Aerospace Engineering Theses and Dissertations

Permanent URI for this collectionhttp://hdl.handle.net/1903/2737

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1980 - 19873

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Start date: 1980End date: 1989

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    Experimental Evaluation of Circulation Control Aerodynamics on a Cylindrical Body
    (1987) Ngo, Hieu Thien; Chopra, Inderjit; Aerospace Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, MD)
    In this study, an experimental investigation is conducted on a two-dimensional circulation control cylinder with blowing taking place from a single spanwise slot to determine its aerodynamic characteristics. The results include detailed pressure distributions (both chordwise and spanwise) for a range of momentum coefficients and slot locations. The measured results showed that the lift coefficients up to 4.8 were produced at momentum coefficients of 0.14 in a turbulent flow condition. The experimental results of lift coeffficients Were correlated satisfactorily with analytical results. The surface flow patterns were observed using the oil and smoke techniques. Also flow field surveys of the model Were obtained using total pressure, yaw and pitch probes. A color video display technique was used to present the results of the flow field surveys. Based on this evidence, a flow field model of the circulation control cylinder is presented.
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    An Expert System for Helicopter Conceptual Design
    (1987) Babuska, Vit; Fabunmi, James A.; Aerospace Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md)
    The objective of this thesis is to demonstrate the applicability of expert systems in helicopter conceptual design by developing an expert assistant which aids the engineer in defining a feasible design configuration. The expert assistant combines some experiential knowledge of the design engineer with a typical conceptual design algorithm to guide the engineer to a reasonable baseline design. The expert assistant was developed on a personal computer using the expert system shell INSIGHT2+®. The design algorithm employed is SSPl, a helicopter weight and sizing program developed at the US Army Applied Technologies Laboratory. A set of heuristic rules was developed which attempts to simulate the thinking of an expert design engineer using SSP1 for helicopter conceptual design. The result, a Prototype expert assistant which aids an engineer in the conceptual design phase, demonstrates the feasibility of expert systems in helicopter design.
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    Dynamics of a Helicopter-Slung Load System
    (1980) Sampath, Prasad; Barlow, Jewel B.; Aerospace Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md)
    Stability of a tandem rotor helicopter (347/HLH) carrying a slung cargo container has been investigated. Lagrange equations were used to write the equations of motion. The cables of the sling were modeled as massless rigid extensible rods, which collapse under compressive loads. Extensibility was provided by considering the rods as linear spring with viscous damping. Aerodynamics of the cable were neglected. Tabulated static aerodynamic data were considered for the helicopter as well as the load. The equations were divided into two sets, one representing the towing vehicle (referred to as Subsystem 1) and the other representing the slung load (referred to as Subsystem 2). Subsystem 2 corresponds to a wind tunnel model of a slung load.