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  Partner: UNT Libraries Government Documents Department
 Decade: 1940-1949
 Year: 1940
 Month: February
Aerodynamics of rotating-wing aircraft with blade-pitch control

Aerodynamics of rotating-wing aircraft with blade-pitch control

Date: February 1, 1940
Creator: Pfluger, A
Description: In the present report, with the aid of the usual computation methods, a rotor is investigated the pitch of whose blades is capable of being controlled in such a manner that it varies linearly with the flapping angle. To test the effect of this linkage on the aircraft performance, the theory is applied to an illustrative example.
Contributing Partner: UNT Libraries Government Documents Department
Damping formulas and experimental values of damping in flutter models

Damping formulas and experimental values of damping in flutter models

Date: February 1, 1940
Creator: Coleman, Robert P
Description: The problem of determining values of structural damping for use in flutter calculations is discussed. The concept of equivalent viscous damping is reviewed and its relation to the structural damping coefficient g introduced in NACA Technical Report No. 685 is shown. The theory of normal modes is reviewed and a number of methods are described for separating the motions associated with different modes. Equations are developed for use in evaluating the damping parameters from experimental data. Experimental results of measurements of damping in several flutter models are presented.
Contributing Partner: UNT Libraries Government Documents Department
Experimental contribution to the study of combustion in compression-ignition engines

Experimental contribution to the study of combustion in compression-ignition engines

Date: February 1, 1940
Creator: Duchene, R
Description: The purpose of this paper is to explain the differences in thermodynamic qualities of two oils and to try to make this differentiation clear enough so that it can be applied to two oils extremely alike, as, for instance a given oil and the same oil to which a small amount of another substance has been added.
Contributing Partner: UNT Libraries Government Documents Department
Experimental Determination of Exhaust Gas Thrust, Special Report

Experimental Determination of Exhaust Gas Thrust, Special Report

Date: February 1, 1940
Creator: Pinkel, Benjamin
Description: This investigation presents the results of tests made on a radial engine to determine the thrust that can be obtained from the exhaust gas when discharged from separate stacks and when discharged from the collector ring with various discharge nozzles. The engine was provided with a propeller to absorb the power and was mounted on a test stand equipped with scales for measuring the thrust and engine torque. The results indicate that at full open throttle at sea level, for the engine tested, a gain in thrust horsepower of 18 percent using separate stacks, and 9.5 percent using a collector ring and discharge nozzle, can be expected at an air speed of 550 miles per hour.
Contributing Partner: UNT Libraries Government Documents Department
A generalized vortex theory of the screw propeller and its application

A generalized vortex theory of the screw propeller and its application

Date: February 1, 1940
Creator: Reissner, Hans
Description: The vortex theory as presented by the author in earlier papers has been extended to permit the solution of the following problems: (1) the investigation of the relation between thrusts and torque distribution and energy loss as given by the induction of helical vortex sheets and by the parasite drag; (2) the checking of the theorem of Betz of the rigidly behaving helical vortex sheet of minimum induced energy loss; (3) the extension of the theory of the screw propeller of minimum energy loss for the inclusion of parasite-drag distribution along the blades. A simple system of diagrams has been developed to systematize the design of airplane propellers for a wide range of parasite-drag distribution along the blades.
Contributing Partner: UNT Libraries Government Documents Department
An investigation of sheet-stiffener panels subjected to compression loads with particular reference to torsionally weak stiffeners

An investigation of sheet-stiffener panels subjected to compression loads with particular reference to torsionally weak stiffeners

Date: February 1, 1940
Creator: Dunn, Louis G
Description: A total of 183 panel specimens of 24ST aluminum alloy with nominal thickness of 0.020, and 0.040 inch with extruded bulb-angle sections of 12 shapes spaced 4 and 5 inches as stiffeners were tested to obtain the buckling stress and the amplitude of the maximum wave when buckled. Bulb angles from 3 to 27 1/2 inches long were tested as pin-end columns. The experimental data are presented as stress-strain and column curves and in tabular form. Some comparisons with theoretical results are presented. Analytical methods are developed that make it possible for the designer to predict with reasonable accuracy the buckling stress and the maximum-wave amplitude of the sheet in stiffened-panel combinations. The scope of the tests was insufficient to formulate general design criteria but the results are presented as a guide for design and an indication of the type of theoretical and experimental work that is needed.
Contributing Partner: UNT Libraries Government Documents Department
Measurement of the forces acting on gliders in towed flight

Measurement of the forces acting on gliders in towed flight

Date: February 1, 1940
Creator: Klenperer, W B
Description: The magnitude, the direction, and the fluctuations of tow forces exerted upon gliders by towing them aloft behind an automobile were measured under a variety of conditions covering a range from gentle to severe types of operation. For these tests, the glider towing force did not exceed 1.6 of the gross weight of the glider. V-G records obtained during the towed-flight period as well as during the subsequent return glide to earth showed accelerations in the range from 3 to -1 g. The results of preliminary airplane tow tests are also presented.
Contributing Partner: UNT Libraries Government Documents Department
Methods and equipment for home laundering.

Methods and equipment for home laundering.

Date: February 1940
Creator: Holbrook, Helen S. (Helen Shepard), b. 1882.
Description: A guide to planning a laundry center at home. Describes various types of equipment and machinery available for washing, drying, and ironing. Describes the products used for laundering and the recommended laundering methods for specific fabric types.
Contributing Partner: UNT Libraries Government Documents Department
A new method of studying the flow of the water along the bottom of a model of a flying-boat hull

A new method of studying the flow of the water along the bottom of a model of a flying-boat hull

Date: February 1, 1940
Creator: Ward, Kenneth E
Description: A new method of studying the flow of the water along the bottom of a model of a flying-boat hull is described. In this method, the model is fitted with a transparent bottom and is divided down the center line by a bulkhead. The flow is observed and photographed through one-half of the model by means of the diffused illumination from a battery of lamps contained in the other half of the model. Photographs of the flow, particularly of the changes that occur when the step ventilates, are shown. The results of the present investigation indicate that the method has considerable promise, chiefly in connection with motion-picture studies.
Contributing Partner: UNT Libraries Government Documents Department
Prevention of damage by the seed-corn maggot to potato seed pieces.

Prevention of damage by the seed-corn maggot to potato seed pieces.

Date: February 1940
Creator: Reid, W. J. (William John), 1902-
Description: Uses results from a scientific study to describe how to best protect potato seed pieces from damage by the seed-corn maggot.
Contributing Partner: UNT Libraries Government Documents Department
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