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Minimum-drag ducted and pointed bodies of revolution based on linearized supersonic theory (open access)

Minimum-drag ducted and pointed bodies of revolution based on linearized supersonic theory

The linearized drag integral for bodies of revolution at supersonic speeds is presented in a double-integral form which is not based on slender-body approximations but which reduces to the equal slender-body expression in the proper limit. With the aid of a suitably chosen auxiliary condition, the minimum-external-wave-drag problem is solved for a transition section connecting two semi-infinite cylinders. The projectile tip is a special case and is compared with the Von Karman projectile tip. Calculations are presented which indicate that the method of analysis gives good first-order results in the moderate supersonic range.
Date: March 1, 1954
Creator: Parker, Hermon M.
System: The UNT Digital Library
An analysis of once-per-revolution oscillating aerodynamic thrust loads on single-rotation propellers on tractor airplanes at zero yaw (open access)

An analysis of once-per-revolution oscillating aerodynamic thrust loads on single-rotation propellers on tractor airplanes at zero yaw

A simplified procedure is shown for calculating the once-per-revolution oscillating aerodynamic thrust loads on propellers of tractor airplanes at zero yaw. The only flow field information required for the application of the procedure is a knowledge of the upflow angles at the horizontal center line of the propeller disk. Methods are presented whereby these angles may be computed without recourse to experimental survey of the flow field. The loads computed by the simplified procedure are compared with those computed by a more rigorous method and the procedure is applied to several airplane configurations which are believed typical of current designs. The results are generally satisfactory.
Date: March 21, 1955
Creator: Rogallo, Vernon L.; Yaggy, Paul F. & McCloud, John L., III
System: The UNT Digital Library
An Analysis of the Effects of Aeroelasticity on Static Longitudinal Stability and Control of a Swept-Wing Airplane (open access)

An Analysis of the Effects of Aeroelasticity on Static Longitudinal Stability and Control of a Swept-Wing Airplane

From Introduction: "The results of the aforementioned study are presented in this report together with the method of analysis employed. The net stability change is shown together with the individual contributions due to flexibility of wing, tail, and fuselage, both including and neglecting the effect of inertial loads."
Date: March 19, 1951
Creator: Skoog, Richard B.
System: The UNT Digital Library
Theoretical analysis of incompressible flow through a radial-inlet centrifugal impeller at various weight flows (open access)

Theoretical analysis of incompressible flow through a radial-inlet centrifugal impeller at various weight flows

A method for the solution of the incompressible nonviscous flow through a centrifugal impeller, including the inlet region, is presented. Several numerical solutions are obtained for four weight flows through an impeller at one operating speed. These solutions are refined in the leading-edge region. The results are presented in a series of figures showing streamlines and relative velocity contours. A comparison is made with the results obtained by using a rapid approximate method of analysis.
Date: March 4, 1955
Creator: Kramer, James J.; Prian, Vasily D. & Wu, Chung-Hua
System: The UNT Digital Library
Requirements for Satisfactory Flying Qualities of Airplanes (open access)

Requirements for Satisfactory Flying Qualities of Airplanes

Report discusses the results of an analysis of available data to determine what measured characteristics are significant in defining satisfactory flying qualities, what characteristics are reasonable to require of an airplane, and what influence the various design features have on the observed flying qualities.
Date: March 24, 1941
Creator: Gilruth, R. R.
System: The UNT Digital Library
A Theoretical Investigation of the Lateral Oscillations of an Airplane With Free Rudder With Special Reference to the Effect of Friction (open access)

A Theoretical Investigation of the Lateral Oscillations of an Airplane With Free Rudder With Special Reference to the Effect of Friction

"Charts showing the variation in dynamic stability with the rudder hinge-moment characteristics are presented. A stabilizing rudder floating tendency combined with a high degree of aerodynamic balance is shown to lead to oscillations of increasing amplitude. This dynamic instability is increased by viscous-friction in the rudder control system" (p. 147).
Date: March 4, 1943
Creator: Greenberg, Harry & Sternfield, Leonard
System: The UNT Digital Library
Critical Compressive Stress for Outstanding Flanges (open access)

