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Principles, Practices, and Progress of Noise Reduction in Airplanes

Description: Note presenting the body of knowledge that has been accumulated in the field of noise reduction in aircraft. Special attention is paid to effective soundproofing schemes.
Date: January 1940
Creator: London, Albert
Partner: UNT Libraries Government Documents Department
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A new method of studying the flow of the water along the bottom of a model of a flying-boat hull

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. Th… more
Date: February 1940
Creator: Ward, Kenneth E.
Partner: UNT Libraries Government Documents Department
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A Generalized Vortex Theory of the Screw Propeller and Its Application

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 f… more
Date: February 1940
Creator: Reissner, Hans
Partner: UNT Libraries Government Documents Department
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Damping formulas and experimental values of damping in flutter models

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. Ex… more
Date: February 1940
Creator: Coleman, Robert P.
Partner: UNT Libraries Government Documents Department
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Wind-tunnel investigation of an NACA 23030 airfoil with various arrangements of slotted flaps

Description: An investigation was made of a large-chord NACA 23030 airfoil with a 40- and a 25.66 percent-chord slotted flap to determine the section aerodynamic characteristics of the airfoil affected by flap chord, slot shape, flap position, and flap deflection. The flap positions for maximum lift, the position for minimum drag at moderate and high lift coefficients, and the complete section aerodynamic characteristics of selected optimum arrangements are given. Envelope polar of various flap arrangements… more
Date: March 1940
Creator: Recant, I. G.
Partner: UNT Libraries Government Documents Department
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The Effects of Piston-Head Shape, Cylinder-Head Shape, and Exhaust Restriction, on the Performance of a Piston-Ported Two-Stroke Cylinder

Description: Report presenting testing of a model of the two-stroke engine described in NACA Technical Note No. 674 for the purpose of observing the scavenging-air flow obtained with various inlet-port arrangements. Three types of cylinder head were tried with the round-edge piston in the engine. Results regarding the effect of port arrangement, pistons, cylinder-head shapes, effect of swirl, and exhaust restrictions are provided.
Date: March 1940
Creator: Rogowski, A. R.; Bouchard, C. L. & Taylor, C. Fayette
Partner: UNT Libraries Government Documents Department
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Wind tunnel tests of an NACA 23021 airfoil equipped with a slotted extensible and a plain extensible flap

Description: "An investigation has been made in the NACA 7- by 10-foot wind tunnel of a large chord NACA 23021 airfoil equipped with two arrangements of a completely extended 15 percent chord extensible flap. One of the flaps had a faired juncture, without a gap; the other was provided with a slot between the trailing edge of the airfoil and the nose of the flap. The results showed that the basic airfoil gave the lowest profile-drag coefficients over the low lift range, the airfoil with the plain extensible… more
Date: November 1940
Creator: Swanson, Robert S. & Harris, Thomas A.
Partner: UNT Libraries Government Documents Department
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A study of unsymmetrical-loading conditions

Description: From Summary: "The force variation along the wing span under combined normal and angular accelerations is considered. Non dimensional curves of section load, shear, and moment are given for: (1) the air load that produces a normal acceleration; (2) the accompanying wing weight and normal inertia loads; (3) aileron and gust air loads that produce angular acceleration; (4) the angular inertia load of the wing. The required aerodynamic load distributions have been obtained by use of wing theory, a… more
Date: April 1940
Creator: Pearson, Henry A.
Partner: UNT Libraries Government Documents Department
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Measurements and Analysis of the Motion of a Canard Airplane Model in Gusts

Description: Report presenting a model of a hypothetical canard airplane, which was designed to be of the same size and general aerodynamic characteristics of a Boeing B-247 airplane in the gust tunnel at one wing loading, one forward speed, one gust velocity, and three gust gradients.
Date: April 1940
Creator: Donely, Philip; Pierce, Harold B. & Pepoon, Philip W.
Partner: UNT Libraries Government Documents Department
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Pressure-distribution investigation on an NACA 0009 airfoil with a 30-percent-chord plain flap and three tabs

