41 Matching Results

Results open in a new window/tab.

Simplified Truss Stability Criteria (open access)

Simplified Truss Stability Criteria

Report presenting a note in two parts regarding simplified truss stability criteria. The first part covers the development of simplified criteria for the stability of planar pin-jointed trusses against buckling in the plane of the truss. The second part constitutes a report on tests carried out to verify the validity of the criteria developed in part one.
Date: July 1944
Creator: Ballhaus, W. F. & Niles, A. S.
System: The UNT Digital Library
Piloting of flying boats with special reference to porpoising and skipping (open access)

Piloting of flying boats with special reference to porpoising and skipping

From Summary: "The various types of hydrodynamic instability - including porpoising, skipping, and yawing - that may be encountered during take-off or landing of a flying boat are described and the piloting technique required for efficient take-offs and landings is discussed. Suggestions are made for assisting a pilot to become familiar with the take-off and landing qualities of a flying boat that is new to him."
Date: February 1944
Creator: Benson, James M.
System: The UNT Digital Library
Dynamics of the Inlet System of a Four-Stroke Engine (open access)

Dynamics of the Inlet System of a Four-Stroke Engine

"Tests were run on a single-cylinder and a multicylinder four-stroke engine in order to determine the effect of the dynamics of the inlet system upon indicated mean effective pressure. Tests on the single-cylinder engine were made at various speeds, inlet valve timings, and inlet pipe lengths. These tests indicated that the indicated mean effective pressure could be raised considerably at any one speed by the use of a suitably long inlet pipe" (p. 1).
Date: 1944
Creator: Boden, R. H. & Schecter, Harry
System: The UNT Digital Library
Plastic Mountings for Aircraft Windshields (open access)

Plastic Mountings for Aircraft Windshields

Note presenting an investigation of several laminated glass windshields to determine their suitability for use in airplanes with pressurized cabins. The various constructions of the extended portions of the windshields which serve for mounting purposes included plastic alone, plastic and one sheet of glass extended, plastic extension reinforced with an aluminum strip, and plastic extension reinforced with a steel strip. The results indicated that the laminated windshields with plastic-mounting extensions reinforced by aluminum or steel were resistant to creep and bursting at pressures of the order that will be encountered in service.
Date: May 1944
Creator: Bradley, Kathryn H. & Axilrod, B. M.
System: The UNT Digital Library
Guides for preventing buckling in axial fatigue tests of thin sheet-metal specimens (open access)

Guides for preventing buckling in axial fatigue tests of thin sheet-metal specimens

From Summary: "Guide fixtures are described by means of which axial fatigue loads including compression may be applied to a thin sheet-metal specimen. Tests indicate that the guides prevented buckling without bypassing the load or injuring the specimen."
Date: April 1944
Creator: Brueggeman, W. C. & Mayer, M., Jr.
System: The UNT Digital Library
Axial Fatigue of 10 Airplane Wing-Beam Specimens by the Resonance Method (open access)

Axial Fatigue of 10 Airplane Wing-Beam Specimens by the Resonance Method

Note presenting axial fatigue tests made by the resonance method on 10 specimens from airplane wing beams. The specimens contained several types of stress raiser, such as rivets, holes, fittings, splices, reinforcing plates, and so forth. The results show a greater fatigue stress concentration factor for the wing-beam specimens than for drilled coupons machined from the flanges or for parallel strip coupons containing idle rivets.
Date: December 1944
Creator: Brueggeman, W. C.; Krupen, P. & Roop, F. C.
System: The UNT Digital Library
Axial Fatigue Tests at Zero Mean Stress of 24S-T Aluminum-Alloy Sheet With and Without a Circular Hole (open access)

Axial Fatigue Tests at Zero Mean Stress of 24S-T Aluminum-Alloy Sheet With and Without a Circular Hole

"Axial fatigue tests were made on 189 coupon specimens of 0.032-inch 24S-T aluminum-alloy sheet and a few supplementary specimens of 0.004-inch sheet. The mean load was zero. The specimens were restrained against lateral buckling by lubricated solid guides described in a previous report on this project. About two-thirds of the 0.032-inch specimens were plain coupons nominally free from stress raisers. The remainder contained a 0.1285-inch drilled hole at the center where the reduced section was 0.5 inch wide" (p. 1).
Date: November 1944
Creator: Brueggeman, W. C.; Mayer, M., Jr. & Smith, W. H.
System: The UNT Digital Library
Performance tests of wire strain gages 1: calibration factors in tension (open access)

Performance tests of wire strain gages 1: calibration factors in tension

Report presenting calibrations in axial tension over the strain range from 0 to 0.0024 are presented for 15 types of single element multistrand wire strain gages. The majority of the gages showed significant differences between the calibration factors for strain increasing and strain decreasing. Improvement in gage performance after preloading was apparent in most cases.
Date: November 1944
Creator: Campbell, William R.
System: The UNT Digital Library
Ovalization of Tubes Under Bending and Compression (open access)

