Technical Report Archive and Image Library (TRAIL) - 427 Matching Results

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The aerodynamic forces on slender plane- and cruciform-wing and body combinations

Description: From Introduction: "Since these results were not applicable to the present problem, a theoretical analysis of the aerodynamic properties of slender wing-body combinations was undertaken. The results of this investigation were first reported in reference 5 and were later extended in reference 6 to include cruciform-wing and body combinations. The present report summarizes and extends the theory and results previously presented in these references."
Date: 1950?~
Creator: Spreiter, John R
Partner: UNT Libraries Government Documents Department

The application of Green's theorem to the solution of boundary-value problems in linearized supersonic wing theory

Description: From Introduction: "The present paper is restricted to a discussion of wing theory subject to the assumptions of linearized compressible flow. It therefore employs solutions of Laplace's equation and the wave equation for cases where the boundary condition are specified in the plane of the wing."
Date: January 1, 1950
Creator: Heaslet, Max A & Lomax, Harvard
Partner: UNT Libraries Government Documents Department

Application of radial-equilibrium condition to axial-flow compressor and turbine design

Description: Basic general equations governing the three-dimensional compressible flow of gas through a compressor or turbine are given in terms of total enthalpy, entropy, and velocity components of the gas. Two methods of solution are obtained for the simplified, steady axially symmetric flow; one involves the use of a number of successive planes normal to the axis of the machine and short distances apart, and the other involves only three stations for a stage in which an appropriate radial-flow path is used. Methods of calculation for the limiting cases of zero and infinite blade aspect ratios and an approximate method of calculation for finite blade aspect ratio are also given. In these methods, the blade loading and the shape of the annular passage wall may be arbitrarily specified.
Date: January 1, 1950
Creator: Wu, Chung-Hua & Wolfenstein, Lincoln
Partner: UNT Libraries Government Documents Department

Blockage corrections for three-dimensional-flow closed-throat wind tunnels, with consideration of the effect of compressibility

Description: Theoretical blockage corrections are presented for a body of revolution and for a three-dimensional unswept wing in a circular or rectangular wind tunnel. The theory takes account of the effects of the wake and of the compressibility of the fluid, and is based on the assumption that the dimensions of the model are small in comparison with those of the tunnel throat. Formulas are given for correcting a number of the quantities, such as dynamic pressure and Mach number, measured in wing-tunnel tests. The report presents a summary and unification of the existing literature on the subject.
Date: January 1, 1950
Creator: Herriot, John G
Partner: UNT Libraries Government Documents Department

The calculation of downwash behind supersonic wings with an application to triangular plan forms

Description: A method is developed consistent with the assumptions of small perturbation theory which provides a means of determining the downwash behind a wing in supersonic flow for a known load distribution. The analysis is based upon the use of supersonic doublets which are distributed over the plan form and wake of the wing in a manner determined from the wing loading. The equivalence in subsonic and supersonic flow of the downwash at infinity corresponding to a given load distribution is proved.
Date: January 1, 1950
Creator: Lomax, Harvard; Sluder, Loma & Heaslet, Max A
Partner: UNT Libraries Government Documents Department

Critical stress of ring-stiffened cylinders in torsion

Description: A chart in terms of nondimensional parameters is presented for the theoretical critical stress in torsion of simply supported cylinders stiffened by identical equally spaced rings of zero torsional stiffness. The results are obtained by solving the equation of equilibrium by means of the Galerkin method. Comparison of the theoretical results with experimental results indicates that ring-stiffened cylinders buckle, on the average, at a buckling stress about 15 percent below the theoretical buckling stress. (author).
Date: January 1, 1950
Creator: Stein, Manuel; Snaders, J Lyell, Jr & Crate, Harold
Partner: UNT Libraries Government Documents Department

Determination of plate compressive strengths at elevated temperatures

Description: The results of local-instability tests of h-section plate assemblies and compressive stress-strain tests of extruded 75s-t6 aluminum alloy, obtained to determine flat-plate compressive strength under stabilized elevated temperature conditions, are given for temperatures up to 600 degrees F. The results show that methods available for calculating the critical compressive stress at room temperature can also be used at elevated temperatures if the applicable compressive stress-strain curve for the material is given.
Date: 1950
Creator: Heimerl, George J. & Roberts, William M.
Partner: UNT Libraries Government Documents Department

The effects of variations in Reynolds number between 3.0 x 10sub6 and 25.0 x 10sub6 upon the aerodynamic characteristics of a number of NACA 6-series airfoil sections

