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From Linear Mechanics to Nonlinear Mechanics

Description: Consideration is given to the techniques used in telecommunication where a nonlinear system (the modulator) results in a linear transposition of a signal. It is then shown that a similar method permits linearization of electromechanical devices or nonlinear mechanical devices. A sweep function plays the same role as the carrier wave in radio-electricity. The linearizations of certain nonlinear functionals are presented.
Date: October 1955
Creator: Loeb, Julien
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General Solutions of Optimum Problems in Nonstationary Flight

Description: "A general method concerning optimum problems in nonstationary flight is developed and discussed. Best flight techniques are determined for the following conditions: climb with minimum time, climb with minimum fuel consumption, steepest climb, descending and gliding flight with maximum time or with maximum distance. Optimum distributions of speed with altitude are derived assuming constant airplane weight and neglecting curvatures and squares of path inclination in the projection of the equatio… more
Date: October 1955
Creator: Miele, Angelo
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Lift on a Bent, Flat Plate

Description: The lift on a bent, flat plate is calculated exactly by the use of conformal mapping. Results are presented in terms permitting direct determination of the angle of zero lift, the lift coefficient, and the lift-curve slope for any flap-chord ratio, flap-deflection angle, and angle of attack.
Date: February 1955
Creator: Keune, F.
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Metallography of Aluminum and Its Alloys: Use of Electrolytic Polishing

Description: Recent methods are described for electropolishing aluminum and aluminum alloys. Numerous references are included of electrolytic micrographic investigations carried out during the period 1948 to 1952. A detailed description of a commercial electrolytic polishing unit, suitable for micrographic examination of aluminum and its alloys, is included.
Date: November 1955
Creator: Jacquet, Pierre A.
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A Method of Quadrature for Calculation of the Laminar and Turbulent Boundary Layer in Case of Plane and Rotationally Symmetrical Flow

Description: "For calculation of the characteristic parameters of the boundary layer (momentum-loss thickness and form parameter for the velocity profile), two quadrature formulas are given which are valid for the laminar as well as for the turbulent state of flow. These formulas cover both the two-dimensional and the rotationally symmetrical case. The calculation of the momentum-loss thickness is carried out by a simple integration of the energy theorem" (p. 1).
Date: May 1955
Creator: Truckenbrodt, E.
open access

NACA Conference on Aerodynamics of High Speed Aircraft

Description: "This document contains reproductions of technical papers presented by staff members of the NACA Laboratories at the NACA Conference on Aerodynamics of High-Speed Aircraft held at the Langley Aeronautical Laboratory November 1, 2, and 3, 1955. The primary purpose of the conference was to convey to contractors of the military services and others concerned with the design of aircraft the results of recent research and to provide those attending with an opportunity to discuss these results. The pa… more
Date: 1955-11-01/1955-11-03
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On the Mechanism of Buckling of a Circular Cylindrical Shell Under Axial Compression

Description: The present paper deals with the buckling of a circular cylindrical shell under axial compression from the viewpoint of energy and the characteristics of deformation. It is shown first, both theoretically and experimentally, that the reason why the buckling of a cylindrical shell is quite different from that of a flat plate is attributable to the existence of a nearly developable surface far apart from the original cylindrical surface. Based upon this result, the experimental fact that the buck… more
Date: July 1955
Creator: Yoshimura, Yoshimaru
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Optimum Flight Paths of Turbojet Aircraft

Description: "The climb of turbojet aircraft is analyzed and discussed including the accelerations. Three particular flight performances are examined: minimum time of climb, climb with minimum fuel consumption, and steepest climb. The theoretical results obtained from a previous study are put in a form that is suitable for application on the following simplifying assumptions: the Mach number is considered an independent variable instead of the velocity; the variations of the airplane mass due to fuel consum… more
Date: September 1955
Creator: Miele, Angelo
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Reduction of the Shimmy Tendency of Tail and Nose-Wheel Landing Gears by Installation of Specially Designed Tires

Description: Shimmy of tail and nose wheels may be eliminated by installation of dampers and use of large trail; however, this produces construction and operational disadvantages. It is more favorable to employ, instead of the customary tail-wheel tires, tires with lesser shimmy tendency. A description of the best possible form for these tires follows: furthermore, a few general concepts regarding the effects of the condition of the tire, of the type of rolling motion, and of the landing, are discussed.
Date: July 1955
Creator: Schrode, H.
open access

Some Measurements of Time and Space Correlation in Wind Tunnel

Description: Results are presented of research obtained by means of an apparatus for measurement of time and space correlation and of a spectral analyzer in the study of the longitudinal component of turbulence velocities in a wind tunnel downstream of a grid of meshes. Application to the case of a flat-plate boundary layer is illustrated. These researches were made at the Laboratoire de Mecanique de l'Atmosphere de l'I.M.F.M. for the O.N.E.R.A.
Date: February 1955
Creator: Favre, A.; Gaviglio, J. & Dumas, R.
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Steady Properly-Banked Turns of Turbojet-Propelled Airplanes

Description: "The problem of a jet-propelled airplane held in a steady turn is treated both in the very general case and also in the particular case when the polar curve can be approximated by a parabola. Once the general solution has been obtained, some typical maneuvers are next studied such as, the turn of maximum bank, of maximum angular velocity, and of minimum radius of curvature. After a brief comparison is made between the turning characteristics of conventional airplanes and jet airplanes, and afte… more
Date: March 1955
Creator: Miele, Angelo
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The Theories of Turbulence

Description: "The theory of turbulence reached its full growth at the end of the 19th century as a result of the work by Boussinesq and Reynolds. It then underwent a long period of stagnation which ended under the impulse given to it by the development of wind tunnels caused by the needs of aviation. Numerous researchers, attempted to put Reynolds' elementary statistical theory into a more precise form. During the war, some isolated scientists - von Weizsacker and Heisenberg in Germany, Kolmogoroff in Russi… more
Date: October 1955
Creator: Agostini, L. & Bass, J.
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Theory of Dynamic Creep

Description: An analysis is given of the causes of the increase in the creep of a material under dynamic loads. A theory of dynamic creep is proposed based on the after-effect theory of Becker. Three circumstances that must be taken into account when theoretically treating dynamic creep are provided.
Date: September 1955
Creator: Predvoditelev, A. A. & Smirnov, B. A.
open access

Theory of Reversible and Nonreversible Cracks in Solids

Description: The Griffith crack theory is reviewed and certain shortcomings of this theory are discussed. A new description for the shape of a crack is given which takes into account the atomic structure of material. Through consideration of the total energy of the system and the shape of the crack, expressions for crack behavior are derived which are considered to remedy the defects of the Griffith theory.
Date: April 1955
Creator: Frenkel, Y. I.
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