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  Partner: UNT Libraries Government Documents Department
 Decade: 1940-1949
 Year: 1942
 Serial/Series Title: NACA Technical Memorandums
 Collection: Technical Report Archive and Image Library
Aerodynamic Heat-Power Engine Operating on a Closed Cycle

Aerodynamic Heat-Power Engine Operating on a Closed Cycle

Date: November 1, 1942
Creator: Ackeret, J. & Keller, D. C.
Description: Hot-air engines with dynamic compressors and turbines offer new prospects of success through utilization of units of high efficiencies and through the employment of modern materials of great strength at high temperature. Particular consideration is given to an aerodynamic prime mover operating on a closed circuit and heated externally. Increase of the pressure level of the circulating air permits a great increase of limit load of the unit. This also affords a possibility of regulation for which the internal efficiency of the unit changes but slightly. The effect of pressure and temperature losses is investigated. A general discussion is given of the experimental installation operating at the Escher Wyss plant in Zurich for a considerable time at high temperatures.
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Aerodynamics of the Fuselage

Aerodynamics of the Fuselage

Date: December 1, 1942
Creator: Multhopp, H.
Description: The present report deals with a number of problems, particularly with the interaction of the fuselage with the wing and tail, on the basis of simple calculating method's derived from greatly idealized concepts. For the fuselage alone it affords, in variance with potential theory, a certain frictional lift in yawed flow, which, similar to the lift of a wing of small aspect ratio, is no longer linearly related to the angle of attack. Nevertheless there exists for this frictional lift something like a neutral stability point the position of which on oblong fuselages appears to be associated with the lift increase of the fuselage in proximity to the zero lift, according to the present experiments. The Pitching moments of the fuselage can be determined with comparatively great reliability so far as the flow conditions in the neighborhood of the axis of the fuselage can be approximated if the fuselage were absent, which, in general, is not very difficult. For the unstable contribution of the fuselage to the static longitudinal stability of the airplane it affords comparatively simple formulas, the evaluation of which offers little difficulty. On the engine nacelles there is, in addition a very substantial wing moment contribution induced ...
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Analytical theory of the Campini propulsion system

Analytical theory of the Campini propulsion system

Date: March 1, 1942
Creator: Campini, S
Description: Following the description of the new propulsion system and the definition of the propulsive efficiency, this efficiency is calculated under various conditions of flight with allowance for all internal losses. The efficiency and consumption curves are plotted, their practical values discussed and the behavior of the system analyzed at various altitudes and speeds. The immediate possibilities of the new system in flight at high and very high altitudes in relation to the theoretical and experimental results are discussed in detail.
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The Compressible Potential Flow Past Elliptic Symmetrical Cylinders at Zero Angle of Attack and with No Circulation

The Compressible Potential Flow Past Elliptic Symmetrical Cylinders at Zero Angle of Attack and with No Circulation

Date: October 1, 1942
Creator: Hantzsche, W. & Wendt, H.
Description: For the tunnel corrections of compressible flows those profiles are of interest for which at least the second approximation of the Janzen-Rayleigh method can be applied in closed form. One such case is presented by certain elliptical symmetrical cylinders located in the center of a tunnel with fixed walls and whose maximum velocity, incompressible, is twice the velocity of flow. In the numerical solution the maximum velocity at the profile and the tunnel wall as well as the entry of sonic velocity is computed. The velocity distribution past the contour and in the minimum cross section at various Mach numbers is illustrated on a worked out-example.
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Contribution to the Design of Plywood Shells

Contribution to the Design of Plywood Shells

Date: October 1, 1942
Creator: Blumrich, S.
Description: The writer sets out to prove by calculation and experiment that by extensive utilization of the skin to carry axial load (reduction of stringer spacing) the stringer sections can be made small enough to afford a substantial saving in structural weight. This saving ranges from 5 to about 40 percent.
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Contribution to the ideal efficiency of screw propellers

