Latest content added for UNT Digital Library Partner: UNT Libraries Government Documents Departmenthttps://digital.library.unt.edu/explore/partners/UNTGD/browse/?fq=str_title_serial:NACA+Technical+Reports&sort=title&fq=untl_collection:TRAIL&start=202011-11-17T22:13:23-06:00UNT LibrariesThis is a custom feed for browsing UNT Digital Library Partner: UNT Libraries Government Documents DepartmentAerodynamic characteristics of circular-arc airfoils at high speeds2011-11-17T22:13:23-06:00https://digital.library.unt.edu/ark:/67531/metadc66021/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc66021/"><img alt="Aerodynamic characteristics of circular-arc airfoils at high speeds" title="Aerodynamic characteristics of circular-arc airfoils at high speeds" src="https://digital.library.unt.edu/ark:/67531/metadc66021/small/"/></a></p><p>From Summary: "The aerodynamic characteristics of eight circular-arc airfoils at speeds of 0.5, 0.8, 0.95, and 1.08 times the speed of sound have been determined in an open-jet air stream 2 inches in diameter, using models of 1-inch chord. The lower surface of each airfoil was plane; the upper surface was cylindrical. As compared with the measurements described in NACA-TR-319, the circular-arc airfoils at speeds of 0.95 and 1.08 times the speed of sound are more efficient than airfoils of the R. A. F. or Clark Y families. At a speed of 0.5 times the speed of sound, the thick circular-arc sections are extremely inefficient, but thin sections compare favorably with those of the R. A. F. family. A moderate round of the sharp edges changes the characteristics very little and is in many instances beneficial. The results indicate that the section of the blades of propellers intended for use at high tip-speeds should be of the circular-arc form for the outer part of the blade and should be changed gradually to the R. A. F. or Clark Y form as the hub is approached."</p>The aerodynamic characteristics of eight very thick airfoils from tests in the variable density wind tunnel2011-11-17T22:13:23-06:00https://digital.library.unt.edu/ark:/67531/metadc66049/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc66049/"><img alt="The aerodynamic characteristics of eight very thick airfoils from tests in the variable density wind tunnel" title="The aerodynamic characteristics of eight very thick airfoils from tests in the variable density wind tunnel" src="https://digital.library.unt.edu/ark:/67531/metadc66049/small/"/></a></p><p>Report presents the results of wind tunnel tests on a group of eight very thick airfoils having sections of the same thickness as those used near the roots of tapered airfoils. The tests were made to study certain discontinuities in the characteristic curves that have been obtained from previous tests of these airfoils, and to compare the characteristics of the different sections at values of the Reynolds number comparable with those attained in flight. The discontinuities were found to disappear as the Reynolds number was increased. The results obtained from the large-scale airfoil, a symmetrical airfoil having a thickness ratio of 21 per cent, has the best general characteristics.</p>The aerodynamic characteristics of four full-scale propellers having different plan forms2011-11-17T22:13:23-06:00https://digital.library.unt.edu/ark:/67531/metadc66301/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc66301/"><img alt="The aerodynamic characteristics of four full-scale propellers having different plan forms" title="The aerodynamic characteristics of four full-scale propellers having different plan forms" src="https://digital.library.unt.edu/ark:/67531/metadc66301/small/"/></a></p><p>From Introduction: "Its main purpose is to present propeller data for four full-scale propellers of Navy design, three of which have somewhat unusual plan forms and the other one has a normal (usual present-day type) plan form. These data may give some clue as to what may be expected from fundamental changes in blade plan form."</p>The Aerodynamic Characteristics of Full-Scale Propellers Having 2, 3, and 4 Blades of Clark Y and R.A.F. 6 Airfoil Sections2011-11-17T22:13:23-06:00https://digital.library.unt.edu/ark:/67531/metadc66298/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc66298/"><img alt="The Aerodynamic Characteristics of Full-Scale Propellers Having 2, 3, and 4 Blades of Clark Y and R.A.F. 6 Airfoil Sections" title="The Aerodynamic Characteristics of Full-Scale Propellers Having 2, 3, and 4 Blades of Clark Y and R.A.F. 6 Airfoil Sections" src="https://digital.library.unt.edu/ark:/67531/metadc66298/small/"/></a></p><p>"Aerodynamic tests were made of seven full-scale 10-foot-diameter propellers of recent design comprising three groups. The first group was composed of three propellers having Clark Y airfoil sections and the second group was composed of three propellers having R.A.F. 6 airfoil sections, the propellers of each group having 2, 3, and 4 blades. The third group was composed of two propellers, the 2-blade propeller taken from the second group and another propeller having the same airfoil section and number of blades but with the width and thickness 50 percent greater" (p. 1).</p>Aerodynamic Characteristics of Horizontal Tail Surfaces2011-11-17T22:13:23-06:00https://digital.library.unt.edu/ark:/67531/metadc66348/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc66348/"><img alt="Aerodynamic Characteristics of Horizontal Tail Surfaces" title="Aerodynamic Characteristics of Horizontal Tail Surfaces" src="https://digital.library.unt.edu/ark:/67531/metadc66348/small/"/></a></p><p>From Summary: "Collected data are presented on the aerodynamic characteristics of 17 horizontal tail surfaces including several with balanced elevators and two with end plates. Curves are given for coefficients of normal force, drag, and elevator hinge moment. A limited analysis of the results has been made. The normal-force coefficients are in better agreement with the lifting-surface theory of Prandtl and Blenk for airfoils of low aspect ratio than with the usual lifting-line theory. Only partial agreement exists between the elevator hinge-moment coefficients and those predicted by Glauert's thin-airfoil theory."