Report presents the results of a great number of tests made to determine the effect of service stresses on the impact resistance, the x-ray diffraction patterns, and the microstructure of 25s aluminum alloy. Many of the specimens were taken from actual propeller blades and others were cut from 13/16-inch rod furnished by the Aluminum Company of America.

"Results are given of drag tests of 4/9-scale model radial air-cooled engine nacelles made as a part of a general investigation of wing-nacelle-propeller interference. A small nacelle of the type commonly used with exposed engine cylinders was tested with various forms of cowling over the cylinders. The effects of cowling-ring position and of angle of ring chord to the thrust line were investigated. An N.A.C.A. cowled nacelle and a smooth body were also tested. The results are given at 50, 75, and 100 miles per hour for -5 degrees, 0 degrees, 5 degrees, 10 degrees, 15 degrees angle of pitch" (p. 1).

A report about metal necessary for economic or industrial development and how the metals are toxic to plants, animals, and humans.

Abstract: This volume presents the Proceedings of the Second International Conference on Precision Measurement and Fundamental Constants, held at the National Bureau of Standards in Gaithersburg, MD, from June 8-12, 1981. Like its 1970 predecessor, the Conference provided an international forum for theoretical, experimental, and applied scientists actively engaged in research on precision measurements relating to the fundamental physical constants, and on the testing of related fundamental theory. More specifically, the purpose of the Conference was to assess the present state of the precision measurement-fundamental constants field, to examine basic limitations, and to explore the prospects for future significant advances. The principal subjects covered were: frequency, wavelength, spectroscopy, quantum electrodynamics, the gas constant, x-ray interferometry, nuclidic masses, uncertainty assignment, gravitational acceleration, mass, electrical quantities, gravity, and relativity. These proceedings contain the vast majority of both the invited review papers and the contributed current research papers presented at the Conference. The new results reported at the Conference were considered for inclusion in the 1983 least-squares adjustment of the constants carried out under the auspices of the Task Group on Fundamental Constants of the Committee on Data for Science and Technology (CODATA).

Note presenting a review of experiments on biaxial alternating stresses and simple combinations of static stress with alternating stress, which is shown to lead to a general criterion for the effect of static stress on the permissible amplitude of alternating stress. Tests were performed to determine the effect of static compression on alternating torsion, which is the one simple combination that had not been previously investigated. The results agree with the criterion.

Report presenting testing demonstrating that fatigue cracks initiate in preexisting slip bands on planes parallel to planes from tests on large-grained specimens of 1100 and 5052 aluminum alloys. The resolved shear stress on the planes in crystal where fatigue cracks had developed were compared to uncracked crystals. Results regarding the location fatigue cracks, number of stress cycles observed, and differences of the crystals observed in the two types of aluminum alloys are provided.

Note presenting a study of the impact behavior of normalized SAE X4130 steel after a variety of repeated stress treatments. Fatigue specimens of several types were used and the effects of surface finish, rest periods, stress amplitude, mean stress, stress concentration, and temperature during repeated stress received consideration.

Note presenting fatigue data for 76S-T61 aluminum alloy for several combinations of bending and torsion with both alternating and mean stresses. The literature on the effect of combined stress and of mean stress in fatigue is reviewed and the results of the present series are compared with those of various theories. Results regarding fatigue data, fatigue fractures, and static tests are provided.

"A number of factors are considered which influence the static and fatigue strength of materials under practical operating conditions as contrasted with the relations obtaining under conditions of the usual testing procedure. Such factors are interruptions in operation, periodically fluctuating stress limits and mean stresses with periodic succession of several groups and stress states, statistical changes and succession of stress limits and mean stresses, frictional corrosion at junctures, and notch effects" (p. 1).

Report presenting an experimental study of the changes in the stress-rupture life, ductility, hardness, and microstructure of S-816 and Inconel 550 specimens that had been exposed to varying amounts and conditions of thermal fatigue. Exposure to thermal-fatigue conditions was found to strengthen S-816 in stress rupture and to weaken Inconel 550.