Contribution to the ideal efficiency of screw propellers

Date: January 1, 1942
Creator: Hoff, Wilhelm
Description: The stipulation of best thrust distribution is applied to the annular elements of the screw propeller with infinitely many blades in frictionless, incompressible flow and an ideal jet propulsion system derived possessing hyperbolic angular velocity distribution along the blade radius and combining the advantage of uniform thrust distribution over the section with minimum slipstream and rotation losses. This system is then compared with a propeller possessing the same angular velocity at all blade elements and the best possible thrust distribution secured by means of an induced efficiency varying uniformly over the radius. Lastly, the case of the lightly loaded propeller also is discussed.
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Control of Torsional Vibrations by Pendulum Masses

Control of Torsional Vibrations by Pendulum Masses

Date: November 1, 1942
Creator: Stieglitz, Albert
Description: Various versions of pendulum masses have been developed abroad within the past few years by means of which resonant vibrations of rotating shafts can be eliminated at a given tuning. They are already successfully employed on radial engines in the form of pendulous counterweights. Compared with the commonly known torsional vibration dampers, the pendulum masses have the advantage of being structurally very simple, requiring no internal damping and being capable of completely eliminating certain vibrations. Unexplained, so far, remains the problem of behavior of pendulum masses in other critical zones to which they are not tuned, their dynamic behavior at some tuning other than in resonance, and their effect within a compound vibration system and at simultaneous application of several differently tuned pendulous masses. These problems are analyzed in the present report. The results constitute an enlargement of the scope of application of pendulum masses, especially for in-line engines. Among other things it is found that the natural frequency of a system can be raised by means of a correspondingly tuned pendulum mass. The formulas necessary for the design of any practical version are developed, and a pendulum mass having two different natural frequencies simultaneously is described.
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Correlation of data on the statistical theory of turbulence

Correlation of data on the statistical theory of turbulence

Date: March 1, 1942
Creator: Wieghardt, K
Description: The statistical theory of turbulence affords an excellent medium for representing the kinematic conditions in turbulent flow and also serves as a valuable aid to exact experimental research. But it is still not developed enough for solving dynamic processes. Even in the simplest case of isotropic turbulence the calculation of the correlation curve or of the decrement of turbulence invariably reaches a point where clear-cut assumptions, such as omission of the inertia terms, or, earlier, mixing length assumptions or even merely general dimensional considerations, must be made.
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The design of propeller blade roots

The design of propeller blade roots

Date: January 1, 1942
Creator: Cordes, G
Description: Predicated on the assumption of certain normal conditions for engine and propeller, simple expressions for the static and dynamic stresses of propeller blade roots are evolved. They, in combination with the fatigue strength diagram of the employed material, afford for each engine power one certain operating point by which the state of stress serving as a basis for the design of the root is defined. Different stress cases must be analyzed, depending on the vibration tendency of engine and use of propeller. The solution affords an insight into the possible introduction of different size classes of propeller.
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Diagrams for calculation of airfoil lattices

Diagrams for calculation of airfoil lattices

Date: July 1, 1942
Creator: Betz, Albert
Description: The field for curved blades is represented by a vortex series with a vortex removed at the blade point. Further, an example of calculation of a curved blade from this series is given, whereby the necessary accuracy required of the different methods in practice is shown according to the case considered.
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Electrical equipment for the experimental study of the dynamics of fluids

Electrical equipment for the experimental study of the dynamics of fluids

Date: March 1, 1942
Creator: Ferrari, Carlo
Description: This report contains the description of electric anemometers and their application to the study of turbulent fluid flows, of electric tanks for the realization of the analogies between electrology and aerodynamics and their application to the study of varied technical problems, and lastly of the electric condenser type dynamometer and its application to the prediction of the aerodynamic forces on wing and airplane models in wind-tunnel tests and in controlled and spontaneous rotations.
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The Formation of Ice on Aircraft