Description: From Summary: "Pressure-distribution tests of an NACA 0009 airfoil with a 30-percent-chord plain flap and three plain tabs, having chords 10, 20, and 30 percent of the flap chord, were made. The purpose of these tests was to continue an investigation to supply structural and aerodynamic section data that may be applied to the design of horizontal and vertical tail surfaces. The results are presented as diagrams of resultant pressures and of resultant-pressure increments for the airfoil with the… more
Date: May 1940
Creator: Ames, Milton B., Jr. & Sears, Richard I.
Partner: UNT Libraries Government Documents Department
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A Flight Investigation of Exhaust-Heat De-Icing

Description: The National Advisory Committee for Aeronautics conducted exhaust-heat de-icing tests in flight to provide data needed in the application of this method. The capacity to extract heat from the exhaust gas for de-icing purposes, the quantity of heat required, and other factors were examined. The results indicate that a wing-heating system employing a spanwise exhaust tube within the leading edge of the wing removed 30 to 35 percent of the heat from exhaust gas entering the wing. Data are given fr… more
Date: November 1940
Creator: Rodert, Lewis A. & Jones, Alun R.
Partner: UNT Libraries Government Documents Department
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A Full-Scale Investigation of the Effect of Several Factors on the Shimmy of Cantering Wheels

Description: "A full-scale investigation has been conducted to determine the effect of various factors on the shimmy of castering wheels. The factors considered were the geometric arrangement, the tire types, the variations of load, the spindle moment of inertia, and the tire inflation. A comparison of the results of the present investigation with those calculated from existing theory was made" (p. 1).
Date: April 1940
Creator: Howard, Walter B., Jr.
Partner: UNT Libraries Government Documents Department
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Pressure-distribution investigation of an NACA 0009 airfoil with an 80-percent-chord plain flap and three tabs

Description: Pressure-distribution tests of an NACA 0009 airfoil with an 80-percent-chord plain flap and three plain tabs, having chord of 10, 20, and 30 percent of the flap chord, were made. Section data suitable for application to the design of horizontal and vertical tail surfaces were obtained. Resultant-pressure diagrams for the airfoil with the flap and the 20-percent-chord tab are presented. Plots are also given of increments of normal-force and hinge-moment coefficients for the airfoil, the flap, an… more
Date: May 1940
Creator: Ames, Milton B., Jr. & Sears, Richard I.
Partner: UNT Libraries Government Documents Department
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The Flow of a Compressible Fluid Past a Sphere

Description: "The flow of a compressible fluid past a sphere fixed in a uniform stream is calculated to the third order of approximation by means of the Janzen-Rayleigh method. The velocity and the pressure distribution over the surface of the sphere are computed and the terms involving the fourth power of the Mach number, neglected in Rayleigh's calculation, are shown to be of considerable importance as the local velocity of sound is approached on the sphere. The critical Mach number, that is, the value of… more
Date: May 1940
Creator: Kaplan, Carl
Partner: UNT Libraries Government Documents Department
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Wind tunnel investigation of fuselage stability in yaw with various arrangements of fins

Description: "An investigation was made in the 7-by-10 foot wind tunnel to determine the effects of dorsal-type fins and various arrangements of fins on the aerodynamic characteristics of a streamline circular fuselage. Comparative plots of the aerodynamic characteristics of the fuselage alone and the fuselage with various fin arrangements are given to show their effects on coefficients of yawing moment, drag, and lateral force. Results are also given for one case in which a rear fin on a circular fuselage … more
Date: November 1940
Creator: Hoggard, H. Page, Jr.
Partner: UNT Libraries Government Documents Department
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Wind-tunnel investigation of two airfoils with 25-percent-chord Gwinn and plain flaps

Description: Aerodynamic force tests of an NACA 23018 airfoil with a Gwinn flap having a chord 25 percent of the overall chord and of an NACA 23015 airfoil with a plain flap having a 25-percent chord were conducted to determine the relative merits of the Gwinn and the plain flaps. The tests indicated that, based on speed-range ratios, the plain flap was more effective than the Gwinn flap. At small flap deflections, the plain flap had lower drag coefficients at lift-coefficient values less than 0.70. For lif… more
Date: May 1940
Creator: Ames, Milton B., Jr.
Partner: UNT Libraries Government Documents Department
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Structural Tests of a Stainless Steel Wing Panel by Hydrostatic Loading

