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A simplified theoretical method of determining the characteristics of a lifting rotor in forward flight

Description: Theoretical derived expressions for the flapping, the thrust, the torque, and the profile drag-lift ratio of nonfeathering rotor with hinged, rectangular, linearly twisted blades are given as simple functions of the inflow velocity and the blade pitch. Representative values of the coefficients of each of the terms in these expressions are tabulated for a series of specified values of the tip-speed ratio. Analysis indicates that the tabulated values can be used to calculate, with reasonable accuracy, the characteristics of any rotor of conventional design.
Date: March 17, 1941
Creator: Bailey, F. J., Jr.

Experimental and theoretical studies of area suction for the control of the laminar boundary layer on an NACA 64A010 airfoil

Description: From Summary: "A low-turbulence wind-tunnel investigation was made of an NACA 64A010 airfoil having a porous surface to determine the reduction in section total-drag coefficient that might be obtained at large Reynolds numbers by the use of suction to produce continuous inflow through the surface of the airfoil (area suction). In addition to the experimental investigation, a related theoretical analysis was made to provide a basis of comparison for the test results."
Date: March 30, 1951
Creator: Braslow, Albert L.; Burrows, Dale L.; Tetervin, Neal & Visconti, Fioravante

Temperature coefficient of the modulus of rigidity of aircraft instrument diaphragm and spring materials

Description: Experimental data are presented on the variation of the modulus of rigidity in the temperature range -20 to +50 degrees C. of a number of metals which are of possible use for elastic elements for aircraft and other instruments. The methods of the torsional pendulum was used to determine the modulus of rigidity and its temperature coefficient for aluminum, duralumin, monel metal, brass, phosphor bronze, coin silver, nickel silver, three high carbon steels, and three alloy steels. It was observed that tensile stress affected the values of the modulus by amounts of 1 per cent or less.
Date: March 7, 1930
Creator: Brombacher, W. G. & Melton, E. R.

Flight investigation of the effect of control centering springs on the apparent spiral stability of a personal-owner airplane

Description: Report presents the results of a flight investigation conducted on a typical high-wing personal-owner airplane to determine the effect of control centering springs on apparent spiral stability. Apparent spiral stability is the term used to describe the spiraling tendencies of an airplane in uncontrolled flight as affected both by the true spiral stability of the perfectly trimmed airplane and by out-of-trim control settings. Centering springs were used in both the aileron and rudder control systems to provide both a positive centering action and a means of trimming the airplane.
Date: March 22, 1951
Creator: Campbell, John P.; Hunter, Paul A.; Hewes, Donald E. & Whitten, James B.

Pressure-sensitive system for gas-temperature control

Description: From Summary: "A thermodynamic relation is derived and simplified for use as a temperature-limiting control equation involving measurement of gas temperature before combustion and gas pressures before and after combustion. For critical flow in the turbine nozzles of gas-turbine engines, the control equation is further simplified to require only measurements upstream of the burner. Hypothetical control systems are discussed to illustrate application of the control equations."
Date: March 4, 1948
Creator: Cesaro, Richard S. & Matz, Norman

A study of the characteristics of human-pilot control response to simulated aircraft lateral motions

Description: Report presents the results of studies made in an attempt to provide information on the control operations of the human pilot. These studies included an investigation of the ability of pilots to control simulated unstable yawing oscillations, a study of the basic characteristics of human-pilot control response, and a study to determine whether and to what extent pilot control response can be represented in an analytical form.
Date: March 14, 1952
Creator: Cheatham, Donald C.

Effect of combustor-inlet conditions on performance of an annular turbojet combustor

Description: From Summary: "The combustion performance, and particularly the phenomenon of altitude operational limits, was studied by operating the annular combustor of a turbojet engine over a range of conditions of air flow, inlet pressure, inlet temperature, and fuel flow. Information was obtained on the combustion efficiencies, the effect on combustion of inlet variables, the altitude operational limits with two different fuels, the pressure losses in the combustor, the temperature and velocity profiles at the combustor outlet, the extent of afterburning, the fuel-injection characteristics, and the condition of the combustor basket."
Date: March 21, 1947
Creator: Childs, J. Howard; McCafferty, Richard J. & Surine, Oakley W.

