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Caltech and aeronautics: a presentation by the California Institute of Technology
Full text linkThe outstanding accomplishment of Caltech in the field of aeronautics is not that it has taught, but that it has always had something new to teach. When most aircraft were glued together from bamboo, balsawood, and canvas, Caltech was teaching the next generation of designers how to build hollow shells of stiffened sheet metal. Today, at the threshold of the Space Age, Caltech is combining astronomy, mathematics, physics, mechanics and chemistry into a new sort of aeronautical science, tailored to the needs of a new era that knows no spatial limitations.
To an important extent, Caltech's contributions to industrial and military aeronautics have been made possible, through the years, by equally valuable contributions, in the form of men, money, and equipment, from industry and government. This support has filled a vital need in the past; it will become even more important in the future.
The following pages tell something of Caltech's role in aeronautics, its research accomplishments, its success as a teacher of men. Most important, this booklet sets forth the direction of Caltech's present and future research. It is an exciting vista
Nobel Prize-Winning Biologist David Baltimore Named President of the California Institute of Technology
No full textThe Effect of Surface Roughness upon 25 ST Aluminum Alloy Subjected to Repeated Tensile Stresses Above the Proportional Limit
Full text linkUtilizing the Repeated Load Hydraulic Testing Machine at the Daniel Guggenheim Aeronautical Laboratory, California Institute of Technology, Pasadena, California, the author, in collaboration with Lt. Comdr. D. J. Hardy, U. S. Navy, investigated the effects of surface roughness upon the cyclic life of 25 ST aluminum alloy when subjected to repeated constant tensile stresses in the region above the proportional limit.
The stress impulses are of such low frequency as to allow consideration of single impulses. The rate of build-up of the impulse and the duration of the impulsive load are such as to create an equivalent static load of substantially the same magnitude as the peak of the impulse loading.
It was found that surface roughness has some effect upon the cyclic life. In the lower stress regions, the greater the degree of surface roughness, the shorter the life appears to be. However, for the range of roughness investigated, 5μ to 200μ, the effect is not so pronounced as is usually found below the proportional limit.
Where the applied stresses reached far up into the plastic range the effect of surface roughness does not seem to follow quite as specific a pattern. Since the loading impulse featured a 0.33 second duration of maximum load, the effects of creep may well have taken over in shaping the life cycle curve with little regard for surface roughness
Reversed Bending Fatigue Properties of 25 S-T, 75 S-T, and 76 S-T Aluminum Alloys
Full text linkNOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document.
The problem of this investigation was to determine the effects of surface roughness and surface stressing on the reversed bending fatigue properties of 25 S-T, 75 ST and 76 S-T aluminum alloys.
Tests were conducted in a stress range from 37,700 psi, to that stress giving a fatigue life of 500,000,000 cycles.
Surface roughness was varied from five micro-inches to 400 micro-inches. Two different machining tools were used to obtain the various degrees of surface roughness: 1/8" radius tool, and a sharp pointed tool.
Surface stressing was obtained by shot peening with 0[...]028 diameter shot at .010/.012 A-2 intensity, and cold rolling at 100 lbs. and 200 lbs. pressure.
It was determined that fatigue life decreased as surface roughness increased in a similar manner for specimens machined with both types of tool; but that endurance limit was not affected by the sharp tool, whereas it was decreased by the 1/8" radius tool.
Shot peening increased fatigue life of 25 S-T by about 500%; it had but slight effect on 76 S-T.
Cold rolling increased fatigue life of 25 S-T and 76 S T by about 2500%. 75 S-T was neither shot peened nor cold rolled.
This work was carried out by the author at the Guggenheim Aeronautical Laboratory, California Institute of Technology under the supervision of Dr. E. E. Sechler
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Power Systems Advanced Research
Full text linkIn the 17 quarters of the project, we have accomplished the following milestones - first, construction of the three multiwavelength laser scattering machines for different light scattering study purposes; second, build up of simulation software package for simulation of field and laboratory particulates matters data; third, carried out field online test on exhaust from combustion engines with our laser scatter system. This report gives a summary of the results and achievements during the project's 16 quarters period. During the 16 quarters of this project, we constructed three multiwavelength scattering instruments for PM2.5 particulates. We build up a simulation software package that could automate the simulation of light scattering for different combinations of particulate matters. At the field test site with our partner, Alturdyne, Inc., we collected light scattering data for a small gas turbine engine. We also included the experimental data feedback function to the simulation software to match simulation with real field data. The PM scattering instruments developed in this project involve the development of some core hardware technologies, including fast gated CCD system, accurately triggered Passively Q-Switched diode pumped lasers, and multiwavelength beam combination system. To calibrate the scattering results for liquid samples, we also developed the calibration system which includes liquid PM generator and size sorting instrument, i.e. MOUDI. In this report, we give the concise summary report on each of these subsystems development results
Pasadena, California Institute of Technology
No full textCalifornia Institute of Technology, Pasadena, Calif.Colo
Flow Field Around a Finite Cone with Shock
Full text linkAn experimental investigation was made to determine the characteristics of the flow over the surface of a 70° cone and at the shock wave for values near the detachment Mach number. The purpose of this investigation was to compare the experimental results obtained with theoretical values.
Tests were made in the GALCIT 2.5" Supersonic Wind Tunnel on a 70° cone at zero angle of attack for five different free stream Mach numbers: 1.49, 1.630, 1.694, 1.86, 1.997.
It was found that theory gives close agreement with experimental results.
This investigation was conducted jointly with Mr. Vincent Muirhead at the California Institute of Technology, Pasadena, California
Repeated Loads Above the Proportional Limit on 24ST Aluminum Alloy
Full text linkThe purpose of this investigation is to study the effect of repeated tensile stresses above the proportional limit on 24ST Aluminum Alloy.
The investigation consisted of two parts: the design and building of testing apparatus which would provide a pure tension stress capable of being repeated many times a minute without shock but with a high rate of loading, and to obtain data by means of runs on prepared samples of the metal under study.
It was found that permanent deformation caused by overstress is not a useful factor in forecasting life expectancy.
It was also found that the effects of "aging" (elapsed time between overstresses), initial cold work, and magnitude of over- stresses applied all have definite influence on the ability of 24ST Aluminum Alloy to withstand further overstressing and require more thorough investigation.
It is considered that this field offers attractive possibilities for further study of the behavior of aircraft materials above the proportional limit with an eye toward increasing accuracy of airplane design.
The investigation was carried out at the Daniel Guggenheim Aeronautical Laboratory, California Institute of Technology, Pasadena, California.</p
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Atomic Energy Commission Report AECU-4588
No full textThis review lists some of the salient features of semiconductor particle counters and cannot claim to contain an exhaustive listing of all the work in the field. Performance results on the surface-barrier counters as developed at California Institute of Technology are included as typical for this type of counter, though comparable results have been obtained elsewhere
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