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An approximate spin design criterion for monoplanes
"A quantitative criterion of merit has been needed to assist airplane designers to incorporate satisfactory spinning characteristics into new designs. An approximate empirical criterion, based on the projected side area and the mass distribution of the airplane, has been formulated in a recent British report. In the present paper, the British results have been analyzed and applied to American designs. A simpler design criterion based solely on the type and the dimensions of the tail, has been developed: it is useful in a rapid estimation of whether a new design is likely to comply with the minimum requirements for safety in spinning" (p. 1).
Date:
June 1939
Creator:
Seidman, Oscar & Donlan, Charles J.
System:
The UNT Digital Library
Two-Dimensional Irrotational Transonic Flows of a Compressible Fluid
The methods of NACA TN No. 995 have been slightly modified and extended in include flows with circulation by considering the alteration of the singularities of the incompressible solution due to the presence of the hypergeometric functions in the analytic continuation of the solution. It was found that for finite Mach numbers the only case in which the nature of the singularity can remain unchanged is for a ratio of specific heats equal to -1. From a study of two particular flows it seems that the effect of geometry cannot be neglected, and the conventional "pressure-correction" formulas are not valid, even in the subsonic region if the body is thick, especially if there is a supersonic region in the flow.
Date:
June 1948
Creator:
Kuo, Yung-Huai
System:
The UNT Digital Library
Effects of Some Present-Day Airplane Design Trends on Requirements for Lateral Stability
Note presenting computations made to determine the effects of some airplane design trends on the fin area and the dihedral angle required for lateral stability. The specific factors studied were wing loading, moments of inertia in roll and yaw, wing chord, and tail length. The results of the computations are presented in the form of diagrams of variations of fin area with dihedral angle for neutral stability.
Date:
June 1941
Creator:
Bamber, Millard J.
System:
The UNT Digital Library
A Generalized Theoretical Investigation of the Hydrodynamic Pitching Moments Experienced by V-Bottom Seaplanes During Step-Landing Impacts and Comparisons With Experiment
Note presenting a theoretical investigation made of the hydrodynamic pitching moments experienced by V-bottom seaplanes during step-landing impacts. The entire immersion process is analyzed from the instant of initial contact until the seaplane rebounds from the water surface.
Date:
June 1948
Creator:
Milwitzky, Benjamin
System:
The UNT Digital Library
Two-dimensional wind-tunnel investigation of a 10.7-percent-thick symmetrical tail section with a 0.40 airfoil-chord control surface and a 0.20 control-surface-chord tab
Report presenting an investigation of a 10.7-percent-thick symmetrical tail section equipped with a flat-side airfoil-chord flap with a flap-chord overhang and a plain flap-chord tab. Airfoil lift, drag, pitching-moment, and flap and tab hinge-moment characteristics were determined at various flap and tab deflections.
Date:
June 1947
Creator:
Braslow, Albert L.
System:
The UNT Digital Library
Experimental Verification of Two Methods for Computing the Take-Off Ground Run of Propeller-Driven Aircraft
Note presenting a comparison between the measured take-off ground run of an airplane equipped with seven different propeller-engine gear-ratio combinations and the computed distances by two different methods. Results indicated that the values of ground run calculated by Diehl's approximate method checked experimental values with 7 percent but were in error as much as 10 to 15 percent under certain conditions. Improved methods of thrust computation may be required in order to avoid large errors and before any more rigorous methods can be substituted for Diehl's method.
Date:
June 1947
Creator:
Gasich, Welko E.
System:
The UNT Digital Library
Meteorological Conditions Associated With Flight Measurements of Atmospheric Turbulence
"The results obtained from a series of flight measurements of atmospheric turbulence within convective-type clouds and from meteorological soundings are presented together with descriptions of the flights and concurrent weather conditions. These results are presented to provide a background of experience for the forecaster and pilot by illustrating the turbulence conditions as indicated by effective gust velocities in convective-type clouds under spring and summer weather conditions along the eastern coast of the United States" (p. 1).
Date:
June 1947
Creator:
Helfand, B. B.
System:
The UNT Digital Library
The Synthesis and Purification of Aromatic Hydrocarbons 3: Isobutylbenzene, Sec-Butylebenzene and Tert-Butylbenzene
Note presenting a description of the synthesis of isobutylbenzene, sec-butylbenzene, and tert-butylbenzene in 11-gallon quantities. The physical properties are tabulated and freezing curves are plotted for the five hydrocarbons.
