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  Partner: UNT Libraries Government Documents Department
 Serial/Series Title: NACA Technical Notes
 Collection: Technical Report Archive and Image Library
The steadiness factor in engine sets

The steadiness factor in engine sets

Date: January 1, 1920
Creator: Margoulis, W
Description: None
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Notes on longitudinal stability and balance

Notes on longitudinal stability and balance

Date: April 1, 1920
Creator: Warner, E P
Description: None
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Airplane performance as influenced by the use of a supercharged engine

Airplane performance as influenced by the use of a supercharged engine

Date: May 1, 1920
Creator: De Bothezat, George
Description: The question of the influence of a supercharged engine on airplane performance is treated here in a first approximation, but one that gives an exact idea of the advantage of supercharging. Considered here is an airplane that climbs first with an ordinary engine, not supercharged, and afterwards climbs with a supercharged engine. The aim is to find the difference of the ceilings reached in the two cases. In the case of our figure, the ceiling from 25,000 feet is increased to 37,000 feet, the supercharging maintaining the power only up to 20,000 feet. This makes, in comparison with an engine without supercharging, an increase of about 50 percent.
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Notes on the theory of the accelerometer

Notes on the theory of the accelerometer

Date: May 1, 1920
Creator: Warner, E P
Description: None
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The problem of the helicopter

The problem of the helicopter

Date: May 1, 1920
Creator: Warner, E P
Description: None
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Relation of rib spacing to stress in wing planes

Relation of rib spacing to stress in wing planes

Date: May 1, 1920
Creator: Zahm, A F
Description: The stress relations to the fabric and the rib consequent upon a change of spacing between ribs in a wing plane are discussed. Considering the wing plane as a static structure, and ignoring the question of aerodynamic efficiency, it appears that the unit stress in the rib and fabric will remain constant for constant p if the linear dimensions of both rib and fabric are increased alike, viz., if wing and fabric remain geometrically similar. Since the bulge and the structural dimensions remain geometrically similar, the whole distended plane remains so, and hence should have the same pressure distribution and efficiency. If therefore the Burgess rule of making the rib spacing always one-fifth of the chord of the plane be valid, it must be valid for all others that are mechanically similar in structure and covering.
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Duralumin

Duralumin

Date: July 1, 1920
Creator: Unger, E & Schmidt, E
Description: The use of duralumin in the construction of aircraft makes an account of the properties of this material desirable especially with reference to its working qualities as developed by experience.
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Notes on the design of supercharged and overdimensioned aircraft engines

Notes on the design of supercharged and overdimensioned aircraft engines

Date: July 1, 1920
Creator: SCHWAGER
Description: None
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Static testing and proposed standard specifications

Static testing and proposed standard specifications

Date: July 1, 1920
Creator: Warner, E P
Description: Static tests fall into two groups, the first of which is designed to load all members of the structure approximately in accordance with the worst loads which they carry in flight, while the second is directed to the testing of specific members which are suspected of weakness and which are difficult to analyze mathematically. The nature of the loading in the second type is different for every different test, but the purpose of the first is defined clearly enough to permit the adoption of some standard set of loading specifications, at least for airplanes of normal design. Here, an attempt is made to carry through an analysis leading to such a standard, the goal being the determination of a load which will simultaneously impose on every member of the airplane structure a stress equal to the worst it will carry in flight.
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Theory of lifting surfaces

Theory of lifting surfaces

Date: July 1, 1920
Creator: Prandtl , L
Description: The general basis of the theory of lifting surfaces is discussed. The problem of the flow of a fluid about a lifting surface of infinite span is examined in terms of the existence of vortexes in the current. A general theory of permanent flow is discussed. Formulas for determining the influence of aspect ratio that may be applied to all wings, whatever their plane form, are given.
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Increase in maximum pressures produced by preignition in internal combustion engines

Increase in maximum pressures produced by preignition in internal combustion engines

Date: August 1, 1920
Creator: Sparrow, S W
Description: None
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The problem of the turbo-compressor

The problem of the turbo-compressor

Date: August 1, 1920
Creator: Devillers, Rene
Description: In terminating the study of the adaptation of the engine to the airplane, we will examine the problem of the turbo-compressor,the first realization of which dates from the war; this will form an addition to the indications already given on supercharging at various altitudes. This subject is of great importance for the application of the turbo-compressor worked by the exhaust gases. As a matter of fact, a compressor increasing the pressure in the admission manifold may be controlled by the engine shaft by means of multiplication gear or by a turbine operated by the exhaust gas. Assuming that the increase of pressure in the admission manifold is the same in both cases, the pressure in the exhaust manifold would be greater in the case in which the compressor is worked by the exhaust gas and there would result a certain reduction of engine power which we must be able to calculate. On the other hand , if the compressor is controlled by the engine shaft, a certain fraction of the excess power supplied is utilized for the rotation of the compressor. In order to compare the two systems, it is there-fore necessary to determine the value of the reduction of ...
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Soaring flight in Guinea

Soaring flight in Guinea

Date: August 1, 1920
Creator: Idrac, P
Description: The term soaring is applied here to the flight of certain large birds which maneuver in the air without moving their wings. The author explains the methods of his research and here gives approximate figures for the soaring flight of the Egyptian Vulture and the African White backed Vulture. Figures are given in tabular form for relative air speed per foot per second, air velocity per foot per second, lift/drag ratio, and selected coefficients. The author argues that although the figures given were taken from a very limited series of observations, they have nevertheless thrown some light on the use by birds of the internal energy of the air.
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Theory of Lifting Surfaces, Part 2