Application of Theodorsen's theory to propeller design

Description: A theoretical analysis is presented for obtaining, by use of Theodorsen's propeller theory, the load distribution along a propeller radius to give the optimum propeller efficiency for any design condition. The efficiencies realized by designing for the optimum load distribution are given in graphs, and the optimum efficiency for any design condition may be read directly from the graph without any laborious calculations. Examples are included to illustrate the method of obtaining the optimum load distributions for both single-rotating and dual-rotating propellers.
Date: March 15, 1948
Creator: Crigler, John L.

Comparison of several methods for obtaining the time response of linear systems to either a unit impulse or arbitrary input from frequency-response data

Description: From Summary: "Several methods of obtaining the time response of Linear systems to either a unit impulse or an arbitrary input from frequency-response data are described and compared. Comparisons indicate that all the methods give good accuracy when applied to a second-order system; the main difference is the required computing time. The methods generally classified as inverse Laplace transform methods were found to be most effective in determining the response to a unit impulse from frequency-response data of higher order systems. Some discussion and examples are given of the use of such methods as flight-data-analysis techniques in predicting loads and motions of a flexible aircraft on the basis of simple calculations when the aircraft frequency response is known."
Date: March 16, 1956
Creator: Donegan, James J. & Huss, Carl R.

Air flow in the boundary layer near a plate

Description: From Summary: "The published data on the distribution of speed near a thin flat plate with sharp leading edge placed parallel to the flow (skin friction plate) are reviewed and the results of some additional measurements are described. The purpose of the experiments was to study the basic phenomena of boundary-layer flow under simple conditions."
Date: March 1936
Creator: Dryden, Hugh L.

Method for calculation of laminar heat transfer in air flow around cylinders of arbitrary cross section (including large temperature differences and transpiration cooling)

Description: "The solution of heat-transfer problems has become vital for many aeronautical applications. The shapes of objects to be cooled can often be approximated by cylinders of various cross sections with flow normal to the axis as, for instance heat transfer on gas-turbine blades and on air foils heated for deicing purposes. A laminar region always exists near the stagnation point of such objects. A method previously presented by E. R. G. Eckert permits the calculation of local heat transfer around the periphery of cylinders of arbitrary cross section in the laminar region for flow of a fluid with constant property values with an accuracy sufficient for engineering purposes" (p. 223).
Date: March 19, 1952
Creator: Eckert, E. R. & Livingood, John N. B.

On some reciprocal relations in the theory of nonstationary flows

Description: In the theory of nonstationary flows about airfoils, the "indicial lift" function ksub1(s) of Wagner and the "alternating lift" function c(k) of Theodorsen have fundamental significance. This paper reports on some interesting relations of the nature of Fourier transforms that exist between these functions. General problems in transient flows about airfoils may be given a unified broad treatment when these functions are employed. Certain approximate results also are reported which are of notable simplicity, and an analogy with transient electrical flows is drawn.
Date: March 28, 1938
Creator: Garrick, I. E.

The prediction of airfoil characteristics

Description: This report describes and develops methods by which the aerodynamic characteristics of an airfoil may be calculated with sufficient accuracy for use in airplane design. These methods for prediction are based on the present aerodynamic theory and on empirical formulas derived from data obtained in the N. A. C. A. variable density wind tunnel at a Reynolds number corresponding approximately to full scale. (author).
Date: March 14, 1928
Creator: Higgins, George J.

Effects of temperature distribution and elastic properties of materials on gas-turbine-disk stresses

Description: From Summary: "Calculations were made to determine the influence of changes in temperature distribution and in elastic material properties on calculated elastic stresses for a typical gas-turbine disk. Severe temperature gradients caused thermal stresses of sufficient magnitude to reduce the operating safety of the disk. Small temperature gradients were found to be desirable because they produced thermal stresses that subtracted from the centrifugal stresses in the region of the rim."
Date: March 29, 1947
Creator: Holms, Arthur G. & Faldetta, Richard D.

Structural response to discrete and continuous gusts of an airplane having wing bending flexibility and a correlation of calculated and flight results

Description: "An analysis is made of the structural response to gusts of an airplane having the degrees of freedom of vertical motion and wing bending flexibility and basic parameters are established. A convenient and accurate numerical solution of the response equations is developed for the case of discrete-gust encounter, an exact solution is made for the simpler case of continuous-sinusoidal-gust encounter, and the procedure is outlined for treating the more realistic condition of continuous random atmospheric turbulence, based on the methods of generalized harmonic analysis. Correlation studies between flight and calculated results are then given to evaluate the influence of wing bending flexibility on the structural response to gusts of two twin-engine transports and one four-engine bomber" (p. 1).
Date: March 4, 1954
Creator: Houbolt, John C. & Kordes, Eldon E.