</p>Aerodynamic Characteristics of NACA 23012 and 23021 Airfoils With 20-Percent-Chord External-Airfoil Flaps of NACA 23012 Section2011-11-17T22:13:23-06:00https://digital.library.unt.edu/ark:/67531/metadc66231/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc66231/"><img alt="Aerodynamic Characteristics of NACA 23012 and 23021 Airfoils With 20-Percent-Chord External-Airfoil Flaps of NACA 23012 Section" title="Aerodynamic Characteristics of NACA 23012 and 23021 Airfoils With 20-Percent-Chord External-Airfoil Flaps of NACA 23012 Section" src="https://digital.library.unt.edu/ark:/67531/metadc66231/small/"/></a></p><p>Report presents the results of an investigation of the general aerodynamic characteristics of the NACA 23012 and 23021 airfoils, each equipped with a 0.20c external flap of NACA 23012 section. The tests were made in the NACA 7 by 10-foot and variable-density wind tunnels and covered a range of Reynolds numbers that included values corresponding to those for landing conditions of a wide range of airplanes. Besides a determination of the variation of lift and drag characteristics with position of the flap relative to the main airfoil, complete aerodynamic characteristics of the airfoil-flap combination with a flap hinge axis selected to give small hinge moments were measured in the two tunnels.</p>The aerodynamic characteristics of seven frequently used wing sections at full Reynolds number2011-11-17T22:13:23-06:00https://digital.library.unt.edu/ark:/67531/metadc65886/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc65886/"><img alt="The aerodynamic characteristics of seven frequently used wing sections at full Reynolds number" title="The aerodynamic characteristics of seven frequently used wing sections at full Reynolds number" src="https://digital.library.unt.edu/ark:/67531/metadc65886/small/"/></a></p><p>This report contains the aerodynamic properties of the wing sections U.S.A. 5, U.S.A. 27, U.S.A. 35 A, U.S.A. 35 B, Clark Y, R.A.F. 15, and Gottingen 387, as determined at various Reynolds numbers up to an approximately full scale value in the variable density wind tunnel of the National Advisory Committee for Aeronautics. It is shown that the characteristics of the wings investigated are affected greatly and in a somewhat erratic manner by variation of the Reynolds number. In general there is a small increase in maximum lift and an appreciable decrease in drag at all lifts.</p>The aerodynamic characteristics of six full-scale propellers having different airfoil sections2011-11-17T22:13:23-06:00https://digital.library.unt.edu/ark:/67531/metadc66308/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc66308/"><img alt="The aerodynamic characteristics of six full-scale propellers having different airfoil sections" title="The aerodynamic characteristics of six full-scale propellers having different airfoil sections" src="https://digital.library.unt.edu/ark:/67531/metadc66308/small/"/></a></p><p>From Summary: "Wind-tunnel tests are reported of six 3-blade 10-foot propellers operated in front of a liquid-cooled engine nacelle. The propellers were identical except for blade airfoil sections, which were: Clark y, R.A.F. 6, NACA 4400, NACA 2400-34, NACA 2rsub200, and NACA 6400. The range of blade angles investigated extended for 15 degrees to 40 degrees for all propellers except the Clark y, for which it extended to 45 degrees. The results showed that the range in maximum efficiency between the highest and lowest values was about 3 percent. The highest efficiencies were for the low-camber sections."</p>Aerodynamic Characteristics of Twenty-Four Airfoils at High Speeds2011-11-17T22:13:23-06:00https://digital.library.unt.edu/ark:/67531/metadc65974/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc65974/"><img alt="Aerodynamic Characteristics of Twenty-Four Airfoils at High Speeds" title="Aerodynamic Characteristics of Twenty-Four Airfoils at High Speeds" src="https://digital.library.unt.edu/ark:/67531/metadc65974/small/"/></a></p><p>"If a propeller is mounted directly on the of a modern high-speed airplane engine, the outer airfoil sections of the propeller travel at speeds approaching the speed of sound. It is possible by the use of gearing and a somewhat larger propeller to reduce the speed of the propeller sections, but only at the expense of additional weight and some frictional loss of power. This report presents the results of this work" (p. 327).</p>Aerodynamic characteristics of wings with cambered external airfoil flaps, including lateral control, with a full-span flap2011-11-17T22:13:23-06:00https://digital.library.unt.edu/ark:/67531/metadc66197/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc66197/"><img alt="Aerodynamic characteristics of wings with cambered external airfoil flaps, including lateral control, with a full-span flap" title="Aerodynamic characteristics of wings with cambered external airfoil flaps, including lateral control, with a full-span flap" src="https://digital.library.unt.edu/ark:/67531/metadc66197/small/"/></a></p><p>From Summary: "The results of a wind-tunnel investigation of the NACA 23012, the NACA 23021, and the Clark Y airfoils, each equipped with a cambered external-airfoil flap, are presented in this report. The purpose of the research was to determine the relative merit of the various airfoils in combination with the cambered flap and to investigate the use of the flap as a combined lateral-control and high-lift device."</p>Aerodynamic Coefficients and Transformation Tables2011-11-17T22:13:23-06:00https://digital.library.unt.edu/ark:/67531/metadc65639/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc65639/"><img alt="Aerodynamic Coefficients and Transformation Tables" title="Aerodynamic Coefficients and Transformation Tables" src="https://digital.library.unt.edu/ark:/67531/metadc65639/small/"/></a></p><p>From Introduction: "The following brief explanation with tables of equivalents in various systems of units, has been prepared in order to facilitate such transformation."