Serial/Series Title
Country
Month
1,423 Matching Results
Results open in a new window/tab.
Results:
1 - 24 of
1,423
next
Determination of the Profile Drag of an Airplane Wing in Flight at High Reynolds Numbers
Report presenting flight tests to determine the profile-drag coefficients of a portion of the original wing surface of an all-metal airplane and a portion of the wing made aerodynamically smooth and more nearly fair than the original section. Tests were also carried out to determine the point of transition from laminar to turbulent boundary layer and to determine the velocity distribution along the upper surface of the wing.
Date:
1939
Creator:
Bicknell, Joseph
System:
The UNT Digital Library
A theoretical study of the effect of forward speed on the free-space sound-pressure field around propellers
Report presenting an analysis of the sound-pressure field of a rotating propeller in forward flight in free space by replacing the normal-pressure distribution over the propeller associated with thrust and torque by a distribution of acoustic pressure doublets acting at the propeller disk. The result is presented for a moving and a fixed observer.
Date:
1954
Creator:
Garrick, I. E. & Watkins, Charles E.
System:
The UNT Digital Library
General Theory of Aerodynamic Instability and the Mechanism of Flutter
"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" (p. 291).
Date:
May 2, 1934
Creator:
Theodorsen, Theodore
System:
The UNT Digital Library
Blockage Corrections for Three-Dimensional-Flow Closed-Throat Wind Tunnels, with Consideration of the Effect of Compressibility
"Theoretical blockage corrections are presented for a body of revolution and for a three-dimensional, unswept wing in a circular or rectangular wind tunnel. The theory takes account of the effects of the wake and of the compressibility of the fluid, and is based on the assumption that the dimensions of the model are small in comparison with those of the tunnel throat. Formulas are given for correcting a number of the quantities, such as dynamic pressure and Mach number, measured in wind tunnel tests" (p. 771).
Date:
1950
Creator:
Herriot, John G.
System:
The UNT Digital Library
The Theory of the Pitot and Venturi Tubes, Part 2
Report discussing several aspects of pitot and venturi tubes, including the energy equation for steady adiabatic flow, introduction of mean speed into the energy equation, isentropic flow of an ideal gas, the theory of the pitot tube, and the theory of the venturi meter.
Date:
1989?
Creator:
Buckingham, E.
System:
The UNT Digital Library
Applications of Modern Hydrodynamics to Aeronautics Part 1: Fundamental Concepts and the Most Important Theorems. Part 2: Applications
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.
Date:
1979%
Creator:
Prandtl, L.
System:
The UNT Digital Library
The Minimum Induced Drag of Aerofoils
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.
Date:
1979-12?
Creator:
Munk, Max M.
System:
The UNT Digital Library
The Aerodynamic Forces on Airship Hulls
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.
Date:
1979%
Creator:
Munk, Max M.
System:
The UNT Digital Library
Elements of the Wing Section Theory and of the Wing Theory
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.
Date:
1925
Creator:
Munk, Max M.
System:
The UNT Digital Library
The Inertia Coefficients of an Airship in a Frictionless Fluid
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.
Date:
1924
Creator:
Bateman, H.
System:
The UNT Digital Library
Flow and Drag Formulas for Simple Quadrics
The pressure distribution and resistance found by theory and experiment for simple quadrics fixed in an infinite uniform stream of practically incompressible fluid are calculated. The experimental values pertain to air and some liquids, especially water; the theoretical refer sometimes to perfect, again to viscid fluids. Formulas for the velocity at all points of the flow field are given. Pressure and pressure drag are discussed for a sphere, a round cylinder, the elliptic cylinder, the prolate and oblate spheroid, and the circular disk. The velocity and pressure in an oblique flow are examined.
Date:
December 1979
Creator:
Zahm, A. F.
