National Advisory Committee for Aeronautics (NACA) - 32 Matching Results

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Flight Tests of the Lateral Control Characteristics of an F6F-3 Airplane Equipped with Spring-Tab Ailerons

Description: Tests were made to determine whether spring-tab ailerons tended to oscillate or flutter in speed ranges up to 400 mph. Flight tests showed spring-tab ailerons had desirable light stick forces and no tendency to overbalance. No flutter tendencies were indicated up to 400 mph, and any oscillations following abrupt control deflections were heavily damped. Recommendations were made for modifications to increase aileron effectiveness at low speeds without affecting lateral control at high speeds by increasing available deflection and modifying spring-tab arrangement.
Date: April 1, 1945
Creator: Williams, Walter C.
Partner: UNT Libraries Government Documents Department

Correlation of exhaust-valve temperatures with engine operating conditions and valve design in an air-cooled cylinder

Description: A semiempirical equation correlating exhaust-valve temperatures with engine operating conditions and exhaust-valve design has been developed. The correlation is based on the theory correlating engine and cooling variables developed in a previous NACA report. In addition to the parameters ordinarily used in the correlating equation, a term is included in the equation that is a measure of the resistance of the complex heat-flow paths between the crown of the exhaust valve and a point on the outside surface of the cylinder head. A means for comparing exhaust valves of different designs with respect to cooling is consequently provided. The necessary empirical constants included in the equation were determined from engine investigations of a large air-cooled cylinder. Tests of several valve designs showed that the calculated and experimentally determined exhaust-valve temperatures were in good agreement.
Date: October 1, 1945
Creator: Zipkin, M. A. & Sanders, J. C.
Partner: UNT Libraries Government Documents Department

Completed Tabulation in the United States of Tests of 24 Airfoils at High Mach Numbers (Derived from Interrupted Work at Guidonia, Italy in the 1.31- by 1.74-Foot High-Speed Tunnel)

Description: Two-dimensional data were obtained in Mach range of from 0.40 to 0.94 and Reynolds Number range of (3.4 - 4.2) X 10 Degrees. Results indicate that thickness ratio is dominating shape parameter at high Mach numbers and that aerodynamic advantages are attainable by using thinnest possible sections. Effects of jet boundaries, Reynolds Number, and Data presented are free from jet-boundary and humidity effects.
Date: June 1, 1945
Creator: Ferri, Antonio
Partner: UNT Libraries Government Documents Department

An Experimental Investigation of the Effect of Propellers Used as Aerodynamic Brakes on Stability and Control

Description: Tests were made of a model representative of a single-engine tractor-type airplane for the purpose of determining the stability and control effects of a propeller used as an aerodynamic brake. The tests were made with single-and dual-rotation propellers to show the effect of type of propeller rotation, and with positive thrust to provide basic data with which to compare the effects of negative thrust. Four configurations of the model were used to give the effects of tilting the propeller thrust axis down 5 deg., raising the horizontal tail, and combining both tilt and raised tail. Results of the tests are reported herein. The effects of negative thrust were found to be significant. The longitudinal stability was increased because of the loss of wing lift and increase of the angle of attack of the tail. Directional stability and both longitudinal and directional control were decreased because of the reduced velocity at the tail. These effects are moderate for moderate braking but become pronounced with full-power braking, particularly at high values of lift coefficient. The effects of model configuration changes were small when compared with the over-all effects of negative-thrust operation; however, improved stability and control characteristics were exhibited by the model with the tilted thrust axis. Raising the horizontal tail improved the longitudinal characteristics, but was detrimental to directional characteristics. The use of dual-rotation propeller reduced the directional trim charges resulting from the braking operation. A prototype airplane was assumed and handling qualities were computed and analyzed for normal (positive thrust) and braking operation with full and partial power. The results of these analyses are presented for the longitudinal characteristics in steady and accelerated flight, and for the directional characteristics in high- and low-speed flight. It was found that by limiting the power output of the engine (assuming the constant-speed propeller ...
Date: July 1, 1945
Creator: Hanson, Frederick H
Partner: UNT Libraries Government Documents Department