Date:
June 1946
Creator:
Buess, C. M.; Karabinos, J. V.; Kunz, P. V. & Gibbons, L. C.
System:
The UNT Digital Library
Investigation of Statistical Nature of Fatigue Properties
Note presenting an experimental program to study the subject of metal fatigue and to determine and evaluate the fundamental factors which influence the behavior. The statistics of the fatigue-fracture curves and endurance limits were determined for a variety of metals and the effects of some metallurgical factors on the statistical nature of fatigue properties were shown.
Date:
June 1952
Creator:
Epremian, E. & Mehl, R. F.
System:
The UNT Digital Library
Studies of high-temperature protection of a titanium-carbide ceramal by chromium-type ceramic-metal coatings
Report presenting an investigation to gain information concerning the durability of metallic coatings as affected by frit content, firing temperature, firing time, and number of coats. Four coatings of various frit content were prepared and applied to ceramals containing 80 percent chromium and 20 percent cobalt and heated at four different temperatures.
Date:
June 1951
Creator:
Moore, Dwight G.; Benner, Stanley G. & Harrison, William N.
System:
The UNT Digital Library
An Investigation of the Effects of Jet-Outlet Cut-Off Angle on Thrust Direction and Body Pitching Moment
Note presenting a wind-tunnel investigation to determine the effects of jet-outlet cut-off angle on the directional and spreading characteristics of an unheated, subsonic air jet, and on the pitching moment of the body from which the jet issued. Results regarding the jet operating with the wind tunnel off, jet off with the wind tunnel operating, jet operating with the wind tunnel operating, and flow studies with the jet operating and the wind tunnel off are provided.
Date:
June 1951
Creator:
Blackaby, James R.
System:
The UNT Digital Library
Practical Methods of Calculation Involved in the Experimental Study of an Autopilot and the Autopilot-Aircraft Combination
Report presenting practical methods for making the calculations required for the analysis of an autopilot and an autopilot-aircraft combination from frequency-response data. From Summary: "Equations are derived for determining the servo-system error voltage for both displacement input signal and displacement plus rate of displacement input signals, the autopilot frequency response for addition of rate of displacement input signal, the servo-system frequency response for a change of gain, and the relation between open-loop and closed-loop frequency responses for the servo system and the autopilot-aircraft combination."
Date:
June 1951
Creator:
Smaus, Louis H. & Stewart, Elwood C.
System:
The UNT Digital Library
Method for calculation of ram-jet performance
Report presenting a method utilizing precalculated solutions graphically presented for calculating subsonic or supersonic ramjet performance parameters with the associated equations and graphs. By assuming constant values of specific-heat ratio and gas constant equal to those of standard air, the thrust-coefficient calculation has been reduced to a few simple operations.
Date:
June 1951
Creator:
Henry, John R. & Bennett, J. Buel
System:
The UNT Digital Library
Effects of Range of Stress and of Special Notches on Fatigue Properties of Aluminum Alloys Suitable for Airplane Propellers
"Laboratory tests were made to obtain information on the load-resisting properties of X76S-T aluminum alloy when subjected to static, impact, and repeated loads. Results are presented from static-load test of unnotched specimens in tension and in torsion and of notched specimens in tension. Charpy impact values obtained from bend tests on notched specimens and tension impact values for both notched and unnotched specimens tested at several different temperatures are included" (p. 1).
Date:
June 1942
Creator:
Dolan, Thomas J.
System:
The UNT Digital Library
Method for calculation of heat transfer in laminar region of air flow around cylinders of arbitrary cross section (including large temperature differences and transpiration cooling)
Report presenting a method permitting 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. The method is applied to circular and elliptic cylinders are the results are described.
Date:
June 1952
Creator:
Eckert, E. R. G. & Livingood, John N. B.
System:
The UNT Digital Library
Acoustical Treatment for the NACA 8- by 6-Foot Supersonic Propulsion Wind Tunnel
"This report presents results of a research and engineering program performed during the first half of 1950 that resulted in an acoustical treatment for the 8- by 6-foot supersonic wind tunnel at the Lewis Flight Propulsion Laboratory" (p. 1).