Description: Results are presented of an investigation made to determine the two-dimensional lift and drag characteristics of nine NACA 6-series airfoil section at Reynolds numbers of 15.0 x 10sub6, 20.0 x 10sub6, and 25.0 x 10sub6. Also presented are data from NACA Technical Report 824 for the same airfoils at Reynolds numbers of 3.0 x 10sub6, 6.0 x 10sub6, and 9.0 x 10sub6. The airfoils selected represent sections having variations in the airfoil thickness, thickness form, and camber. The characteristics of an airfoil with a split flap were determined in one instance, as was the effect of surface roughness. Qualitative explanations in terms of flow behavior are advanced for the observed types of scale effect.
Date: 1950
Creator: Loftin, Laurence K., Jr. & Bursnall, William J.
Partner: UNT Libraries Government Documents Department

Elastic and plastic buckling of simply supported solid-core sandwich plates in compression

Description: A solution is presented for the problem of the compressive buckling of simply supported, flat, rectangular, solid-core sandwich plates stressed either in the elastic range or in the plastic range. Charts for the analysis of long sandwich plates are presented for plates having face materials of 24s-t3 aluminum alloy, 76s-t6 alclad aluminum alloy, and stainless steel. A comparison of computed and experimental buckling stresses of square solid-core sandwich plates indicates fair agreement between theory and experiment.
Date: January 1, 1950
Creator: Seide, Paul & Stowell, Elbridge Z
Partner: UNT Libraries Government Documents Department

Equilibrium operating performance of axial-flow turbojet engines by means of idealized analysis

Description: A method of predicting equilibrium operating performance of turbojet engines has been developed, with the assumption of simple model processes for the components. Results of the analysis are plotted in terms of dimensionless parameters comprising critical engine dimensions and over-all operating variables. This investigation was made of an engine in which the ratio of axial inlet-air velocity to compressor-tip velocity is constant, which approximates turbojet engines with axial-flow compressors. Experimental correlation of the theory with data from several existing axial-flow-type engines was good and showed close correlation between calculated and measured performance.
Date: January 1, 1950
Creator: Sanders, John C & Chapin, Edward C
Partner: UNT Libraries Government Documents Department

Flight investigation of the effect of various vertical-tail modifications on the directional stability and control characteristics of a propeller-driven fighter airplane

Description: A flight investigation was made to determine the effect of various vertical-tail modifications and of some combinations of these modifications on the directional stability and control characteristics of a propeller-driven fighter airplane. Six different vertical-tail configurations were investigated to determine the lateral-directional oscillation characteristics, the sideslip characteristics, the yaw due to ailerons in rudder-fixed rolls from turns and pull-outs, the trim changes due to speed changes, and the tim changes due to power changes. Results of the tests showed that increasing the aspect ratio of the vertical tail by 40 percent while increasing the area by only 12 percent approximately doubled the directional stability of the airplane. The pilots considered the directional characteristics of the airplane unsatisfactory with original vertical tail but satisfactory with the enlarged vertical tail. The ventral and dorsal fins tested had little effect on the directional stability of the airplane but were effective in eliminating rudder-force reversals in high-engine-power sideslips.
Date: January 1, 1950
Creator: Johnson, Harold I
Partner: UNT Libraries Government Documents Department

Flutter of a uniform wing with an arbitrarily placed mass according to a differential-equation analysis and a comparison with experiment

Description: A method is presented for the calculation of the flutter speed of a uniform wing carrying an arbitrarily placed concentrated mass. The method, an extension of recently published work by Goland and Luke, involves the solution of the differential equations of motion of the wing at flutter speed and therefore does not require the assumption of specific normal modes of vibration. The order of the flutter determinant to be solved by this method depends upon the order of the system of differential equations and not upon the number of modes of vibration involved. The differential equations are solved by operational methods, and a brief discussion of operational methods as applied to boundary-value problems is included in one of two appendixes. A comparison is made with experiment for a wing with a large eccentrically mounted weight and good agreement is obtained. Sample calculations are presented to illustrate the method; and curves of amplitudes of displacement, torque, and shear for a particular case are compared with corresponding curves computed from the first uncoupled normal modes.
Date: 1950
Creator: Runyan, Harry L. & Watkins, Charles E.
Partner: UNT Libraries Government Documents Department

