National Advisory Committee for Aeronautics (NACA) - 4,114 Matching Results

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Longitudinal stability and control with special reference to slipstream effects

Description: Report presents the results of a study of data obtained in the NACA full-scale wind tunnel concerning the effects of interference and of propeller operation on longitudinal stability and control. The data include pitching moments for various power conditions for airplanes with tails removed and with tails set at various stabilizer and elevator angles. A number of surveys of the dynamic pressure and the flow direction in the region of the horizontal tail surface are also included. Results are given for eight airplanes, including a model of a four-engine airplane tested both as a tractor and as a pushed and a model of two-engine pusher. The effects are shown of propeller operation on the downwash angles and the dynamic pressures at the tail and on the pitching-moment contribution of the propeller and the wing.
Date: January 1, 1940
Creator: Katzoff, S
Partner: UNT Libraries Government Documents Department

Mechanical Properties of Flush-Riveted Joints

Description: The strength of representative types of flush-riveted joints has been determined by testing 865 single-shearing, double-shearing, and tensile specimens representing 7 types of rivet and 18 types of joint. The results, presented in graphic form, show the stress at failure, type of failure, and d/t ratio. In general, dimpled joints were appreciably stronger than countersunk or protruding-head joints, but their strength was greatly influenced by constructional details. The optimum d/t ratios have been determined for the several kinds of joints. Photomicrographs of each type show constructional details and, in several instances, cracks in the sheet.
Date: January 1, 1940
Creator: Brueggeman, W C & Roop, Frederick C
Partner: UNT Libraries Government Documents Department

Mechanical properties of flush-riveted joints

Description: Report discusses the strength of several types of flush-riveted joints, including single-shearing, double-shearing, and tensile specimens. The stress at failure, type of failure, and d/t ratio are provided. Dimpled joints were found to be the strongest, but their strength was heavily influenced by the details of their construction.
Date: January 1940
Creator: Bruggeman, Wm. C. & Roop, Frederick C.
Partner: UNT Libraries Government Documents Department

Mechanism of flutter.a theoretical and experimental investigation of the flutter problem

Description: The results of the basic flutter theory originally devised in 1934 and published as NACA Technical Report no. 496 are presented in a simpler and more complete form convenient for further studies. The paper attempts to facilitate the judgement of flutter problems by a systematic survey of the theoretical effects of the various parameters. A large number of experiments were conducted on cantilever wings, with and without ailerons, in the NACA high-speed wind tunnel for the purpose of verifying the theory and to study its adaptability to three-dimensional problems. The experiments included studies on wing taper ratios, nacelles, attached floats, and external bracings. The essential effects in the transition to the three-dimensional problem have been established. Of particular interest is the existence of specific flutter modes as distinguished from ordinary vibration modes. It is shown that there exists a remarkable agreement between theoretical and experimental results.
Date: January 1, 1940
Creator: Theodorsen, Theodore & Garrick, I E
Partner: UNT Libraries Government Documents Department

Piston temperatures in an air-cooled engine for various operating conditions

Description: As part of a program for the study of piston cooling, this report presents the results of tests conducted on a single-cylinder, air-cooled, carburetor engine to determine the effect of engine operating conditions on the temperatures at five locations on the piston.
Date: January 1, 1940
Creator: Manganiello, Eugene J
Partner: UNT Libraries Government Documents Department

Preliminary investigation of the flying qualities of airplanes

Description: The National Advisory Committee for Aeronautics is undertaking an investigation of the flying qualities of airplanes. The work consists in the determination of the significant qualities susceptible of measurement, the development of the instruments required to make the measurements, and the accumulation of data on the flying qualities of existing airplanes, which data are to serve as a basis for quantitative specifications for the flying qualities of future designs. A tentative schedule of measurable flying qualities has been prepared and the instruments needed for their measurements have been assembled. A trial of the schedule and the instruments has been made using the Stinson SR-8e airplane. The results showed that, although the original schedule and instruments are basically satisfactory some further development is required to eliminate nonessential items and to expedite flight testing. The report describes and discusses the work done with this airplane.
Date: January 1, 1940
Creator: Soule, H A
Partner: UNT Libraries Government Documents Department

Preliminary wind-tunnel investigation of an NACA 23012 airfoil with various arrangements of venetian-blind flaps

Description: Report presents the results of an investigation made in the NACA 7 by 10-foot wind tunnel of a large-chord NACA 23012 airfoil with several arrangements of venetian-blind flaps to determine the aerodynamic section characteristics as affected by the over-all flap chord, the chords of the slats used to form the flap, the slat spacing, the number of slats and the position of the flap with respect to the wing. Complete section data are given in the form of graphs for all the combinations tested.
Date: January 1, 1940
Creator: Wenzinger, Carl J. & Harris, Thomas A.
Partner: UNT Libraries Government Documents Department

Propeller rotation noise due to torque and thrust

Description: Sound pressure of the first four harmonics of rotation from a full-scale two-blade propeller were measured and are compared with values calculated from theory. The comparison is made (1) for the space distribution with constant tip speed and (2) for fixed space angles with variable tip speed. A relation for rotation noise from an element of radius developed by Gutin is given showing the effect of number of blades on the rotation noise.
Date: January 1, 1940
Creator: Deming, Arthur F
Partner: UNT Libraries Government Documents Department

