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  Partner: UNT Libraries Government Documents Department
 Decade: 1940-1949
 Serial/Series Title: NACA Technical Memorandums
 Collection: Technical Report Archive and Image Library
Supplement to Comparison of automatic control systems

Supplement to Comparison of automatic control systems

Date: August 1, 1941
Creator: Oppelt, W
Description: This analysis deals with the indirect regulator, wherefrom the behavior of the direct regulator is deduced as a limiting case. The prime mover is looked upon as "independent of the load": a change in the adjusting power (to be applied) for the control link (as, for example, in relation to the adjusting path (eta) with pressure valves or the rudder of vessels) does not modify the actions of the prime mover. Mass forces and friction are discounted; "clearance" also is discounted in the transmission links of the regulator.
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Method of characteristics for three-dimensional axially symmetrical supersonic flows.

Method of characteristics for three-dimensional axially symmetrical supersonic flows.

Date: January 1, 1947
Creator: Sauer, R
Description: An approximation method for three-dimensional axially symmetrical supersonic flows is developed; it is based on the characteristics theory (represented partly graphically, partly analytically). Thereafter this method is applied to the construction of rotationally symmetrical nozzles. (author).
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On laminar and turbulent friction

On laminar and turbulent friction

Date: September 1, 1946
Creator: Von Karman, TH
Description: Report deals, first with the theory of the laminar friction flow, where the basic concepts of Prandtl's boundary layer theory are represented from mathematical and physical points of view, and a method is indicated by means of which even more complicated cases can be treated with simple mathematical means, at least approximately. An attempt is also made to secure a basis for the computation of the turbulent friction by means of formulas through which the empirical laws of the turbulent pipe resistance can be applied to other problems on friction drag. (author).
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A Ram-Jet Engine for Fighters

A Ram-Jet Engine for Fighters

Date: October 1, 1947
Creator: Sanger, E & Bredt, I
Description: Simple and accurate calculations are made of the flow process in a continuous compressorless Lorin jet-propulsion unit. Experimental confirmation is given from towing tests on an airplane at flying speeds up to 200 miles per second. An analysis is made of the performance of a fighter-type airplane designed for utilization of this propulsion system.
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Force and pressure-distribution measurements on a rectangular wing with a slotted droop nose and with either plain and split flaps in combination or a slotted flap.

Force and pressure-distribution measurements on a rectangular wing with a slotted droop nose and with either plain and split flaps in combination or a slotted flap.

Date: March 1, 1947
Creator: Lemme, H G
Description: Force measurements and pressure distribution measurements on the midsection were made on a rectangular wing with slotted droop nose and end plates, on which could be placed a choice of either a plain flap-split flap combination or a slotted flap. (author).
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Investigations on the stability, oscillation, and stress conditions of airplanes with tab control.  Second partial report : application of the solutions  obtained in the first partial report to tab-controlled airplanes.

Investigations on the stability, oscillation, and stress conditions of airplanes with tab control. Second partial report : application of the solutions obtained in the first partial report to tab-controlled airplanes.

Date: September 1, 1949
Creator: Filzek, B
Description: The first partial report, FB 2000, contained a discussion of the derivation of the equations of motion and their solutions for a tab-controlled airplane; the results obtained there are now to be applied to the longitudinal motion of tab-controlled airplanes. In view of the abundance of structural factors and aerodynamic parameters, a general discussion of the problems is unfeasible. Thus it is demonstrated on the basis of examples what stability, oscillation, and stress conditions are to be expected for tab-controlled airplanes. (author).
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Airfoil measurements in the DVL high-speed wind tunnel (2.7-meter diameter)

Airfoil measurements in the DVL high-speed wind tunnel (2.7-meter diameter)

Date: June 1, 1949
Creator: Gothert, B
Description: Report is a brief summary of investigations on symmetrical and cambered airfoils in the DVL high-speed tunnel. Some information on the effects of low aspect ratio are also included.
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Investigation of the Behavior of Thin-Walled Panels with Cutouts

Investigation of the Behavior of Thin-Walled Panels with Cutouts

Date: September 1, 1946
Creator: Podorozhny, A. A.
Description: The present paper deals with the computation and methods of reinforcement of stiffened panels with cutouts under bending loads such as are applied to the sides of a fuselage. A comparison is maade between the computed and test results. Results are presented of tests on panels with cutouts under tensile and compressive loads.
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Investigations of Compression Shocks and Boundary Layers in Gases Moving at High Speed

Investigations of Compression Shocks and Boundary Layers in Gases Moving at High Speed

Date: January 1, 1947
Creator: Ackeret, J.; Feldmann, F. & Rott, N.
Description: The mutual influences of compression shocks and friction boundary layers were investigated by means of high speed wind tunnels.Schlieren optics provided a clear picture of the flow phenomena and were used for determining the location of the compression shocks, measurement of shock angles, and also for Mach angles. Pressure measurement and humidity measurements were also taken into consideration.Results along with a mathematical model are described.
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The Calculation of Compressible Flows with Local Regions of Supersonic Velocity

