Application of a transonic potential flow code to the static aeroelastic analysis of three-dimensional wings

Since the aerodynamic theory is nonlinear, the method requires the coupling of two iterative processes - an aerodynamic analysis and a structural analysis. A full potential analysis code, FLO22, is combined with a linear structural analysis to yield aerodynamic load distributions on and deflections of elastic wings. This method was used to analyze an aeroelastically-scaled wind tunnel model of a proposed executive-jet transport wing and an aeroelastic research wing. The results are compared with the corresponding rigid-wing analyses, and some effects of elasticity on the aerodynamic loading are noted

An exploratory study of finite difference grids for transonic unsteady aerodynamics

Unsteady aerodynamic forces are calculated by the XTRAN2L finite difference program which solves the complete two dimensional unsteady transonic small perturbation equation. The unsteady forces are obtained using a pulse transfer function technique which assumes the flow field behaves in a locally linear fashion about a mean condition. Forces are calculated for a linear flat plate using the default grids from the LTRAN2-NLR, LTRAN2-HI, and XTRAN3S programs. The forces are compared to the exact theoretical values for flat plate, and grid generated boundary and internal numerical reflections are observed to cause significant errors in the unsteady airloads. Grids are presented that alleviate the reflections while reducing computational time up to fifty-three percent and program size up to twenty-eight percent. Forces are presented for a six percent thick parabolic arc airfoil which demonstrate that the transform technique may be successfully applied to nonlinear transonic flows

Time-marching transonic flutter solutions including angle-of-attack effects

Transonic aeroelastic solutions based upon the transonic small perturbation potential equation were studied. Time-marching transient solutions of plunging and pitching airfoils were analyzed using a complex exponential modal identification technique, and seven alternative integration techniques for the structural equations were evaluated. The HYTRAN2 code was used to determine transonic flutter boundaries versus Mach number and angle-of-attack for NACA 64A010 and MBB A-3 airfoils. In the code, a monotone differencing method, which eliminates leading edge expansion shocks, is used to solve the potential equation. When the effect of static pitching moment upon the angle-of-attack is included, the MBB A-3 airfoil can have multiple flutter speeds at a given Mach number

Methodology for Integrating Aerial Photography and LANDSAT TM Imagery for Inventory of Forest Land Cover

Forest cover for 7.25 million acres (2.93 million hectares) in southeastern Georgia was characterized for the years 1988 and 1994 with the intent of assessing the efficacy of remote sensing procedures for broad scale forest inventory. Landsat-5 Thematic Mapper digital satellite scenes of seven spectral bands were obtained for winter and summer of each year and were analyzed two separate 14-band multi-temporal images. Images were geo-referenced to the universal transverse mercator (UTM) coordinate system prior to classification. Spectral classification with the 1SOCLUSTER algorithm produced 250 categories. Color infrared aerial photographs were mapped to the digital imagery and were used to convert spectral categories to land cover features. For this study, land features of interest were limited to water, marsh, pine forest, hardwood forest, mixed pine/hardwood forest, urban, and where distinguishable, clearcut and agriculture. Accuracy assessment techniques indicated very good consistency

Urban Violence among African American Males: Integrating Family, Neighborhood, and Peer Perspectives

Even though rates have declined in recent years, violence is a serious problem in many American cities. This paper reviews recent perspectives on violence among young, urban African American males. Special attention is afforded the father absent hypothesis, the effect of poverty, the character of neighborhoods, the roots of self-efficacy, and peer influence, particularly the influence of street codes. The latter are argued both to regulate some situational behavior and to promote the use of violence in disputes over social status, drugs, and money. The authors discuss implications for policy and community development

Book Reviews

Reviews of the following books: History of Belfast in the 20th Century: by Jay David and Tim Hughes, with Megan Pinette; At Home With The General: A Visit to the Joshua L. Chamberlain Museum by Allan M. Levinsky; “Do Your Job!” An Illustrated Bicentennial History of the Portsmouth Naval Shipyard, 1800-2000 by Richard E. Winslow, III; Super U: The History and Politics of the University of Maine System by James Libb