Stability of Castering Wheels for Aircraft Landing Gears

Description: A theoretical study was made of the shimmy of castering wheels. The theory is based on the discovery of a phenomenon called kinematic shimmy. Experimental checks, use being made of a model having low-pressure tires, are reported and the applicability of the results to full scale is discussed. Theoretical methods of estimating the spindle viscous damping and the spindle solid friction necessary to avoid shimmy are given. A new method of avoiding shimmy -- lateral freedom -- is introduced.
Date: January 1, 1940
Creator: Kantrowitz, Arthur
Partner: UNT Libraries Government Documents Department

Static thrust and power characteristics of six full-scale propellers

Description: Static thrust and power measurements were made of six full-scale propellers. The propellers were mounted in front of a liquid-cooled-engine nacelle and were tested at 15 different blade angles in the range from -7 1/2 degrees to 35 degrees at 0.75r. The test rig was located outdoors and the tests were made under conditions of approximately zero wind velocity.
Date: January 1, 1940
Creator: Hartman, Erwin P & Biermann, David
Partner: UNT Libraries Government Documents Department

Stress distribution in and equivalent width of flanges of wide, thin-wall steel beams

Description: The use of different forms of wide-flange, thin-wall steel beams is becoming increasingly widespread. Part of the information necessary for a national design of such members is the knowledge of the stress distribution in and the equivalent width of the flanges of such beams. This problem is analyzed in this paper on the basis of the theory of plane stress. As a result, tables and curves are given from which the equivalent width of any given beam can be read directly for use in practical design. An investigation is given of the limitations of this analysis due to the fact that extremely wide and thin flanges tend to curve out of their plane toward the neutral axis. A summary of test data confirms very satisfactorily the analytical results.
Date: January 1, 1940
Creator: Winter, George
Partner: UNT Libraries Government Documents Department

Tensile elastic properties of typical stainless steels and nonferrous metals as affected by plastic deformation and by heat treatment

Description: A general discussion is given of the relationships between stress, strain, and permanent set. From stress-set curves are derived proof stresses based on five different percentages of permanent set. The influence of prior plastic extension on these values is illustrated and discussed. A discussion is given of the influence of work-hardening, rest interval, and internal stress on the form of the proof stress-extension curve.
Date: January 1, 1940
Creator: Mcadam, D J & Mebs, R W
Partner: UNT Libraries Government Documents Department

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 but with a representative gust shape (a sharp-edge gust), the reduction was only 3 percent. The results also indicate that the flap tended to reduce the longitudinal stability of the airplane. Computations made of the effectiveness and the action of the flap were in good agreement with the experimental results.
Date: January 1, 1940
Creator: Donely, Philip & Shufflebarger, C C
Partner: UNT Libraries Government Documents Department

A theoretical study of lateral stability with an automatic pilot

Description: The influence of automatic operation of the aileron and rudder controls on the lateral stability of an airplane is discussed. The control deflections are assumed to be proportional to the deviations and to the rates of deviation of the airplane from steady-flight conditions. The effects of changes in the types of deviation governing control application are considered. For one simple method of control in which the aileron deflection is proportional to the angle of bank and the rudder deflection is proportional to the angle of yaw, the effect of lag in control application is studied and regions of stability with and without lag are given. For the simple control with lag, curves are included that show the variations in the roots of the stability equation with changes in the amount of control applied. It is concluded that, although the simple control provides a satisfactory means of varying most of the lateral stability characteristics, the stability in azimuth will always be poor for such a control.
Date: January 1, 1940
Creator: Imlay, Frederick H
Partner: UNT Libraries Government Documents Department

Stresses in single-spar wing constructions with incompletely built-up ribs

Description: It is shown that the force distribution resulting from incomplete ribs in single spar wing structures may be determined with the aid of the shear field method by a statistically indeterminate computation. A numerical computation is given of the force distribution of a wing structure whose two neighboring incomplete ribs with web missing in half the section are torsionally loaded.
Date: January 30, 1940
Creator: Reinitzhuber, F
Partner: UNT Libraries Government Documents Department

Aerodynamics of rotating-wing aircraft with blade-pitch control

Description: From Introduction: "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."
Date: February 1940
Creator: Pfluger, A
Partner: UNT Libraries Government Documents Department

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. Experimental results of measurements of damping in several flutter models are presented.
Date: February 1, 1940
Creator: Coleman, Robert P.
Partner: UNT Libraries Government Documents Department

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

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.
Date: February 1, 1940
Creator: Duchene, R
Partner: UNT Libraries Government Documents Department

Experimental Determination of Exhaust Gas Thrust, Special Report

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.
Date: February 1940
Creator: Pinkel, Benjamin & Voss, Fred
Partner: UNT Libraries Government Documents Department

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 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.
Date: February 1, 1940
Creator: Reissner, Hans
Partner: UNT Libraries Government Documents Department

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

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.
Date: February 1, 1940
Creator: Dunn, Louis G
Partner: UNT Libraries Government Documents Department

Measurement of the forces acting on gliders in towed flight

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.
Date: February 1, 1940
Creator: Klenperer, W B
Partner: UNT Libraries Government Documents Department