Ovalization of Tubes Under Bending and Compression

"An empirical equation has been developed that gives the approximate amount of ovalization for tubes under bending loads. Tests were made on tubes in the d/t range from 6 to 14, the latter d/t ratio being in the normal landing gear range. Within the range of the series of tests conducted, the increase in ovalization due to a compression load in combination with a bending load was very small" (p. 1).
Date: March 1944
Creator: Demer, L. J. & Kavanaugh, E. S.
System: The UNT Digital Library
Development of detonation detector suitable for use in flight (open access)

Development of detonation detector suitable for use in flight

Report presenting an apparatus for making quantitative measurements of the vibrations excited by detonation in the cylinder head of an aircraft engine. The apparatus consisted of pick-up units, an amplifying system, and a cathode-ray oscillograph with a high-speed-camera recording system. A large number of records were taken under various operating conditions in a single-cylinder aircraft engine.
Date: December 1944
Creator: Draper, C. S.; Taylor, E. S.; Lancor, J. H. & Coffey, R. T.
System: The UNT Digital Library
The numerical solution of compressible fluid flow problems (open access)

The numerical solution of compressible fluid flow problems

Numerical methods have been developed for obtaining the steady, adiabatic flow field of a frictionless, perfect gas about arbitrary two-dimensional bodies. The solutions include the subsonic velocity regions, the supersonic velocity regions, and the transition compression shocks, if required. Furthermore, the rotational motion and entropy changes following shocks are taken into account. Extensive use is made of the relaxation method. In this report the details of the methods of solution are emphasized so as to permit others to solve similar problems. Solutions already obtained are mentioned only by way of illustrating the possibilities of the methods described. The methods can be applied directly to wind tunnel and free air tests of arbitrary airfoil shapes at subsonic, sonic, and supersonic speeds.
Date: May 1944
Creator: Emmons, Howard W.
System: The UNT Digital Library
Applicability of Similarity Principles to Structural Models (open access)

Applicability of Similarity Principles to Structural Models

"A systematic account is given in part I of the use of dimensional analysis in constructing similarity conditions for models and structures. The analysis covers large deflections, buckling, plastic behavior, and materials with nonlinear stress-strain characteristics, as well as the simpler structural problems" (p. 1).
Date: July 1944
Creator: Goodier, J. N. & Thomson, W. T.
System: The UNT Digital Library
The Shear of Aluminum Alloy Driven Rivets as Affected by Increasing D/T Ratios (open access)

The Shear of Aluminum Alloy Driven Rivets as Affected by Increasing D/T Ratios

"A decrease in shear strengths for increasing D/t ratios was shown in a previous investigation of protruding-head aluminum alloy rivets in double shear conducted at Aluminum Research Laboratories in 1942. Since single shear joints are more common than double shear joints, it was desirable to extend the investigation to single shear joints. This reports describes the results of this investigation of single shear joints and also includes the results of the previous investigation on double shear joints" (p. 1).
Date: July 1944
Creator: Hartman, E. C. & Wescoat, C.
System: The UNT Digital Library
Normal Pressure Tests on Unstiffened Flat Plates (open access)

Normal Pressure Tests on Unstiffened Flat Plates

"Flat sheet panels of aluminum alloy (all 17S-T except for two specimens of 24S-T) were tested under normal pressures with clamped edge supports in the structures laboratory of the Guggenheim Aeronautical Laboratory, California Institute of Technology. The thicknesses used ranged from 0.010 to 0.080 inch; the panel sizes ranged from 10 by 10 inches to 10 by 40 inches; and the pressure range was from 0 to 60-pounds-per-square-inch gage. Deflection patterns were measured and maximum tensile strains in the center of the panel were determined by electric strain gages" (p. 1).
Date: September 1944
Creator: Head, Richard M. & Sechler, Ernest J.
System: The UNT Digital Library
Bibliography of piston ring lubrication (open access)

Bibliography of piston ring lubrication

Report presenting a survey of the technical information contained in the literature on the subject of lubrication, friction, and wear of aircraft engine piston rings.
Date: October 1944
Creator: Hersey, Mayo D.
System: The UNT Digital Library
A Least-Squares Procedure for the Solution of the Lifting-Line Integral Equation (open access)

A Least-Squares Procedure for the Solution of the Lifting-Line Integral Equation

Note presenting a least-squares procedure adapted to numerical calculation for the approximate solution of the Prandtl lifting-line equation. Sufficient data are tabulated to permit a solution of the equation by purely numerical methods for an arbitrary symmetrical variation of the chord and the angle of attack.
Date: February 1944
Creator: Hildebrand, Francis B.
System: The UNT Digital Library
The Influence of the Aerodynamic Span Effect on the Magnitude of the Torsional-Divergence Velocity and on the Shape of the Corresponding Deflection Mode (open access)

The Influence of the Aerodynamic Span Effect on the Magnitude of the Torsional-Divergence Velocity and on the Shape of the Corresponding Deflection Mode

