Technical Report Archive and Image Library (TRAIL) - 32 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

Correlation of the drag characteristics of a typical pursuit airplane obtained from high-speed wind-tunnel and flight tests

Description: In order to obtain a correlation of drag data from wind-tunnel and flight tests at high Mach numbers, a typical pursuit airplane, with the propeller removed, was tested in flight at Mach numbers up to 0.755, and the results were compared with wind-tunnel tests of a 1/3-scale model of the airplane. The tests results show that the drag characteristics of the test airplane can be predicted with satisfactory accuracy from tests in the Ames 16-foot high-speed wind tunnel of the Ames Aeronautical Laboratory at both high and low Mach numbers. It is considered that this result is not unique with the airplane.
Date: January 1, 1948
Creator: Nissen, James M; Gadebero, Burnett L & Hamilton, William T
Partner: UNT Libraries Government Documents Department

Damping in pitch and roll of triangular wings at supersonic speeds

Description: A method is derived for calculating the damping coefficients in pitch and roll for a series of triangular wings and a restricted series of sweptback wings at supersonic speeds. The elementary "supersonic source" solution of the linearized equation of motion is used to find the potential function of a line of doublets, and the flows are obtained by surface distributions of these doublet lines. The damping derivatives for triangular wings are found to be a function of the ratio of the tangent of the apex angle to the tangent of the Mach angle. As this ratio becomes equal to and greater than 1.0 for triangular wings, the damping derivatives, in pitch and in roll, become constant. The damping derivative in roll becomes equal to one-half the value calculated for an infinite rectangular wing, and the damping derivative in pitch for pitching about the apex becomes equal to 3.375 times that of an infinite rectangular wing.
Date: January 1, 1948
Creator: Brown, Clinton E & Adams, Mac C
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: January 1, 1948
Creator: Millenson, M B & Manson, S S
Partner: UNT Libraries Government Documents Department

The development and application of high-critical-speed nose inlets

Description: An analysis of the nose-inlet shapes developed in previous investigations to represent the optimum from the standpoint of critical speed has shown that marked similarity exists between the nondimensional profiles of inlets which have widely different proportions and critical speeds. With the nondimensional similarity of such profiles established, the large differences in the critical speeds of these nose inlets must be a function of their proportions. An investigation was undertaken in the Langley 8-foot high-speed tunnel to establish the effects of nose-inlet proportions on critical Mach number to develop a rational method for the design of high-critical-speed nose inlets to meet desired requirements. The test results data have been arranged in the form of design charts from NACA 1-series nose-inlet proportions and can be selected for given values of critical Mach number and airflow quantity. Examples of nose-inlet selections are presented for a typical jet-propulsion installation (critical Mach number of 0.83) and for two conventional radial-engine installations (critical Mach number of 0.76).
Date: January 1, 1948
Creator: Baals, Donald D; Smith, Norman F & Wright, John B
Partner: UNT Libraries Government Documents Department

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

Description: 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. From this investigation it was concluded that high vibratory-stress positions are unaffected by the addition of centrifugal force. Nonrotating vibration surveys of blades therefore are valuable in predicting high vibratory-stress locations under operating conditions.
Date: January 1, 1948
Creator: Simpkinson, Scott H; Eatherton, Laurel J & Millenson, Morton B
Partner: UNT Libraries Government Documents Department

The effects of aerodynamic heating and heat transfer on the surface temperature of a body of revolution in steady supersonic flight

Description: An approximate method for determining the convective cooling requirement in the laminar boundary-layer region of a body of revolution in high-speed flight was developed and applied to an example body. The cooling requirement for the example body was determined as a function of Mach number, altitude, size, and a surface-temperature parameter. The maximum value of Mach number considered was 3.0 and the altitudes considered were those within the lower constant-temperature region of the atmosphere (40,000 to 120,000 ft.). The extent of the laminar boundary layer was determined approximately at each condition as a function of the variables considered.
Date: January 1, 1948
Creator: Scherrer, Richard
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.
Date: January 1, 1948
Creator: Pinkel, I Irving
Partner: UNT Libraries Government Documents Department

Estimation of F-3 and F-4 knock-limited performance ratings for ternary and quaternary blends containing triptane or other high-antiknock aviation-fuel blending agents

Description: Charts are presented that permit the estimation of F-3 and F-4 knock-limited performance ratings for certain ternary and quaternary fuel blends. Ratings for various ternary and quaternary blends estimated from these charts compare favorably with experimental F-3 and F-4 ratings. Because of the unusual behavior of some of the aromatic blends in the F-3 engine, the charts for aromatic-paraffinic blends are probably less accurate than the charts for purely paraffinic blends.
Date: January 1, 1948
Creator: Barnett, Henry C
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. For fully developed flow, turbulent as well as laminar, the velocity gradient at the burner wall is a satisfactory variable for correlating the fuel-air ratio required for blow-off of seated flames for fuel-air ratios of less than 15 percent. For turbulent flames, wall velocity serves as a correlating variable in the same fuel-air-ratio range. (author).
Date: January 1, 1948
Creator: Bollinger, Lowell M & Williams, David T
Partner: UNT Libraries Government Documents Department

Extension of Useful Operating Range of Axial-Flow Compressors by Use of Adjustable Stator Blades