"This report summarizes numerous theories relating to creep phenomena and the extent of current knowledge on the subject. Various possible mechanisms by which creep occurs both in single crystals and in polycrystals are described. An extensive bibliography of published works in this field is also included" (p. 1).

Note presenting a study to gain information as to the fundamental mechanism of fretting corrosion. The specific questions to be answered were whether chemical action played an important role in fretting of metal surfaces and whether any such action would improve the corrosion resistance of the metal investigated. The results indicated that the chemical action is of primary importance in fretting-corrosion effects and oxide formation does not give any protection to the metals but rather increases the rate of wear.

A report regarding the general geology and mines of the East Titanic Mining District, in Tuah and Juab Counties, Utah.

Report presenting experiments to study the start of fretting and cause of damage during the early stages of fretting of steel-steel combinations at a frequency 5 cycles per minute, an amplitude of 0.006 inch, a load of 150 grams, in air with relative humidity of less than 10 percent. Pure iron, glass, and iron oxide powder compacts were used in supplementary experiments.

"An analysis of the principal results of recent NACA lateral control research is made by utilizing the experience and progress gained during the course of the investigation. Two things are considered of primary importance in judging the effectiveness of different control devices: the (calculated) banking and yawing motion of a typical small airplane caused by a deflection of the control, and the stick force required to produce this deflection. The report includes a table in which a number of different lateral control devices are compared on these bases" (p. 1).

Report presenting the National Bureau of Standards' research program designed to determine and explain acid-base behavior in aprotic organic solvents and to develop methods and reference materials for determining total acid and base content and relative strengths of acids and bases in the media.

From Abstract: "This treatise is an attempt to provide a rational descriptive and analytical basis for tire mechanics. Chapters of this book are contributed by active research workers in the fields of rubber and textile properties, friction, material properties, tire stress problems, tire design and construction, vehicle skid and handling, and tire mechanical properties."

A report about erosion, deposition, soil formation, and water flow. It discusses hazards such as landslides, dust storms, floods, topsoil loss, ecosystem change, water contamination, and soil contamination.

Note presenting a summary of all phases of an investigation of fretting corrosion that has been conducted over a period of several years. Part I describes a test machine for measuring fretting damage under controlled experimental conditions. Part II presents data for mild steel fretted against itself, with a number of characteristics taken into consideration. Part III suggest a mechanism for the fretting process.

Report presenting the technical reports of the National Advisory Committee for Aeronautics from 1953. The report is divided into the technical activities of NACA, the committee organization and membership, and the financial report. The technical reports are divided into a general overview of NACA, unitary wind tunnels, aerodynamic research, power plants for aircraft, aircraft construction, operating problems, and reserch publications.

Report includes the National Advisory Committee for Aeronautics letter of submittal to the President, Congressional report, summaries of the committee's activities and research accomplished, bibliographies, and financial report.

"In accordance with act of Congress, approved March 3, 1915, as amended (U.S.C., title 50, .sw 151), which established the National Advisory Committee for Aeronautics, the Committee submits its Forty-fourth Annual Report for the fiscal year 1958. This is the Committee's final report to the Congress. The National Aeronautics and Space Act of 1958 (Public Law 85-568) provides in section 301 that the NACA "shall cease to exist" and "all functions, powers, duties, and obligations, and all real and personal property, personnel (other than members of the Committee), funds, and records of the NACA shall be transferred to the National Aeronautics and Space Administration" (p. ix).

Report includes the National Advisory Committee for Aeronautics letter of submittal to the President, Congressional report, summaries of the committee's activities and research accomplished, bibliographies, and financial report.

Report includes the National Advisory Committee for Aeronautics letter of submittal to the President, summaries of the committee's activities and research accomplished, bibliographies, and financial report.