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 Decade: 1970-1979
 Year: 1979
 Collection: National Advisory Committee for Aeronautics Collection
The Inertia Coefficients of an Airship in a Frictionless Fluid

The Inertia Coefficients of an Airship in a Frictionless Fluid

Date: December 1, 1979
Creator: Bateman, H.
Description: The apparent inertia of an airship hull is examined. The exact solution of the aerodynamical problem is studied for hulls of various shapes with special attention given to the case of an ellipsoidal hull. So that the results for the ellipsoidal hull may be readily adapted to other cases, they are expressed in terms of the area and perimeter of the largest cross section perpendicular to the direction of motion by means of a formula involving a coefficient kappa which varies only slowly when the shape of the hull is changed, being 0.637 for a circular or elliptic disk, 0.5 for a sphere, and about 0.25 for a spheroid of fineness ratio. The case of rotation of an airship hull is investigated and a coefficient is defined with the same advantages as the corresponding coefficient for rectilinear motion.
Contributing Partner: UNT Libraries Government Documents Department
Pressure Distribution on Joukowski Wings

Pressure Distribution on Joukowski Wings

Date: December 1, 1979
Creator: Blumenthal, O.
Description: The hydrodynamics and mathematical models as applied to the potential flow about a Joukowski wing are presented.
Contributing Partner: UNT Libraries Government Documents Department
The Aerodynamic Forces on Airship Hulls

The Aerodynamic Forces on Airship Hulls

Date: December 1, 1979
Creator: Munk, M. M.
Description: The new method for making computations in connection with the study of rigid airships, which was used in the investigation of Navy's ZR-1 by the special subcommittee of the National Advisory Committee for Aeronautics appointed for this purpose is presented. The general theory of the air forces on airship hulls of the type mentioned is described and an attempt was made to develop the results from the very fundamentals of mechanics.
Contributing Partner: UNT Libraries Government Documents Department
The Minimum Induced Drag of Aerofoils

The Minimum Induced Drag of Aerofoils

Date: December 1, 1979
Creator: Munk, M. M.
Description: Equations are derived to demonstrate which distribution of lifting elements result in a minimum amount of aerodynamic drag. The lifting elements were arranged (1) in one line, (2) parallel lying in a transverse plane, and (3) in any direction in a transverse plane. It was shown that the distribution of lift which causes the least drag is reduced to the solution of the problem for systems of airfoils which are situated in a plane perpendicular to the direction of flight.
Contributing Partner: UNT Libraries Government Documents Department
Elements of the Wing Section Theory and of the Wing Theory

Elements of the Wing Section Theory and of the Wing Theory

Date: December 1, 1979
Creator: Munk, Max M.
Description: Results are presented of the theory of wings and of wing sections which are of immediate practical value. They are proven and demonstrated by the use of the simple conceptions of kinetic energy and momentum only.
Contributing Partner: UNT Libraries Government Documents Department
Remarks on the Pressure Distribution over the Surface of an Ellipsoid, Moving Translationally Through a Perfect Fluid

Remarks on the Pressure Distribution over the Surface of an Ellipsoid, Moving Translationally Through a Perfect Fluid

Date: December 1, 1979
Creator: Munk, Max M.
Description: The pressure distribution over ellipsoids when in translatory motion through a perfect fluid is calculated. A method to determine the magnitude of the velocity and of the pressure at each point of the surface of an ellipsoid of rotation is described.
Contributing Partner: UNT Libraries Government Documents Department
Applications of Modern Hydrodynamics to Aeronautics. Part 1: Fundamental Concepts and the Most Important Theorems. Part 2: Applications

Applications of Modern Hydrodynamics to Aeronautics. Part 1: Fundamental Concepts and the Most Important Theorems. Part 2: Applications

Date: December 1, 1979
Creator: Prandtl, L.
Description: A discussion of the principles of hydrodynamics of nonviscous fluids in the case of motion of solid bodies in a fluid is presented. Formulae are derived to demonstrate the transition from the fluid surface to a corresponding 'control surface'. The external forces are compounded of the fluid pressures on the control surface and the forces which are exercised on the fluid by any solid bodies which may be inside of the control surfaces. Illustrations of these formulae as applied to the acquisition of transformations from a known simple flow to new types of flow for other boundaries are given. Theoretical and experimental investigations of models of airship bodies are presented.
Contributing Partner: UNT Libraries Government Documents Department
General Potential Theory of Arbitrary Wing Sections

General Potential Theory of Arbitrary Wing Sections

Date: December 1, 1979
Creator: Theodorsen, T.
Description: The problem of determining the two dimensional potential flow around wing sections of any shape is examined. The problem is condensed into the compact form of an integral equation capable of yielding numerical solutions by a direct process. An attempt is made to analyze and coordinate the results of earlier studies relating to properties of wing sections. The existing approximate theory of thin wing sections and the Joukowski theory with its numerous generalizations are reduced to special cases of the general theory of arbitrary sections, permitting a clearer perspective of the entire field. The method which permits the determination of the velocity at any point of an arbitrary section and the associated lift and moments is described. The method is also discussed in terms for developing new shapes of preassigned aerodynamical properties.
Contributing Partner: UNT Libraries Government Documents Department
General Theory of Aerodynamic Instability and the Mechanism of Flutter

General Theory of Aerodynamic Instability and the Mechanism of Flutter

Date: December 1, 1979
Creator: Theodorsen, Theodore
Description: The aerodynamic forces on an oscillating airfoil or airfoil-aileron combination of three independent degrees of freedom were determined. The problem resolves itself into the solution of certain definite integrals, which were identified as Bessel functions of the first and second kind, and of zero and first order. The theory, based on potential flow and the Kutta condition, is fundamentally equivalent to the conventional wing section theory relating to the steady case. The air forces being known, the mechanism of aerodynamic instability was analyzed. An exact solution, involving potential flow and the adoption of the Kutta condition, was derived. The solution is of a simple form and is expressed by means of an auxiliary parameter k. The flutter velocity, treated as the unknown quantity, was determined as a function of a certain ratio of the frequencies in the separate degrees of freedom for any magnitudes and combinations of the airfoil-aileron parameters.
Contributing Partner: UNT Libraries Government Documents Department
Graphic Construction of Joukowski Wings

Graphic Construction of Joukowski Wings

Date: December 1, 1979
Creator: Trefftz, E.
Description: A plot of the cross sectional outline of a Joukowski wing is presented.
Contributing Partner: UNT Libraries Government Documents Department
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