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 Serial/Series Title: NACA Technical Reports
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Aerodynamic theory and test of strut forms. Part I

Aerodynamic theory and test of strut forms. Part I

Date: May 1928
Creator: Smith, R H
Description: 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).
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Aerodynamic theory and tests of strut forms. Part II

Aerodynamic theory and tests of strut forms. Part II

Date: May 1929
Creator: Smith, R H
Description: 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. This study is the strut sequel to Fuhrmann's research on airship forms, the one being a study in two dimensions, the other in three. A comparison of results indicates that the agreement between theory and experiment is somewhat better for bodies of revolution than for cylinders when both are shaped for slight resistance. The consistent deficiency of the experimental suctions which is found in the case of struts was not found in the case of airships, for which the experimental suctions were sometimes above sometimes below their theoretical values.
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Aerofoils and aerofoil structural combinations

Aerofoils and aerofoil structural combinations

Date: 1918?
Creator: Gorrell, Edgar S & Martin, H S
Description: 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.
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Aeronautic instruments. Section I : general classification of instruments and problems including bibliography

Aeronautic instruments. Section I : general classification of instruments and problems including bibliography

Date: 1925
Creator: Hersey, Mayo D.
Description: 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.
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Aeronautic instruments. Section II : altitude instruments

Aeronautic instruments. Section II : altitude instruments

Date: 1923?
Creator: Mears, A. H.; Henrickson, H. B. & Brombacher, W. G.
Description: 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.
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Aeronautic instruments. Section III : aircraft speed instruments

Aeronautic instruments. Section III : aircraft speed instruments

Date: 1923?
Creator: Hunt, Franklin L. & Stearns, H. O.
Description: 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.
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Aeronautic instruments. Section IV : direction instruments

Aeronautic instruments. Section IV : direction instruments

Date: 1923?~
Creator: Franklin, W. S.; Stillman, M. H.; Sanford, R. L.; Warner, John A. C.; Sylvander, R. C. & Rounds, E. W.
Description: 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. Principal types of gyroscopic inclinometers are described and requirements stated. 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.
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Aeronautic instruments. Section V : power plant instruments

Aeronautic instruments. Section V : power plant instruments

Date: 1923
Creator: Washburn, G. E.; Sylvander, R. C.; Mueller, E. F.; Wilhelm, R. M.; Eaton, H. N. & Warner, John A. C.
Description: 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. Methods of testing and calibrating gasoline depth gauges are given. The Schroeder, R. A. E., and the Mark II flowmeters are described.
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Aeronautic instruments. Section VI : aerial navigation and navigating instruments

Aeronautic instruments. Section VI : aerial navigation and navigating instruments

Date: 1923?~
Creator: Eaton, H. N.
Description: 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.
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Aeronautic instruments. Section VI : oxygen instruments

Aeronautic instruments. Section VI : oxygen instruments

Date: 1923?~
Creator: Hunt, F. L.
Description: 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.
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Aeronautic instruments. Section VIII : recent developments and outstanding problems

Aeronautic instruments. Section VIII : recent developments and outstanding problems

Date: 1923
Creator: Hunt, F. L.
Description: 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.
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Aeronautic Power Plant Investigations

Aeronautic Power Plant Investigations

Date: May 1, 1917
Creator: Dickinson, H. C.
Description: Report presents the design of radiators, spark plugs and test equipment used to test the performance of aeronautic engines at high altitudes.
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Air conditions close to the ground and the effect on airplane landings

Air conditions close to the ground and the effect on airplane landings

Date: April 3, 1934
Creator: Thompson, F L; Peck, W C & Beard, A P
Description: 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.
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Air-consumption parameters for automatic mixture control of aircraft engines

Air-consumption parameters for automatic mixture control of aircraft engines

Date: September 1, 1944
Creator: Shames, Sidney J
Description: Data obtained from Navy calibration tests of an 18-cylinder, two-row, radial engine of 3350-cubic-inch displacement and a 14-cylinder, two-row, radial engine of 2600-cubic-inch displacement (carburetor types) were analyzed to show the correlation between the air consumption of these engines and the parameters that evaluate the air consumption from intake-manifold temperature and pressure, exhaust back pressure, and engine speed.
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Air flow around finned cylinders