</p>The aerodynamic effects of wing cut-outs2011-11-17T22:13:23-06:00https://digital.library.unt.edu/ark:/67531/metadc66137/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc66137/"><img alt="The aerodynamic effects of wing cut-outs" title="The aerodynamic effects of wing cut-outs" src="https://digital.library.unt.edu/ark:/67531/metadc66137/small/"/></a></p><p>From Introduction: "The information now available concerning wing cut-outs or applicable to the analysis of their effects is plentiful (references 1 to 7) but too disconnected and unorganized to be of the greatest possible usefulness. In connection with the interference program being conducted in the N.A.C.A. varible-density wind tunnel, an analysis was therefore made of existing material to determine the qualitative effects of the different features of wing cut-outs, and to obtain means of calculating wing characteristics as affected by them."</p>Aerodynamic forces and loadings on symmetrical circular-arc airfoils with plain leading-edge and plain trailing-edge flaps2011-11-17T17:13:32-06:00https://digital.library.unt.edu/ark:/67531/metadc60514/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc60514/"><img alt="Aerodynamic forces and loadings on symmetrical circular-arc airfoils with plain leading-edge and plain trailing-edge flaps" title="Aerodynamic forces and loadings on symmetrical circular-arc airfoils with plain leading-edge and plain trailing-edge flaps" src="https://digital.library.unt.edu/ark:/67531/metadc60514/small/"/></a></p><p>From Summary: "An investigation has been made in the Langley two-dimensional low-turbulence tunnel and in the Langley two-dimensional low-pressure tunnel of 6- and 10-percent-thick symmetrical circular-arc airfoil sections at low Mach numbers and several Reynolds numbers. The airfoils were equipped with 0.15-chord plain leading-edge flaps and 0.20-chord plan trailing-edge flaps. The section lift and pitching-moment characteristics were determined for both airfoils with the flaps deflected individually and in combination."</p>The Aerodynamic Forces and Moments Exerted on a Spinning Model of the NY-1 Airplane as Measured by the Spinning Balance2011-11-17T22:13:23-06:00https://digital.library.unt.edu/ark:/67531/metadc66114/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc66114/"><img alt="The Aerodynamic Forces and Moments Exerted on a Spinning Model of the NY-1 Airplane as Measured by the Spinning Balance" title="The Aerodynamic Forces and Moments Exerted on a Spinning Model of the NY-1 Airplane as Measured by the Spinning Balance" src="https://digital.library.unt.edu/ark:/67531/metadc66114/small/"/></a></p><p>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."</p>The Aerodynamic Forces on Airship Hulls2011-11-11T19:22:00-06:00https://digital.library.unt.edu/ark:/67531/metadc53403/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc53403/"><img alt="The Aerodynamic Forces on Airship Hulls" title="The Aerodynamic Forces on Airship Hulls" src="https://digital.library.unt.edu/ark:/67531/metadc53403/small/"/></a></p><p>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.</p>The Aerodynamic Forces on Airship Hulls2011-11-17T22:13:23-06:00https://digital.library.unt.edu/ark:/67531/metadc65834/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc65834/"><img alt="The Aerodynamic Forces on Airship Hulls" title="The Aerodynamic Forces on Airship Hulls" src="https://digital.library.unt.edu/ark:/67531/metadc65834/small/"/></a></p><p>"This report describes the new method for making computations in connection with the study of rigid airship, which was used in the investigation of the navy's ZR-1 by the special subcommittee of the National Advisory Committee for Aeronautics appointed for this purpose. It presents the general theory of the air forces on airship hulls of the type mentioned, and an attempt has been made to develop the results from the very fundamentals of mechanics without reference to some of the modern highly developed conceptions, which may not yet be thoroughly known to readers uninitiated into modern aerodynamics, and which may, perhaps, for all time remain restricted to a small number of specialists" (p. 5).</p>The Aerodynamic Forces on Slender Plane- and Cruciform-Wing and Body Combinations2011-11-17T17:13:32-06:00https://digital.library.unt.edu/ark:/67531/metadc60294/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc60294/"><img alt="The Aerodynamic Forces on Slender Plane- and Cruciform-Wing and Body Combinations" title="The Aerodynamic Forces on Slender Plane- and Cruciform-Wing and Body Combinations" src="https://digital.library.unt.edu/ark:/67531/metadc60294/small/"/></a></p><p>From Introduction: "Since these results were not applicable to the present problem, a theoretical analysis of the aerodynamic properties of slender wing-body combinations was undertaken. The results of this investigation were first reported in reference 5 and were later extended in reference 6 to include cruciform-wing and body combinations. The present report summarizes and extends the theory and results previously presented in these references."</p>The aerodynamic plane table2011-11-17T22:13:23-06:00https://digital.library.unt.edu/ark:/67531/metadc65817/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc65817/"><img alt="The aerodynamic plane table" title="The aerodynamic plane table" src="https://digital.library.unt.edu/ark:/67531/metadc65817/small/"/></a></p><p>This report gives the description and the use of a specially designed aerodynamic plane table.