National Advisory Committee for Aeronautics (NACA) - 14 Matching Results

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Force- and Pressure-Distribution Measurements on Eight Fuselages

Description: The present report deals with force- and pressure-distribution measurements on a number of fuselage forms of varying slenderness ratio, varying rearward position of maximum thickness, and varying nose ratio. The effect of these parameters on the force and moment coefficients was determined. The linearity of the difference between the theoretical and experimental fuselage moments with the friction lift made it possible to indicate a neutral point and its travel with the different parameters. The pressure-distribution measurements yielded absolute values for the increase of velocity. A comparison with the theory indicated good agreement at small angles of attack, but considerable differences at greater angles of attack, where potential flow could no longer be assumed.
Date: October 1, 1948
Creator: Lange, G.
Partner: UNT Libraries Government Documents Department

The Influence of the Diameter Ratio on the Characteristics Diagram of the Axial Compressor

Description: With the further development of axial blowers into highly loaded flow machines, the influence of the diameter ratio upon air output and efficiency gains in significance. Clarification of this matter is important for single-stage axial compressors, and is of still greater importance for multistage ones, and particularly for aircraft power plants. Tests with a single-stage axial blower gave a decrease in the attainable maximum pressure coefficient and optimum efficiency as the diameter ratio increased. The decrease must be ascribed chiefly to the guide surface of the hub and housing between the blades increasing with the diameter ratio.
Date: April 1948
Creator: Eckert, B.; Pflüger, F. & Weinig, F.
Partner: UNT Libraries Government Documents Department

Maintaining Laminar Flow in the Boundary Layer using a Swept-Back Wing

Description: The positions of boundary-layer transition were ascertained experimentally for a swept-back wing and a wing without sweepback which were alike in all other respects and were compared for the same angle of attack (R(sub e) = 5.6 x 10(exp 5)). The swept-back wing in a definite range of angle of attack resulted in a backward shift of the transition point on the suction side of the wing. The favorable effect of sweepback on the position of the transition point is confirmed, consequently. In addition to decreasing the drag at high Mach numbers, the swept-back wing is acknowledged to have additional advantages. These are: (1) Decrease of the pressure drag. The reduction factor is approximately equal to the cosine of the angle of sweepback. (2) Backward shift of the transition point. There are no known experiments which establish experimentally the advantage anticipated. It appeared justifiable, therefore, to carry out some fundamental experiments which might furnish some idea of the magnitude of the advantage expected. Such an experiment is reported in what follows; the advantage of the sweepback appears clearly.
Date: February 1, 1948
Creator: Brennecke
Partner: UNT Libraries Government Documents Department

Measurements on Compressor-Blade Lattices

Description: From Summary: "At the end of 1940 an investigation of a guide-vane lattice for the compressor of a TL unit [NACA comment: Turbojet] was requested. The greatest possible Mach number had to be attained. The investigation was conducted with an annular lattice subjected to axial flow. A direct-current shunt motor with a useful output of 235 horsepower at an engine speed of 1800 qm was available for driving the necessary blower."
Date: August 1948
Creator: Weinig, F.
Partner: UNT Libraries Government Documents Department

Nonstationary Gas Flow in Thin Pipes of Variable Cross Section

Description: Characteristic methods for nonstationary flows have been published only for the special case of the isentropic flow up until the present, althought they are applicable in various places to more difficult questions too. This report derives the characteristic method for the flows which depend only on the position coordinates and time. At the same time the treatment of compression shocks is shown.
Date: December 1, 1948
Creator: Guderley, G.
Partner: UNT Libraries Government Documents Department

On the Sound Field of a Rotating Propeller

Description: The sound field of a rotating propeller is teated theoretically on the basis of aerodynamic principles. For the lower harmonics, the directional characteristics and the radiated sound energy are determined and are in conformity with existing experimental results.
Date: October 1, 1948
Creator: Gutin, L.
Partner: UNT Libraries Government Documents Department

Planing of Watercraft

Description: The present report deals with the processes accompanying the planing of a planing boat or a seaplane on water . The study is largely based upon theoretical investigations; mathematical problems and proofs are not discussed. To analyze theoreticaly actual planing processes, giving due consideration to all aspects of the problem, is probably not possible. The theories therefore treat various simple limiting cases, which in their entirety give a picture of the planing processes and enable the interpretation of the experimental results. The discussion is concerned with the stationary planing attitude: the boat planes at a constant speed V on an originally smooth surface.
Date: April 1, 1948
Creator: Wagner, Herbert
Partner: UNT Libraries Government Documents Department

The Problem of Torsion in Prismatic Members of Circular Segmental Cross Section

Description: The problem is solved by approximation, by setting up a function complying with the differential equation of the stress function, and determining the coefficients appearing in it in such a way that the boundary condition is fulfilled as nearly as possible. For the semicircle, for which the solution is known, the method yields very accurate values; the approximated stress distribution is in good agreement with the accurately computed distribution. Stress and strain measurements indicate that the approximate solution is in sufficiently exact agreement with reality for segmental cross sections.
Date: September 1, 1948
Creator: Weigand, A.
Partner: UNT Libraries Government Documents Department

Test Report on Three- and Six-Component Measurements on a Series of Tapered Wings of Small Aspect Ratio

Description: The investigations of the reports to 4 on wings of small aspect ratio are continued. The present report deals with the results of the three- and six-component measurements and the flow pictures of the triangular wing series with the aspect ratio Lambda = 3 to Lambda = 1.
Date: May 1, 1948
Creator: Lange & Wacke
Partner: UNT Libraries Government Documents Department

Theoretical Analysis of Stationary Potential Flows and Boundary Layers at High Speed

Description: The present report consists of two parts. The first part deals with the two-dimensional stationary flow in the presence of local supersonic zones. A numerical method of integration of the equation of gas dynamics is developed. Proceeding from solutions at great distance from the body the flow pattern is calculated step by step. Accordingly the related body form is obtained at the end of the calculation. The second part treats the relationship between the displacement thickness of laminar and turbulent boundary layers and the pressure distribution at high speeds. The stability of the boundary layer is investigated, resulting in basic differences in the behavior of subsonic and supersonic flows. Lastly, the decisive importance of the boundary layer for the pressure distribution, particularly for thin profiles, is demonstrated.
Date: April 1948
Creator: Oswaititsch, K. & Wieghardt, K.
Partner: UNT Libraries Government Documents Department

Venturi Tube with Varying Mass Flow

Description: Measurements on three tubes with flow regulated by suction at the trainling edge of the tube are described. It was possible to vary the mass of air flowing through the tube over a large range. Such tubes could be used for shrouded propellers.
Date: March 1, 1948
Creator: Regenscheit, B.
Partner: UNT Libraries Government Documents Department

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

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.
Date: April 1, 1948
Creator: Weber & Kehl
Partner: UNT Libraries Government Documents Department