The Calculation of Compressible Flows with Local Regions of Supersonic Velocity

Date: March 1, 1947
Creator: Goethert, B. & Kawalki, K. H.
Description: This report addresses a method for the approximate calculation of compressible flows about profiles with local regions of supersonic velocity. The flow around a slender profile is treated as an example.
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Drag Reduction by Suction of the Boundary Layer Separated Behind Shock Wave Formation at High Mach Numbers

Drag Reduction by Suction of the Boundary Layer Separated Behind Shock Wave Formation at High Mach Numbers

Date: July 1, 1947
Creator: Regenscheit, B.
Description: With an approach of the velocity of flight of a ship to the velocity of sound, there occurs a considerable increase of the drag. The reason for this must be found in the boundary layer separation caused by formation of shock waves. It will be endeavored to reduce the drag increase by suction of the boundary layer. Experimental results showed that drag increase may be considerably reduced by this method. It was, also, observed that, by suction, the position of shock waves can be altered to a considerable extent.
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Temperatures and Stresses on Hollow Blades For Gas Turbines

Temperatures and Stresses on Hollow Blades For Gas Turbines

Date: September 1, 1947
Creator: Pollmann, Erich
Description: The present treatise reports on theoretical investigations and test-stand measurements which were carried out in the BMW Flugmotoren GMbH in developing the hollow blade for exhaust gas turbines. As an introduction the temperature variation and the stress on a turbine blade for a gas temperature of 900 degrees and circumferential velocities of 600 meters per second are discussed. The assumptions onthe heat transfer coefficients at the blade profile are supported by tests on an electrically heated blade model. The temperature distribution in the cross section of a blade Is thoroughly investigated and the temperature field determined for a special case. A method for calculation of the thermal stresses in turbine blades for a given temperature distribution is indicated. The effect of the heat radiation on the blade temperature also is dealt with. Test-stand experiments on turbine blades are evaluated, particularly with respect to temperature distribution in the cross section; maximum and minimum temperature in the cross section are ascertained. Finally, the application of the hollow blade for a stationary gas turbine is investigated. Starting from a setup for 550 C gas temperature the improvement of the thermal efficiency and the fuel consumption are considered as well as the increase of ...
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Gas Jets

Gas Jets

Date: August 1, 1944
Creator: Chaplygin, S.
Description: A brief summary of the contents of this paper is presented here. In part I the differential equations of the problem of a gas flow in two dimensions is derived and the particular integrals by which the problem on jets is solved are given. Use is made of the same independent variables as Molenbroek used, but it is found to be more suitable to consider other functions. The stream function and velocity potential corresponding to the problem are given in the form of series. The investigation on the convergence of these series in connection with certain properties of the functions entering them forms the subject of part II. In part III the problem of the outflow of a gas from an infinite vessel with plane walls is solved. In part IV the impact of a gas jet on a plate is considered and the limiting case where the jet expands to infinity changing into a gas flow is taken up in more detail. This also solved the equivalent problem of the resistance of a gaseous medium to the motion of a plate. Finally, in part V, an approximate method is presented that permits a simpler solution of the problem of ...
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Investigations on Experimental Impellers for Axial Blowers

Investigations on Experimental Impellers for Axial Blowers

Date: April 1, 1947
Creator: Encke, W.
Description: A selection of measurements obtained on experimental impellers for axial blowers will be reported. In addition to characteristic curves plotted for low and for high peripheral velocities, proportions and blade sections for six different blower models and remarks on the design of blowers will be presented.
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Investigation of Flow in a Centrifugal Pump

Investigation of Flow in a Centrifugal Pump

Date: July 1, 1946
Creator: Fischer, Karl
Description: The investigation of the flow in a centrifugal pump indicated that the flow patterns in frictional fluid are fundamentally different from those in frictionless fluid. In particular, the dead air space adhering to the section side undoubtedly causes a reduction of the theoretically possible delivery head. The velocity distribution over a parallel circle is also subjected to a noticeable change as a result of the incomplete filling of the passages. The relative velocity on the pressure side of the vane, which for passages completely filled with active flow would differ little from zero even at comparatively lower than normal delivery volume, is increased, so that no rapid reverse flow occurs on the pressure side of the vane even for smaller delivery volume. It was established, further, that the flow ceases to be stationary for very small quantities of water. The inflow to the impeller can be regarded as radial for the operating range an question. The velocity triangles at the exit are subjected to a significant alteration in shape ae a result of the increased peripheral velocity, which may be of particular importance in the determination of the guide vane entrance angle.
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The Flow Through Axial Turbine Stages of Large Radial Blade Length

The Flow Through Axial Turbine Stages of Large Radial Blade Length

Date: April 1, 1947
Creator: Eckert & Korbacher
Description: A calulation of the flow in turbine blading is reported that includes the calculation of effect of centrifugal force. Frictional losses on the stator blades and rotor blades are allowed.
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Gas-Dynamic Investigations of the Pulse-Jet Tube, Parts 1 and 2