Free-space oscillating pressures near the tips of rotating propellers

Description: The theory is given for calculating the free-space oscillating pressures associated with a rotating propeller, at any point in space. Because of its complexity this analysis is convenient only for use in the critical region near the propeller tips where the assumptions used by Gutin to simplify his final equations are not valid. Good agreement was found between analytical and experimental results in the tip Mach number range 0.45 to two, three, four, five, six, on eight-blade propellers and for a range of tip clearances from 0.04 to 0.30 times the propeller diameter. If the power coefficient, tip Mach number, and the tip clearance are known for a given propeller, the designer may determine from these charts the average maximum free-space oscillating pressure in the critical region near the plane of rotation. A section of the report is devoted to the fuselage response to these oscillating pressures and indicates some of the factors to be considered in solving the problems of fuselage vibration and noise.
Date: 1950
Creator: Hubbard, Harvey H. & Regier, Arthur A.
Partner: UNT Libraries Government Documents Department

Frequency response of linear systems from transient data

Description: Methods are presented that use general correlative time-response input and output data for a linear system to determine the frequency-response function of that system. These methods give an exact description of any linear system for which such transient data are available. Examples are shown of application of a method to both an underdamped and a critically damped exact second-order system, and to an exact first-order system with and without dead time. Experimental data for a turbine-propeller engine showing the response of engine speed to change in propeller-blade angle are presented and analyzed.
Date: January 1, 1950
Creator: Laverne, Melvin E. & Boksenbom, Aaron S.
Partner: UNT Libraries Government Documents Department

Fundamental effects of aging on creep properties of solution-treated low-carbon n-155 alloy

Description: A method is developed whereby the fundamental mechanisms are investigated by which processing, heat treatment, and chemical composition control the properties of alloys at high temperatures. The method used metallographic examination -- both optical and electronic --studies of x-ray diffraction-line widths, intensities, and lattice parameters, and hardness surveys to evaluate fundamental structural conditions. Mechanical properties at high temperatures are then measured and correlated with these measured structural conditions. In accordance with this method, a study was made of the fundamental mechanism by which aging controlled the short-time creep and rupture properties of solution-treated low-carbon n-155 alloy at 1200 degrees F.
Date: January 1, 1950
Creator: Frey, D N; Freeman, J W & White, A E
Partner: UNT Libraries Government Documents Department

Further experiments on the flow and heat transfer in a heated turbulent air jet

Description: Measurements have been made of the mean-total-head and mean-temperature fields in a round turbulent jet with various initial temperatures. The results show that the jet spreads more rapidly as its density becomes lower than that of the receiving medium, even when the difference is not sufficiently great to cause dynamic-pressure function. Rough analytical considerations have given the same relative spread. The effective "turbulent Prandtl number" for a section of the fully developed jet was found to be equal to the true (laminar) Prandtl number within the accuracy measurement.
Date: January 1, 1950
Creator: Corrsin, Stanley & Uberoi, Mahinder S
Partner: UNT Libraries Government Documents Department

General algebraic method applied to control analysis of complex engine types

Description: A general algebraic method of attack on the problem of controlling gas-turbine engines having any number of independent variables was utilized employing operational functions to describe the assumed linear characteristics for the engine, the control, and the other units in the system. Matrices were used to describe the various units of the system, to form a combined system showing all effects, and to form a single condensed matrix showing the principal effects. This method directly led to the conditions on the control system for noninteraction so that any setting disturbance would affect only its corresponding controlled variable. The response-action characteristics were expressed in terms of the control system and the engine characteristics. The ideal control-system characteristics were explicitly determined in terms of any desired response action.
Date: January 1, 1950
Creator: Boksenbom, Aaron S & Hood, Richard
Partner: UNT Libraries Government Documents Department

An introduction to the physical aspects of helicopter stability

Description: In order to provide engineers interested in rotating-wing aircraft, but with no specialized training in stability theory, some understanding of the factors that influence the flying qualities of the helicopter, an explanation is made of both the static stability and the stick-fixed oscillation in hovering and forward flight in terms of fundamental physical quantities. Three significant stability factors -- static stability with angle of attack, static stability with speed, and damping due to a pitching or rolling velocity -- are explained in detail.
Date: January 1, 1950
Creator: Gessow, Alfred & Amer, Kenneth B
Partner: UNT Libraries Government Documents Department

Investigation at low speeds of the effect of aspect ratio and sweep on rolling stability derivatives of untapered wings

