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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.
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.
Contributing Partner: UNT Libraries Government Documents Department
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.
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.
Contributing Partner: UNT Libraries Government Documents Department
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.
Contributing Partner: UNT Libraries Government Documents Department
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.
Contributing Partner: UNT Libraries Government Documents Department
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.
Contributing Partner: UNT Libraries Government Documents Department
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