Technical Report Archive and Image Library (TRAIL) - 38 Matching Results

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Accuracy of Airspeed Measurements and Flight Calibration Procedures

Description: From Summary: "The sources of error that may enter into the measurement of airspeed by pitot-static methods are reviewed in detail together with methods of flight calibration of airspeed installations. Special attention is given to the problem of accurate measurements of airspeed under conditions of high speed and maneuverability required of military airplanes." (author).
Date: 1948
Creator: Huston, Wilber B.
Partner: UNT Libraries Government Documents Department

Determination of Stresses in Gas-turbine Disks Subjected to Plastic Flow and Creep

Description: From Summary: "A finite-difference method previously presented for computing elastic stresses in rotating disks is extended to include the computation of the disk stresses when plastic flow and creep are considered. A finite-difference method is employed to eliminate numerical integration and to permit nontechnical personnel to make the calculations with a minimum of engineering supervision. Illustrative examples are included to facilitated explanation of the procedure by carrying out the computations on a typical gas-turbine disk through a complete running cycle."
Date: 1948
Creator: Millenson, M. B. & Manson, S. S.
Partner: UNT Libraries Government Documents Department

Effect of centrifugal force on the elastic curve of a vibrating cantilever beam

Description: From Summary: "A study was made to determine the effect of rotation on the dynamic-stress distribution in vibrating cantilever beams. The results of a mathematical analysis are presented together with experimental results obtained by means of stroboscopic photographs and strain gages. The theoretical analysis was confined to uniform cantilever beams; the experimental work was extended to include a tapered cantilever beam to simulate an aircraft propeller blade. Calculations were made on nondimensional basis for second and third mode vibration; the experiments were conducted on beams of various lengths, materials, and cross sections for second-mode vibration."
Date: 1948
Creator: Simpkinson, Scott H.; Eatherton, Laurel J. & Millenson, Morton B.
Partner: UNT Libraries Government Documents Department

Experiments on Stability of Bunsen-Burner Flames for Turbulent Flow

Description: "The results of a study of the stability of propane-air flames on bunsen-burner tubes are presented. Fuel-air ratio, tube diameter, and Reynolds number were the primary variables. Regions of stability are outlined in plots of fuel-air ratio as a function of Reynolds number for flames seated on the burner lip and for flames suspended well above the burner" (p. 1).
Date: 1948
Creator: Bollinger, Lowell M. & Williams, David T.
Partner: UNT Libraries Government Documents Department

Full-scale investigation of aerodynamic characteristics of a typical single-rotor helicopter in forward flight

Description: From Summary: "As part of the general helicopter research program being undertaken by the National Advisory Committee for Aeronautics to provide designers with fundamental rotor information, the forward-flight performance characteristics of a typical single-rotor helicopter, which is equipped with main and tail rotors, have been investigated in the Langley full-scale tunnel. The test conditions included operation of tip-speed ratios from 0.10 to 0.27 and at thrust coefficients from 0.0030 to 0.0060. Results obtained with production rotor were compared with those for an alternate set of blades having closer rib spacing and a smoother and more accurately contoured surface in order to evaluate the performance gains that are available by the use of rotor blades having an improved surface condition."
Date: 1948
Creator: Dingeldein, Richard C. & Schaefer, Raymond F.
Partner: UNT Libraries Government Documents Department

Knocking combustion observed in a spark-ignition engine with simultaneous direct and Schlieren high-speed motion pictures and pressure records

Description: Simultaneous direct and Schlieren photographs at 40,000 frames per second and correlated pressure records were taken of knocking combustion in a special spark-ignition engine to ascertain the intensity of certain end-zone reactions previously noted from Schlieren photography alone. A violent propagated homogeneous autoignition, or a similar phenomenon, previously observed, was again observed. The pressure records show autoignition of varying violence before the passage of a probable detonation wave. Extensive autoignition without occurrence of gas vibrations was seen in one explosion.
Date: 1948
Creator: Osterstrom, Gordon E.
Partner: UNT Libraries Government Documents Department

