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  Partner: UNT Libraries Government Documents Department
 Serial/Series Title: NACA Technical Reports
 Collection: National Advisory Committee for Aeronautics Collection
The Limiting Velocity in Falling from a Great Height

The Limiting Velocity in Falling from a Great Height

Date: January 1, 1919
Creator: Wilson, Edwin Bidwell
Description: The purpose of this report is to give a simple treatment of the problem of calculating the final or limiting velocity of an object falling in vertical motion under gravity in a resisting medium. The equations of motion are easily set up and integrated when the density of the medium is constant and the resistance varies as the square of the velocity. The results show that the fundamental characteristics of the vertical motion under gravity in a resisting medium is the approach to a terminal or limiting velocity, whether the initial downward velocity is less or greater than the limiting velocity. This method can be used to calculate the terminal velocity of a bomb trajectory.
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Preliminary report on free flight tests

Preliminary report on free flight tests

Date: January 1, 1920
Creator: Warner, E P
Description: Results are presented for a series of tests made by the Advisory Committee's staff at Langley Field during the summer of 1919 with the objectives of determining the characteristics of airplanes in flight and the extent to which the actual characteristics differ from those predicted from tests on models in the wind tunnel, and of studying the balance of the machines and the forces which must be applied to the controls in order to maintain longitudinal equilibrium.
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Bomb trajectories

Bomb trajectories

Date: January 1, 1920
Creator: Wilson, Edwin Bidwell
Description: The report is a mathematical treatise dealing with the trajectories of bombs of high terminal velocity, dropped from a great altitude.
Contributing Partner: UNT Libraries Government Documents Department
The aerodynamic properties of thick aerofoils suitable for internal bracing

The aerodynamic properties of thick aerofoils suitable for internal bracing

Date: January 1, 1920
Creator: Norton, F H
Description: 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. This type of wing is of interest because it eliminates the resistance of the interplane bracing, a portion of the airplane that sometimes absorbs one-quarter of the total power required to fly, and because these wings may be made to give a very high maximum lift. 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.
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Comparison of United States and British standard pitot tubes

Comparison of United States and British standard pitot tubes

Date: January 1, 1920
Creator: Zahm, A F
Description: The results shown in this report give a comprehensive comparison of the accuracy of United States and British standard pitot tubes.
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The Parker variable camber wing

The Parker variable camber wing

Date: January 1, 1920
Creator: Parker, H F
Description: This report deals with the problem of increasing the speed range of an airplane by varying the camber of a wing surface. The variable camber wing offers many advantages over the variable incidence type of speed range.
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Construction of models for tests in wind tunnels

Construction of models for tests in wind tunnels

Date: January 1, 1920
Creator: Norton, F H
Description: Report deals with the methods of constructing aerofoils and all other parts of a model airplane, including discussion of the degree of accuracy.
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Friction of aviation engines

Friction of aviation engines

Date: January 1, 1928
Creator: Sparrow, S W
Description: The first portion of this report discusses measurements of friction made in the altitude laboratory of the Bureau of Standards between 1920 and 1926 under research authorization of the National Advisory Committee for Aeronautics. These are discussed with reference to the influence of speed, barometric pressure, jacket-water temperature, and throttle opening upon the friction of aviation engines. The second section of the report deals with measurements of the friction of a group of pistons differing from each other in a single respect, such as length, clearance, area of thrust face, location of thrust face, etc. Results obtained with each type of piston are discussed and attention is directed particularly to the fact that the friction chargeable to piston rings depends upon piston design as well as upon ring design. This is attributed to the effect of the rings upon the thickness and distribution of the oil film which in turn affects the friction of the piston to an extent which depends upon its design.
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Characteristics of propeller sections tested in the variable density wind tunnel

Characteristics of propeller sections tested in the variable density wind tunnel

Date: January 1, 1928
Creator: Jacobs, Eastman N
Description: Tests were carried out in the variable density wind tunnel of the National Advisory Committee for Aeronautics on six airfoil sections used by the Bureau of Aeronautics as propeller sections. The sections were tested at pressures of 1 and 20 atmospheres corresponding to Reynolds numbers of about 170,000 and 3,500,000. The results obtained, besides providing data for the design of propellers, should be of special interest because of the opportunity afforded for the study of scale effect on a family of airfoil sections having different thickness ratios. (author).
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Some factors affecting the reproducibility of penetration and the cut-off of oil sprays for fuel-injection engines

Some factors affecting the reproducibility of penetration and the cut-off of oil sprays for fuel-injection engines

Date: January 1, 1928
Creator: Beardsley, E G
Description: This investigation was undertaken at the Langley Memorial Aeronautical Laboratory in connection with a general research on fuel-injection for aircraft. The purpose of the investigation was to determine the factors controlling the reproducibility of spray penetration and secondary discharges after cut-off. The development of single sprays from automatic injection valves was recorded by means of special high-speed photographic apparatus capable of taking 25 consecutive pictures of the moving spray at a rate of 4,000 per second. The effect of two types of injection valves, injection-valve tube length, initial pressure in the injection-valve tube, speed of the injection control mechanism, and time of spray cut-off, on the reproducibility of spray penetration, and on secondary discharges were investigated. It was found that neither type of injection valve materially affected spray reproducibility. The initial pressure in the injection-valve tube controlled the reproducibility of spray penetrations. An increase in the initial pressure or in the length of the injection-valve tube slightly increased the spray penetration within the limits of this investigation. The speed of the injection-control mechanism did not affect the penetration. Analysis of the results indicates that secondary discharges were caused in this apparatus by pressure waves initiated by the rapid opening of ...
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