Summary of all cycle II.5 shear and boundary layer measurements, aerodynamics

The two measurement systems were used to measure mean velocity and velocity, mass flux, and total temperature fluctuations in the turbulent boundary on the fuselage of a KC-135 aircraft. The boundary layer thickness ranged between about 20 and 30 cm for the range of flight Mach numbers from about 0.25 to 0.85 and Reynolds numbers between 3 and 6 x 10 to the 6th power/m. The adaptation of each system for use in airborne applications is discussed. The data obtained from each system are given and compared with each other and they indicate that the two systems represent viable ones for use in future airborne turbulence experiments

Financial Impacts of Regional Differences in Beef Cattle Operations

The sensitivity of net cash farm income to changes in selected production variables, output prices, and input costs varies significantly across representative U.S. beef cattle operations. Larger changes in profitability result from changes in productivity and output prices than from changes in input costs.Livestock Production/Industries,

High temperature polyimide foams for shuttle upper surface thermal insulation

Polyimide foams developed by Monsanto Company were examined for use as upper surface space shuttle thermal insulation. It was found that postcured polyimide foams having a density of 64 kg/cu m (4 lb/cu ft) had acceptable physical properties up to and exceeding 700 K (800 F). Physical tests included cyclic heating and cooling in vacuum, weight and dimensional stability, mechanical strength and impact resistance, acoustic loading and thermal conductivity. Molding and newly developed postcuring procedures were defined

Separated flow

A brief overview of flow separation phenomena is provided. Langley has many active research programs in flow separation related areas. Three cases are presented which describe specific examples of flow separation research. In each example, a description of the fundamental fluid physics and the complexity of the flow field is presented along with a method of either reducing or controlling the extent of separation. The following examples are discussed: flow over a smooth surface with an adverse pressure gradient; flow over a surface with a geometric discontinuity; and flow with shock-boundary layer interactions. These results will show that improvements are being made in the understanding of flow separation and its control

Deformation and spallation of shocked Cu bicrystals with Σ3 coherent and symmetric incoherent twin boundaries

We perform molecular dynamics simulations of Cu bicrystals with two important grain boundaries (GBs), Σ3 coherent twin boundaries (CTB), and symmetric incoherent twin boundaries (SITB) under planar shock wave loading. It is revealed that the shock response (deformation and spallation) of the Cu bicrystals strongly depends on the GB characteristics. At the shock compression stage, elastic shock wave can readily trigger GB plasticity at SITB but not at CTB. The SITB can induce considerable wave attenuation such as the elastic precursor decay via activating GB dislocations. For example, our simulations of a Cu multilayer structure with 53 SITBs (∼1.5-μm thick) demonstrate a ∼80% elastic shock decay. At the tension stage, spallation tends to occur at CTB but not at SITB due to the high mobility of SITB. The SITB region transforms into a threefold twin via a sequential partial dislocation slip mechanism, while CTB preserves its integrity before spallation. In addition, deformation twinning is a mechanism for inducing surface step during shock tension stage. The drastically different shock response of CTB and SITB could in principle be exploited for, or benefit, interface engineering and materials design

Impact of Alternative Property and Sales Tax Policies on Texas Representative Cotton Farms

The call for school finance reform has threatened to modify or possibly remove the current property and sales and use tax exemptions currently benefiting Texas cotton producers. This study utilizes a whole farm simulation model to evaluate the economic and financial impact of three alternative sales and/or property tax policy changes on Texas cotton farms along with their respective landowners. Results indicate that removing sales tax exemptions would most adversely impact producers, while removing property tax exemptions has a more negative effect on landowners.Agribusiness, Agricultural and Food Policy, Crop Production/Industries,

The NASA/MSFC global reference atmospheric model: 1990 version (GRAM-90). Part 1: Technical/users manual

A technical description of the NASA/MSFC Global Reference Atmospheric Model 1990 version (GRAM-90) is presented with emphasis on the additions and new user's manual descriptions of the program operation aspects of the revised model. Some sample results for the new middle atmosphere section and comparisons with results from a three dimensional circulation model are provided. A programmer's manual with more details for those wishing to make their own GRAM program adaptations is also presented

Mission-oriented requirements for updating MIL-H-8501. Volume 1: STI proposed structure

The structure of a new flying and ground handling qualities specification for military rotorcraft is presented. This preliminary specification structure is intended to evolve into a replacement for specification MIL-H-8501A. The new structure is designed to accommodate a variety of rotorcraft types, mission flight phases, flight envelopes, and flight environmental characteristics and to provide criteria for three levels of flying qualities, a systematic treatment of failures and reliability, both conventional and multiaxis controllers, and external vision aids which may also incorporate synthetic display content. Existing and new criteria were incorporated into the new structure wherever they could be substantiated