Critical Compressive Stress for Outstanding Flanges

A chart is presented for the values of the coefficient in the formula for the critical compressive stress at which buckling may be expected to occur in outstanding flanges. These flanges are flat rectangular plates supported along the loaded edges, supported and elastically restrained along one unloaded edge, and free along the other unloaded edge. The mathematical derivations of the formulas required for construction of the chart are given.
Date: March 14, 1941
Creator: Lundquist, Eugene E. & Stowell, Elbridge Z.
System: The UNT Digital Library
Critical Compressive Stress for Flat Rectangular Plates Supported Along All Edges and Elastically Restrained Against Rotation along the Unloaded Edges (open access)

Critical Compressive Stress for Flat Rectangular Plates Supported Along All Edges and Elastically Restrained Against Rotation along the Unloaded Edges

A chart is presented for the values of the coefficient in the formula for the critical compressive stress at which buckling may be expected to occur in flat rectangular plates supported along all edges and, in addition, elastically restrained against rotation along the unloaded edges. The mathematical derivations of the formulas required in the construction of the chart are given.
Date: March 8, 1941
Creator: Lundquist, Eugene E. & Stowell, Elbridge Z.
System: The UNT Digital Library
Restraint provided a flat rectangular plate by a sturdy stiffener along an edge of the plate (open access)

Restraint provided a flat rectangular plate by a sturdy stiffener along an edge of the plate

From Summary: "A sturdy stiffener is defined as a stiffener of such proportions that it does not suffer cross-sectional distortion when moments are applied to some part of the cross section. When such a stiffener is attached to one edge of a plate, it will resist rotation of that edge of the plate by means of its torsional properties. A formula is given for the restraint coefficient provided the plate by such a stiffener. This coefficient is required for the calculation of the critical compressive stress of the plate."
Date: March 13, 1941
Creator: Lundquist, Eugene E. & Stowell, Elbridge Z.
System: The UNT Digital Library
Shear lag in box beams methods of analysis and experimental investigations (open access)

Shear lag in box beams methods of analysis and experimental investigations

The bending stresses in the covers of box beams or wide-flange beams differ appreciably from the stresses predicted by the ordinary bending theory on account of shear deformation of the flanges. The problem of predicting these differences has become known as the shear-lag problem. The first part of this paper deals with methods of shear-lag analysis suitable for practical use. The second part of the paper describes strain-gage tests made by the NACA to verify the theory. Three tests published by other investigators are also analyzed by the proposed method. The third part of the paper gives numerical examples illustrating the methods of analysis. An appendix gives comparisons with other methods, particularly with the method of Ebner and Koller.
Date: March 7, 1941
Creator: Kuhn, Paul & Chiarito, Patrick T.
System: The UNT Digital Library
High-Speed Tests of Conventional Radial-Engine Cowlings (open access)

High-Speed Tests of Conventional Radial-Engine Cowlings

The drag characteristics of eight radial-engine cowlings have been determined over a wide speed range in the NACA 8-foot high-speed wind tunnel. The pressure distribution over all cowlings was measured, to and above the speed of the compressibility burble, as an aid in interpreting the force tests. One-fifth-scale models of radial-engine cowlings on a wing-nacelle combination were used in the tests.
Date: March 30, 1939
Creator: Robinson, Russell G. & Becker, John V.
System: The UNT Digital Library
The effect of torsional flexibility on the rolling characteristics at supersonic speeds of tapered unswept wings (open access)

The effect of torsional flexibility on the rolling characteristics at supersonic speeds of tapered unswept wings

From Summary: "An analysis is presented of the effect of torsional flexibility on the rolling characteristics at supersonic speeds of tapered unswept wings with partial-span constant-percent-chord ailerons extending inboard from the wing tip. The geometric variables considered are aspect ratio, taper ratio, aileron span, and aileron chord. The shape of the wing-torsional-stiffness curve is assumed and the twisting moment is considered to result solely from the pressure distribution caused by aileron deflection, so that the necessity of using a successive-approximation method is avoided."
Date: March 8, 1949
Creator: Tucker, Warren A. & Nelson, Robert L.
System: The UNT Digital Library
Application of Theodorsen's theory to propeller design (open access)

