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Reciprocity relations in aerodynamics

Description: From Introduction: "The purpose of the present paper is twofold. First, a close connection will be established between reverse-flow theorems in subsonic and supersonic, steady-state wing theory and known reciprocity relations between two solutions of the equation the flow field."
Date: May 1952
Creator: Heaslet, Max A. & Spreiter, John R.
open access

A Low-Speed Experimental Investigation of the Effect of a Sandpaper Type of Roughness on Boundary-Layer Transition

Description: Report describing the effects of an area of roughness on the velocity and turbulence measurements of an airfoil. It details the effects of the size, location, and height of the roughness on the Reynolds number. From Summary: "An investigation was made in the Langley low-turbulence pressure tunnel to determine the effect of size and location of a sandpaper type of roughness on the Reynolds number for transition."
Date: 1958
Creator: Horton, Elmer A. & von Doenhoff, Albert E.
open access

Two-dimensional subsonic compressible flows past arbitrary bodies by the variational method

Description: Instead of solving the nonlinear differential equation which governs the compressible flow, an approximate method of solution by means of the variational method is used. The general problem of steady irrotational flow past an arbitrary body is formulated. Two examples were carried out, namely, the flow past a circular cylinder and the flow past a thin curved surface. The variational method yields results of velocity and pressure distributions which compare excellently with those found by existi… more
Date: March 1951
Creator: Wang, Chi-Teh
open access

Effect of Pressure on the Spontaneous Ignition Temperature of Liquid Fuels

Description: Report presenting an investigation of spontaneous ignition temperatures from 1 to 9 atmospheres in the air for n-heptane, isooctane, benzene, JP-4, and JP-5 fuels. Time lags before ignition were measured at each pressure for all fuels. Results regarding the effect of pressure, general comparisons of all fuels, and ignition-lag experiments are provided.
Date: October 1956
Creator: O'Neal, Cleveland, Jr.
open access

A Method for Studying the Transient Blade-Flapping Behavior of Lifting Rotors at Extreme Operating Conditions

Description: Note presenting a method for studying the transient behavior of the flapping motion, as well as for calculating the steady-state flapping amplitudes, of free-to-cone and seesaw rotors operating at extreme flight conditions. The method is general and can be applied to blades of any airfoil section, mass distribution, twist, plan-form taper, root cutout, and flapping-hinge geometry.
Date: January 1955
Creator: Gessow, Alfred & Crim, Almer D.
open access

The results of wind-tunnel tests to a Mach number of 0.90 of a four-engine, propeller-driven airplane configuration having a wing with 40 degrees of sweepback and an aspect ratio of 10

Description: Report presenting a wind-tunnel investigation to provide data for the study of the effects of operating propellers on the longitudinal characteristics of a four-engine tractor airplane configuration with a wing of 40 degrees of sweepback and an aspect ratio of 10. Coefficients of lift, longitudinal force, pitching moment, propeller thrust, and propeller power are presented in tabular form for various values of advance ratio at constant angles of attack.
Date: September 1956
Creator: Edwards, George G.; Dickson, Jerald K.; Sutton, Fred B. & Demele, Fred A.
open access

Experimental Investigation of the Strength of Multiweb Beams With Corrugated Webs

Description: "The results of an experimental investigation of the strength of multiweb beams with corrugated webs are reported. Included in the investigation were two types of connection between the web and the skin. A comparison between the structural efficiency of corrugated-web and channel-web multiweb beams is presented, and it is shown that, for a considerable range of the structural index, corrugated-web beams can be built which are structurally more efficient than channel-web beams" (p. 1).
Date: October 1956
Creator: Fraser, Allister F.
open access

An optimum switching criterion for a third-order contactor acceleration control system

Description: A switching criterion for optimum performance of a third-order contractor acceleration control system having complex roots is presented. Analytical and analog-computer methods are utilized to determine this criterion. The resulting optimum transient responses are presented and compared with those of an equivalent linear system.
Date: August 1956
Creator: Passera, Anthony L. & Willoh, Ross G., Jr.
open access

