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Calculation of the Bending Stresses in Helicopter Rotor Blades

Description: A comparatively rapid method is presented for determining theoretically the bending stresses of helicopter rotor blades in forward flight. The method is based on the analysis of the properties of a vibrating beam, and its uniqueness lies in the simple solution of the differential equation which governs the motion of the bent blades.
Date: March 1951
Creator: de Guillenchmidt, P.
Item Type: Refine your search to only Report
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Correction Factors for Wind Tunnels of Elliptic Section With Partly Open and Partly Closed Test Section

Description: Jet boundary corrections for partly open and partly closed elliptical wind tunnels for the cases of one and two solid wall segments are presented. Also presented are the combinations of model span and extent of the solid portion of the tunnel wall for which the average correction factor is zero.
Date: March 1951
Creator: Riegels, Fritz W.
Item Type: Refine your search to only Report
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Critical Velocities of Ultracentrifuges

Description: The Euler equations for the rotation of a solid body are applied to the problem of the motion of ultracentrifuges. Particular attention is paid to the problem of the passage of an ultracentrifuge rotor through the critical velocity. The factors that affect the passage of rotors through the critical point are stressed.
Date: March 1951
Creator: Sokolov, V. I.
Item Type: Refine your search to only Report
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Development of a Laminar Boundary Layer Behind a Suction Point

Description: A theoretical investigation is made of the development of a laminar boundary layer behind a suction slot that is assumed to cut off part of the boundary layer without exerting any sink effect. The development, which is approximate, is based on the heat conduction equation. The heat conduction equation enters the analysis through a linearization of the Prandtl-Mises form of the boundary-layer equation.
Date: March 1952
Creator: Wuest, Walter
Item Type: Refine your search to only Report
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Formation of a Vortex at the Edge of a Plate

Description: The flow about the plate of infinite width may be represented as a potential flow with discontinuity surfaces which extend from the plate edges. On the basis of a similitude requirement one succeeds in finding a solution of this problem for the plate of infinite width which is correct for the very beginning of the motion of the fluid. Starting from this solution, the further development of the vortex distribution and shape of the surface are observed in the case of a plate of finite width.
Date: March 1956
Creator: Anton, Leo
Item Type: Refine your search to only Report
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Friction and Wear

Description: From the practical point of view, this analysis shows that each problem of friction or wear requires its particular solution. There is no universal solution; one or other of the factors predominates and defines the choice of the solution. In certain cases, copper alloys of great thermal conductivity are preferred; in others, plastics abundantly supplied with water. Sometimes, soft antifriction metals are desirable to distribute the load; at other times, hard metals with high resistance to abras… more
Date: March 1952
Creator: Pomey, Jacques
Item Type: Refine your search to only Report
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Heat Transfer, Diffusion, and Evaporation

Description: Memorandum presenting an investigation of the equations that relate heat transfer, diffusion, and evaporation. The report shows that more accurate equations must be substituted for those used in previous investigations of the relation between the quantity of matter exchanged by diffusion and the quantity of heat transferred by conduction.
Date: March 1954
Creator: Nusselt, Wilhelm
Item Type: Refine your search to only Report
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The Interaction of a Reflected Shock Wave with the Boundary Layer in a Shock Tube

Description: "Ideally, the reflection of a shock from the closed end of a shock tube provides, for laboratory study, a quantity of stationary gas at extremely high temperature. Because of the action of viscosity, however, the flow in the real case is not one-dimensional, and a boundary layer grows in the fluid following the initial shock wave. In this paper simplifying assumptions are made to allow an analysis of the interaction of the shock reflected from the closed end with the boundary layer of the initi… more
Date: March 1958
Creator: Mark, Herman
Item Type: Refine your search to only Report
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Interim Report on Fatigue Characteristics of a Typical Metal Wing