</p>The aerodynamic properties of thick aerofoils suitable for internal bracing2011-11-17T22:13:23-06:00https://digital.library.unt.edu/ark:/67531/metadc65724/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc65724/"><img alt="The aerodynamic properties of thick aerofoils suitable for internal bracing" title="The aerodynamic properties of thick aerofoils suitable for internal bracing" src="https://digital.library.unt.edu/ark:/67531/metadc65724/small/"/></a></p><p>From Introduction: "The object of this investigation was to determine the characteristics of various types of wings having sufficient depth to entirely inclose the wing bracing, and also to provide data for the further design of such sections. Results of the investigation of the following subjects are given: (1) effect of changing the upper and lower camber of thick aerofoils of uniform section; (2) effect of thickening the center and thinning the tips of a thin aerofoil; (3) effect of adding a convex lower surface to a tapered section; (4) effect of changing the mean thickness with constant center and tip sections; and (5) effect of varying the chord along the span."</p>The Aerodynamic Properties of Thick Airfoils 22011-11-17T22:13:23-06:00https://digital.library.unt.edu/ark:/67531/metadc65803/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc65803/"><img alt="The Aerodynamic Properties of Thick Airfoils 2" title="The Aerodynamic Properties of Thick Airfoils 2" src="https://digital.library.unt.edu/ark:/67531/metadc65803/small/"/></a></p><p>"This investigation is an extension of NACA report no. 75 for the purpose of studying the effect of various modifications in a given wing section, including changes in thickness, height of lower camber, taper in thickness, and taper in plan form with special reference to the development of thick, efficient airfoils. The method consisted in testing the wings in the NACA 5-foot wind tunnel at speeds up to 50 meters (164 feet) per second while they were being supported on a new type of wire balance. Some of the airfoils developed showed results of great promise" (p. 521).</p>Aerodynamic theory and test of strut forms. Part I2011-11-17T22:13:23-06:00https://digital.library.unt.edu/ark:/67531/metadc65966/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc65966/"><img alt="Aerodynamic theory and test of strut forms. Part I" title="Aerodynamic theory and test of strut forms. Part I" src="https://digital.library.unt.edu/ark:/67531/metadc65966/small/"/></a></p><p>This report presents the first part of a two part study made under this title. In this part the symmetrical inviscid flow about an empirical strut of high service merit is found by both the Rankine and the Joukowsky methods. The results can be made to agree as closely as wished. Theoretical stream surfaces as well as surfaces of constant speed and pressure in the fluid about the strut are found. The surface pressure computed from the two theories agrees well with the measured pressure on the fore part of the model but not so well on the after part. From the theoretical flow speed the surface friction is computed by an empirical formula. The drag integrated from the friction and measured pressure closely equals the whole measured drag. As the pressure drag and the whole drag are accurately determined, the friction formula also appears trustworthy for such fair shapes. (author).</p>Aerodynamic theory and tests of strut forms 22011-11-17T22:13:23-06:00https://digital.library.unt.edu/ark:/67531/metadc65989/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc65989/"><img alt="Aerodynamic theory and tests of strut forms 2" title="Aerodynamic theory and tests of strut forms 2" src="https://digital.library.unt.edu/ark:/67531/metadc65989/small/"/></a></p><p>This report presents the second of two studies under the same title. In this part five theoretical struts are developed from distributed sources and sinks and constructed for pressure and resistance tests in a wind tunnel. The surface pressures for symmetrical inviscid flow are computed for each strut from theory and compared with those found by experiment. The theoretical and experimental pressures are found to agree quantitatively near the bow, only qualitatively over the suction range, the experimental suctions being uniformly a little low, and not at all near the stern.</p>Aerofoils and Aerofoil Structural Combinations2011-11-17T22:13:23-06:00https://digital.library.unt.edu/ark:/67531/metadc65638/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc65638/"><img alt="Aerofoils and Aerofoil Structural Combinations" title="Aerofoils and Aerofoil Structural Combinations" src="https://digital.library.unt.edu/ark:/67531/metadc65638/small/"/></a></p><p>Report presents results of wind tunnel tests of cambered aerofoils and body-wing combinations used for biplanes. Aerodynamic characteristics including drag, lift-drift ratio and stability derivatives are given.</p>Aeronautic instruments. Section 1: general classification of instruments and problems including bibliography2011-11-17T22:13:23-06:00https://digital.library.unt.edu/ark:/67531/metadc65775/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc65775/"><img alt="Aeronautic instruments. Section 1: general classification of instruments and problems including bibliography" title="Aeronautic instruments. Section 1: general classification of instruments and problems including bibliography" src="https://digital.library.unt.edu/ark:/67531/metadc65775/small/"/></a></p><p>This report is intended as a technical introduction to the series of reports on aeronautic instruments. It presents a discussion of those subjects which are common to all instruments. First, a general classification is given, embracing all types of instruments used in aeronautics. Finally, a classification is given of the various problems confronted by the instrument expert and investigator. In this way the following groups of problems are brought up for consideration: problems of mechanical design, human factor, manufacturing problems, supply and selection of instruments, problems concerning the technique of testing, problems of installation, problems concerning the use of instruments, problems of maintenance, and physical research problems. This enumeration of problems which are common to instruments in general serves to indicate the different points of view which should be kept in mind in approaching the study of any particular instrument.