Air flow around finned cylinders

Date: November 7, 1935
Creator: Brevoort, M J & Rollin, Vern G
Description: 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.
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Air flow in a separating laminar boundary layer

Air flow in a separating laminar boundary layer

Date: December 1, 1934
Creator: Schubauer, G. B.
Description: 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.
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Air flow in the boundary layer near a plate

Air flow in the boundary layer near a plate

Date: March 1936
Creator: Dryden, Hugh L.
Description: 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.
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Air flow in the boundary layer of an elliptic cylinder

Air flow in the boundary layer of an elliptic cylinder

Date: August 6, 1938
Creator: Schubauer, G B
Description: The boundary layer of an elliptic cylinder of major and minor axis 11.78 and 3.98 inches, respectively, was investigated in air stream in which the turbulence could be varied. Conditions were arranged so that the flow was two-dimensional with the major axis of the ellipse parallel to the undisturbed stream. Speed distributions across the boundary layer were determined with a hot-wire anemometer at a number of positions about the surface for the lowest and highest intensities of turbulence, with the air speed in both cases sufficiently high to produce a turbulent boundary layer over the downstream part of the surface. The magnitude and the frequency of the speed fluctuations in the boundary layer were also measured by the use of the conventional type of hot-wire turbulence apparatus. Stream turbulence was found to affect both the nature of transition from laminar to turbulent flow in the layer and the position on the surface at which transition occurred. Transition was then investigated in detail with stream turbulence of several different scales and intensities.
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Air flow through poppet valves

Air flow through poppet valves

Date: 1918
Creator: Lewis, G W & Nutting, E M
Description: 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.
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Air force and moment for N-20 wing with certain cut-outs

Air force and moment for N-20 wing with certain cut-outs

Date: November 29, 1926
Creator: Smith, R H
Description: 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.
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Air force tests of sperry messenger model with six sets of wings

Air force tests of sperry messenger model with six sets of wings

Date: 1928?~
Creator: Shoemaker, James M
Description: 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. Maximum lift coefficient was increased with increasing scale for all the airfoils except the Gottingen 387, for which it was slightly decreased. A comparison is made between the results of these tests and those obtained from tests made in this tunnel on airfoils alone. (author).
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Air forces and moments on triangular and related wings with subsonic leading edges oscillating in supersonic potential flow

Air forces and moments on triangular and related wings with subsonic leading edges oscillating in supersonic potential flow

Date: 1952?~
Creator: Watkins, Charles E & Berman, Julian N
Description: This analysis treats the air forces and moments in supersonic potential flow on oscillating triangular wings and a series of sweptback and arrow wings with subsonic leading edges and supersonic trailing edges. For the wings undergoing sinusoidal torsional oscillations simultaneously with vertical translations, the linearized velocity potential is derived in the form of a power series in terms of a frequency parameter. This method can be useful for treatment of similar problems for other plan forms and for wings undergoing other sinusoidal motions. For triangular wings, as many terms of such a series expansion as may be derived can be determined; however, the terms after the first few become very cumbersome. Closed expressions that include the reduced frequency to the fifth power, an order which is sufficient for a large class of practical application, are given for the velocity potential and for the components of chordwise section force and moment coefficients. These wings are found to exhibit the possibility of undamped torsional oscillations for certain ranges of Mach number and locations of the axis of rotation. The ranges of these parameters are delineated for triangular wings.
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Air forces, moments and damping on model of fleet airship Shenandoah

Air forces, moments and damping on model of fleet airship Shenandoah

Date: 1922~
Creator: Zahm, A F; Smith, R H & Louden, F A
Description: 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.
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The air forces on a model of the sperry messenger airplane without propeller

The air forces on a model of the sperry messenger airplane without propeller

Date: 1926?~
Creator: Munk, Max M & Diehl, Walter S
Description: 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. A 1/10 scale model of the sperry messenger airplane with USA-5 wings was tested without a propeller at various Reynolds numbers up to the full scale value. Two series of tests were: the first on the original model which was of the usual simplified construction, and the second on a modified model embodying a great amount of detail. The experimental results show that the scale effect is almost entirely confined to the drag. It was also found that the model should be geometrically similar to the full-scale airplane if the test data are to be directly applicable to full scale.
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