"A procedure which takes into account the aerodynamic span effect is given for the determination of the torsional-divergence velocities of monoplanes. The explicit solutions obtained in several cases indicate that the aerodynamic span effect may increase the divergence velocities found by means of the section-force theory by as much as 17 to 40 percent. It is found that the magnitude of the effect increases with increasing degree of stiffness taper and decreases with increasing degree of chord taper" (p. 1).
Date: February 1944
Creator: Hildebrand, Francis B. & Reissner, Eric
System: The UNT Digital Library
Determination of stress-strain relations from "offset" yield strength values (open access)

Determination of stress-strain relations from "offset" yield strength values

Report presenting an investigation of the shape of stress-strain curve for a material, especially when the material is subjected to compression, which may cause materials to become unstable at stresses beyond the elastic range. The ratio of stresses to effective modulus is explored in equation form.
Date: February 1944
Creator: Hill, H. N.
System: The UNT Digital Library
Numerical procedures for the calculation of the stresses in monocoques 2: diffusion of tensiles stringer loads in reinforced flat panels with cut-outs (open access)

Numerical procedures for the calculation of the stresses in monocoques 2: diffusion of tensiles stringer loads in reinforced flat panels with cut-outs

Report presenting experiments with a flat reinforced sheet model, the longitudinals of which were loaded axially. Two groups of sheets, one with one panel and one with two panels, were cut out and the stress distributions in stringers and sheet was measured with electric strain gages.
Date: November 1944
Creator: Hoff, N. J. & Kempner, Joseph
System: The UNT Digital Library
The inward bulge type buckling of monocoque cylinders 1: calculation of the effect upon the buckling stress of a compressive force, a nonlinear direct stress distribution, and a shear force (open access)

The inward bulge type buckling of monocoque cylinders 1: calculation of the effect upon the buckling stress of a compressive force, a nonlinear direct stress distribution, and a shear force

"In the present part I of a series of reports on the inward bulge type buckling of monocoque cylinders the buckling load in combined bending and compression is first derived. Next the reduction in the buckling load because of a nonlinear direct stress distribution is determined. In experiments nonlinearity may result from an inadequate stiffness of the end attachments in actual airplanes from the existence of concentrated loads or cut-outs" (p. 1).
Date: October 1944
Creator: Hoff, N. J. & Klein, Bertram
System: The UNT Digital Library
The Inward Bulge Type Buckling of Monocoque Cylinders 2: Experimental Investigation of the Buckling in Combined Bending and Compression (open access)

The Inward Bulge Type Buckling of Monocoque Cylinders 2: Experimental Investigation of the Buckling in Combined Bending and Compression

This paper is the second part of a series of reports on the inward bulge type buckling of monocoque cylinders. It presents the results of an experimental investigation of buckling in combined bending and compression. In the investigation it was found that the theory developed in part I of the present series predicts the buckling load in combined bending and compression with the same degree of accuracy as the older theory does in pure bending.
Date: October 1944
Creator: Hoff, N. J.; Fuchs, S. J. & Cirillo, Adam J.
System: The UNT Digital Library
Numerical procedures for the calculation of the stresses in monocoques 1: diffusion of tensile stringer loads in reinforced panels (open access)

Numerical procedures for the calculation of the stresses in monocoques 1: diffusion of tensile stringer loads in reinforced panels

Report presenting experiments with both curved and flat reinforced sheet models, the longitudinals of which were loaded axially. The stress distribution in longitudinals and sheet was measured with electric strain gages.
Date: June 1944
Creator: Hoff, N. J.; Levy, Robert S. & Kempner, Joseph
System: The UNT Digital Library
A unit laboratory engine oil system providing for a remote indication of oil flow and oil consumption together with blow-by measurement (open access)

A unit laboratory engine oil system providing for a remote indication of oil flow and oil consumption together with blow-by measurement

From Summary: "A unit oil system and oil-weighing device designed for laboratory engine tests to permit the remote measurement of oil-flow rate and oil consumption is described. The system regulates the oil pressure and temperature and is closed to make possible the accurate measurement of blow-by gas. The oil is weighed by a self-contained diaphragm and pilot-valve assembly, which uses compressed air as the transmitting medium. Several of those unit systems have given satisfactory service for more than a year."
Date: September 1944
Creator: Koffel, William K. & Biermann, Arnold E.
System: The UNT Digital Library
Analysis of Square Shear Web Above Buckling Load (open access)

Analysis of Square Shear Web Above Buckling Load

"A solution of Von Karman's fundamental equations for plates with large deflections is presented for the case of a shear web divided into square panels by reinforcing struts. Numerical solutions are given for struts of infinite rigidity and for struts the weight of which is one-fourth the weight of the sheet. The results are compared with Wagner's diagonal tension theory as extended by Kuhn and by Langhaar. It is found that the diagonal tension theory as developed by Kuhn agrees best with the present paper in the practical range when r=1/4. Kuhn's theory is in especially good agreement for the force in the strut when r=1/4" (p. 1).
Date: July 1944
Creator: Levy, Samuel; Fienup, Kenneth L. & Woolley, Ruth M.
System: The UNT Digital Library