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  Partner: UNT Libraries Government Documents Department
 Decade: 1920-1929
 Collection: National Advisory Committee for Aeronautics Collection
Variation in the number of revolutions of air propellers

Variation in the number of revolutions of air propellers

Date: March 1, 1923
Creator: Achenbach, W
Description: None
Contributing Partner: UNT Libraries Government Documents Department
Air forces on airfoils moving faster than sound

Air forces on airfoils moving faster than sound

Date: June 1925
Creator: Ackeret, J
Description: We are undertaking the task of computing the air forces on a slightly cambered airfoil in the absence of friction and with an infinite aspect ratio. We also assume in advance that the leading edge is very sharp and that its tangent lies in the direction of motion.
Contributing Partner: UNT Libraries Government Documents Department
Drag measurements of two thin wing sections at different index values

Drag measurements of two thin wing sections at different index values

Date: June 1, 1927
Creator: Ackeret, J
Description: It is stated that the index value 6000, as found in normal tests of wing sections with a 20 cm chord, falls in the same region where the transition of laminar to turbulent flow takes place on thin flat plates. It is to be expected that slightly cambered, thin wing sections will behave similarly. The following test of two such wing sections were made for the purpose of verifying this supposition.
Contributing Partner: UNT Libraries Government Documents Department
Experiments on airfoils with trailing edge cut away

Experiments on airfoils with trailing edge cut away

Date: September 1, 1927
Creator: Ackeret, J
Description: Airfoils with their trailing edge cut away are often found on aircraft, as the fins on the hulls of flying boats and the central section of the wings for affording better visibility. It was therefore of some interest to discover the effect of such cutaways on the lift and drag and on the position of the center of pressure. For this purpose, systematic experiments were performed on two different airfoils, a symmetrical airfoil and an airfoil of medium thickness, with successive shortenings of their chords.
Contributing Partner: UNT Libraries Government Documents Department
Recent experiments at the Gottingen Aerodynamic Institute

Recent experiments at the Gottingen Aerodynamic Institute

Date: July 1, 1925
Creator: Ackeret, J
Description: This report presents the results of various experiments carried out at the Gottingen Aerodynamic Institute. These include: experiments with Joukowski wing profiles; experiments on an airplane model with a built-in motor and functioning propeller; and the rotating cylinder (Magnus Effect).
Contributing Partner: UNT Libraries Government Documents Department
Removing boundary layer by suction

Removing boundary layer by suction

Date: January 1, 1927
Creator: Ackeret, J
Description: Through the utilization of the "Magnus effect" on the Flettner rotor ship, the attention of the public has been directed to the underlying physical principle. It has been found that the Prandtl boundary-layer theory furnishes a satisfactory explanation of the observed phenomena. The present article deals with the prevention of this separation or detachment of the flow by drawing the boundary layer into the inside of a body through a slot or slots in its surface.
Contributing Partner: UNT Libraries Government Documents Department
Experiments with an airfoil from which the boundary layer is removed by suction

Experiments with an airfoil from which the boundary layer is removed by suction

Date: August 1926
Creator: Ackeret, J; Betz, A & Schrenk, O
Description: Our attempts to improve the properties of airfoils by removing the boundary layer by suction, go back to 1922. The object of the suction is chiefly to prevent the detachment of the boundary layer from the surface of the airfoil. At large angles of attack, such detachment prevents the attainment of the great lift promised by the theory, besides greatly increasing the drag, especially of thick airfoils. This report gives results of those experiments.
Contributing Partner: UNT Libraries Government Documents Department
Air cooling : an experimental method of evaluating the cooling effect of air streams on air-cooled cylinders

Air cooling : an experimental method of evaluating the cooling effect of air streams on air-cooled cylinders

Date: May 1927
Creator: Alcock, J F
Description: In this report is described an experimental method which the writer has evolved for dealing with air-cooled engines, and some of the data obtained by its means. Methods of temperature measurement and cooling are provided.
Contributing Partner: UNT Libraries Government Documents Department
Glues used in airplane parts

Glues used in airplane parts

Date: January 1, 1920
Creator: Allen, S W & Truax, T R
Description: This report was prepared for the National Advisory Committee for Aeronautics and presents the results of investigations conducted by the Forest Products Laboratory of the United States Forest Service on the manufacture, preparation, application, testing and physical properties of the different types of glues used in wood airplane parts.
Contributing Partner: UNT Libraries Government Documents Department
Combustion of liquid fuels in diesel engine