The Minimum Energy Loss Propeller

Description: Various cases are presented of the solution of the problem ot the most efficient propeller, more general cases being considered than the one by Betz in 1919: namely, that of a propeller under a limiting light load, The problem is solved directly and also with the aid of the Ritz method which became readily applicable after the author proposed a method for the solution of the propeller problem, in general, with the aid of trigonometric series. The design of a propeller with the aid of this method is given and an analysis is made of the effect of the fuselage and of the viscosity coefficient mu on the character of the solution of the variational problem.
Date: March 1, 1945
Creator: Poliakhov, N.
Partner: UNT Libraries Government Documents Department

Calculation of Turbulent Expansion Processes

Description: On the basis of certain formulas recently established by L. Prandtl for the turbulent interchange of momentum in stationary flows, various cases of "free turbulence" - that is, of flows without boundary walls - are treated in the present report. Prandtl puts the apparent shearing stress introduced by the turbulent momentum interchange. This present report deals first with the mixing of an air stream of uniform velocity with the adjacent still air, than with the expansion or diffusion of an air jet in the surrounding air space.
Date: September 1, 1945
Creator: Tollmien, Walter
Partner: UNT Libraries Government Documents Department

A New Apparatus for Measuring the Temperature at Machine Parts Rotating at High Speeds

Description: After a brief survey of the available methods for measuring the temperatures of machine parts at high speed, in particular turbine blades and rotors, an apparatus is described which is constructed on the principle of induction. Transmission of the measuring current by sliding contacts therefore is avoided. Up-to-date experiments show that it is possible to give the apparatus a high degree of sensitivity and accuracy. In comparison with sliding contact types, the present apparatus shows the important advantage that it operates for any length of time without wear, and that the contact difficulties, particularly occurring at high sliding speeds,are avoided.
Date: April 1, 1945
Creator: Gnam, E.
Partner: UNT Libraries Government Documents Department

Micromechanical Study of Metals

Description: The Institut Scientifique Experimental des Transports at Moscow established toward the end of 1925 had since its inception included in its program the study of the mechanism of plastic deformation and the problems associated with it with reference to the materials of the means of transport. Before the program thus determined upon could be carried out, it was necessary to adopt a method of research, or, more exactly, a system of such methods. Because of the modest equipment of the laboratory of the recently established institute, the choice of any particular method was determined not only by the advantages it offered but also by the resources available. As a result of a series of studies and investigations, a method was determined upon which in this paper will be denoted as the micromechanical method. The underlying basis of this method is already known. As will be seen from the description that follows, the micromechanical method is merely a combination of the micrographic study of plastic deformations with mechanical tests on small specimens. It is a well-known fact that a number of investigators have largely employed and still are employing these two procedures and have thereby obtained good results. The authors of the present paper have found it useful to combine the two methods, by making the two studies simultaneously on the sane specimen.
Date: July 1, 1945
Creator: Velikov, P. A.; Stchapov, N. P. & Lorenz, W. F.
Partner: UNT Libraries Government Documents Department

New Method of Determining the Polar Curve of an Airplane in Flight

Description: A fundamental defect of existing methods for the determination of the polar of an airplane in flight is the impossibility of obtaining the thrust or the resistance of the propeller for any type airplane with any type engine. The new method is based on the premise that for zero propeller thrust the mean angle of attack of the blade is approximately the same for all propellers if this angle is reckoned from the aerodynamic chord of the profile section. This angle was determined from flight tests. Knowing the mean angle of the blade setting the angle of attack of the propeller blade at zero thrust can be found and the propeller speed in gliding obtained. The experimental check of the new method carried out on several airplanes gave positive results. The basic assumptions for the construction of the polars and the method of analyzing the flight data are given.
Date: March 1, 1945
Creator: Yegorov, B. N.
Partner: UNT Libraries Government Documents Department

Some Effects of Compressibility on the Flow Through Fans and Turbines

Description: "The laws of conservation of mass, momentum, and energy are applied to the compressible flow through a two-dimensional cascade of airfoils. A fundamental relation between the ultimate upstream and downstream flow angles, the inlet Mach number, and the pressure ratio across the cascade is derived. Comparison with the corresponding relation for incompressible flow shows large differences. The fundamental relation reveals two ranges of flow angles and inlet Mach numbers, for which no ideal pressure ratio exists" (p. 123).
Date: August 1, 1945
Creator: Perl, W. & Epstein, H. T.
Partner: UNT Libraries Government Documents Department