Description: Constant amplitude fatigue tests of seventy-two P-51D "Mustang" wings are reported. The tests were performed by a vibrational loading system and by an hydraulic loading device for conditions with and without varying amounts of pre-load. The results indicate that: (a) the frequency of occurrence of fatigue at any one location is related to the range of the loads applied, (b) the rate of propagation of visible cracks is more or less constant for a large portion of the life of the specimen, and (c… more
Date: March 1956
Creator: Kepert, J. L. & Payne, A. O.
Item Type: Refine your search to only Report
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Investigation of Aperiodic Time Processes With Autocorrelation and Fourier Analysis

Description: "Autocorrelation and frequency analyses of a series of aperiodic time events, in particular, filtered noises and sibilant sounds, were made. The position and band width of the frequency ranges are best obtained from the frequency analysis, but the energies contained in the several bands are most easily obtained from the autocorrelation function. The mean number of zero crossings of the time function was determined from the curvature of the latter function in the vicinity of the zero crossing, a… more
Date: March 1958
Creator: Exner, Marie Luise
Item Type: Refine your search to only Report
open access

NACA Conference on Aircraft Loads, Structures, and Flutter

Description: "This document contains reproductions of technical papers on some of the most recent research results on aircraft loads, flutter, and structures from the NACA laboratories. These papers were presented by members of the staff of the NACA laboratories at the Conference held at the Langley Aeronautical Laboratory March 5, 6, and 7, 1957. The primary purpose of this Conference was to convey to contractors of the military services and others concerned with the design of aircraft these recent researc… more
Date: March 5, 1957
Item Type: Refine your search to only Report
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NACA Conference on High-Speed Aerodynamics: A Compilation of Papers Presented

Description: A reproduction of the technical papers presented by staff members of the NACA Laboratories at the NACA Conference on High-Speed Aerodynamics at the Ames Aeronautical Laboratory during March 18-20, 1958. The primary purpose of the conference was to convey to military services and contractors the results of recent research and to provide an opportunity to discuss the results.
Date: 1958-03-18/1958-03-20
Item Type: Refine your search to only Report
open access

On the Gas Dynamics of a Rotating Impeller

Description: It is shown that for a compressible flow with constant entropy the pressure rise maintains the direct relation to the circulation around the blades existing for incompressible flow. In contrast, however, the torque, and with it the power consumption, is increased because of sound waves traveling to infinity already at subsonic circumferential speeds.
Date: March 1956
Creator: Busemann, Adolf
Item Type: Refine your search to only Report
open access

State and Development of Flutter Calculation

Description: This report discusses the need for considering a wide variation in certain of the basic flutter parameters in conducting a flutter analysis. Conclusions are drawn stating that design charts or simple rules may be misleading. Due to inherent difficulties, dynamic model testing may also yield misleading results. The general flutter equations and various methods of solution are discussed. Of particular interest, curves are presented showing computational effort plotted against a number of degrees … more
Date: March 1951
Creator: Teichmann, Alfred
Item Type: Refine your search to only Report
open access

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
Item Type: Refine your search to only Report
open access

Study of the Supersonic Propeller

Description: In this paper a propeller having all sections operating at supersonic speeds is designated a supersonic propeller regardless of flight speed. Analyses assume subsonic flight speeds but very high rotational speeds. A very elementary analysis of the efficiency of a jet-propeller system is presented. A propeller analysis based on conventional vortex blade element theory is presented and reduced to a single point method which leads to an expression for optimum advance ratio in terms of hub-tip diam… more
Date: March 1953
Creator: Fabri, Jean & Siestrunck, Raymond
Item Type: Refine your search to only Report
open access

Two-Dimensional Symmetrical Inlets With External Compression

Description: The purpose of inlets like, for instance, those of air-cooled radiators and scoops is to take a certain air quantity out of the free stream and to partly convert the free-stream velocity into pressure. In the extreme case this pressure conversion may occur either entirely in the interior of the inlet (inlet with internal compression) or entirely in the free stream ahead of the inlet (inlet with external compression). In this report a theory for two-dimensional inlets with external compression i… more
Date: March 1950
Creator: Ruden, P.
Item Type: Refine your search to only Report
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