Combustion of liquid fuels in diesel engine

Date: October 1, 1924
Creator: Alt, Otto
Description: Hitherto, definite specifications have always been made for fuel oils and they have been classified as more or less good or non-utilizable. The present aim, however, is to build Diesel engines capable of using even the poorest liquid fuels and especially the waste products of the oil industry, without special chemical or physical preparation.
Contributing Partner: UNT Libraries Government Documents Department
A resume of the advances in theoretical aeronautics made by Max M. Munk

A resume of the advances in theoretical aeronautics made by Max M. Munk

Date: January 1, 1926
Creator: Ames, Joseph S
Description: In order to apply profitably the mathematical methods of hydrodynamics to aeronautical problems, it is necessary to make simplifications in the physical conditions of the latter. To begin with, it is allowable in many problems, as Prandtl has so successfully shown, to treat the air as having constant density and as free of viscosity. But this is not sufficient. It is also necessary to specify certain shapes for the solid bodies whose motion through the air is discussed, shapes suggested by the actual solids - airships or airfoils - it is true, but so chosen that they lead to solvable problems. In a valuable paper presented by Dr. Max M. Munk, of the National Advisory Committee for Aeronautics, Washington, to the Delft Conference in April, 1924, these necessary simplifying assumptions are discussed in detail. It is the purpose of the present paper to present in as simple a manner as possible some of the interesting results obtained by Dr. Munk's methods.
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Experiments on autorotation

Experiments on autorotation

Date: September 1, 1926
Creator: Anderlik, E
Description: This article deals principally with Professor Bairstow's experiments on autorotation, in which the wing is free to rotate about an axis in its plane of symmetry, which axis is parallel with the direction of the wind.
Contributing Partner: UNT Libraries Government Documents Department
The stresses in columns under combined axial and side loads

The stresses in columns under combined axial and side loads

Date: July 1, 1922
Creator: Arnstein, Karl
Description: The problem before us is to determine the total stresses in an axially loaded column of any degree of restraint which is also subject to transverse bending both from a uniformly distributed load and from concentrated loads.
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Some principles governing the establishment of meteorological stations along air routes

Some principles governing the establishment of meteorological stations along air routes

Date: March 1, 1922
Creator: Aujames, P
Description: The organization of a meteorological service for an air route involves the solution of two distinct problems: distribution and grouping of meteorological stations and communications. Experience gained in the establishment of two lines, Paris-Warsaw and Constantinople-Bucharest enables us to establish certain principles, which may be of interest to note here.
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:The fundamental principles of high-speed semi-diesel engines. Part II: a discussion of the semi-diesel principle and its application to various types of solid-injection engines

:The fundamental principles of high-speed semi-diesel engines. Part II: a discussion of the semi-diesel principle and its application to various types of solid-injection engines

Date: April 1, 1926
Creator: BUCHNER
Description: Three high-speed semi-diesel engines are examined through the use of indicator diagrams. Different fuel nozzles and fuels are investigated and conclusions are drawn.
Contributing Partner: UNT Libraries Government Documents Department
:The fundamental principles of high-speed semi-diesel engines. Part III: a discussion of fuel mixing and ignition, with special reference to engines with precombustion chambers

:The fundamental principles of high-speed semi-diesel engines. Part III: a discussion of fuel mixing and ignition, with special reference to engines with precombustion chambers

Date: April 1, 1926
Creator: BUCHNER
Description: A continuation of the discussion and overview of the present state of development of high-speed semi-diesel engines.
Contributing Partner: UNT Libraries Government Documents Department
Langley Field wind tunnel apparatus

Langley Field wind tunnel apparatus

Date: January 1, 1922
Creator: Bacon, D L
Description: None
Contributing Partner: UNT Libraries Government Documents Department
Langley Field wind tunnel apparatus

Langley Field wind tunnel apparatus

Date: October 1, 1921
Creator: Bacon, D L
Description: The difficulties experienced in properly holding thin tipped or tapered airfoils while testing on an N.P.L. type aerodynamic balance even at low air speeds, and the impossibility of holding even solid metal models at the high speeds attainable at the National Advisory Committee's wind tunnel, necessitated the design of a balance which would hold model airfoils of any thickness and at speeds up to 150 m.p.h. In addition to mechanical strength and rigidity, it was highly desirable that the balance readings should require a minimum amount of correction and mathematical manipulation in order to obtain the lift and drag coefficients and the center of pressure. The balance described herein is similar to one in use at the University of Gottingen, the main difference lying in the addition of a device for reading the center of pressure directly, without the necessity of any correction whatsoever. Details of the design and operation of the device are given.
Contributing Partner: UNT Libraries Government Documents Department
Preliminary experiments to determine scale and slip-stream effects on a 1/24th size model of a JN4H biplane

