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Analysis of Ground Effect on the Lifting Airscrew

Description: "A study is presented of ground effect as applied to the lifting airscrew of the type used in modern gyroplanes and helicopters. The mathematical analysis of the problem has been verified by tests made of three rotor models in the presence of a large circular "ground plane." The results of the study are presented in the form of convenient charts" (p. 1).
Date: December 1941
Creator: Knight, Montgomery & Hefner, Ralph A.
Partner: UNT Libraries Government Documents Department
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Hydrodynamic Tests of a 1/10-Size Model of the Hull of the Latécoère 521 Flying Boat: NACA Model 83

Description: From Summary: "A 1/10-size model of the hull of the French flying boat Latecoere 521 was tested in the NACA tank. This model is one of a series of models of the hulls of actual flying boats of both foreign and domestic type that are being tested in the NACA tank to provide information regarding the water characteristics of a variety of forms of hull and to illustrate the development of present-day types of flying boat. The lines and the offsets of the hull were obtained from the manufacturer th… more
Date: December 1941
Creator: Olson, Roland E. & Lina, Lindsay J.
Partner: UNT Libraries Government Documents Department
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Analytical Determination of Control System Pulley-Axis Angles

Description: From Introduction: "The ideas developed in this paper are presented as a means of saving the designer's time and as a method of reduction of control-system friction by an accurate calculation of pulley-axis angles without the errors and difficult checking incident to any graphical method."
Date: September 1941
Creator: Driggs, I. H.
Partner: UNT Libraries Government Documents Department
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Shear Lag in Corrugated Sheets Used for the Chord Member of a Box Beam

Description: "The problem of the distribution of normal stress across a wide corrugated sheet used as the chord of a box-beam-like structure is investigated theoretically and experimentally. Expressions are developed giving the stress distribution in beams, symmetrical or unsymmetrical, about a plane passed spanwise through the center of the sheet. The experiments were arranged to insure bending without torsion and surveys of the normal stresses were made by means of mechanical and electrical strain gages" … more
Date: January 1941
Creator: Newell, Joseph S. & Reissner, Eric
Partner: UNT Libraries Government Documents Department
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Stresses and Deflections in Thin Shells and Curved Plates Due to Concentrated and Variously Distributed Loading

Description: Note presenting tests made on cylindrical and spherical shells to determine the local stresses and deflections produced by concentrated and variously distributed loading. The results are correlated with those of earlier experiments, and empirical formulas based on the data are proposed. Data are presented on the effect of severe prestressing on stiffness and on the efficiency of welded lugs of various forms in transmitting a load to a thin shell without producing excessive local stresses.
Date: May 1941
Creator: Roark, Raymond J.
Partner: UNT Libraries Government Documents Department
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The End-Plate Effect of a Horizontal-Tail Surface on Vertical Tail Surface

Description: Note presenting the end-plate effect of the horizontal-tail surface on the vertical-tail surface as theoretically studied by derivation of the flow corresponding to the condition of minimum induced drag and by solution of the usual lifting-line equations. The results obtained by the two methods were considerably different, indicated that the condition derived is not a close approximation to the actual condition.
Date: February 1941
Creator: Katzoff, S. & Mutterperl, William
Partner: UNT Libraries Government Documents Department
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Compression tests of some 17S-T aluminum-alloy specimens of I cross section

Description: Report presenting testing of specimens cut from a specially extruded I-beam of 17S-T aluminum alloy with one flange wider than the other under axial compression. Only the two longest specimens failed as columns, while the shorter ones failed by local buckling. The agreement between experimental and calculated values of critical stress can be improved by considering the effect of restraint at the loaded edges of the web and adopting a more accurate buckling treatment beyond the elastic range.
Date: March 1941
Creator: Hill, H. N.
Partner: UNT Libraries Government Documents Department
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Effect of Alternately High and Low Repeated Stresses Upon the Fatigue Strength of 25S-T Aluminum Alloy

Description: "Fatigue tests were made on one lot of 3/4 inch diameter rolled-and-drawn 25S-T aluminum-alloy rod normal in composition and tensile properties. The specimens were tested at 3500 cycles per second in a rotating-beam fatigue test machine. Tests were made for three ratios (20:1, 50:1, and 200:1) of the number of cycles applied at low stress to the number applied at high stress. In general, failure occurred when the number of cycles at either the low or the high stress approached the ordinary fati… more
Date: January 1941
Creator: Stickley, G. W.
Partner: UNT Libraries Government Documents Department
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Two-Stage Supercharging