The Formation of Ice on Aircraft

Date: August 1, 1942
Creator: Bleeker, W.
Description: The phenomenon accompanying the formation of ice on aircraft has been frequently discussed. The consequences of ice formation have been briefly analyzed in an article , but a definite physical solution of the problem has not been reached up to the present. Most of the authors agree that subcooled water droplets play a prominent part, but they fail to specify the exact manner in which this occurs.
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Heat Transfer in the Turbulent Boundary Layer of a Compressible Gas at High Speeds

Heat Transfer in the Turbulent Boundary Layer of a Compressible Gas at High Speeds

Date: October 1, 1942
Creator: Frankl, F.
Description: The Reynolds law of heat transfer from a wall to a turbulent stream is extended to the case of flow of a compressible gas at high speeds. The analysis is based on the modern theory of the turbulent boundary layer with laminar sublayer. The investigation is carried out for the case of a plate situated in a parallel stream. The results are obtained independently of the velocity distribution in the turbulent boundar layer.
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The Icing of Aircraft

The Icing of Aircraft

Date: September 1, 1942
Creator: Robitzsch, M.
Description: This technical memorandum presents a theoretical study of the processes accompanying the formation of ice on solid bodies. It discusses vapor pressure and sublimation in two air masses separated by a boundary area.
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Investigation of lubricants under boundary friction

Investigation of lubricants under boundary friction

Date: May 1, 1942
Creator: Heidebroek, E & Pietsch, E
Description: Numerous observations of such lubrication processes within range of boundary friction on journal bearings and gear tooth profiles have strengthened the supposition that it should be possible to study the attendant phenomena with engineering methods and equipment. These considerations formed the basis of the present studies, which have led to the discovery of relations governing the suitability of bearing surfaces and the concept of "lubricating quality.".
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The Navier-Stokes Stress Principle for Viscous Fluids

The Navier-Stokes Stress Principle for Viscous Fluids

Date: September 1, 1942
Creator: Mohr, Ernst
Description: The Navier-Stokes stress principle is checked in the light of Maxwell's mechanism of friction and in connection herewith the possibility of another theorem is indicated. The Navier-Stokes stress principle is in general predicated upon the conception of the plastic body. Hence the process is a purely phenomenological one, which Newton himself followed with his special theorem for one-dimensional flows. It remained for Maxwell to discover the physical mechanism by which the shear inflow direction is developed: According to it, this shear is only 'fictitious' as it merely represents the substitute for a certain transport on macroscopic motion quantity, as conditioned by Brown's moiecular motion and the diffusion, respectively. It is clear that this mechanism is not bound to the special case of the one-dimensioilal flows, but holds for any flow as expression of the diffusion, by which a fluid differs sharply from a plastic body. If it is remembered, on the other hand, that the cause of the stresses on the plastic body lies in a certain cohesion of the molecules, it appears by no means self evident that this difference in the mechanism of friction between fluid and plastic body should not prevail in the stress principle as well, ...
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New method of extrapolation of the resistance of a model planing boat to full size

New method of extrapolation of the resistance of a model planing boat to full size

Date: March 1, 1942
Creator: Sottorf, W
Description: The previously employed method of extrapolating the total resistance to full size with lambda(exp 3) (model scale) and thereby foregoing a separate appraisal of the frictional resistance, was permissible for large models and floats of normal size. But faced with the ever increasing size of aircraft a reexamination of the problem of extrapolation to full size is called for. A method is described by means of which, on the basis of an analysis of tests on planing surfaces, the variation of the wetted surface over the take-off range is analytically obtained. The friction coefficients are read from Prandtl's curve for turbulent boundary layer with laminar approach. With these two values a correction for friction is obtainable.
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On the symmetrical potential flow of compressible fluid past a circular cylinder in the tunnel in the subcritical zone

On the symmetrical potential flow of compressible fluid past a circular cylinder in the tunnel in the subcritical zone