Description: A low-scale wind-tunnel investigation was conducted in rolling flow to determine the effects of aspect ratio and sweep (when varied independently) on the rolling stability derivatives for a series of untapered wings. The rolling-flow equipment of the Langley stability tunnel was used for the tests. The data of the investigation have been used to develop a method of accounting for the effects of the drag on the yawing moment due to rolling throughout the lift range.
Date: January 1, 1950
Creator: Goodman, Alex & Fisher, Lewis R
Partner: UNT Libraries Government Documents Department

Investigation of the NACA 4-(3)(8)-045 Two-Blade Propellers at Forward Mach Numbers to 0.725 to Determine the Effects of Compressibility and Solidity on Performance

Description: As part of a general investigation of propellers at high forward speeds, tests of two 2-blade propellers having the NACA 4-(3)(8)-03 and NACA 4-(3)(8)-45 blade designs have been made in the Langley 8-foot high-speed tunnel through a range of blade angle from 20 degrees to 60 degrees for forward Mach numbers from 0.165 to 0.725 to establish in detail the changes in propeller characteristics due to compressibility effects. These propellers differed primarily only in blade solidity, one propeller having 50 percent and more solidity than the other. Serious losses in propeller efficiency were found as the propeller tip Mach number exceeded 0.91, irrespective of forward speed or blade angle. The magnitude of the efficiency losses varied from 9 percent to 22 percent per 0.1 increase in tip Mach number above the critical value. The range of advance ratio for peak efficiency decreased markedly with increase of forward speed. The general form of the changes in thrust and power coefficients was found to be similar to the changes in airfoil lift coefficient with changes in Mach number. Efficiency losses due to compressibility effects decreased with increase of blade width. The results indicated that the high level of propeller efficiency obtained at low speeds could be maintained to forward sea-level speeds exceeding 500 miles per hour.
Date: January 1, 1950
Creator: Stack, John; Draley, Eugene C; Delano, James B & Feldman, Lewis
Partner: UNT Libraries Government Documents Department

Line-vortex theory for calculation of supersonic downwash

Description: The perturbation field induced by a line vortex in a supersonic stream and the downwash behind a supersonic lifting surface are examined to establish approximate methods for determining the downwash behind supersonic wings. Lifting-lines methods are presented for calculating supersonic downwash. A bent lifting-line method is proposed for computing the downwash field behind swept wings. When applied to triangular wings with subsonic leading edges, this method gives results that, in general, are in good agreement with the exact linearized solution. An unbent lifting-line method (horseshoe-vortex system) is proposed for unswept wings. This method is applied to determine downwash behind rectangular wings with aspect ratios of 2 and 4. Excellent agreement with exact linearized theory is obtained for both aspect ratios by placing the lifting line at the 1/2-chord point. The use of lifting-lines therefore appears promising for obtaining estimates of the downwash behind supersonic wings.
Date: January 1, 1950
Creator: Mirels, Harold & Haefeli, Rudolph C
Partner: UNT Libraries Government Documents Department

Linearized compressible-flow theory for sonic flight speeds

Description: The partial differential equation for the perturbation velocity potential is examined for free-stream Mach numbers close to and equal to one. It is found that, under the assumptions of linearized theory, solutions can be found consistent with the theory for lifting-surface problems both in stationary three-dimensional flow and in unsteady two-dimensional flow. Several examples are solved including a three dimensional swept-back wing and two dimensional harmonically-oscillating wing, both for a free stream Mach number equal to one. Momentum relations for the evaluation of wave and vortex drag are also discussed. (author).
Date: January 1, 1950
Creator: Heaslet, Max A; Lomax, Harvard & Spreiter, John R
Partner: UNT Libraries Government Documents Department

The longitudinal stability of elastic swept wings at supersonic speed

Description: The longitudinal stability characteristics of elastic swept wings of high aspect ratio experiencing bending and torsional deformations are calculated for supersonic speed by the application of linearized lifting-surface theory. A parabolic wing deflection curve is assumed and the analysis is simplified by a number of structural approximations. The method is thereby limited in application to wings of high aspect ratio for which the root effects are small. Expressions for the lift, pitching-moment, and span load distribution characteristics are derived in terms of the elastic properties of the wing; namely, the design stress, the modulus of elasticity, the shearing modulus, and the maximum design load factor. The analysis applies to wings with leading edges swept behind the Mach lines. In all cases, however, the trailing edge is sonic or supersonic. Application of the method of analysis to wings with leading edges swept ahead of the Mach lines is discussed.
Date: 1950
Creator: Frick, C. W. & Chubb, R. S.
Partner: UNT Libraries Government Documents Department