Lifting-Surface-Theory Aspect-Ratio Corrections to the Lift and Hinge-Moment Parameters for Full-Span Elevators on Horizontal Tail Surfaces

Description: A limited number of lifting-surface-theory solutions for wings with chordwise loadings resulting from angle of attack, parabolic-ac camber, and flap deflection are now available. These solutions were studied with the purpose of determining methods of extrapolating the results in such a way that they could be used to determine lifting-surface-theory values of the aspect-ratio corrections to the lift and hinge-moment parameters for both angle-of-attack and flap-deflection-type loading that could be used to predict the characteristics of horizontal tail surfaces from section data with sufficient accuracy for engineering purposes. Such a method was devised for horizontal tail surfaces with full-span elevators. In spite of the fact that the theory involved is rather complex, the method is simple to apply and may be applied without any knowledge of lifting-surface theory. A comparison of experimental finite-span and section value and of the estimated values of the lift and hinge-moment parameters for three horizontal tail surfaces was made to provide an experimental verification of the method suggested. (author).
Date: January 1, 1948
Creator: Crandall, Stewart M. & Swanson, Robert S.
Partner: UNT Libraries Government Documents Department

Summary of Drag Characteristics of Practical-Construction Wing Sections

Description: The effect of several parameters on the drag characteristics of practical-construction wing sections have been considered and evaluated. The effects considered were those of surface roughness, surface waviness, compressive load, and de-icers. The data were obtained from a number of tests in the Langley two-dimensional low-turbulence tunnels.
Date: January 1, 1948
Creator: Quinn, John H., Jr.
Partner: UNT Libraries Government Documents Department

Theoretical and experimental data for a number of NACA 6A-series airfoil sections

Description: The NACA 6a-series airfoil sections were designed to eliminate the trailing-edge cusp which is characteristic of the NACA 6a-series sections. Theoretical data are presented for NACA 6a-series basic thickness forms having the position of minimum pressure of 30, 40, and 50 percent chord and with thickness ratios varying from 6 percent to 15 percent. Also presented are data for a mean line designed to maintain straight sides on the cambered sections.
Date: 1948
Creator: Loftin, Laurence K., Jr.
Partner: UNT Libraries Government Documents Department

Theoretical symmetric span loading at subsonic speeds for wings having arbitrary plan form

Description: From Summary: "A method is shown by which the symmetric span loading for a certain class of wings can be simply found. The geometry of these wings is limited only to the extent that they must have symmetry about the root chord, must have a straight quarter-chord line over the semispan, and must have no discontinuities in twist. A procedure is shown for finding the lift-curve slope, pitching moment, center of lift, and induced drag from the span load distribution. A method of accounting for the effects of Mach number and for changes in section lift-curve slope is also given."
Date: 1948
Creator: DeYoung, John & Harper, Charles W.
Partner: UNT Libraries Government Documents Department

The use of source-sink and doublet distributions extended to the solution of boundary-value problems in supersonic flow

Description: "A direct analogy is established between the use of source-sink and doublet distributions in the solution of specific boundary-value problems in subsonic wing theory and the corresponding problems in supersonic theory. The correct concept of the "finite part" of an integral is introduced and used in the calculation of the improper integrals associated with supersonic doublet distributions. The general equations developed are shown to include several previously published results and particular examples are given for the loading on rolling and pitching triangular wings with supersonic leading edges" (p. 157).
Date: January 1948
Creator: Heaslet, Max A. & Lomax, Harvard
Partner: UNT Libraries Government Documents Department

Analysis of variation of piston temperature with piston dimensions and undercrown cooling