Date: June 1, 1942
Creator: Lamla, Ernst
Description: The two-dimensional symmetrical potential flow of compressible fluid past a circular cylinder placed in the center line of a straight tunnel is analyzed in second approximation according to the Jansen-Rayleigh method. The departure of the profile from the exact circular shape can be kept to the same magnitude as for the incompressible flow. The velocities in the narrowest section of the tunnel wall and at the profile edge are discussed in detail.
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The Performance of a Vaneless Diffuser Fan

The Performance of a Vaneless Diffuser Fan

Date: December 1, 1942
Creator: Polikovsky, V. & Nevelson, M.
Description: The present paper is devoted to the theoretical and experimental investigation of one of the stationary elements of a fan, namely, the vaneless diffuser. The method of computation is based on the principles developed by Pfleiderer (Forschungsarbeiten No. 295). The practical interest of this investigation arises from the fact that the design of the fan guide elements - vaneless diffusers, guide vanes, spiral casing - is far behind the design of the impeller as regards accuracy and. reliability. The computations conducted by the method here presented have shown sufficiently good agreement with the experimental data and indicate the limits within which the values of the coefficient of friction lie.
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Prediction of downwash and dynamic pressure at the tail from free-flight measurements

Prediction of downwash and dynamic pressure at the tail from free-flight measurements

Date: July 1, 1942
Creator: Eujen, E
Description: The present measurements form a continuation of earlier flight tests published in a previous report for predicting the downwash at the tail of an airplane. The method makes use of the tail itself as integrating contact surface to the extent that, beginning from the measurement of the self-alignment of the elevator, the mean downwash angle and dynamic pressure at the tail are determined. The instrumental accuracy is considerably improved if the elevator is completely separate from the controls during the tests, because the effect of friction on the self-alignment of the elevator is then reduced to a minimum and a finer elevator weight balance is rendered possible. The structural design of the push-rod uncoupling mechanism is also described.
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Pressure distribution on wings in reversed flow

Pressure distribution on wings in reversed flow

Date: April 1, 1942
Creator: Naumann, A
Description: The series of pressure distribution measurements at three test sections on NACA airfoils 2212 and M6 within 170 to 210 angles of attack in reversed flow proved to be largely independent of the profile form. In contradiction to the pressure distribution in normal flow considerable negative pressure from the upper surface spills over onto the lower surface, and vice versa, even in the zone of sound flow. The results are presented as chord-wise pressure and load distribution. The spanwise lift distribution and the total lift coefficients of the wing obtained by integration manifest approximate agreement with the behavior of a diagonally disposed flat plate. By consideration of the ground effect (represented by a flat wall) the lower surface of the wing shows an increase in the low pressure.
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Propeller blade stresses caused by periodic displacement of the propeller shaft

Propeller blade stresses caused by periodic displacement of the propeller shaft

Date: June 1, 1942
Creator: Meyer, J
Description: The present report deals with different vibration stresses of the propeller and their removal by an elastic coupling of propeller and engine. A method is described for protecting the propeller from unstable oscillations and herewith from the thus excited alternating gyroscopic moments. The respective vibration equations are set down and the amount of elasticity required is deduced.
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Recent results in rocket flight technique

Recent results in rocket flight technique

Date: April 1, 1942
Creator: Sanger, Eugen
Description: The concept of the effective ejection velocity of a rocket engine is explained and the magnitude of the attainable ejection velocity theoretically and experimentally investigated. Velocities above 3000 meters per second (6700 mph) are actually measured and the possibilities of further increases shown.
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Recording rapidly changing cylinder-wall temperatures

Recording rapidly changing cylinder-wall temperatures

Date: May 1, 1942
Creator: Meier, Adolph
Description: The present report deals with the design and testing of a measuring plug suggested by H. Pfriem for recording quasi-stationary cylinder wall temperatures. The new device is a resistance thermometer, the temperature-susceptible part of which consists of a gold coating applied by evaporation under high vacuum and electrolytically strengthened. After overcoming initial difficulties, calibration of plugs up to and beyond 400 degrees C was possible. The measurements were made on high-speed internal combustion engines. The increasing effect of carbon deposit at the wall surface with increasing operating period is indicated by means of charts.
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