Gas-Dynamic Investigations of the Pulse-Jet Tube, Parts 1 and 2

Date: February 1, 1947
Creator: Shultz-Grunow, F.
Description: Based upon a simplified representation of the mode of operation of the pulse-jet tube, the effect of the influences mentioned in the title were investigated and it will be shown that, for a jet tube with a fccmndesigned to be aerodynamically favorable, the ability to operate is at least questionable. By taking into account the course of the development of pressure by combustion, a new insight has been obtained into the processes of motion within the jet tube, an insight that explains a number of empirical observations, namely: certain particulars of the sequence of pressure variations; the existence of an optimum valve-opening ratio; the occurrence of an intrusion of air; and the existence of a flight speed above lrhichthe jet tube ceases to operate. At too great an opening ratio or at too great a flight s-peed, the continuous flow through the tube is too predominant over the oscilla~ory process to perinitthe occurrence of an explosion powerful enough to maintain continuous operation. Certain possible means of making the operation of the jet tube more independent of the flight speed and of reducing the flow losses were proposed and discussed.
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Some Basic Laws of Isotropic Turbulent Flow

Some Basic Laws of Isotropic Turbulent Flow

Date: September 1, 1945
Creator: Loitsianskii, L. G.
Description: An Investigation is made of the diffusion of artificially produced turbulence behind screens or other turbulence producers. The method is based on the author's concept of disturbance moment as a certain theoretically well-founded measure of turbulent disturbances.
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Theory of Wings in Nonstationary Flow

Theory of Wings in Nonstationary Flow

Date: June 1, 1947
Creator: Nekrasov, A. I.
Description: This paper gives an overview of equations for vibration and flutter affecting airplane wings in nonstationary flow.
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Possibilities of Reducing the Length of Axial Superchargers for Aircraft Motors

Possibilities of Reducing the Length of Axial Superchargers for Aircraft Motors

Date: January 1, 1947
Creator: Eckert, B.
Description: Axial blowers are gaining importance as aircraft engine superchargers. However, the pressure head obtainable per stage is small. Due to the necessary great number of stages, the physical length of the blower becomes too great for an airworthy device. This report discusses several types of construction that permit a reduction in the length of the blower.
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Wind-Tunnel Measurements on the Henschel Missile "Zitterrochen" in Subsonic and Supersonic Velocities

Wind-Tunnel Measurements on the Henschel Missile "Zitterrochen" in Subsonic and Supersonic Velocities

Date: April 1, 1948
Creator: Weber & Kehl
Description: At the request of the Henschel Aircraft Works. A. G. Berlin. three models of the missile "Zitterrochen" were investigated at subsonic velocities.(open jet 215-millimeter diameter) and at supersonic velocities (open jet 110 by 130 millimeters) in order to determine the effect of various wing forms on the air forces and moments. Three-component measurements were taken, and one model was also investigated with deflected control plates.
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Calculations and Experimental Investigations on the Feed-Power Requirement of Airplanes with Boundary-Layer Control

Calculations and Experimental Investigations on the Feed-Power Requirement of Airplanes with Boundary-Layer Control

Date: September 1, 1947
Creator: Krueger, W.
Description: Calculations and test results are given about the feed-power requirement of airplanes with boundary-layer control. Curves and formulas for the rough estimate of pressure-loss and feed-power requirement are set up for the investigated arrangements which differ structurally and aerodynamically. According to these results the feed power for three different designs is calculated at the end of the report.
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Susceptibility to Welding Cracking, Welding Sensitivity, Susceptibility to Welding Seam Cracking, and Test Methods for These Failures

Susceptibility to Welding Cracking, Welding Sensitivity, Susceptibility to Welding Seam Cracking, and Test Methods for These Failures

Date: June 1, 1949
Creator: Zeyen, K. L.
Description: In the years after the First World war a very rapid development, which even today has by no means come to an end, took place in the field of welding; here also, as in most technical innovations, failures made their appearance. Thereupon comprehensive Investigations were undertaken by steel manufacturers and consumers with cooperation of the authorities. b most cases the reasons for failure could be determined and eliminated and further occurrences avoided by the use of new test methods.
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On the Motions of an Oscillating System Under the Influence of Flip-Flop Controls

On the Motions of an Oscillating System Under the Influence of Flip-Flop Controls

Date: November 1, 1949
Creator: Fluegge-Lotz, I. & Klotter, K.
Description: So-called flip-flop controls (also called "on-off-course controls") are frequently preferred to continuous controls because of their simple construction. Thus they are used also for the steering control of airplanes. Such a body possesses-even if one thinks, for instance, only of the symmetric longitudinal motion - three degrees of freedom so that a study of its motions under the influence of an intermittent control is at least lengthy. Thus, it is suggested that an investigation of the basic effect of such a control first be made on a system with one degree of freedom. Furthermore, we limit ourselves in the resent report to the investigation of an "ideal" control where the control surface immediately obeys the command given by the "steering control function". Thus the oscillation properties of the control surface and the defects in linkage, sensing element, and mixing device are, at first, neglected. As long as the deviations from the "ideal" control may be neglected in practice, also the motion of the control surface takes place at the heat of the motion of the principal system. The aim of our investigation is to obtain a survey of the influence of the system and control coefficients on the damping behavior ...
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