Description: From Summary: "A theoretical analysis is presented that permits estimation of the changes in piston-temperature distribution induced by variations in the crown thickness, the ring-groove-pad thickness, and the undercrown surface heat-transfer coefficient. The analysis consists of the calculation of operating temperatures at various points in the piston body on the basis of the experimentally determined surface heat-transfer coefficients and boundary-region temperatures, as well as arbitrarily selected surface coefficients."
Date: January 15, 1948
Creator: Sanders, J. C. & Schramm, W. B.
Partner: UNT Libraries Government Documents Department

Sound-Level Measurements of a Light Airplane Modified to Reduce Noise Reaching the Ground

Description: "An Army liaison-type airplane, representative of personal airplanes in the 150 to 200 horsepower class, has been modified to reduce propeller and engine noise according to known principles of airplane-noise reduction. Noise-level measurements demonstrate that, with reference to an observer on the ground, a noisy airplane of this class can be made quiet -- perhaps more quiet than necessary. In order to avoid extreme and unnecessary modifications, acceptable noise levels must be determined" (p. 115).
Date: February 12, 1948
Creator: Vogeley, A. W.
Partner: UNT Libraries Government Documents Department

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
Partner: UNT Libraries Government Documents Department

Determination of stresses in gas-turbine disks subjected to plastic flow and creep

Description: A finite-difference method previously presented for computing elastic stresses in rotating disks is extended to include the computation of the disk stresses when plastic flow and creep are considered. A finite-difference method is employed to eliminate numerical integration and to permit nontechnical personnel to make the calculations with a minimum of engineering supervision. Illustrative examples are included to facilitate explanation of the procedure by carrying out the computations on a typical gas-turbine disk through a complete running cycle. The results of the numerical examples presented indicate that plastic flow markedly alters the elastic-stress distribution.
Date: March 5, 1948
Creator: Millenson, M. B. & Manson, S. S.
Partner: UNT Libraries Government Documents Department

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.
Partner: UNT Libraries Government Documents Department

Appreciation and Prediction of Flying Qualities

Description: "The material given in this report summarizes some of the results of recent research that will aid the designers of an airplane in selecting or modifying a configuration to provide satisfactory stability and control characteristics. The requirements of the NACA for satisfactory flying qualities, which specify the important stability and control characteristics of an airplane from the pilot's standpoint, are used as the main topics of the report. A discussion is given of the reasons for the requirements, of the factors involved in obtaining satisfactory flying qualities, and of the methods used in predicting the stability and control characteristics of an airplane" (p. 1).
Date: April 12, 1948
Creator: Phillips, William H.
Partner: UNT Libraries Government Documents Department

Aerodynamic characteristics at high speeds of related full-scale propellers having different blade-section cambers

Description: From Summary: "Wind-tunnel tests of a full-scale two-blade NACA 10-(10)(08)-03 (high camber) propeller have been made for a range of blade angles from 20 degrees to 55 degrees at airspeeds up to 500 miles per hour. The results of these tests have been compared with results from previous tests of the NACA 10-(3) (08)-03 (low camber) and NACA 10-(5)(08)-03 (medium camber) propellers to evaluate the effects of blade-section camber on propeller aerodynamic characteristics."
Date: May 6, 1948
Creator: Maynard, Julian D. & Salters, Leland B., Jr.
Partner: UNT Libraries Government Documents Department

On the Theory of Oscillating Airfoils of Finite Span in Subsonic Compressible Flow

Description: "The problem of oscillating lifting surface of finite span in subsonic compressible flow is reduced to an integral equation. The kernel of the integral equation is approximated by a simpler expression, on the basis of the assumption of sufficiently large aspect ratio. With this approximation the double integral occurring in the formulation of the problem is reduced to two single integrals, one of which is taken over the chord and the other over the span of the lifting surface" (p. 969).
Date: May 18, 1948
Creator: Reissner, Eric
Partner: UNT Libraries Government Documents Department