System:
The UNT Digital Library
Flow and Force Equations for a Body Revolving in a Fluid
A general method for finding the steady flow velocity relative to a body in plane curvilinear motion, whence the pressure is found by Bernoulli's energy principle is described. Integration of the pressure supplies basic formulas for the zonal forces and moments on the revolving body. The application of the steady flow method for calculating the velocity and pressure at all points of the flow inside and outside an ellipsoid and some of its limiting forms is presented and graphs those quantities for the latter forms.
Date:
December 1979
Creator:
Zahm, A. F.
System:
The UNT Digital Library
General Potential Theory of Arbitrary Wing Sections
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.
Date:
November 4, 1932
Creator:
Theodorsen, T. & Garrick, I. E.
System:
The UNT Digital Library
Impingement of Cloud Droplets on a Cylinder and Procedure for Measuring Liquid-Water Content and Droplet Sizes in Supercooled Clouds by Rotating Multicylinder Method
"Evaluation of the rotating multicylinder method for the measurement of droplet-size distribution, volume-median droplet size, and liquid-water content in clouds showed that small uncertainties in the basic data eliminate the distinction between different cloud droplet-size distributions and are a source of large errors in the determination of the droplet size. Calculations of the trajectories of cloud droplets in incompressible and compressible flow fields around a cylinder were performed on a mechanical analog constructed for the study of the trajectories of droplets around aerodynamic bodies" (p. 1).
Date:
September 5, 1952
Creator:
Brun, R. J.; Lewis, W.; Perkins, P. J. & Serafini, J. S.
System:
The UNT Digital Library
Determination of Stresses in Gas-turbine Disks Subjected to Plastic Flow and Creep
From Summary: "A finite-difference method previously presented for computing elastic stresses in rotating disks is extended to include the computation of the disk stresses when plastic flow and creep are considered. A finite-difference method is employed to eliminate numerical integration and to permit nontechnical personnel to make the calculations with a minimum of engineering supervision. Illustrative examples are included to facilitated explanation of the procedure by carrying out the computations on a typical gas-turbine disk through a complete running cycle."
Date:
1948
Creator:
Millenson, M. B. & Manson, S. S.
System:
The UNT Digital Library
Design of Wind Tunnels and Wind Tunnel Propellers, 2
Report presenting a continuation of a previous study in order to supply further data to the designers of wind tunnels. Particular emphasis was placed on the study of directional variation in the wind stream. The results indicated that placing radial vanes directly before the propeller actually increased the efficiency of the tunnel to a considerable extent.
Date:
1921
Creator:
Norton, F. H. & Warner, E. P.
System:
The UNT Digital Library
On the plane potential flow past a lattice of arbitrary airfoils
The two-dimensional, incompressible potential flow past a lattice of airfoils of arbitrary shape is investigated theoretically. The problem is treated by usual methods of conformal mapping in several stages, one stage corresponding to the mapping of the framework of the arbitrary line lattice and another significant stage corresponding to the Theodorsen method for the mapping of the arbitrary single wing profile into a circle. A particular feature in the theoretical treatment is the special handling of the regions at an infinite distance in front of and behind the lattice. Expressions are given for evaluation of the velocity and pressure distribution at the airfoil boundary. An illustrative numerical example is included.
Date:
November 19, 1943
Creator:
Garrick, I. E.
System:
The UNT Digital Library
Icing-protection requirements for reciprocating-engine induction system
From Summary: "Despite the development of relatively ice-free fuel-metering systems, the widespread use of alternate and heated-air intakes, and the use of alcohol for emergency de-icing, icing of aircraft-engine induction systems is a serious problem. Investigations have been made to study and to combat all phases of this icing problem. From these investigations, criterions for safe operation and for design of new induction systems have been established. The results were obtained from laboratory investigations of carburetor-supercharger combinations, wind-tunnel investigations of air scoops, multicylinder-engine studies, and flight investigations. Characteristics of three forms of ice, impact, throttling, and fuel evaporation were studied."
Date:
June 20, 1949
Creator:
Coles, Willard D.; Rollin, Vern G. & Mulholland, Donald R.
