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Some notes on gasoline-engine development

Description: Experiments were carried out using a special engine with small glass windows and a stroboscope to record various aspects of engine performance. Valve position, supercharging, and torque recoil were all investigated with this experimental apparatus.
Date: July 1, 1927
Creator: Ricardo, H R
Partner: UNT Libraries Government Documents Department

Some problems on the theory of creep

Description: The term creep of metals is applied to the phenomenon in which, at temperatures beyond a certain limit, the metal subjected to a load slowly undergoes deformation with time. For the case of steel, the creep phenomenon must be taken into account at temperatures above 400 degrees C. Very slow deformations for a prolonged period are cumulative and lead either to inadmissible changes in the dimensions of a structural part or to its failure. The theory of creep constitutes part of the mechanics of dense media and the mechanical formulation of the problem may be given as the following: a body is subjected to the action of a given system of forces, or initial displacements are prescribed on its surface. It is required to find the stress distribution in the body and the changes or its deformations with time. For the solution of the problem of creep as thus formulated, a mechanical theory of creep is required. Such theory must necessarily bear an external, overall character based, not on the investigation of microprocesses, but on the results of mechanical tests.
Date: April 1, 1953
Creator: Rabotnov, Y N
Partner: UNT Libraries Government Documents Department

Some remarks concerning soaring flight

Description: The publication of the following details is due to the desire of the editor to have the problems of soaring flight treated on the occasion of the Rhone Soaring Flight Contest. Soaring flight is defined as motorless flight without loss of height. Some calculations are provided in order to maximize the potential effects of wind and air currents.
Date: October 1921
Creator: Prandtl, L.
Partner: UNT Libraries Government Documents Department

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 1, 1955
Creator: Favre, A; Gaviglio, J & Dumas, R
Partner: UNT Libraries Government Documents Department

A study of curvilinear flight

Description: When an airplane describes a curve it takes a certain time for it to turn from level to inclined position and then back to level again. In the following, we express the motion about the horizontal axis as "roll" or "bank" and the motion perpendicular to the vertical axis, i.e., the actual curve, as "turn." Equations and tables provide results on various aspects of turns, control settings, acceleration, inertia moments, and angular velocity.
Date: April 1, 1931
Creator: Kruse, Helmuth
Partner: UNT Libraries Government Documents Department

The steady spin

Description: With the object of further clarifying the problem of spinning, the equilibrium of the forces and moments acting on an airplane is discussed in light of the most recent test data. Convinced that in a spin the flight attitude by only small angles of yaw is more or less completely steady, the study is primarily devoted to an investigation of steady spin with no side slip. At small angles, wholly arbitrary and perfectly steady spins may be forced, depending on the type of control displacements. But at large angles only very steep and only "approaching steady" spins are possible, no matter what the control displacements.
Date: July 1, 1931
Creator: Fuchs, Richard & Schmidt, Wilhelm
Partner: UNT Libraries Government Documents Department

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 after the effect of compressibility upon the turn is examined, the effects of the salient aerodynamic and structural parameters upon the behavior of the plane in curvilinear flight are summarized in the conclusions.
Date: March 1, 1955
Creator: Miele, Angelo
Partner: UNT Libraries Government Documents Department

Statistical analysis of service stresses in aircraft wings

Description: On the wing structures of modern high speed aircraft, in particular, the comparatively high-service stresses and the consistently increasing number of hours of operation during the life of the separate airplane parts make the studies of strength requirement under recurrent stresses appear of major concern. The DVL has therefore made exhaustive studies for this structural group of airplanes, some results of which are reported here.
Date: June 1942
Creator: Kaul, Hans W.
Partner: UNT Libraries Government Documents Department

Status of wing flutter

Description: This report presents a survey of previous theoretical and experimental investigations on wing flutter covering thirteen cases of flutter observed on airplanes. The direct cause of flutter is, in the majority of cases, attributable to (mass-) unbalanced ailerons. Under the conservative assumption that the flutter with the phase angle most favorable for excitation occurs only in two degrees of freedom, the lowest critical speed can be estimated from the data obtained on the oscillation bench. Corrective measures for increasing the critical speed and for definite avoidance of wing flutter, are discussed.
Date: January 1, 1936
Creator: Kussner, H G
Partner: UNT Libraries Government Documents Department