Description: A theory has been developed for resetting the blade angles of an axial-flow compressor in order to improve the performance at speeds and flows other than the design and thus extend the useful operating range of the compressor. The theory is readily applicable to the resetting of both rotor and stator blades or to the resetting of only the stator blades and is based on adjustment of the blade angles to obtain lift coefficients at which the blades will operate efficiently. Calculations were made for resetting the stator blades of the NACA eight-stage axial-flow compressor for 75 percent of design speed and a series of load coefficients ranging from 0.28 to 0.70 with rotor blades left at the design setting. The NACA compressor was investigated with three different blade settings: (1) the design blade setting, (2) the stator blades reset for 75 percent of design speed and a load coefficient of 0.48, and (3) the stator blades reset for 75 percent of design speed and a load coefficient of 0.65.
Date: January 1, 1948
Creator: Sinnette, John T & Voss, William J
Partner: UNT Libraries Government Documents Department

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

Description: 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. The wind tunnel results are shown to be in fair agreement with the results of both flight tests and theoretical predictions.
Date: January 1, 1948
Creator: Dingeldein, Richard C & Schaefer, Raymond F
Partner: UNT Libraries Government Documents Department

A general small-deflection theory for flat sandwich plates

Description: A small-deflection theory is developed for the elastic behavior of orthotropic flat plates in which deflections due to shear are taken into account. In this theory, which covers all types of flat sandwich construction, a plate is characterized by seven physical constants (five stiffnesses and two Poisson ratios) of which six are independent. Both the energy expression and the differential equations are developed. Boundary conditions corresponding to simply supported, clamped, and elastically restrained edges are considered.
Date: January 1, 1948
Creator: Libove, Charles & Batdorf, S B
Partner: UNT Libraries Government Documents Department

The interdependence of various types of autoignition and knock

Description: A study of the relations existing among pin-point autoignition, homogeneous autoignition, and knock has been made by means of the NACA high-speed camera and the full-view combustion apparatus. High-speed photographic records of combustion, together with corresponding pressure-time traces, of benzene, 2,2,3-trimethylbutane, S-4, and M-4 fuels at various engine conditions have shown the engine conditions under which each of these phenomena occur and the relation of these phenomena to one another.
Date: January 1, 1948
Creator: Olsen, H Lowell & Miller, Cearcy D
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: January 1, 1948
Creator: Osterstrom, Gordon E
Partner: UNT Libraries Government Documents Department

Laminar-boundary-layer oscillations and transition on a flat plate

Description: This is an account of an investigation in which oscillations were discovered in the laminar boundary layer along a flat plate. These oscillations were found during the course of an experiment in which transition from laminar to turbulent flow was being studied on the plate as the turbulence in the wind stream was being reduced to unusually low values by means of damping screens. The first part of the paper deals with experimental methods and apparatus, measurements of turbulence and sound, and studies of transition. A description is then given of the manner in which oscillations were discovered and how they were found to be related to transition, and then how controlled oscillations were produced and studied in detail.
Date: January 1, 1948
Creator: Schubauer, G B & Skramstad, H K
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

On similarity rules for transonic flows

Description: A method used by Tsien to derive similarity rules for hypersonic flows is utilized to derive Von Karman's similarity rules for transonic flows. At the lower limit of the transonic region of flow the theory yields a formula for the critical stream Mach numbers of a given family of symmetrical profiles. It is further shown that this formula can also be obtained by means of the Prandtl-Glauert small-perturbation method. Investigation of the behavior of the similarity parameter in the region where the thickness coefficient approaches zero and the critical stream Mach number approaches unity shows that it possesses a limiting value characteristic of the prescribed family of shapes.
Date: January 1, 1948
Creator: Kaplan, Carl
Partner: UNT Libraries Government Documents Department

Pressure-sensitive system for gas-temperature control

Description: 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: January 1, 1948
Creator: Cesaro, Richard S & Matz, Norman
Partner: UNT Libraries Government Documents Department

Stability derivatives of triangular wings at supersonic speeds

Description: The analysis of the stability derivatives of low-aspect-ratio triangular wings at subsonic and supersonic speeds, given in NACA TN no. 1423, is extended to apply to triangular wings having large vertex angles and traveling at supersonic speeds. The lift, rolling moment due to sideslip, and damping in roll and pitch for this more general case have been treated elsewhere on the basis of the theory of small disturbances. The surface potentials for angle of attack and rolling taken therefrom are used to obtain the several side-force and yawing-moment derivatives that depend on leading-edge suction, and a tentative value for the rolling moment due to yawing. The lift and moment due to downward acceleration are obtained on the basis of an unpublished unsteady-flow solution. All the known stability derivatives of the triangular wing at supersonic speeds, regardless of source, are summarized for convenience and presented with respect to both body axes and stability axes. The results are limited to Mach numbers for which the triangular wing is contained within the Mach cone for its vertex. The spanwise variation of Mach number in the case of yawing is neglected, although the effect must be of importance.
Date: January 1, 1948
Creator: Ribner, Herbert S & Malvestuto, Frank S , Jr
Partner: UNT Libraries Government Documents Department

Subsonic flow over thin oblique airfoils at zero lift

Description: A previous report gave calculations for the pressure distribution over thin oblique airfoils at supersonic speed. The present report extends the calculations to subsonic speeds. It is found that the flows again can be obtained by the superposition of elementary conical flow fields. In the case of the swept-back wing the pressure distributions remain qualitatively similar at subsonic and supersonic speeds. Thus a distribution similar to the Ackeret type of distribution appears on the root sections of the swept-back wing at Mach=0. The resulting positive pressure drag on the root section is balanced by negative drags on outboard sections.
Date: January 1, 1948
Creator: Jones, Robert T
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: January 1, 1948
Creator: Loftin, Laurence K., Jr.
Partner: UNT Libraries Government Documents Department