Description: "The arrangement of the parts and the installation and control problems of the two-stage mechanically driven superchargers for aircraft engines are discussed. Unless an entirely new form of supercharging is developed, there will be a definite need for a two-stage centrifugal supercharger. It is shown that the two-stage mechanically driven supercharger itself is a comparatively simple device; the complications arise from the addition of inter-coolers and controls" (p. 1).
Date: February 1941
Creator: Buck, Richard S.
Partner: UNT Libraries Government Documents Department
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Effect of several supercharger control methods on engine performance

Description: Report presenting an analytical comparison of a variety of superchargers using the same hypothetical engine, which include a single-speed, a two-speed, and a variable-speed DVL centrifugal supercharger, the Szydlowski-Planiol supercharger with a single-speed and a two-speed transmission, and a turbosupercharger.
Date: February 1941
Creator: Wasielewski, Eugene W. & King, J. Austin
Partner: UNT Libraries Government Documents Department
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Tests on Stiffened Circular Cylinders

Description: "Compressive tests were made of two series of stiffened circular cylindrical shells under axial load. All the shells were 16 inches in diameter by 24 inches in length and were made of aluminum-alloy sheet curved to the proper radius and welded with one longitudinal weld. The ratios of diameter to thickness of shell wall in the two series of specimens were 258 and 572" (p. 1).
Date: March 1941
Creator: Holt, Marshall
Partner: UNT Libraries Government Documents Department
open access

Tests of Round and Flat Spoilers on a Tapered Wing in the NACA 19-Foot Pressure Wind Tunnel

Description: "Several arrangements of round and flat spanwise spoilers attached to the upper surface of a tapered wing were tested in the NACA 19-foot pressure wind tunnel to determine the most effective type, location, and size of spoiler necessary to reduce greatly the lift on the wings of large flying boats when moored. The effect of the various spoilers on the lift, the drag, and the pitching-moment characteristics of the tapered wing was measured over a range of angles of attack from zero to maximum li… more
Date: March 1941
Creator: Wenzinger, Carl J. & Bowen, John D.
Partner: UNT Libraries Government Documents Department
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Tests of a gust-alleviating wing in the gust tunnel

Description: "Tests were made in the NACA gust tunnel to determine the effectiveness of a torsionally flexible wing with the torsion axis ahead of the locus of the section aerodynamic centers in reducing airplane accelerations due to atmospheric gusts. For three gust shapes, a series of flights was made with the airplane model equipped with either a torsionally flexible or a rigid wing. The results indicated that the torsionally flexible wing reduced the maximum acceleration increment 5 percent for the shar… more
Date: April 1941
Creator: Shufflebarger, C. C.
Partner: UNT Libraries Government Documents Department
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Wind-Tunnel Investigation of Several Factors Affecting the Performance of a High-Speed Pursuit Airplane With Air-Cooled Radial Engine

Description: Report details an investigation into various potential improvements and modifications to pursuit airplanes. NACA low-drag airfoil sections and their use for reducing drag and increasing compressibility speeds were examined. Other items covered include the propeller slipstream, high-speed cowling arrangement, and placement of wing guns.
Date: November 1941
Creator: Wenzinger, Carl J.
Partner: UNT Libraries Government Documents Department
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Some effects of rainfall on flight of airplanes and on instrument indications

Description: "Several possible effects of heavy rain on the aerodynamic performance of an airplane and of heavy rain and associated atmospheric phenomena on the indications of flight instruments are briefly considered. It is concluded that the effects of heavy rain on the performance of an airplane are not so great as to force the airplane down from moderate altitudes. Serious malfunctioning of the air-speed indicator may occur, however, as a result of flooding of the pitot-static head and subsequent accumu… more
Date: April 1941
Creator: Rhode, Richard V.
Partner: UNT Libraries Government Documents Department
open access

Effect of Aging on Mechanical Properties of Aluminum-Alloy Rivets

Description: "Curves and tabular data present the results of strength tests made during and after 2 1/2 years of aging on rivets and rivet wire of 3/16-inch nominal diameter. The specimens were of aluminum alloy: 24S, 17S, and A17S of the duralumin type and 53S of the magnesium-silicide type" (p. 1).
Date: April 1941
Creator: Roop, Frederick C.
Partner: UNT Libraries Government Documents Department
open access

