimum spark timing on the combustion, on the cylinder temperature, and on the performance characteristics of an engine. A single-cylinder test unit utilizing an air-cooled cylinder and a carburetor and operating with gasoline having an octane rating of 92 was used. The investigation covered a range of fuel-air ratios from 0.053 to 0.118. Indicator diagrams and engine-performance data were taken for each change in engine conditions" (p. 1).
From Introduction: "An analysis of a square web above the buckling load was presented in reference 1. The analysis of reference 1 therefore was repeated for a shear web with depth/width = 2.5. Comparison of the results with those for the square web then would indicate the effect in the depth-width ratio."
From Introduction: "In references 1, 2, and 3, flight measurements of the performance of a conventional, single-rotor helicopter equipped with its production fabric-covered main rotor blades are presented."
"A study is presented of ground effect as applied to the lifting airscrew of the type used in modern gyroplanes and helicopters. The mathematical analysis of the problem has been verified by tests made of three rotor models in the presence of a large circular "ground plane." The results of the study are presented in the form of convenient charts" (p. 1).
From Summary: "The purpose of this investigation was to determine whether such airplanes could be made to fly uncontrolled for an indefinite period of time without getting into dangerous attitudes and for a reasonable period of time (one to three minutes) without deviating excessively from their original course. The results of this analysis indicated that the uncontrolled motions of a personal airplane could be made safe as regards spiral tendencies and could be greatly improved as regards maintenance of course without resort to an autopilot."
Report presenting an investigation of a method to analyze and to estimate performance of jet engines, which was applied to the study of the characteristics of a research turbojet engine built for the investigation. Results regarding the compressor performance, turbine performance, combustion chamber, and interaction of jet engine components are provided.
Note presenting the performance of the turbine component of a research jet engine investigated with cold air. The interaction and matching of the turbine with the eight-stage compressor were computed with the combination considered as a jet engine and overall performance of the engine was then determined. Results regarding the performance of the first stator ring, turbine performance, and turbine-compressor matching are provided.
From Introduction: "The magnitude of hydrodynamic loads experienced by seaplanes during a landing impact has been investigated experimentally and theoretically by the National Advisory Committee for Aeronautics. The results as reported in references 1 and 2 provide a rational means of determining loads on conventional V-bottom hulls in a step landing."
From Introduction: "The results of the tests made with unheated internal flow are reported in reference 1. It is the purpose of this paper to attempt to express simply the efficiency loss as a function of the parameters which govern propeller operation and the internal air flow. The derived equations are correlated with the data presented in reference 1."
"A solution of Von Karman's fundamental equations for plates with large deflections is presented for the case of a shear web divided into square panels by reinforcing struts. Numerical solutions are given for struts of infinite rigidity and for struts the weight of which is one-fourth the weight of the sheet. The results are compared with Wagner's diagonal tension theory as extended by Kuhn and by Langhaar. It is found that the diagonal tension theory as developed by Kuhn agrees best with the present paper in the practical range when r=1/4. Kuhn's theory is in especially good agreement for the force in the strut when r=1/4" (p. 1).
From Introduction: "This paper summarizes the results of an analysis of V-G records taken on Douglas DC-2 airplanes during the period from June 1935 to December 1940. The operational life is compared with the operational lives of other airplanes flown on different routes during the corresponding period."
From Introduction: "The results of analyses of V-G data given in references 1 to 5 have shown that the flight loads of airplanes operated in commercial transport service are influenced by operating speeds and by forecasting and dispatching practices as reflected in differences between operations during the prewar and wartime periods. The available data are summarized and the flight results are compared with the results of analyses made in references 1 to 5."
From Introduction: "The present paper has been prepared to give the results of the analysis of the V-G records obtained from three Boeing S-307 airplanes operating in Caribbean region and the northern part of South America during the period from 1940 to 1944."
From Introduction: "The present report is the second prepared to give the results of an analysis of V-G data from commercial transport airplanes. The present report is concerned with an analysis of data obtained with Douglas DC-3 airplanes flying over three transcontinental routes in the United States."
From Introduction: "Acceleration and airspeed data obtained from V-G records collected during commercial transport operations (references 1 and 2) are being analyzed in some detail to determine the flight loads and operating speeds as functions of airplane, route, season, and prewar and wartime operations."
