319 Matching Results

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Flight Investigation at High Speeds of Profile Drag of Wing of a P-47d Airplane Having Production Surfaces Covered With Camouflage Paint

Description: Report presenting a flight investigation made at high speeds to determine the profile drag of a P-47D airplane wing with production surfaces covered with camouflage paint. The results indicated that a minimum profile-drag coefficient of 0.0097 was attained for lift coefficients from 0.16 to 0.25 at Mach numbers less than 0.67.
Date: March 1946
Creator: Zalovcik, John A. & Daum, Fred L.
Partner: UNT Libraries Government Documents Department

An Investigation of Aircraft Heaters 8: A Simplified Method for the Calculation of the Unit Thermal Conductance Over Wings

Description: Report presenting a simplified approximate method of calculating the unit thermal conductance along an airfoil as a function of distance from the leading edge, by use of heat transfer data for smooth cylinders and smooth flat plates. Several examples are used in order to show the effectiveness of the method.
Date: March 1943
Creator: Martinelli, R. C.; Guibert, A. G.; Morrin, E. H. & Boelter, L. M. K.
Partner: UNT Libraries Government Documents Department

A Method for the Design of Cooling Systems for Aircraft Power-Plant Installations

Description: Report presenting a method of organizing design calculations for the cooling systems of aircraft power-plant installations for use by representatives of airplane and engine companies invited to participate in the NACA power-plant installation section.
Date: March 1942
Creator: Rubert, Kennedy F. & Knopf, George S.
Partner: UNT Libraries Government Documents Department

A Theoretical Investigation of the Lateral Oscillations of an Airplane With Free Rudder With Special Reference to the Effect of Friction

Description: Report presenting charts showing the variation in dynamic stability with the rudder hinge-moment characteristics. A stabilizing rudder floating tendency combined with a high degree of aerodynamic balance is shown to lead to oscillations of increasing amplitude.
Date: March 1943
Creator: Greenberg, Harry & Sternfield, Leonard
Partner: UNT Libraries Government Documents Department

A Theoretical Investigation of the Lateral Oscillations of an Airplane With Free Rudder With Special Reference to the Effect of Friction

Description: "Charts showing the variation in dynamic stability with the rudder hinge-moment characteristics are presented. A stabilizing rudder floating tendency combined with a high degree of aerodynamic balance is shown to lead to oscillations of increasing amplitude. This dynamic instability is increased by viscous-friction in the rudder control system" (p. 147).
Date: March 4, 1943
Creator: Greenberg, Harry & Sternfield, Leonard
Partner: UNT Libraries Government Documents Department

The Theoretical Lift of Flat Swept-Back Wings at Supersonic Speeds

Description: Note presenting an application of the method of superposition of linearized conical flows to the calculatin of the aerodynamic properties of thin, flat, swept-back wings at an angle of attack. Various cases are distinguished, depending on the sweep of the leading and trailing edges relative to their respective Mach lines. The results of the calculations emphasize the indications of the theory that the determining factor in the aerodynamic performance of wings is the disposition of area relative to the Mach lines.
Date: March 1948
Creator: Cohen, Doris
Partner: UNT Libraries Government Documents Department

Theory and Application of Hot-Wire Instruments in the Investigation of Turbulent Boundary Layers

Description: Report presenting an account of the recent developments in hot-wire instruments for use in turbulent boundary layers to determine the magnitude of the several components of the turbulent velocity fluctuations together with the correlation between them and turbulent shearing stress.
Date: March 1946
Creator: Schubauer, G. B. & Klebanoff, P. S.
Partner: UNT Libraries Government Documents Department

Turbulent Flow Between Rotating Cylinders

Description: "The turbulent air flow between rotating cylinders was investigated. The distributions of mean speed and of turbulence were measured in the gap between a rotating inner and a stationary outer cylinder. The measurements led to the conclusion that the turbulent flow in the gap cannot be considered two dimensional, but that a particular type of secondary motion takes place. It is shown that the experimentally found velocity distribution can be fully understood under the assumption that this secondary motion consists of three-dimensional ring-shape vortices" (p. 1).
Date: March 1943
Creator: Shih-I, Pai
Partner: UNT Libraries Government Documents Department

Measurement of Knock Characteristics in Spark-Ignition Engines

Description: This paper presents a discussion of three potential sources of error in recording engine knocking which are: the natural oscillation of the membrane, the shock process between test contacts, and the danger of burned contacts. Following this discussion, the paper calls attention to various results which make the bouncing-pin indicator appear fundamentally unsuitable for recording knock phenomena.
Date: March 1940
Creator: Sch├╝tz, R.
Partner: UNT Libraries Government Documents Department

Protection of Nonmetallic Aircraft From Lightning 3: Electrical Effects in Glider Towlines

Description: Report presenting an exploration of the electrical effects that glider tows operating in or near a thunderstorm may experience. The three primary hazards are a direct lightning strike, a lightning strike that passes to some intermediate point on the towline, and an electrical current of appreciable magnitude flowing in the towline the whole time that the tow is within a few miles of the thunderstorm.
Date: March 1944
Partner: UNT Libraries Government Documents Department

Protection of Nonmetallic Aircraft From Lightning 4: Electrocution Hazards From Inductive Voltages

Description: Report presenting tests made on an XCG-7 all-wood glider on a PT-19A training airplane with a tubular metal fuselage and wooden wings by passing electrical surges simulating lightning discharges through the aircraft and measuring the voltage induced between various points which might be touched by an occupant. While certain recommendations for electrical protection are provided, the personnel in a metal fuselage aircraft are reasonably well protected from induced voltage shock without other protection.
Date: March 1945
Partner: UNT Libraries Government Documents Department