</p>Aeronautic instruments. Section 2: altitude instruments2011-11-17T22:13:23-06:00https://digital.library.unt.edu/ark:/67531/metadc65776/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc65776/"><img alt="Aeronautic instruments. Section 2: altitude instruments" title="Aeronautic instruments. Section 2: altitude instruments" src="https://digital.library.unt.edu/ark:/67531/metadc65776/small/"/></a></p><p>This report is Section two of a series of reports on aeronautic instruments (Technical Report nos. 125 to 132, inclusive). This section discusses briefly barometric altitude determinations, and describes in detail the principal types of altimeters and barographs used in aeronautics during the recent war. This is followed by a discussion of performance requirements for such instruments and an account of the methods of testing developed by the Bureau of Standards. The report concludes with a brief account of the results of recent investigations. For accurate measurements of altitude, reference must also be made to thermometer readings of atmospheric temperature, since the altitude is not fixed by atmospheric pressure alone. This matter is discussed in connection with barometric altitude determination.</p>Aeronautic Instruments Section 3: Aircraft Speed Instruments2011-11-17T22:13:23-06:00https://digital.library.unt.edu/ark:/67531/metadc65777/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc65777/"><img alt="Aeronautic Instruments Section 3: Aircraft Speed Instruments" title="Aeronautic Instruments Section 3: Aircraft Speed Instruments" src="https://digital.library.unt.edu/ark:/67531/metadc65777/small/"/></a></p><p>Part 1 contains a discussion and description of the various types of air speed measuring instruments. The authors then give general specifications and performance requirements with the results of tests on air speed indicators at the Bureau of Standards. Part 2 reports methods and laboratory apparatus used at the Bureau of Standards to make static tests. Methods are also given of combining wind tunnel tests with static tests. Consideration is also given to free flight tests. Part 3 discusses the problem of finding suitable methods for the purpose of measuring the speed of aircraft relative to the ground.</p>Aeronautic Instruments Section 4: Direction Instruments2011-11-17T22:13:23-06:00https://digital.library.unt.edu/ark:/67531/metadc65778/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc65778/"><img alt="Aeronautic Instruments Section 4: Direction Instruments" title="Aeronautic Instruments Section 4: Direction Instruments" src="https://digital.library.unt.edu/ark:/67531/metadc65778/small/"/></a></p><p>Part one points out the adequacy of a consideration of the steady state gyroscopic motion as a basis for the discussion of displacements of the gyroscope mounted on an airplane, and develops a simple theory on this basis. Part two describes a new type of stabilizing gyro mounted on top of a spindle by means of a universal joint, the spindle being kept in a vertical position by supporting it as a pendulum of which the bob is the driving motor. Methods of tests and the difficulties in designing a satisfactory and reliable compass for aircraft use in considered in part three. Part four contains a brief general treatment of the important features of construction of aircraft compasses and description of the principal types used.</p>Aeronautic instruments. Section 5 : power plant instruments2011-11-17T22:13:23-06:00https://digital.library.unt.edu/ark:/67531/metadc65779/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc65779/"><img alt="Aeronautic instruments. Section 5 : power plant instruments" title="Aeronautic instruments. Section 5 : power plant instruments" src="https://digital.library.unt.edu/ark:/67531/metadc65779/small/"/></a></p><p>Part 1 gives a general discussion of the uses, principles, construction, and operation of airplane tachometers. Detailed description of all available instruments, both foreign and domestic, are given. Part 2 describes methods of tests and effect of various conditions encountered in airplane flight such as change of temperature, vibration, tilting, and reduced air pressure. Part 3 describes the principal types of distance reading thermometers for aircraft engines, including an explanation of the physical principles involved in the functioning of the instruments and proper filling of the bulbs. Performance requirements and testing methods are given and a discussion of the source of error and results of tests. Part 4 gives methods of tests and calibration, also requirements of gauges of this type for the pressure measurement of the air pressure in gasoline tanks and the engine oil pressure on airplanes. Part 5 describes two types of gasoline gauges, the float type and the pressure type.</p>Aeronautic instruments. Section 6 : aerial navigation and navigating instruments2011-11-17T22:13:23-06:00https://digital.library.unt.edu/ark:/67531/metadc65781/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc65781/"><img alt="Aeronautic instruments. Section 6 : aerial navigation and navigating instruments" title="Aeronautic instruments. Section 6 : aerial navigation and navigating instruments" src="https://digital.library.unt.edu/ark:/67531/metadc65781/small/"/></a></p><p>This report outlines briefly the methods of aerial navigation which have been developed during the past few years, with a description of the different instruments used. Dead reckoning, the most universal method of aerial navigation, is first discussed. Then follows an outline of the principles of navigation by astronomical observation; a discussion of the practical use of natural horizons, such as sea, land, and cloud, in making extant observations; the use of artificial horizons, including the bubble, pendulum, and gyroscopic types. A description is given of the recent development of the radio direction finder and its application to navigation.