Description: Note presenting testing of a simplified type of all-metal wing construction of 18-8, spot-welded except for skin attachment, by means of hydrostatic loading, the wing being proportioned to permit close representation of typical conditions by means of the waterhead. The results showed the possibility of eliminating almost all of the stiffeners from a stressed-skin wing, the possible reduction of weight in a lightly loaded wing and of substantial cost in the construction of any all-metal wing.
Date: November 1940
Creator: Upson, Ralph H.
Partner: UNT Libraries Government Documents Department
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Flight investigation of control-stick vibration of the YG-1B autogiro

Description: From Summary: "As a preliminary step in an investigation of control-stick vibration in direct-control autogiros, the periodic variations in the moments transmitted through the control system of a YG-1B autogiro were recorded in flight. The results of the measurements are presented in the form of coefficients of Fourier series expressing the varying part of the lateral and the longitudinal moments acting between rotor and fuselage at the control trunnions. The most important component of the var… more
Date: June 1940
Creator: Bailey, F. J., Jr.
Partner: UNT Libraries Government Documents Department
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Factors Affecting Heat Transfer in the Internal-Combustion Engine

Description: Note presenting a method developed for the direct measurement of the average heat-transfer coefficient from the gases in the cylinder during the cycle of operation of an internal-combustion engine. Experimental measurmeents were made with a heat collector projecting through a spark-plug hole into the combustion chamber of the test engine in order to examine the effects of several engine-operating and design parameters on the mean heat transfer to the collector.
Date: December 1940
Creator: Ku, P. M.
Partner: UNT Libraries Government Documents Department
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A Method of Measuring Piston Temperatures

Description: "A method that makes use of thermocouples has been developed to measure the temperature of engine pistons operating at high speeds. The thermocouples installed on the moving piston are connected with a potentiometer outside the engine by means of pneumatically operated plungers, which make contact with the piston thermocouples for about 10 crankshaft degrees at the bottom of the piston stroke. The equipment is operated satisfactory at engine speeds of 2,400 r.p.m. and shows promise of successfu… more
Date: June 1940
Creator: Pinkel, Benjamin & Manganiello, Eugene J.
Partner: UNT Libraries Government Documents Department
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Mathematical Analysis of Aircraft Intercooler Design

Description: "A mathematical analysis has been made to show the method of obtaining the dimensions of the intercooler that will use the least total power for a given set of design conditions. The results of this analysis have been used in a sample calculation and, on the basis of this calculation, a new inter cooler arrangement is suggested. Because the length of the two air passages of the new arrangement is short in comparison with the third dimension, the height of the intercooler, this intercooler arran… more
Date: October 1940
Creator: Joyner, Upshur T.
Partner: UNT Libraries Government Documents Department
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Internal-Flow Systems for Aircraft

Description: "An investigation has been made to determine efficient arrangements for an internal-flow system of an aircraft when such a system operates by itself or in combination with other flow systems. The investigation included a theoretical treatment of a problem and tests in the NACA 5-foot vertical wind tunnel of inlet and outlet openings in a flat plate and in a wing. When an internal-flow system tends to decrease the final velocity of it's wake, the results showed that it should be arranged in seri… more
Date: October 1940
Creator: Rogallo, F. M.
Partner: UNT Libraries Government Documents Department
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The Development of Electrical Strain Gages

Description: "The design, construction, and properties of an electrical-resistance strain gage consisting of fine wires molded in a laminated plastic are described. The properties of such gages are discussed and also the problems of molding of wires in plastic materials, temperature compensation, and cementing and removal of the gages. Further work to be carried out on the strain gage, together with instrument problems, is discussed" (p. 1).
Date: January 1940
Creator: de Forest, A. V. & Leaderman, H.
Partner: UNT Libraries Government Documents Department
open access

Tests of a gust-alleviating flap in the gust tunnel

Description: "Tests were made to determine the effectiveness of a long-period dynamically overbalanced flap in reducing airplane accelerations due to atmospheric gusts. For two gust shapes, one gust velocity, one forward velocity, and one wing loading, a series of flights was made with the flap locked and was then repeated with the flap free to operate. The records were evaluated by routine methods. The results indicate that the flap reduced the maximum acceleration increment 39 percent for a severe gust bu… more
Date: January 1940
Creator: Donely, Philip & Shufflebarger, C. C.
Partner: UNT Libraries Government Documents Department
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