Tabulation of Mass-Flow Parameters for Use in Design of Turbomachine Blade Rows for Ratios of Specific Heats of 1.3 and 1.4

Description: Report presenting mass-flow tables for ratios of specific heats for the entire range of critical velocity ratio. The tables enable a quick and accurate determination of the integrated average specific mass flow across a region where the end-point velocities are known. A numerical example using the tables is also provided.
Date: October 1956
Creator: Whitney, Warren J.
open access

On possible similarity solutions for three-dimensional incompressible laminar boundary layers 2: similarity with respect to stationary polar coordinates

Description: From Summary: "Solutions of mainstream flow patterns for three-dimensional, laminar, incompressible thin-boundary-layer flows (over flat or slightly curved surfaces) having similarity with respect to stationary polar coordinates in the plane of the surface are derived. The solutions are summarized in a table."
Date: November 1956
Creator: Herzig, Howard Z. & Hansen, Arthur G.
open access

A Dynamic-Model Study of the Effect of Added Weights and Other Structural Variations on the Blade Bending Strains of an Experimental Two-Blade Jet-Driven Helicopter in Hovering and Forward Flight

Description: Report presenting an investigation of the blades of an experimental two-blade jet-driven helicopter when subject to a condition of near resonance between the frequencies of the first elastic bending mode of the blades and third harmonic component of the aerodynamic loading that results in high bending strains in normal flight conditions. Various changes in design configuration on the blade bending strains were explored. Results regarding the preliminary studies, effects of variation in flight c… more
Date: May 1955
Creator: McCarty, John Locke & Brooks, George W.
open access

Investigation of a related series of turbine-blade profiles in cascade

Description: Report presenting an application of airfoil design methods to a series of related turbine-blade profiles to satisfy the conditions of inlet flow angle and turning angle encountered in the usual range of turbine operation. Satisfactory flow conditions were obtained in all of the blade passages tested. Results regarding the turning angles, wake losses, surface pressure distributions, critical Mach numbers, application of compressibility corrections to low-speed tests, and selection of design camb… more
Date: October 1956
Creator: Dunavant, James C. & Erwin, John R.
open access

Supersonic flow past nonlifting bumped and indented bodies of revolution

Description: Linear-theory values of the supersonic pressure field and wave drag of nonlifting bumped and indented bodies of revolution are presented and compared with the corresponding properties of a smooth body. The comparisons indicate that relatively small surface irregularities cause large pressure disturbances and changes in wave drag. The interference drag produced by bumps and indentations is discussed and a correction for the curvature of the characteristics is applied.
Date: September 1956
Creator: McLean, F. Edward & Rennemann, Conrad, Jr.
open access

Investigation of Statistical Nature of Fatigue Properties

Description: Note presenting an experimental program to study the subject of metal fatigue and to determine and evaluate the fundamental factors which influence the behavior. The statistics of the fatigue-fracture curves and endurance limits were determined for a variety of metals and the effects of some metallurgical factors on the statistical nature of fatigue properties were shown.
Date: June 1952
Creator: Epremian, E. & Mehl, R. F.
open access

Stability Limits and Burning Velocities of Laminar Hydrogen-Air Flames at Reduced Pressure

Description: Note presenting laminar burning velocity measured at pressures of 1 atmosphere and below and critical boundary velocity gradient for flashback at pressures below 1 atmosphere over a range of compositions for hydrogen-air burner flames. Pressure exponents of 0.23 for burning velocity and 1.35 for flashback velocity gradient was found. Results regarding blowoff and general stability loop, burning velocity, relations among various combustion properties, and reaction order from pressure exponents a… more
Date: November 1956
Creator: Fine, Burton
open access

Determination of Ram-Jet Combustion-Chamber Temperatures by Means of Total-Pressure Surveys