</p>Aeronautic Instruments Section 6: Oxygen Instruments2011-11-17T22:13:23-06:00https://digital.library.unt.edu/ark:/67531/metadc65780/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc65780/"><img alt="Aeronautic Instruments Section 6: Oxygen Instruments" title="Aeronautic Instruments Section 6: Oxygen Instruments" src="https://digital.library.unt.edu/ark:/67531/metadc65780/small/"/></a></p><p>This report contains statements as to amount of oxygen required at different altitudes and the methods of storing oxygen. The two types of control apparatus - the compressed oxygen type and the liquid oxygen type - are described. Ten different instruments of the compressed type are described, as well as the foreign instruments of the liquid types. The performance and specifications and the results of laboratory tests on all representative types conclude this report.</p>Aeronautic Instruments Section 8: Recent Developments and Outstanding Problems2011-11-17T22:13:23-06:00https://digital.library.unt.edu/ark:/67531/metadc65782/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc65782/"><img alt="Aeronautic Instruments Section 8: Recent Developments and Outstanding Problems" title="Aeronautic Instruments Section 8: Recent Developments and Outstanding Problems" src="https://digital.library.unt.edu/ark:/67531/metadc65782/small/"/></a></p><p>This report is section VIII of a series of reports on aeronautic instruments. The preceding reports in this series have discussed in detail the various types of aeronautic instruments which have reached a state of practical development such that they have already found extensive use. It is the purpose of this paper to discuss briefly some of the more recent developments in the field of aeronautic instrument design and to suggest some of the outstanding problems awaiting solution.</p>Aeronautic Power Plant Investigations2011-11-17T22:13:23-06:00https://digital.library.unt.edu/ark:/67531/metadc65642/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc65642/"><img alt="Aeronautic Power Plant Investigations" title="Aeronautic Power Plant Investigations" src="https://digital.library.unt.edu/ark:/67531/metadc65642/small/"/></a></p><p>Report presents the design of radiators, spark plugs and test equipment used to test the performance of aeronautic engines at high altitudes.</p>Air conditions close to the ground and the effect on airplane landings2011-11-17T22:13:23-06:00https://digital.library.unt.edu/ark:/67531/metadc66146/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc66146/"><img alt="Air conditions close to the ground and the effect on airplane landings" title="Air conditions close to the ground and the effect on airplane landings" src="https://digital.library.unt.edu/ark:/67531/metadc66146/small/"/></a></p><p>This report presents the results of an investigation undertaken to determine the feasibility of making glide landings in gusty air. Wind velocities were measured at several stations between the ground and a height of 51 feet, and flight tests were made to determine the actual influence of gusts on an airplane gliding close to the ground.</p>Air-Consumption Parameters for Automatic Mixture Control of Aircraft Engines2011-11-17T17:13:32-06:00https://digital.library.unt.edu/ark:/67531/metadc60083/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc60083/"><img alt="Air-Consumption Parameters for Automatic Mixture Control of Aircraft Engines" title="Air-Consumption Parameters for Automatic Mixture Control of Aircraft Engines" src="https://digital.library.unt.edu/ark:/67531/metadc60083/small/"/></a></p><p>From Introduction: "The purpose of this analysis was to investigate the use of a function of intake-manifold pressure, exhaust back pressure, intake manifold temperature, and engine speed in place of a venturi as a means of measuring engine air consumption and to determine if this function is suitable for automatic mixture control."</p>Air flow around finned cylinders2011-11-17T22:13:23-06:00https://digital.library.unt.edu/ark:/67531/metadc66213/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc66213/"><img alt="Air flow around finned cylinders" title="Air flow around finned cylinders" src="https://digital.library.unt.edu/ark:/67531/metadc66213/small/"/></a></p><p>Report presents the results of a study made to determine the air-flow characteristics around finned cylinders. Air-flow distribution is given for a smooth cylinder, for a finned cylinder having several fin spacings and fin widths, and for a cylinder with several types of baffle with various entrance and exit shapes. The results of these tests show: that flow characteristics around a cylinder are not so critical to changes in fin width as they are to fin spacing; that the entrance of the baffle has a marked influence on its efficiency; that properly designed baffles increase the air flow over the rear of the cylinder; and that these tests check those of heat-transfer tests in the choice of the best baffle.</p>Air flow in a separating laminar boundary layer2011-11-17T22:13:23-06:00https://digital.library.unt.edu/ark:/67531/metadc66183/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc66183/"><img alt="Air flow in a separating laminar boundary layer" title="Air flow in a separating laminar boundary layer" src="https://digital.library.unt.edu/ark:/67531/metadc66183/small/"/></a></p><p>Report discussing the speed distribution in a laminar boundary layer on the surface of an elliptic cylinder, of major and minor axes 11.78 and 3.98 inches, respectively, has been determined by means of a hot-wire anemometer. The direction of the impinging air stream was parallel to the major axis. Special attention was given to the region of separation and to the exact location of the point of separation. An approximate method, developed by K. Pohlhausen for computing the speed distribution, the thickness of the layer, and the point of separation, is described in detail; and speed-distribution curves calculated by this method are presented for comparison with experiment.