Application of Theodorsen's theory to propeller design

A theoretical analysis is presented for obtaining, by use of Theodorsen's propeller theory, the load distribution along a propeller radius to give the optimum propeller efficiency for any design condition. The efficiencies realized by designing for the optimum load distribution are given in graphs, and the optimum efficiency for any design condition may be read directly from the graph without any laborious calculations. Examples are included to illustrate the method of obtaining the optimum load distributions for both single-rotating and dual-rotating propellers.
Date: March 15, 1948
Creator: Crigler, John L.
System: The UNT Digital Library
Determination of stresses in gas-turbine disks subjected to plastic flow and creep (open access)

Determination of stresses in gas-turbine disks subjected to plastic flow and creep

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 facilitate explanation of the procedure by carrying out the computations on a typical gas-turbine disk through a complete running cycle. The results of the numerical examples presented indicate that plastic flow markedly alters the elastic-stress distribution.
Date: March 5, 1948
Creator: Millenson, M. B. & Manson, S. S.
System: The UNT Digital Library
Critical Stress of Thin-Walled Cylinders in Axial Compression (open access)

Critical Stress of Thin-Walled Cylinders in Axial Compression

Empirical design curves are presented for the critical stress of thin-wall cylinders loaded in axial compression. These curves are plotted in terms of the nondimensional parameters of small-deflection theory and are compared with theoretical curves derived for the buckling of cylinders with simply supported and clamped edges. An empirical equation is given for the buckling of cylinders having a length-radius ratio greater than about 0.75.
Date: March 20, 1947
Creator: Batdorf, S. B.; Schildcrout, Murry & Stein, Manuel
System: The UNT Digital Library
Effect of combustor-inlet conditions on performance of an annular turbojet combustor (open access)

Effect of combustor-inlet conditions on performance of an annular turbojet combustor

From Summary: "The combustion performance, and particularly the phenomenon of altitude operational limits, was studied by operating the annular combustor of a turbojet engine over a range of conditions of air flow, inlet pressure, inlet temperature, and fuel flow. Information was obtained on the combustion efficiencies, the effect on combustion of inlet variables, the altitude operational limits with two different fuels, the pressure losses in the combustor, the temperature and velocity profiles at the combustor outlet, the extent of afterburning, the fuel-injection characteristics, and the condition of the combustor basket."
Date: March 21, 1947
Creator: Childs, J. Howard; McCafferty, Richard J. & Surine, Oakley W.
System: The UNT Digital Library
Analysis of cooling limitations and effect of engine-cooling improvements on level-flight cruising performance of four-engine heavy bomber (open access)

Analysis of cooling limitations and effect of engine-cooling improvements on level-flight cruising performance of four-engine heavy bomber

From Introduction: "The difficulties experienced in cooling the exhaust-valve seats of the rear-row cylinders have been overcome to a considerable extent by improving the mixture distribution through application of the injection impeller (reference 1) and by augmenting the flow of cooling air to the critical baffles (reference 2). Flight tests of this airplane (reference 3) indicated that the temperatures of exhaust-valve seats on rear-row cylinders were markedly lowered by these modifications and that airplane range, altitude, and gross weight previously limited by these temperatures could be greatly increased."
Date: March 14, 1946
Creator: Marble, Frank E.; Miller, Marlon A. & Bell, E. Barton
System: The UNT Digital Library
Effects of temperature distribution and elastic properties of materials on gas-turbine-disk stresses (open access)

Effects of temperature distribution and elastic properties of materials on gas-turbine-disk stresses

From Summary: "Calculations were made to determine the influence of changes in temperature distribution and in elastic material properties on calculated elastic stresses for a typical gas-turbine disk. Severe temperature gradients caused thermal stresses of sufficient magnitude to reduce the operating safety of the disk. Small temperature gradients were found to be desirable because they produced thermal stresses that subtracted from the centrifugal stresses in the region of the rim."
Date: March 29, 1947
Creator: Holms, Arthur G. & Faldetta, Richard D.
System: The UNT Digital Library
Consideration of Dynamic Loads on the Vertical Tail by the Theory of Flat Yawing Maneuvers (open access)

Consideration of Dynamic Loads on the Vertical Tail by the Theory of Flat Yawing Maneuvers

"Dynamic yawing effects on vertical-tail loads are considered by a theory of flat yawing maneuvers. A comparison is shown between computed loads and the loads measured in flight on a fighter airplane. The dynamic effects were investigated on a large flying boat for both an abrupt rudder deflection and sinusoidal rudder deflection" (p. 91).
Date: March 15, 1946
Creator: Boshar, John & Davis, Philip
System: The UNT Digital Library
A Simplified Method of Elastic-Stability Analysis for Thin Cylindrical Shells (open access)