A visual photographic study of cylinder lubrication

Description: From Summary: "A V-type engine provided with a glass cylinder was used to study visually the lubrication characteristics of an aircraft-type piston. Photographs and data were obtained with the engine motored at engine speeds up to 1000 r.p.m. and constant cylinder-head pressures of 0 and 50 pounds per square inch. A study was made of the orientation of the piston under various operating conditions, which indicated that the piston was inclined with the crown nearest the major-thrust cylinder face throughout the greater part of the cycle. The piston moved laterally in the cylinder under the influence of piston side thrust."
Date: August 1, 1945
Creator: Shaw, Milton C. & Nussdorfer, Theodore
Partner: UNT Libraries Government Documents Department

Effects of Compressibility on the Maximum Lift Characteristics and Spanwise Load Distribution of a 12-Foot-Span Fighter-Type Wing of NACA 230-Series Airfoil Sections

Description: Lift characteristics and pressure distribution for a NACA 230 wing were investigated for an angle of attack range of from -10 to +24 degrees and Mach range of from 0.2 to 0.7. Maximum lift coefficient increased up to a Mach number of 0.3, decreased rapidly to a Mach number of 0.55, and then decreased moderately. At high speeds, maximum lift coefficient was reached at from 10 to 12 degrees beyond the stalling angle. In high-speed stalls, resultant load underwent a moderate shift outward.
Date: November 1, 1945
Creator: West, F E
Partner: UNT Libraries Government Documents Department

Data for Design of Entrance Vanes from Two-Dimensional Tests of Airfoils in Cascade

Description: As a part of a program of the NACA directed toward increasing the efficiency of compressors and turbines, data were obtained for application to the design of entrance vanes for axfax-flow compressors or turbines. A series of blower-blade sections with relatively high critical speeds have been developed for turning air efficiently from 0 deg to 80 deg starting with an axial direction. Tests were made of five NACA 65-series blower blades (modified NACA 65(216)-010 airfoils) and of four experimentally designed blower blades in a stationary cascade at low Mach numbers. The turning effectiveness and the pressure distributions of these blade sections at various angles of attack were evaluated over a range of solidities near 1. Entrance-vane design charts are presented that give a blade section and angle of attack for any desired turning angle. The blades thus obtained operate with peak-free pressure distributions. Approximate critical Mach numbers were calculated from the pressure distributions.
Date: January 1, 1945
Creator: Zimmey, Charles M. & Lappi, Viola M.
Partner: UNT Libraries Government Documents Department

Calculations of economy of 18-cylinder radial aircraft engine with exhaust-gas turbine geared to the crankshaft

Description: Calculations based on dynamometer test-stand data obtained on an 18-cylinder radial engine were made to determine the improvement in fuel consumption that can be obtained at various altitudes by gearing an exhaust-gas turbine to the engine crankshaft in order to increase the engine-shaft work.
Date: January 1, 1945
Creator: Hannum, Richard W. & Zimmerman, Richard H.
Partner: UNT Libraries Government Documents Department

Numerical Evaluation by Harmonic Analysis of the (Epsilon)-Function of the Theodorsen Arbitrary-Airfoil Potential Theory

Description: Finite trigonometric series is fitted by harmonic analysis as an approximation function to the psi function of the Theodorsen arbitrary-airfoil potential theory. By harmonic synthesis, the corresponding conjugate trigonometric series is used as an approximation to the epsilon function. A set of coefficients of particularly simple form is obtained algebraically for direct calculation of the epsilon values from the corresponding set of psi values. Complete derivation of this process is presented.
Date: September 1, 1945
Creator: Naiman, Irven
Partner: UNT Libraries Government Documents Department

Charts for the minimum-weight design of 24S-T aluminum-alloy flat compression panels with longitudinal Z-section stiffeners

Description: Design charts are developed for 24s-t aluminum-alloy flat compression panels with longitudinal z-section stiffeners. These charts make possible the design of the lightest panels of this type for a wide range of design requirements. Examples of the use of the charts are given and it is pointed out on the basis of these examples that, over a wide range of design conditions, the maintenance of buckle-free surfaces does not conflict with the achievement of high structural efficiency. The achievement of the maximum possible structural efficiency with 24s-t aluminum-alloy panels, however, requires closer stiffener spacings than those now in common use.
Date: January 1, 1945
Creator: Schuette, Evan H.
Partner: UNT Libraries Government Documents Department