Model Tests of a Wing-Duct System for Auxiliary Air Supply

Description: Report discusses the design of a cooling system developed for a Pratt & Whitney H-2800 engine equipped with a two-stage supercharger. The wing-duct system was newly developed and was determined to be a valuable method for cooling engine auxiliaries by combining simplicity with low drag and excellent cooling capabilities.
Date: January 1941
Creator: Bierman, David & Corson, Blake W., Jr.
Partner: UNT Libraries Government Documents Department
open access

Spin Tests of a Low-Wing Monoplane to Investigate Scale Effect in the Model Test Range

Description: "Concurrent tests were performed on a 1/16 and a 1/20 scale model (wing spans of 2.64 and 2.11 ft. respectively) of a modern low wing monoplane in the NACA 15 foot free-spinning wind tunnel. Results are presented in the form of charts that afford a direct comparison between the spins of the two models for a number of different conditions. Qualitatively, the same characteristic effects of control disposition, mass distribution, and dimensional modifications were indicated by both models" (p. 1).
Date: May 1941
Creator: Donlan, Charles J.
Partner: UNT Libraries Government Documents Department
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Methods of analyzing wind-tunnel data for dynamic flight conditions

Description: The effects of power on the stability and the control characteristics of an airplane are discussed and methods of analysis are given for evaluating certain dynamic characteristics of the airplane that are not directly discernible from wind tunnel tests alone. Data are presented to show how the characteristics of a model tested in a wind tunnel are affected by power. The response of an airplane to a rolling and a yawing disturbance is discussed, particularly in regard to changes in wing dihedral… more
Date: July 22, 1941
Creator: Donlan, C. J. & Recant, I. G.
Partner: UNT Libraries Government Documents Department
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Requirements for Satisfactory Flying Qualities of Airplanes

Description: Report discusses the results of an analysis of available data to determine what measured characteristics are significant in defining satisfactory flying qualities, what characteristics are reasonable to require of an airplane, and what influence the various design features have on the observed flying qualities.
Date: March 24, 1941
Creator: Gilruth, R. R.
Partner: UNT Libraries Government Documents Department
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A study by high-speed photography of combustion and knock in a spark-ignition engine

Description: "The study of combustion in a spark-ignition engine given in Technical Report no. 704 has been continued. The investigation was made with the NACA high-speed motion-picture camera and the NACA optical engine indicator. The camera operates at the rate of 40,000 photographs a second and makes possible the study of phenomena occurring in time intervals as short as 0.000025 second. Photographs are presented of combustion without knock and with both light and heavy knocks, the end zone of combustion… more
Date: December 9, 1941
Creator: Miller, Cearcy D.
Partner: UNT Libraries Government Documents Department
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On the Use of Residue Theory for Treating the Subsonic Flow of a Compressible Fluid

Description: "A new mathematical technique, due to Milne-Thomson, is used to obtain an improved form of the method of Poggi for calculating the effect of compressibility on the subsonic flow past an obstacle. By means of this new method, the difficult surface integrals of the original Poggi method can be replaced by line integrals. These line integrals are then solved by the use of residue theory. In this way an equation is obtained giving the second-order effect of compressibility on the velocity of the fl… more
Date: September 8, 1941
Creator: Kaplan, Carl
Partner: UNT Libraries Government Documents Department
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Test of single-stage axial-flow fan

Description: "A single-stage axial fan was built and tested in the shop of the propeller-research tunnel of the NACA. The fan comprised a simple 24-blade rotor having a diameter of 21 inches and a solidity of 0.86 and a set of 37 contravanes having a solidity of 1.33. The rotor was driven by a 25-horsepower motor capable of rotating at a speed of 3600 r.p.m. The fan was tested for volume, pressure, and efficiency over a range of delivery pressures and volumes for a wide range of contravane and blade-angle s… more
Date: September 22, 1941
Creator: Bell, E. Barton
Partner: UNT Libraries Government Documents Department
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Determination of optimum plan forms for control surfaces

Description: Solutions found for a range of airfoil plan forms indicate that, regardless of the characteristics of the tail surface, the chord of the rudder or of the elevator should be very nearly constant over its span. The optimum ailerons are also of a characteristic shape, varying little with the plan form of the wing.
Date: January 30, 1941
Creator: Jones, Robert T. & Cohen, Doris
Partner: UNT Libraries Government Documents Department
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