System:
The UNT Digital Library
Line-Vortex Theory for Calculation of Supersonic Downwash
"The perturbation field induced by a line vortex in a supersonic stream and the downwash behind a supersonic lifting surface are examined to establish approximate methods for determining the downwash behind supersonic wings. Lifting-lines methods are presented for calculating supersonic downwash. A bent lifting-line method is proposed for computing the downwash field behind swept wings. When applied to triangular wings with subsonic leading edges, this method gives results that, in general, are in good agreement with the exact linearized solution" (p. 635).
Date:
April 29, 1949
Creator:
Mirels, Harold & Haefeli, Rudolph C.
System:
The UNT Digital Library
A radar method of calibrating airspeed installations on airplanes in maneuvers at high altitudes and at transonic and supersonic speeds
A method of calibrating the static-pressure source of a pitot static airspeed installation on an airplane in level flight, dives, and other maneuvers at high altitude and at transonic and supersonic speeds is described. The method principally involves the use of radar-phototheodolite tracking equipment. The various sources of error in the method are discussed and sample calibrations are included.
Date:
August 31, 1949
Creator:
Zalovcik, John A.
System:
The UNT Digital Library
The reversibility theorem for thin airfoils in subsonic and supersonic flow
A method introduced by Munk is extended to prove that the light-curve slope of thin wings in either subsonic flow or supersonic flow is the same when the direction of flight of the wing is reversed. It is also shown that the wing reversal does not change the thickness drag, damping-in-roll parameter or the damping-in-pitch parameter.
Date:
June 26, 1949
Creator:
Brown, Clinton E.
System:
The UNT Digital Library
Equilibrium Operating Performance of Axial-Flow Turbojet Engines by Means of Idealized Analysis
"A method of predicting equilibrium operating performance of turbojet engines has been developed, with the assumption of simple model processes for the components. Results of the analysis are plotted in terms of dimensionless parameters comprising critical engine dimensions and over-all operating variables. This investigation was made of an engine in which the ratio of axial inlet-air velocity to compressor-tip velocity is constant, which approximates turbojet engines with axial-flow compressors" (p. 673).
Date:
February 25, 1949
Creator:
Sanders, John C. & Chapin, Edward C.
System:
The UNT Digital Library
Comparative drag measurements at transonic speeds of rectangular sweptback NACA 65-009 airfoils mounted on a freely falling body
From Summary: "Directly comparable drag measurements have been made of an airfoil with a conventional rectangular plan form and an airfoil with a sweptback plan form mounted on freely falling bodies. Both airfoils had NACA 65-009 sections and were identical in span, frontal area, and chord perpendicular to the leading edge. The sweptback plan form incorporated a sweepback angle of 45 degrees. The data obtained have been used to establish the relation between the airfoil drag coefficients and the free-stream Mach number over a range of Mach numbers from 0.90 to 1.27. The results of the measurements indicate that the drag of the sweptback plan form is less than 0.3 that of the rectangular plan form at a Mach number of 1.00 and is less than 0.4 that at a Mach number of 1.20."
Date:
August 9, 1945
Creator:
Mathews, Charles W. & Thompson, Jim Rogers
System:
The UNT Digital Library
Theoretical comparison of several methods of thrust augmentation for turbojet engines
"A theoretical investigation of tail-pipe burning, water injection at the compressor inlet, combination tail-pipe burning plus water injection, bleedoff, and rocket-assist methods thrust augmentation for turbojet engines was made for an engine representative of those in current use. The effect of augmented liquid ratio on augmented thrust ratio and the effects of altitude and flight Mach number on the performance of various methods were determined. The additional take-off weight involved by the use of the different thrust augmentation methods, as well as the effect of the various thrust augmentation methods on the range of a representative aircraft was also investigated" (p. 727).
Date:
October 27, 1948
Creator:
Hall, Eldon W. & Wilcox, E. Clinton
System:
The UNT Digital Library