Description: Note presenting a method by which the total temperature of the gases at the combustion-chamber outlet of a ramjet engine may be determined from the loss in total pressure measured across the combustion chamber. Values of total-temperature ratio across the combustion chamber of a 20-inch ram jet were obtained in the altitude wind tunnel over a range of pressure altitudes.
Date: December 1951
Creator: Pinkel, I. Irving
open access

Band-Pass Shock and Vibration Absorbers for Application to Aircraft Landing Gear

Description: Note presenting a description of a new class of frequency-selective shock absorbers called band-pass shock absorbers, which were conceived as a means of overcoming some of the limitations of conventional shock absorbers. The shock absorbers may be designed to isolate two bodies from each other over certain ranges of exciting frequencies or rates of load application while coupling them over the remainder of the frequency spectrum.
Date: October 1956
Creator: Schnitzer, Emanuel
open access

Studies of high-temperature protection of a titanium-carbide ceramal by chromium-type ceramic-metal coatings

Description: Report presenting an investigation to gain information concerning the durability of metallic coatings as affected by frit content, firing temperature, firing time, and number of coats. Four coatings of various frit content were prepared and applied to ceramals containing 80 percent chromium and 20 percent cobalt and heated at four different temperatures.
Date: June 1951
Creator: Moore, Dwight G.; Benner, Stanley G. & Harrison, William N.
open access

A General Theory of Three-Dimensional Flow in Subsonic and Supersonic Turbomachines of Axial-, Radial-, and Mixed-Flow Types

Description: Note presenting a general theory of steady three-dimensional flow of a nonviscous fluid in subsonic and supersonic turbomachines with arbitrary hub and casing shapes and a finite number of blades. The equations obtained to describe the fluid flow on these stream surfaces show clearly the several approximations involved in ordinary two-dimensional treatments.
Date: January 1952
Creator: Wu, Chung-Hua
open access

A velocity-correction formula for the calculation of transonic Mach number distributions over diamond-shaped airfoils

Description: Report presenting a velocity-correction formula for the purpose of calculating, from the known Mach number distribution for a diamond-shaped airfoil at a stream Mach number of 1.0, Mach number distributions on the same airfoil at speeds from a Mach number of about 0.8 to shock-attachment Mach number. An expression for the rate of change of local Mach number with stream Mach number is derived and an explicit equation for the drag coefficient as a function of stream Mach number and thickness rat… more
Date: November 1951
Creator: Ivey, H. Reese & Harder, Keith C.
open access

Effect of heat and power extraction on turbojet-engine performance 1: analytical method of performance evaluation with compressor-outlet air bleed

Description: Report presenting an analytical investigation of the performance of a turbojet engine with air bled off at the compressor outlet. A wide range of engine and flight conditions are covered and air bleeds of 0 to 15 percent of the air mass flow are considered. Results are provided in the form of generalized performance charts that are applicable to a wide range of operating conditions.
Date: March 1950
Creator: Hensley, Reece V.; Rom, Frank E. & Koutz, Stanley L.
open access

Stress and distortion measurements in a 45 degree swept box beam subjected to antisymmetrical bending and torsion

Description: Report presenting an untapered aluminum-alloy box beam representing the main structural component of a full-span, two-spar, 45 degree swept wing with a carry-through section subjected to antisymmetrical tip bending and twisting loads such that stresses were kept below the proportional limit. Results regarding stresses due to antisymmetrical bending, stresses due to antisymmetrical torsion, distortions due to antisymmetrical bending, and distortions due to antisymmetrical torsion are provided.
Date: April 1950
Creator: Zender, George W. & Heldenfels, Richard R.
open access

Tables of wing-aileron coefficients of oscillating air forces for two-dimensional supersonic flow

Description: Report presenting the wing-aileron coefficients of oscillating air forces for two-dimensional supersonic flow for a variety of Mach numbers. Various ratios of control-surface chord to airfoil chord are employed in the calculation and for each combination of chord ratio and Mach number, approximate 35 values of reduced frequency are utilized.
Date: March 1950
Creator: Huckel, Vera & Durling, Barbara J.
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