Equations for the Design of Two-Dimensional Supersonic Nozzles

Description: "Equations are presented for obtaining the wall coordinates of two-dimensional supersonic nozzles. The equations are based on the application of the method of characteristics to irrotational flow of perfect gases in channels. Curves and tables are included for obtaining the parameters required by the equations for the wall coordinates. A brief discussion of characteristics as applied to nozzle design is given to assist in understanding and using the nozzle-design method of this report. A sample design is shown" (p. 1).
Date: June 1, 1948
Creator: Pinkel, I. Irving
Partner: UNT Libraries Government Documents Department

Analysis of Performance of Jet Engine From Characteristics of Components 2: Interaction of Components as Determined From Engine Operation

Description: "In order to understand the operation and the interaction of jet-engine components during engine operation and to determine how component characteristics may be used to compute engine performance, a method to analyze and to estimate performance of such engines was devised and applied to the study of the characteristics of a research turbojet engine built for this investigation. An attempt was made to correlate turbine performance obtained from engine experiments with that obtained by the simpler procedure of separately calibrating the turbine with cold air as a driving fluid in order to investigate the applicability of component calibration. The system of analysis was also applied to prediction of the engine and component performance with assumed modifications of the burner and bearing characteristics, to prediction of component and engine operation during engine acceleration, and to estimates of the performance of the engine and the components when the exhaust gas was used to drive a power turbine" (p. 1).
Date: June 2, 1948
Creator: Goldstein, Arthur W.; Alpert, Sumner; Beede, William & Kovach, Karl
Partner: UNT Libraries Government Documents Department

Stability derivatives at supersonic speeds of thin rectangular wings with diagonals ahead of tip Mach lines

Description: The investigation includes steady and accelerated vertical and longitudinal motions and steady rolling, yawing, sideslipping, and pitching for Mach numbers and aspect ratios greater than those for which the Mach line from the leading edge of the tip section intersects the trailing edge of the opposite tip section. The stability derivatives are derived with respect to principal body axes and then transformed to a system of stability axes. Theoretical results are obtained, by means of the linearized theory, for the surface-velocity-potential functions, surface-pressure distributions, and stability derivatives for various motions at supersonic speeds of thin flat rectangular wings without dihedral.
Date: June 30, 1948
Creator: Harmon, Sidney M.
Partner: UNT Libraries Government Documents Department

Prediction of the Effects of Propeller Operation on the Static Longitudinal Stability of Single-Engine Tractor Monoplanes with Flaps Retracted

Description: "The effects of propeller operation on the static longitudinal stability of single-engine tractor monoplanes are analyzed, and a simple method is presented for computing power-on pitching-moment curves for flap-retracted flight conditions. The methods evolved are based on the results of powered-model wind-tunnel investigations of 28 model configurations. Correlation curves are presented from which the effects of power on the downwash over the tail and the stabilizer effectiveness can be rapidly predicted" (p. 399).
Date: July 13, 1948
Creator: Weil, Joseph & Sleeman, William C., Jr.
Partner: UNT Libraries Government Documents Department

Correlation of cylinder-head temperatures and coolant heat rejections of a multicylinder, liquid-cooled engine of 1710-cubic-inch displacement

Description: "Data obtained from an extensive investigation of the cooling characteristics of four multicylinder, liquid-cooled engines have been analyzed and a correlation of both the cylinder-head temperatures and the coolant heat rejections with the primary engine and coolant variables was obtained. The method of correlation was previously developed by the NACA from an analysis of the cooling processes involved in a liquid-cooled-engine cylinder and is based on the theory of nonboiling, forced-convection heat transfer. The data correlated included engine power outputs from 275 to 1860 brake horsepower; coolant flows from 50 to 320 gallons per minute; coolants varying in composition from 100 percent water to 97 percent ethylene glycol and 3 percent water; and ranges of engine speed, manifold pressure, carburetor-air temperature, fuel-air ratio, exhaust-gas pressure, ignition timing, and coolant temperature" (p. 207).
Date: August 31, 1948
Creator: Lundin, Bruce T.; Povolny, John H. & Chelko, Louis J.
Partner: UNT Libraries Government Documents Department