Preliminary experiments to determine scale and slip-stream effects on a 1/24th size model of a JN4H biplane

Date: January 1, 1923
Creator: Bacon, D L
Description: This work was undertaken to obtain results on a small model of a complete airplane which might be used for comparison with corresponding tests made in full flight. Somewhat similar tests have been previously made at various other laboratories; but as certain discrepancies exist between corresponding tests in different tunnels, it has been deemed advisable to obtain a direct comparison for this particular installation. The present work covers tests on a one-twenty-fourth scale model at speeds varying from 6.7 m/sec. (15 m.p.h.) to 40.2 m/sec, (90 m.p.h.). A slip stream correction has been obtained by the use of a small belt-driven propeller mounted in front of the model, and force coefficients thus obtained are compared with the measurements of the same forces made in full flight on a geometrically similar airplane. This report gives lift, drag, and longitudinal moment values obtained in tests of a particularly accurate model over a wide range of speeds. A measure of the slip stream corrections on lift and drag forces was obtained by the use of a power-driven model propeller. Measurements were also made of forces and longitudinal moments for all angles from 0 degree to 360 degrees.
Contributing Partner: UNT Libraries Government Documents Department
Similitude tests on wind sections

Similitude tests on wind sections

Date: March 1, 1921
Creator: Bacon, D L
Description: None
Contributing Partner: UNT Libraries Government Documents Department
The resistance of spheres in wind tunnels and in air

The resistance of spheres in wind tunnels and in air

Date: January 1, 1924
Creator: Bacon, D L & Reid, E G
Description: To supplement the standardization tests now in progress at several laboratories, a broad investigation of the resistance of spheres in wind tunnels and free air has been carried out by the National Advisory Committee for Aeronautics. The subject has been classed in aerodynamic research, and in consequence there is available a great mass of data from previous investigations. This material was given careful consideration in laying out the research, and explanation of practically all the disagreement between former experiments has resulted. A satisfactory confirmation of Reynolds law has been accomplished, the effect of means of support determined, the range of experiment greatly extended by work in the new variable density wind tunnel, and the effects of turbulence investigated by work in the tunnels and by towing and dropping tests in free air. It is concluded that the erratic nature of most of the previous work is due to support interference and differing turbulence conditions. While the question of support has been investigated thoroughly, a systematic and comprehensive study of the effects of scale and quality of turbulence will be necessary to complete the problem, as this phase was given only general treatment.
Contributing Partner: UNT Libraries Government Documents Department
The distribution of lift over wing tips and ailerons

The distribution of lift over wing tips and ailerons

Date: January 1, 1924
Creator: Bacon, David L
Description: This investigation was carried out in the 5-foot wind tunnel of the Langley Memorial Aeronautical Laboratory for the purpose of obtaining more complete information on the distribution of lift between the ends of wing spars, the stresses in ailerons, and the general subject of airflow near the tip of a wing. It includes one series of tests on four models without ailerons, having square, elliptical, and raked tips respectively, and a second series of positively and negatively raked wings with ailerons adjusted to different settings. The results show that negatively raked tips give a more uniform distribution of air pressure than any of the other three arrangements, because the tip vortex does not disturb the flow at the trailing edge. Aileron loads are found to be less severe on wings with negative application to the calculation of aileron and wing stresses and also to facilitate the proper distribution of load in sand testing. Contour charts show in great detail the complex distribution lift over the wing.
Contributing Partner: UNT Libraries Government Documents Department
Model supports and their effects on the results of wind tunnel tests

Model supports and their effects on the results of wind tunnel tests

Date: February 1, 1923
Creator: Bacon, David L
Description: The airflow about a model while being tested is often sufficiently affected by the model support to lead to erroneous conclusions unless appropriate corrections are used. In this paper some new material on the subject is presented, together with a review of the airfoil support corrections used in several other laboratories.
Contributing Partner: UNT Libraries Government Documents Department
The "Universal" adjustable and reversible propeller built by Paragon Engineers, Inc., Baltimore, Md

The "Universal" adjustable and reversible propeller built by Paragon Engineers, Inc., Baltimore, Md

Date: November 1, 1922
Creator: Bacon, David L
Description: A device which does for the aircraft what change speed gears do for the automobile is the invention of Spencer Heath. It comprises a system of special blades and a mechanism for varying the pitch of the blades from zero to 360 degrees, while in flight or otherwise.
Contributing Partner: UNT Libraries Government Documents Department
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