Effect of Finite Span on the Airload Distributions for Oscillating Wings 1: Aerodynamic Theory of Oscillating Wings of Finite Span

Description: Note presenting a formula for the pressure distribution on an oscillating lifting surface of finite span under the assumption of a ratio of span to average chord that is not too small. It is found that the effect of three-dimensionality of the flow may be incorporated in the results of the two-dimensional theory by adding a correction factor to the basic function of the two-dimensional theory.
Date: March 1947
Creator: Reissner, Eric
Partner: UNT Libraries Government Documents Department

On the Flow of a Compressible Fluid by the Hodography Method 1: Unification and Extension of Present-Day Results

Description: Report presenting elementary basic solutions of the equations of motion of a compressible fluid in the hodograph variables are developed and used to provide a basis for comparison in the form of velocity correction formulas, of corresponding compressible and incompressible flows.
Date: March 1944
Creator: Garrick, I. E. & Kaplan, Carl
Partner: UNT Libraries Government Documents Department

Full-Scale Investigation of the Blade Motion of the PV-2 Helicopter Rotor

Description: Note presenting an investigation of the PV-2 helicopter rotor to determine the basic performance characteristics of a fully articulated rotor. Results are presented of the blade-motion observations at the 0.75-radius station for a limited range of flight conditions. Both the measured results and a comparison with theoretical results are provided.
Date: March 1948
Creator: Migotsky, Eugene
Partner: UNT Libraries Government Documents Department

Critical Combinations of Longitudinal and Transverse Direct Stress for an Infinitely Long Flat Plate With Edges Elastically Restrained Against Rotation

Description: Report presenting a theoretical investigation of the buckling of an infinitely long flat plate with edges elastically restrained against rotation under combinations of longitudinal and transverse direct stress. Interaction curves are presented that give the critical combinations of stress for several different degrees of elastic edge restraint, including simple support and complete fixity.
Date: March 1946
Creator: Batdorf, S. B.; Stein, Manuel & Libove, Charles
Partner: UNT Libraries Government Documents Department

Frequency-Response Method for Determination of Dynamic Stability Characteristics of Airplanes With Automatic Controls

Description: Note presenting a frequency-response method for determining the critical control-gearing and hunting oscillations of airplanes with automatic pilots. The method is graphical and has several advantages over the standard numerical procedure based on Routh's discriminant. Several examples are worked out to illustrate the application of the frequency-response method in determining the effect of automatic-pilot lag or lead on critical control gearing and in determining the amplitude and frequency of hunting.
Date: March 1947
Creator: Greenberg, Harry
Partner: UNT Libraries Government Documents Department

A Simplified Method of Elastic-Stability Analysis for Thin Cylindrical Shells

Description: "This paper develops a new method for determining the buckling stresses of cylindrical shells under various loading conditions. In part I, the equation for the equilibrium of cylindrical shells introduced by Donnell in NACA report no. 479 to find the critical stresses of cylinders in torsion is applied to find critical stresses for cylinders with simply supported edges under other loading conditions. In part II, a modified form of Donnell's equation for the equilibrium of thin cylindrical shells is derived which is equivalent to Donnell's equation but has certain advantages in physical interpretation and in ease of solution, particularly in the case of shells having clamped edges" (p. 285).
Date: March 20, 1947
Creator: Batdorf, S. B.
Partner: UNT Libraries Government Documents Department

Critical Stress of Thin-Walled Cylinders in Axial Compression

Description: Empirical design curves are presented for the critical stress of thin-wall cylinders loaded in axial compression. These curves are plotted in terms of the nondimensional parameters of small-deflection theory and are compared with theoretical curves derived for the buckling of cylinders with simply supported and clamped edges. An empirical equation is given for the buckling of cylinders having a length-radius ratio greater than about 0.75.
Date: March 20, 1947
Creator: Batdorf, S. B.; Schildcrout, Murry & Stein, Manuel
Partner: UNT Libraries Government Documents Department

Critical Combinations of Shear and Direct Stress for Simply Supported Rectangular Flat Plates

Description: Note presenting an investigation of the buckling of a simply supported rectangular flat plate under combinations of shear and direct stress by means of an energy method. The critical combinations of stress for several length-width ratios were determined to an accuracy of about 1 percent in conjunction with a modified matrix iteration method. Results regarding the shear and longitudinal stress and shear and transverse stress are provided.
Date: March 1947
Creator: Batdorf, S. B. & Stein, Manuel
Partner: UNT Libraries Government Documents Department

The Friction of Piston Rings

Description: "The coefficient of friction between piston ring and cylinder liner was measured in relation to gliding acceleration, pressure, temperature, quantity of oil and quality of oil. Comparing former lubrication-technical tests, conclusions were drawn as to the state of friction. The coefficients of friction as figured out according to the hydrodynamic theory were compared with those measured by tests" (p. 1).
Date: March 1945
Creator: Tischbein, Hans W.
Partner: UNT Libraries Government Documents Department

Buckling Stresses of Simply Supported Rectangular Flat Plates in Shear

Description: "The present paper evaluates the shear buckling stresses of rectangular flat plates with simply supported edges more accurately than previous work on this problem. Both symmetric (odd number of buckles) and antisymmetric (even number of buckles) patterns were considered. A curve is presented from which the critical stresses may be obtained when the dimensions of the plate are known" (p. 1).
Date: March 1947
Creator: Stein, Manuel & Neff, John
Partner: UNT Libraries Government Documents Department