Investigation of damping liquids for aircraft instruments 2

Description: "Data are presented on the kinematic viscosity, in the temperature range -50 degrees to +30 degrees C. of pure liquids and of solutions of animal oils, vegetable oils, mineral oils, glycerine, and ethylene glycol in various low freezing point solvents. It is shown that the thermal coefficient of kinematic viscosity as a function of the kinematic viscosity of the solutions of glycerine and ethylene glycol in alcohols is practically independent of the temperature and the chemical composition of the individual liquids. This is similarly true for the mineral oil group and, for a limited temperature interval, for the pure animal and vegetable oils. The efficiency of naphthol, hydroquinone, and diphenylamine to inhibit the change of viscosity of poppyseed and linseed oils was also investigated" (p. 679).
Date: March 28, 1931
Creator: Houseman, M. R. & Keulegan, G. H.

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" (p. 273).
Date: March 4, 1940
Creator: Imlay, Frederick H.

Span-load distribution as a factor in stability in roll

Description: "This report gives the results of pressure-distribution tests made to study the effects on lateral stability of changing the span-load distribution on a rectangular monoplane wing model of fairly thick section. Three methods of changing the distribution were employed: variation in profile along the span to a thin symmetrical section at the tip, twist from +5 degrees to -15 degrees at the tip, and sweepback from +20 degrees to -20 degrees. The tests were conducted in a 5-foot closed-throat atmospheric wind tunnel" (p. 567).
Date: March 4, 1931
Creator: Knight, Montgomery & Noyes, Richard W.

Theoretical analysis of incompressible flow through a radial-inlet centrifugal impeller at various weight flows

Description: A method for the solution of the incompressible nonviscous flow through a centrifugal impeller, including the inlet region, is presented. Several numerical solutions are obtained for four weight flows through an impeller at one operating speed. These solutions are refined in the leading-edge region. The results are presented in a series of figures showing streamlines and relative velocity contours. A comparison is made with the results obtained by using a rapid approximate method of analysis.
Date: March 4, 1955
Creator: Kramer, James J.; Prian, Vasily D. & Wu, Chung-Hua

Analysis of spanwise temperature distribution in three types of air-cooled turbine blade

Description: From Summary: An approximate method for determining the allowable stress-limited blade-temperature distribution is included, with brief accounts of a method for determining the maximum allowable effective gas temperatures and the cooling-air requirements. Numerical examples that illustrate the use of the various temperature-distribution equations and of the nondimensional charts are also included.
Date: March 1, 1950
Creator: Livingood, John N. B. & Brown, W. Byron

Investigations at supersonic speeds of 22 triangular wings representing two airfoil sections for each of 11 apex angles

Description: The results of tests of 22 triangular wings, representing two leading-edge shapes for each of 11 apex angles, at Mach numbers 1.62, 1.92, and 1.40 are presented and compared with theory. All wings have a common thickness ratio of 8 percent and a common maximum-thickness point at 18 percent chord. Lift, drag, and pitching moment are given for all wings at each Mach number. The relation of transition in the boundary layer, shocks on the wing surfaces, and characteristics of the pressure distributions is discussed for several wings.
Date: March 30, 1949
Creator: Love, Eugene S.

Critical Compressive Stress for Flat Rectangular Plates Supported Along All Edges and Elastically Restrained Against Rotation along the Unloaded Edges

Description: A chart is presented for the values of the coefficient in the formula for the critical compressive stress at which buckling may be expected to occur in flat rectangular plates supported along all edges and, in addition, elastically restrained against rotation along the unloaded edges. The mathematical derivations of the formulas required in the construction of the chart are given.
Date: March 8, 1941
Creator: Lundquist, Eugene E. & Stowell, Elbridge Z.

Critical Compressive Stress for Outstanding Flanges

Description: A chart is presented for the values of the coefficient in the formula for the critical compressive stress at which buckling may be expected to occur in outstanding flanges. These flanges are flat rectangular plates supported along the loaded edges, supported and elastically restrained along one unloaded edge, and free along the other unloaded edge. The mathematical derivations of the formulas required for construction of the chart are given.
Date: March 14, 1941
Creator: Lundquist, Eugene E. & Stowell, Elbridge Z.