The performance and application of high speed long life LH2 hybrid bearings for reusable rocket engine turbomachinery

Data are presented for two different experimental programs which were conducted to investigate the characteristics of a hybrid (hydrostatic/ball) bearing operating in liquid hydrogen. The same bearing design was used in both programs. Analytical predictions were made of the bearing characteristics and are compared with the experimental results when possible. The first program used a bearing tester to determine the steady state, transient, and cyclic life characteristics of the bearing over a wide range of operating conditions. The second program demonstrated the feasibility of applying hybrid bearings to an actual high speed turbopump by retrofitting and then testing an existing liquid hydrogen turbopump with the bearings

Response of Veterinarians to the Strong Vocational Interest Blank for Men

The selection of students for the veterinary college at Iowa State College has become a real problem. Every year several times the enrollment capacity applies for entrance, and from this large group the few who are to be allowed admission must be carefully selected. In selecting these students, chief reliance has been placed on past scholastic records, both high school and pre-professional training in college, and upon various measures of scholastic aptitude. At present, a veterinary aptitude test is being developed by W. A. Owens of the Department of Psychology and L. C. Payne, School of Veterinary Medicine, Iowa State College. This test will aid materially in the solution of the problem. In an attempt to contribute some further aid in the selection of professional students, a study of the interests of veterinarians was undertaken. This study consists of the standardization of the Strong Vocational Interest Blank for Men on a group of veterinarians plus additional studies in the correlates of an interest score determined by this new scale

Photographic Study of Liquid-Oxygen Boiling and Gas Injection in the Injector of a Chugging Rocket Engine

High-speed motion pictures were taken of conditions in the injector liquid-oxygen cavity of an RL-10 rocket engine during throttled engine operation. Photographs were taken during operation of the engine in the chugging region as the helium gas was injected to stabilize combustion, during operation at rated thrust, and during transition into chugging conditions as the gas injection was discontinued. Results of the investigation indicate that, during chugging rocket operation of the RL-10 engine, a high population of fairly large bubbles formed and collapsed within the liquid-oxygen cavity at the same frequency as the chamber pressure oscillations. When gaseous helium was injected into the liquid-oxygen cavity, a fog rapidly spread over the entire field of view, and the system immediately became stable. The injection of gaseous helium at rated conditions produced a very slight increase in engine performance but not enough to produce a net gain in a typical mission payload with the extra equipment needed. The inherent low-frequency system instability associated with the fuel system at low thrust levels was reduced by injecting either gaseous helium or hydrogen. Complete stabilization was achieved in some cases, and a reduction in the severity of the oscillations in others. This was apparently due to the anchoring of the phase change front to the location of the gas injection

Some aspects of flox-methane rocket engine throttling

Four injector designs and two chamber profiles were experimentally evaluated for structural integrity, combustion efficiency, and resistance to combustion instabilities. Vacuum thrust measurements were used as a primary measure of combustion efficiency. Stability rating to test the sensitivity of the injectors to high frequency combustion was conducted, but not extensively. To map the boundary between stable operation and chugging instability, chamber pressure was throttled downward from 689.5 to 206.9 kN/sq m abs (100 to 30 psia). Best operational results were obtained with an injector configuration having no hydraulic swirlers, a 0.00102-m (0.040-in.) recessed FLOX tube, and a nonflared exit in the methane annulus. This injector design exhibited stable combustion and good integrity of hardware, and it exceeded the design goal efficiency (88 percent) at the 10 to 1 throttled condition

Childhood Inequality in China

In recent decades, China has transformed from a relatively egalitarian society to a highly unequal one. What are the implications of high levels of inequality for the lives of children? Drawing on two newly available, nationally representative datasets, the China Family Panel Studies and the China Education Panel Survey, we develop a comprehensive portrait of childhood inequality in post-reform China. Analyses reveal stark disparities between children from different socioeconomic backgrounds in family environments and in welfare outcomes, including physical health, psychosocial health, and educational performance. We argue that childhood inequality in China is driven not only by the deprivations of poverty, but also by the advantages of affluence, as high socioeconomic status children diverge from their middle and low socioeconomic status counterparts on various family environment and child welfare measures

A Longitudinal Study of the Interests of Veterinarians

The newly-revised SVIB was restandardized on 362 members of the Iowa Veterinary Medical Association. Ninety-eight of these veterinarians in this 1966 criterion group were also members of the 1949 criterion groups when the SVIB veterinarian scale was first established. The answer sheets from both the 1949 and the 1966 criterion groups were scored by the newly devised scoring key and a comparison made of score changes over this period. In addition the response-choice frequencies to the items common to both the old and the new SVIB by the longitudinal group were determined and significant shifts were noted and reported in detail. In general, the longitudinal group displayed a lessening of interest in scientific activities and an increase of interest in managerial, business, and financial activities over the 17 year period

Correlates of Achievement in a Veterinary Medicine Curriculum

A correlational study was made of test scores and achievement of Veterinary Medicine students who graduated in the spring of 1959 from Iowa State University. Cumulative grade point averages were obtained at the time of graduation and correlated with selection data obtained at the time of admission to the College of Veterinary Medicine in the fall of 1955. These data included: pre-veterinary grade point averages; interest scores on the Strong Vocational Interest Blank; Veterinary Aptitude Test scores; American Council on Educational Psychological Examination (College Edition), Quantitative and Linguistic scores; and numerical ratings made by a faculty committee during screening interviews with the candidates for admission. Pre-veterinary grade point average and interview rating contributed the only statistically significant correlations with achievement