From Introduction: "This paper gives the results of an analysis of V-G data taken on four Sikorsky S-42A flying boats operated on Caribbean routes and along the east coast of South America during the period from 1936 to 1939. The available S-42A data are summarized and flight-load results are compared with the results of analyses made in the past."
Note presenting an analysis that was undertaken as part of an investigation of low-density fibrous core materials for sandwich construction. This particular investigation found that honeycomb structure exhibit promise as core materials because of their high strength-weight ratios. A formula has been derived that considerably reduced the amount of testing necessary to evaluate the effectiveness of the materials.
From Introduction: "The flare assumed is based primarily on reference 1, in which information permitting calculation of the flare characteristics of an airplane was obtained from flight tests. The results of calculations for airplanes having constant lift-drag ratio during the flare are plotted in chart form."
From Introduction: "It is the purpose of this paper to describe the physical properties that are necessary to specify mixture quality in a system containing fuel and dry air and to evaluate the theoretical rolation between these properties and the physical properties of the mixture."
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."
From Introduction: "Because of the importance of spray height, it is the purpose of the work considered in this report to attempt to determine a correlation for the main spray height in relatively smooth water."
"This report is the second phase of a broad program of study of the transient motions of helicopters in autorotative flight. The first phase (reference 1) dealt with the steady-state condition of autorotative vertical descent. This report is concerned with the the transition from the steady condition of hovering to the steady autorotative descent" (p. 1).
From Introduction: "In the present paper, the variation of effective gust velocity in convective-type clouds with altitude is investigated. Data obtained during 1941 and 1942 at altitudes up to 34,000 feet and data obtained more recently from the Thunderstorm Project (reference 5) at altitudes up to 26,000 feet are utilized for this purpose. Consideration is given in analyzing the results both to data for the range
From Summary: "This paper does not attempt to establish criterions for directional stability and control; rather, the emphasis is placed on providing some basis for design to specified criterions. An example applying the design methods has been included."
Investigations were made to develop a simplified method for designing exhaust-pipe shrouds to provide desired or maximum cooling of exhaust installations. Analysis of heat exchange and pressure drop of an adequate exhaust-pipe shroud system requires equations for predicting design temperatures and pressure drop on cooling air side of system. Present experiments derive such equations for usual straight annular exhaust-pipe shroud systems for both parallel flow and counter flow. Equations and methods presented are believed to be applicable under certain conditions to the design of shrouds for tail pipes of jet engines.
From Introduction: "The present paper contains the development of a recurrence formula for the bolt loads for the simplified case of a symmetrical butt joint with bolts spaced evenly in line with the applied load. The method presented herein is based on the fundamental relationship which was developed in reference 1 between the loads on any two successive bolts. The present paper also gives the results of an experimental investigation conducted to substantiate further the adequacy of the elastic theory as well as to yield additional data on the critical bolt load and the behavior of long joints in the plastic range and at the ultimate load."
From Introduction: "The results of analytical and experimental investigations conducted at the NACA Cleveland laboratory to determine the performance of an explosion-cycle combustion chamber with a timed inlet valve and several fixed-area exhaust nozzles are presented herein. These values are compared with theoretical values obtained from an analysis of an ideal constant-volume cycle and an approximate constant-volume cycle, which is presented."
From Introduction: "The ideas developed in this paper are presented as a means of saving the designer's time and as a method of reduction of control-system friction by an accurate calculation of pulley-axis angles without the errors and difficult checking incident to any graphical method."
"A matrix method of determining transmission, scattering, and absorption of radiation, such as gamma rays and neutrons, in large thickness of matter is presented. Experimental data as yet unavailable are required for complete utilization of the method. Material radioactivity whose intensity may be considered to be independent of time is also treated" (p. 1).
"This report is the result of the first part of a broad program to analyze the transient motions of a helicopter, which occur in the various phases of flight following power failure" (p. 1).
From Introduction: "The investigations in this paper were made to obtain more generalized mathematical analyses of monocoque structure subjected to internal pressure. It is also assumed that the principle of superposition can be applied, so that stress analysis of a structure with combined internal pressure and external load can be made without excessive complication."
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