Learjet Model 55 Wing Analysis with Landing Loads

The NASTRAN analysis was used to determine the impact of new landing loads on the Learjet Model 55 wing. These new landing loads were the result of a performance improvement effort to increase the landing weight of the aircraft to 18,000 lbs. from 17,000 lbs. and extend the life of the tires and brakes by incorporating larger tires and heavy duty brakes. Landing loads for the original 17,000 lb. airplane landing configuration were applied to the full airplane NASTRAN model. The analytical results were correlated with the strain gage data from the original landing load static tests. The landing loads for the 18,000 lb. airplane were applied to the full airplane NASTRAN model, and a comparison was made with the original Model 55 data. The results of this comparison enable Learjet to determine the difference in stress distribution in the wing due to these two different sets of landing loads

Computer Aided Modeling and Post Processing with NASTRAN Analysis

Computer aided engineering systems are invaluable tools in performing NASTRAN finite element analysis. These techniques are implemented in both the pre-processing and post-processing phases of the NASTRAN analysis. The finite element model development, or pre-processing phase, was automated with a computer aided modeling program called Supertabl, and the review and interpretation of the results of the NASTRAN analysis, or post-processing phase, was automated with a computer aided plotting program called Output Display. An intermediate program, Nasplot, which was developed in-house, has also helped to cut down on the model checkout time and reduce errors in the model. An interface has been established between the finite element computer aided engineering system and the Learjet computer aided design system whereby data can be transferred back and forth between the two. These systems have significantly improved productivity and the ability to perform NASTRAN analysis in response to product development requests

Development of the Learjet 28/29 Wing Using NASTRAN Analysis

The structural development work performed on the Learjet 28/29 wing using NASTRAN analysis is discussed. The work included the basic sizing of primary structural members such as wing skins, wing skin splices, and spar caps, as well as the calculation of preliminary weight estimates utilizing the weight computation routine in NASTRAN. The eight spar redundancy of the Learjet wing made this task somewhat more complex than for more determinate type wing structures. Some of the problems that were encountered and the solutions and methods that were used are described

Determination of Elevator and Rudder Hinge Forces on the Learjet Model 55 Aircraft

The empennage structure on the Learjet 55 aircraft was quite similar to the empennage structure on earlier Learjet models. However, due to an important structural change in the vertical fin along with the new loads environment on the 50 series aircraft, a structural test was required on the vertical fin, but the horizontal tail was substantiated by a comparative analysis with previous tests. NASTRAN analysis was used to investigate empennage deflections, stress levels, and control surface hinge forces. The hinge force calculations were made with the control surfaces in the deflected as well as undeflected configurations. A skin panel buckling analysis was also performed, and the non-linear effects of buckling were simulated in the NASTRAN model to more accurately define internal loads and stress levels. Comparisons were then made between the Model 55 and the Model 35/36 stresses and internal forces to determine which components were qualified by previous tests. Some of the methods and techniques used in this analysis are described

COMPARISON OF THREATENED NEOSHO MADTOM DENSITIES BETWEEN RIVERSCAPES DIFFERING IN ANTHROPOGENIC STRESSORS, WITH A PARTICULAR FOCUS ON RECOVERY FROM MINING-DERIVED METAL POLLUTION

Water pollution imperils the Neosho Madtom (Noturus placidus), which is threatened in Kansas and federally. Within Kansas madtom densities were historically lower in the Spring River compared to the Cottonwood and Neosho Rivers, especially within the Spring River below tributary inputs that delivered cadmium, lead, and zinc pollution from the Tri-State Mining District. Studies suggest that madtoms are less numerous in waters containing elevated metal concentrations because of direct toxicity and lower benthic macroinvertebrate availability, which is also depressed by elevated metal concentrations. However, long-term reductions in metal concentrations in the Spring River have occurred, but to date no study has examined whether madtom and macroinvertebrate densities have responded to this improving water quality. We addressed this question by comparing madtom densities and macroinvertebrate biomass between the Neosho-Cottonwood and Spring Rivers, and within the Spring River above and below metal pollution inputs. However, madtoms are imperiled by environmental factors and anthropogenic stressors beyond mining-derived metal pollution, so we also examined if food availability (i.e., macroinvertebrate biomass), watershed characteristics (i.e., the upstream proximity of small and large dams, upstream watershed area, and percent open water in the upstream watershed), and local habitat variables (i.e., turbidity, depth, velocity, and percent gravel/pebble substrate) were related to madtom densities. We found that madtom and macroinvertebrate population densities in the Spring River were similar to those of the Neosho-Cottonwood River system, and densities in the Spring River downstream of mining-impacted tributaries were similar to those upstream of pollution. Furthermore, macroinvertebrate availability and watershed characteristics were not associated with madtom abundance. However, turbidity and depth were associated with madtom densities, such that an increase in turbidity or decrease in depth resulted in higher madtom densities. Our results highlight the benefits that water quality improvements can have on stream organisms, especially those that are imperiled

Gathering Places, Cultivating Spaces: An Archaeology of a Chesapeake Neighborhood through Enslavement and Emancipation, 1775--1905

This study is a community-level analysis of an African American plantation neighborhood grounded in archaeological excavations at the Quarterpath Site (44WB0124), an antebellum quartering complex and post-Emancipation tenant residence occupied circa 1840s-1905 in lower James City County, Virginia. It asserts that the Quarterpath domestic quarter was a gathering place, a locus of social interaction in a vibrant and long established Chesapeake plantation neighborhood complex.;By the antebellum period, as marriage abroad, or off-plantation, became the most common form of long term social union within plantation communities, enslaved social and kin ties in the Chesapeake region were typically geographically dispersed, enjoining multiple domestic areas across dynamic rural plantation neighborhoods. Such neighborhoods came to comprise 1) Sets of interrelated places common across virtually all large Chesapeake plantations, and 2) Sets of social relationships that transcended plantation borders, becoming invested and embedded in local places over time.;This work examines the ways in which structures of community became embedded in a variety of familiar places across the Quarterpath neighborhood as enslaved persons appropriated plantation landscapes through habitual practices and meaningful bodily orientations. It expands the frame of reference beyond the core domestic homesites to embrace the other grounds and places where residents spent much of their time, places in which relationships were built with neighbors performing common tasks on familiar grounds. It offers new insights to archaeological analyses concerning African American domestic sites throughout the African Atlantic diaspora, envisioning home grounds as dynamic social configurations embedded within mosaics of local places that came to embody community, family, and roots. It is an archaeology of a community in transition but it is also an archaeology of landscapes. It adopts a methodologically innovative approach intended to address often overlooked interpretive contexts and horizons of meaning, exploring mechanisms of community development and associated processes of place-making in a pre- and post-Emancipation African American community

Analysis of the Learjet 35/36 Wing and Correlation with Experimental Results

Two NASTRAN models of the Gates Learjet Corporation Model 35/36 Wing were developed. The models and the problems encountered in their development are discussed. A skin buckling analysis used for the ultimate loading conditions is presented. A discussion of the static tests and the correlation of the static test with the NASTRAN results and the results of a supplementary semimonocoque beam analysis are also included