</p>Air flow in the boundary layer near a plate2011-11-17T22:13:23-06:00https://digital.library.unt.edu/ark:/67531/metadc66220/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc66220/"><img alt="Air flow in the boundary layer near a plate" title="Air flow in the boundary layer near a plate" src="https://digital.library.unt.edu/ark:/67531/metadc66220/small/"/></a></p><p>From Summary: "The published data on the distribution of speed near a thin flat plate with sharp leading edge placed parallel to the flow (skin friction plate) are reviewed and the results of some additional measurements are described. The purpose of the experiments was to study the basic phenomena of boundary-layer flow under simple conditions."</p>Air Flow in the Boundary Layer of an Elliptic Cylinder2011-11-17T22:13:23-06:00https://digital.library.unt.edu/ark:/67531/metadc66310/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc66310/"><img alt="Air Flow in the Boundary Layer of an Elliptic Cylinder" title="Air Flow in the Boundary Layer of an Elliptic Cylinder" src="https://digital.library.unt.edu/ark:/67531/metadc66310/small/"/></a></p><p>From Introduction: "The present investigation was carried out for the purpose of supplementing the earlier work with information on the boundary layer under such conditions of air speed and turbulence that transition occurs and the layer is partly laminar and partly turbulent. In the work reported in reference 1, the air speed was about 12 feet per second, and it was assumed that the boundary layer remained in the laminar condition until after separation because the separation point remained fixed and the pressure distribution about the cylinder was unaffected until an air speed of 15 feet per second was reached."</p>Air Flow Through Poppet Valves2011-11-17T22:13:23-06:00https://digital.library.unt.edu/ark:/67531/metadc65644/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc65644/"><img alt="Air Flow Through Poppet Valves" title="Air Flow Through Poppet Valves" src="https://digital.library.unt.edu/ark:/67531/metadc65644/small/"/></a></p><p>Report discusses the comparative continuous flow characteristics of single and double poppet valves. The experimental data presented affords a direct comparison of valves, single and in pairs of different sizes, tested in a cylinder designed in accordance with current practice in aviation engines.</p>Air force and moment for N-20 wing with certain cut-outs2011-11-17T22:13:23-06:00https://digital.library.unt.edu/ark:/67531/metadc65919/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc65919/"><img alt="Air force and moment for N-20 wing with certain cut-outs" title="Air force and moment for N-20 wing with certain cut-outs" src="https://digital.library.unt.edu/ark:/67531/metadc65919/small/"/></a></p><p>From Introduction: "The airplane designer often finds it necessary, in meeting the requirements of visibility, to remove area or to otherwise locally distort the plan or section of an airplane wing. This report, prepared for the Bureau of Aeronautics January 15, 1925, contains the experimental results of tests on six 5 by 30 inch N-20 wing models, cut out or distorted in different ways, which were conducted in the 8 by 8 foot wind tunnel of the Navy Aerodynamical Laboratory in Washington in 1924. The measured and derived results are given without correction for vl/v for wall effect and for standard air density, p=0.00237 slug per cubic foot."</p>Air Force Tests of Sperry Messenger Model With Six Sets of Wings2011-11-17T22:13:23-06:00https://digital.library.unt.edu/ark:/67531/metadc65922/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc65922/"><img alt="Air Force Tests of Sperry Messenger Model With Six Sets of Wings" title="Air Force Tests of Sperry Messenger Model With Six Sets of Wings" src="https://digital.library.unt.edu/ark:/67531/metadc65922/small/"/></a></p><p>From Summary: "The purpose of this test was to compare six well-known airfoils, the R.A.F 15, U.S.A. 5, U.S.A. 27, U.S.A. 35-B, Clark Y, and Gottingen 387, fitted to the Sperry Messenger model, at full scale Reynolds number as obtained in the variable density wind tunnel of the National Advisory Committee for Aeronautics; and to determine the scale effect on the model equipped with all the details of the actual airplane. The results show a large decrease in minimum drag coefficient upon increasing the Reynolds number from about one-twentieth scale to full scale. A comparison is made between the results of these tests and those obtained from tests made in this tunnel on airfoils alone."</p>Air forces and moments on triangular and related wings with subsonic leading edges oscillating in supersonic potential flow2011-11-17T17:13:32-06:00https://digital.library.unt.edu/ark:/67531/metadc60458/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc60458/"><img alt="Air forces and moments on triangular and related wings with subsonic leading edges oscillating in supersonic potential flow" title="Air forces and moments on triangular and related wings with subsonic leading edges oscillating in supersonic potential flow" src="https://digital.library.unt.edu/ark:/67531/metadc60458/small/"/></a></p><p>From Introduction: "This report is concerned with the derivation of expressions for the velocity potential and associated forces and moments for oscillating triangular wings in supersonic flow. The purpose of the present report is to make use of the expanded form of the velocity potential to obtain the forces and moments, based on the first terms of this potential, for a rigid triangular wing performing vertical and pitching sinusoidal oscillations in mixed supersonic flow."