A Simplified Method of Elastic-Stability Analysis for Thin Cylindrical Shells

"This paper develops a new method for determining the buckling stresses of cylindrical shells under various loading conditions. In part I, the equation for the equilibrium of cylindrical shells introduced by Donnell in NACA report no. 479 to find the critical stresses of cylinders in torsion is applied to find critical stresses for cylinders with simply supported edges under other loading conditions. In part II, a modified form of Donnell's equation for the equilibrium of thin cylindrical shells is derived which is equivalent to Donnell's equation but has certain advantages in physical interpretation and in ease of solution, particularly in the case of shells having clamped edges" (p. 285).
Date: March 20, 1947
Creator: Batdorf, S. B.
System: The UNT Digital Library
Method for Calculation of Laminar Heat Transfer in Air Flow Around Cylinders of Arbitrary Cross Section (Including Large Temperature Differences and Transpiration Cooling) (open access)

Method for Calculation of Laminar Heat Transfer in Air Flow Around Cylinders of Arbitrary Cross Section (Including Large Temperature Differences and Transpiration Cooling)

"The solution of heat-transfer problems has become vital for many aeronautical applications. The shapes of objects to be cooled can often be approximated by cylinders of various cross sections with flow normal to the axis as, for instance heat transfer on gas-turbine blades and on air foils heated for deicing purposes. A laminar region always exists near the stagnation point of such objects. A method previously presented by E. R. G. Eckert permits the calculation of local heat transfer around the periphery of cylinders of arbitrary cross section in the laminar region for flow of a fluid with constant property values with an accuracy sufficient for engineering purposes" (p. 223).
Date: March 19, 1952
Creator: Eckert, E. R. G. & Livingood, John N. B.
System: The UNT Digital Library
Displacement Effect of a Three-Dimensional Boundary Layer (open access)

Displacement Effect of a Three-Dimensional Boundary Layer

"A method is described for determining the "displacement surface" of known three-dimensional compressible boundary-layer flow in terms of the mass-flow defects associated with the profiles of the two velocity components parallel to the surface. The result is a generalization of the plane flow concept of displacement thickness introduced in order to describe how a thin boundary layer distorts the outer nonviscous flow. Numerical values are found for the known three-dimensional boundary-layer flow about a cone at a small angle of attack to a supersonic stream" (p. 367).
Date: March 6, 1952
Creator: Moore, Franklin K.
System: The UNT Digital Library
Investigation of wear and friction properties under sliding conditions of some materials suitable for cages of rolling-contact bearings (open access)

Investigation of wear and friction properties under sliding conditions of some materials suitable for cages of rolling-contact bearings

"An investigation of wear and friction properties of a number of materials sliding against SAE 52100 steel was conducted. These materials included brass, bronze, beryllium copper, monel, nichrome v, 24S-T aluminum, nodular iron, and gray cast iron. The metals investigated may be useful as possible cage (separator or retainer) materials for rolling-contact bearings of high-speed turbine engines. The ability of materials to form surface films that prevent welding is a most important factor in both dry friction and boundary lubrication" (p. 117).
Date: March 26, 1951
Creator: Johnson, Robert L.; Swikert, Max A. & Bisson, Edmond E.
System: The UNT Digital Library
Flight investigation of the effect of control centering springs on the apparent spiral stability of a personal-owner airplane (open access)

Flight investigation of the effect of control centering springs on the apparent spiral stability of a personal-owner airplane

Report presents the results of a flight investigation conducted on a typical high-wing personal-owner airplane to determine the effect of control centering springs on apparent spiral stability. Apparent spiral stability is the term used to describe the spiraling tendencies of an airplane in uncontrolled flight as affected both by the true spiral stability of the perfectly trimmed airplane and by out-of-trim control settings. Centering springs were used in both the aileron and rudder control systems to provide both a positive centering action and a means of trimming the airplane.
Date: March 22, 1951
Creator: Campbell, John P.; Hunter, Paul A.; Hewes, Donald E. & Whitten, James B.
System: The UNT Digital Library