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 of freedom used in a flutter analysis.
Date: March 1, 1951
Creator: Teichmann, Alfred
Partner: UNT Libraries Government Documents Department

Stall-proof airplanes

Description: My lecture has to do with the following questions. Is the danger of stalling necessarily inherent in the airplane in its present form and structure, or can it be diminished or eliminated by suitable means? Do we possess such means or devices and how must they operate? In this connection I will devote special attention to the exhibition of stall-proof airplanes by Fokker under the auspices of the English Air Ministry, which took place in Croyden last April.
Date: January 1, 1927
Creator: Lachmann, G
Partner: UNT Libraries Government Documents Department

The source of propeller noise

Description: A two blade propeller of 40 cm diameter and zero pitch was explored for its noise development; it could be whirled up to 17,000 rpm - i.e., a tip speed of 355 meters/second. To obtain the power loss N(sub m) of the propeller for comparison with the produced acoustical power N(sub A) the engine performance characteristics were measured with and without propeller. The result is the sought-for relation c, that is, curve c' after correction with the engine efficiency.
Date: May 1, 1937
Creator: Ernsthausen, W.
Partner: UNT Libraries Government Documents Department

The span as a fundamental factor in airplane design

Description: Previous theoretical investigations of steady curvilinear flight did not afford a suitable criterion of "maneuverability," which is very important for judging combat, sport and stunt-flying airplanes. The idea of rolling ability, i.e., of the speed of rotation of the airplane about its X axis in rectilinear flight at constant speed and for a constant, suddenly produced deflection of the ailerons, is introduced and tested under simplified assumptions for the air-force distribution over the span. This leads to the following conclusions: the effect of the moment of inertia about the X axis is negligibly small, since the speed of rotation very quickly reaches a uniform value.
Date: September 1, 1928
Creator: Lachmann, G
Partner: UNT Libraries Government Documents Department

Static longitudinal stability of "Ente" airplanes

Description: The stability conditions of Ente (duck) airplanes are investigated in this report. In developing the formulas, which afford an approximate solution, the unimportant effect of the height of the C.G. and the moment of the residual resistance are neglected. The effect of downwash from the forward horizontal empennage on the wing are also disregarded.
Date: March 1931
Creator: Kiel, Heinrich Georg
Partner: UNT Libraries Government Documents Department

Static soaring flight over flat sea coasts

Description: Static soaring flight has hitherto been accomplished by means of two sources of energy: ascending air currents in the vicinity of obstacles and those produced by unequal heating. The latter has not yet been practically tested in soaring flight.
Date: November 1923
Creator: Georgii, W
Partner: UNT Libraries Government Documents Department

Standards for discharge measurement with standardized nozzles and orifices

Description: The following standards give the standardized forms for two throttling devices, standard nozzles and standard orifices, and enable them to be used in circular pipes without calibration. The definition of the standards are applicable in principle to the calibration and use of nonstandardized throttling devices, such as the venturi tube. The standards are valid, likewise, as a basis for discharge measurements in the German acceptance standards.
Date: September 1, 1940
Partner: UNT Libraries Government Documents Department

Propeller problems

Description: This report tries to give a comprehensive survey of the most important propeller problems such as the shape of propellers and the effect of atmospheric conditions on propeller performance.
Date: December 1928
Creator: Betz, A.
Partner: UNT Libraries Government Documents Department

Synthetic resins in aircraft construction - their composition, properties, present state of development and application to light structures

Description: This report gives a brief review of the properties that have been attained with the synthetic materials with which we are at present familiar. Results of investigations are presented as well as possibilities for construction applications. Endurance strength and bonding tests are also presented.
Date: November 1937
Creator: Riechers, K.
Partner: UNT Libraries Government Documents Department

Tests of lead-bronze bearings in the DVL bearing-testing machine

Description: The lead-bronze bearings tested in the DVL machine have proven themselves very sensitive to load changes as in comparison with bearings of light metal. In order to prevent surface injuries and consequently running interruptions, the increase of the load has to be made in small steps with sufficient run-in time between steps. The absence of lead in the running surface, impurities in the alloy (especially iron) and surface irregularities (pores) decreases the load-carrying capacity of the bearing to two or three times that of the static load.
Date: June 1, 1940
Creator: Fischer, G
Partner: UNT Libraries Government Documents Department