</p>Air forces, moments and damping on model of fleet airship Shenandoah2011-11-17T22:13:23-06:00https://digital.library.unt.edu/ark:/67531/metadc65867/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc65867/"><img alt="Air forces, moments and damping on model of fleet airship Shenandoah" title="Air forces, moments and damping on model of fleet airship Shenandoah" src="https://digital.library.unt.edu/ark:/67531/metadc65867/small/"/></a></p><p>From Introduction: "To furnish data for the design of the fleet airship Shenandoah, a model was made and tested in the 8 by 8 foot wind tunnel for wind forces, moments, and damping, under conditions described in this report. The results are given for air of standard density. P=0.00237 slugs per cubic foot with vl/v correction, and with but a brief discussion of the aerodynamic design features of the airship."</p>The air forces on a model of the sperry messenger airplane without propeller2011-11-17T22:13:23-06:00https://digital.library.unt.edu/ark:/67531/metadc65877/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc65877/"><img alt="The air forces on a model of the sperry messenger airplane without propeller" title="The air forces on a model of the sperry messenger airplane without propeller" src="https://digital.library.unt.edu/ark:/67531/metadc65877/small/"/></a></p><p>From Summary: "This is a report on a scale effect research which was made in the variable-density wind tunnel of the National Advisory Committee for Aeronautics at the request of the Army Air Service. While the present report is of a preliminary nature, the work has progressed far enough to show that the scale effect is almost entirely confined to the drag."</p>The air forces on a systematic series of biplane and triplane cellule models2011-11-17T22:13:23-06:00https://digital.library.unt.edu/ark:/67531/metadc65908/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc65908/"><img alt="The air forces on a systematic series of biplane and triplane cellule models" title="The air forces on a systematic series of biplane and triplane cellule models" src="https://digital.library.unt.edu/ark:/67531/metadc65908/small/"/></a></p><p>Report discussing the air forces on a systematic series of biplane and triplane cellule models which are measured in the atmospheric density tunnel.</p>Air propellers in yaw2011-11-17T22:13:23-06:00https://digital.library.unt.edu/ark:/67531/metadc66255/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc66255/"><img alt="Air propellers in yaw" title="Air propellers in yaw" src="https://digital.library.unt.edu/ark:/67531/metadc66255/small/"/></a></p><p>Report presents the results of tests conducted at Stanford University of a 3-foot model propeller at four pitch settings and at 0 degree, 10 degrees, 20 degrees, and 30 degrees yaw.</p>Aircraft Accidents: Method of Analysis2011-11-17T22:13:23-06:00https://digital.library.unt.edu/ark:/67531/metadc66012/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc66012/"><img alt="Aircraft Accidents: Method of Analysis" title="Aircraft Accidents: Method of Analysis" src="https://digital.library.unt.edu/ark:/67531/metadc66012/small/"/></a></p><p>The revised report includes the chart for the analysis of aircraft accidents, combining consideration of the immediate causes, underlying causes, and results of accidents, as prepared by the special committee, with a number of the definitions clarified. A brief statement of the organization and work of the special committee and of the Committee on Aircraft Accidents; and statistical tables giving a comparison of the types of accidents and causes of accidents in the military services on the one hand and in civil aviation on the other, together with explanations of some of the important differences noted in these tables.</p>Aircraft Accidents: Method of Analysis2011-11-17T22:13:23-06:00https://digital.library.unt.edu/ark:/67531/metadc65962/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc65962/"><img alt="Aircraft Accidents: Method of Analysis" title="Aircraft Accidents: Method of Analysis" src="https://digital.library.unt.edu/ark:/67531/metadc65962/small/"/></a></p><p>From Introduction Purpose and Organization: "This report on a method of analysis of aircraft accidents has been prepared by a special committee on the nomenclature, subdivision, and classification of aircraft accidents organized by the National Advisory Committee for Aeronautics in response to a request dated February 18, 1928, from the Air Coordination Committee consisting of the Assistant Secretaries for Aeronautics in the Departments of War, Navy, and Commerce."</p>Aircraft Accidents: Methods of Analysis2011-11-17T22:13:23-06:00https://digital.library.unt.edu/ark:/67531/metadc66234/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc66234/"><img alt="Aircraft Accidents: Methods of Analysis" title="Aircraft Accidents: Methods of Analysis" src="https://digital.library.unt.edu/ark:/67531/metadc66234/small/"/></a></p><p>This report is a revision of NACA-TR-357. It was prepared by the Committee on Aircraft Accidents. The purpose of this report is to provide a basis for the classification and comparison of aircraft accidents, both civil and military.</p>Aircraft compass characteristics2011-11-17T22:13:23-06:00https://digital.library.unt.edu/ark:/67531/metadc66209/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc66209/"><img alt="Aircraft compass characteristics" title="Aircraft compass characteristics" src="https://digital.library.unt.edu/ark:/67531/metadc66209/small/"/></a></p><p>From Summary: "A description of the test methods used at the National Bureau of Standards for determining the characteristics of aircraft compasses is given. The methods described are particularly applicable to compasses in which mineral oil is used as the damping liquid. Data on the viscosity and density of certain mineral oils used in United States Navy aircraft compasses are presented. Results of flight tests are presented."</p>