Computer program to prepare airfoil characteristic data for use in helicopter performance calculations

A computer program developed to prepare wind tunnel generated airfoil data for input into helicopter performance prediction programs is described. The program provides for numerically cross plotting the data, plotting the data, and tabulating and punching the tabulated result into computer cards for use in the rotorcraft flight simulation model

Cooling slope casting to obtain thixotropic feedstock

Thixoforming, and related semi-solid processing routes for metallic alloys, require feedstock with a non-dendritic microstructure in the semi-solid state. The material then behaves in a thixotropic way in that, when it is sheared it flows and can be forced to fill a die and, when it is allowed to stand it thickens again. The New Rheocasting (the NRC process) is a recently developed semi-solid processing route. There are two versions of this route. In one, molten alloy is poured directly into a tilted mould and, through careful temperature control during cooling, a spheroidal semi-solid microstructure is achieved. The material in the mould is then upended into a shot sleeve and hence forced into a die. Alternatively, the molten alloy is poured onto a cooling slope and thence into a mould before processing. The aim of the work described in this paper was to develop understanding of the microstructural development during the initial stages of this process. The results for pouring A356 aluminium alloy via a cooling slope into a mould are presented

Full-potential modeling of blade-vortex interactions

A comparison is made of four different models for predicting the unsteady loading induced by a vortex passing close to an airfoil. (1) The first model approximates the vortex effect as a change in the airfoil angle of attack. (2) The second model is related to the first but, instead of imposing only a constant velocity on the airfoil, the distributed effect of the vortex is computed and used. This is analogous to a lifting surface method. (3) The third model is to specify a branch cut discontinuity in the potential field. The vortex is modeled as a jump in potential across the branch cut, the edge of which represents the center of the vortex. (4) The fourth method models the vortex expressing the potential as the sum of a known potential due to the vortex and an unknown perturbation due to the airfoil. The purpose of the current study is to investigate the four vortex models described above and to determine their relative merits and suitability for use in large three-dimensional codes

Teddy - A two-dimensional Lagrangian code for determining the wave propagation in elastic-plastic media

Finite difference methods and two dimensional Lagrangian code for determining wave propagation in elastic-plastic media - TEDDY progra

Axial Ratio of Edge-On Spiral Galaxies as a Test For Extended Bright Radio Halos

We use surface brightness contour maps of nearby edge-on spiral galaxies to determine whether extended bright radio halos are common. In particular, we test a recent model of the spatial structure of the diffuse radio continuum by Subrahmanyan and Cowsik which posits that a substantial fraction of the observed high-latitude surface brightness originates from an extended Galactic halo of uniform emissivity. Measurements of the axial ratio of emission contours within a sample of normal spiral galaxies at 1500 MHz and below show no evidence for such a bright, extended radio halo. Either the Galaxy is atypical compared to nearby quiescent spirals or the bulk of the observed high-latitude emission does not originate from this type of extended halo.Comment: 6 Pages, 4 Figures, 1 Table; To Appear In ApJ Letter

Ambivalent sexism and perceptions of men and women who violate gendered family roles

This study draws on ambivalent sexism theory to explore the role of benevolent and hostile gender attitudes in determining perceptions of individuals who comply with traditional gender roles or violate them. Three hundred and eleven participants were presented with a description of a male or a female target who was either a primary breadwinner or a primary caregiver. As hypothesized, hostile sexism predicted more negative perceptions of a female breadwinner, whereas benevolent sexism predicted more positive perceptions of a female caregiver. Moreover, participants who endorsed hostile attitudes toward men reacted more positively to a nontraditional male caregiver, whereas those who endorsed benevolent attitudes toward men reacted more negatively to a male caregiver. Implications regarding the nature of ambivalent gender attitudes are discussed

Space Shuttle Main Engine (SSME) Pogo testing and results

To effectively assess the Pogo stability of the space shuttle vehicle, it was necessary to characterize the structural, propellant, and propulsion dynamics subsystems. Extensive analyses and comprehensive testing programs were established early in the project as an implementation of management philosophy of Pogo prevention for space shuttle. The role of the space shuttle main engine (SSMF) in the Pogo prevention plans, the results obtained from engine ground testing with analysis, and measured data from STS-1 flight are discussed

Polyimide polymers provide improved ablative materials

Principle heat absorption of silica-reinforced plastic ablative materials occurs from the in-depth reaction of silica with carbon to form silicon monoxide and carbon monoxide. The higher the degree of completion of this reaction, the higher the capacity of the ablative material to absorb heat

Polyimide polymers provide higher char yield for graphitic structures

Technique for manufacture of graphite composites uses high-char-forming processable polyimide resin systems to produce the graphitic matrix. Only three cyclic steps are required to yield a 99.7 percent graphite product