Theory of Lifting Surfaces, Part 2

Date: August 1, 1920
Creator: Prandtl, L.
Description: A mathematical model is presented towards a theory of lifting and resistance on wings. It consists of a theory of multiplanes, conditions of flow at a great distance from the wing, lifting systems of minimum resistance, and free stream and stream limited by walls.
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Drag or negative traction of geared-down supporting propellers in the downward vertical glide of a helicopter

Drag or negative traction of geared-down supporting propellers in the downward vertical glide of a helicopter

Date: September 1, 1920
Creator: Toussaint, A
Description: Discussed here are computations of drag or negative traction of geared down supporting propellers in the downward vertical glide of a helicopter. By means of Frounde's Theory, the maximum value of the drag of a windmill is calculated. For wooden propellers, the author finds that the difference between the drag and the weight is proportional to the number of blades and is larger for propellers of small diameter; thus it is 25 kg. for a six blade propeller with a diameter of 2 m. 50. The author notes that if we are to adopt large propellers, we must have recourse to a different method of construction, resulting in large dimension propellers much lighter than those made of wood. In discussing insufficient drag, the author notes that the question of the drag of geared down supporting propellers can only be decided by experiment.
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The dynamometer hub

The dynamometer hub

Date: September 1, 1920
Creator: Stieber, W
Description: The construction of the dynamometer hub is illustrated and explained, and its electrical and aviation motor tests, as well as those in free flight, described.
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Experience with geared propeller drives for aviation engines

Experience with geared propeller drives for aviation engines

Date: September 1, 1920
Creator: Kutzbach, K
Description: I. The development of the gear wheels: (a) bending stresses; (b) compressive stresses; (c) heating; (d) precision of manufacture. II. General arrangement of the gearing. III. Vibration in the shaft transmission. An overview is given of experience with geared propeller drives for aviation engines. The development of gear wheels is discussed with emphasis upon bending stresses, compressive stresses, heating, and precision in manufacturing. With respect to the general arrangement of gear drives for airplanes, some principal rules of mechanical engineering that apply with special force are noted. The primary vibrations in the shaft transmission are discussed. With respect to vibration, various methods for computing vibration frequency and the influence of elastic couplings are discussed.
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Recent efforts and experiments in the construction of aviation engines

Recent efforts and experiments in the construction of aviation engines

Date: September 1, 1920
Creator: SCHWAGER
Description: It became evident during World War I that ever-increasing demands were being placed on the mean power of aircraft engines as a result of the increased on board equipment and the demands of aerial combat. The need was for increased climbing efficiency and climbing speed. The response to these demands has been in terms of lightweight construction and the adaptation of the aircraft engine to the requirements of its use. Discussed here are specific efforts to increase flying efficiency, such as reduction of the number of revolutions of the propeller from 1400 to about 900 r.p.m. through the use of a reduction gear, increasing piston velocity, locating two crankshafts in one gear box, and using the two-cycle stroke. Also discussed are improvements in the transformation of fuel energy into engine power, the raising of compression ratios, the use of super-compression with carburetors constructed for high altitudes, the use of turbo-compressors, rotary engines, and the use of variable pitch propellers.
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Notes on specifications for French airplane competitions

Notes on specifications for French airplane competitions

Date: October 1, 1920
Creator: Margoulis, W
Description: Given here are the rules officially adopted by the Aeronautical Commission of the Aero Club of France for a flight competition to be held in France in 1920 at the Villacoublay Aerodrome. The prize will be awarded to the pilot who succeeds in obtaining the highest maximum and lowest minimum speeds, and in landing within the shortest distance.
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Tests of the Daimler D-IVa engine at a high altitude test bench

Tests of the Daimler D-IVa engine at a high altitude test bench

Date: October 1, 1920
Creator: Noack, W G
Description: Reports of tests of a Daimler IVa engine at the test-bench at Friedrichshafen, show that the decrease of power of that engine, at high altitudes, was established, and that the manner of its working when air is supplied at a certain pressure was explained. These tests were preparatory to the installation of compressors in giant aircraft for the purpose of maintaining constant power at high altitudes.
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Development of the inflow theory of the propeller

Development of the inflow theory of the propeller

Date: November 1, 1920
Creator: Betz, A
Description: None
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Gottingen Wind Tunnel for testing aircraft models

Gottingen Wind Tunnel for testing aircraft models

Date: November 1, 1920
Creator: Prandtl, L
Description: Given here is a brief description of the Gottingen Wind Tunnel for the testing of aircraft models, preceded by a history of its development. Included are a number of diagrams illustrating, among other things, a sectional elevation of the wind tunnel, the pressure regulator, the entrance cone and method of supporting a model for simple drag tests, a three-component balance, and a propeller testing device, all of which are discussed in the text.
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Horizontal buoyancy in wind tunnels

Horizontal buoyancy in wind tunnels

Date: November 1, 1920
Creator: Zahn, A F
Description: None
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Italian and French experiments on wind tunnels

Italian and French experiments on wind tunnels

Date: November 1, 1920
Creator: Knight, WM
Description: Given here are the results of experiments conducted by Colonel Costanzi of the Italian Army to determine the influence of the surrounding building in which a wind tunnel was installed on the efficiency of the installation, and how the efficiency of the installation was affected by the design of the tunnel. Also given are the results of a series of experiments by Eiffel on 34 models of tunnels of different dimensions. This series of experiments was started in order to find out if, by changing the shape of the nozzle or of the diffuser of the large tunnel at Auteuil, the efficiency of the installation could be improved.
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