Date:
June 1955
Creator:
Beranek, Leo L.; Labate, Samuel & Ingard, Uno
System:
The UNT Digital Library
Two-dimensional shear flow in a 90 degrees elbow
Report presenting an investigation of two-dimensional, incompressible, non-viscous shear flows in a 90 degree elbow in order to better understand the motion of real fluids in flow machinery. Solutions are presented for linear and sinusoidal velocity distributions across the inlet of the elbow.
Date:
June 1952
Creator:
Kramer, James J. & Stanitz, John D.
System:
The UNT Digital Library
Wind-tunnel investigation of the effect of clipping the tips of triangular wings of different thickness, camber, and aspect ratio - transonic bump method
Report presenting an investigation on a transonic bump to determine the aerodynamic characteristics of a series of triangular wings. Four basic triangular-wing plan forms with different aspect ratios, taper ratios, and combinations of tip clipping were tested over a range of Mach and Reynolds numbers. Results regarding angle of attack, drag coefficient, pitching-moment coefficient with lift coefficient, and various curves are provided.
Date:
June 1956
Creator:
Emerson, Horace F.
System:
The UNT Digital Library
Tests of Bonded and Riveted Sheet-Stringer Panels
Note presenting tests performed on 21 sheet-stringer panels of 75S-T6 aluminum alloy with alclad sheets nominally 0.051 inch thick and stringers nominally 3.5 inches apart. Three panels of different types, with five stringers each and overall dimensions of approximate 18 by 15 inches, were tested in axial flat-end compression. Results regarding the flat-end compression, protruding-stringer compression, and bending are provided.
Date:
June 1954
Creator:
Mordfin, Leonard & Wilks, I. E.
System:
The UNT Digital Library
Design and experimental evaluation of a light-weight turbine-wheel assembly
Report presenting lightweight design concepts, which were developed and tested in a full-scale turbine wheel with a tip diameter of 34.3 inches and a tip speed of 1190 feet per second. It consisted of a rotor of two thin alloy disks attached with spacers and bolts and hollow turbine blades. Testing indicated that it would be particularly applicable to an expendable missile engine.
Date:
June 1957
Creator:
Morgan, W. C. & Kemp, R. H.
System:
The UNT Digital Library
Effect of the proximity of the wing first-bending frequency and the short-period frequency on the airplane dynamic-response factor
Report presenting a study of the effect of the frequency of the lowest wing structural mode on the airplane center-of-gravity dynamic-response factor was made my employing simplified transfer functions.
Date:
June 1958
Creator:
Huss, Carl R. & Donegan, James J.
System:
The UNT Digital Library
Stresses in and general instability of monocoque cylinders with cutouts 2: calculation of the stresses in a cylinder with a symmetric cutout
A numerical procedure is presented for the calculation of the stresses in a monocoque cylinder with a cutout. In the procedure the structure is broken up into a great many units; the forces in these units corresponding to specified distortions of the units are calculated; a set of linear equations is established expressing the equilibrium conditions of the units in the distorted state; and the simultaneous linear equations are solved. A fully worked out numerical example, corresponding to the application of a pure bending moment, gave results in good agreement with experiments carried out earlier at the Polytechnic Institute of Brooklyn.
Date:
June 1946
Creator:
Hoff, N. J.; Boley, Bruno A. & Klein, Bertram
System:
The UNT Digital Library
Flight Measurements of the Vibratory Bending and Torsional Stresses on a Modified Supersonic Propeller for Forward Mach Numbers up to 0.95
Note presenting vibratory stress measurements obtained in flight on a modified supersonic propeller for forward mach numbers up to 0.95. The magnitude of the vibratory bending stress was low in relation to the strength of the material throughout the flight range of the airplane. Results of a propeller feathering operation at a Mach number of 0.95 indicated no excessive stresses.
Date:
June 1958
Creator:
O'Bryan, Thomas C.
System:
The UNT Digital Library
Results of an experimental investigation of small viscous dampers
Report presenting the results of an experimental investigation of several small viscous dampers. The characteristics of the dampers are presented in the form of the magnitudes of the damping forces and spring forces as a function of the maximum velocity of the piston. The results indicated that the temperature has a large effect on the force produced by the dampers and demonstrated the necessity for consideration of the heat generated and dissipated as a result of work done by the dampers.
Date:
June 1958
Creator:
Silveira, Milton A.; Maglieri, Domenic J. & Brooks, George W.
System:
The UNT Digital Library