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Articles 1 - 5 of 5
Full-Text Articles in Aerospace Engineering
Closed-Loop Propulsive Control For Very Low Perigee Orbit Energy Management And Stabilization, Tyler J. Gardner
Closed-Loop Propulsive Control For Very Low Perigee Orbit Energy Management And Stabilization, Tyler J. Gardner
All Graduate Theses and Dissertations, Spring 1920 to Summer 2023
Within the past decade, the United States Air Force has begun exploring options for using smaller satellites, known as SmallSats and CubeSats, to decrease the time it takes to design and build new satellites. If used properly, a rapid development environment for satellites could improve the Air Force's ability to respond to new technologies and threats. Other organizations such as NASA and universities have been using SmallSats and CubeSats for research and development missions.
While smaller satellites are usually much cheaper to develop and require less time to create, limited volume strictly constrains the size of instrumentation and avionics that …
Analytic Guidance Strategies For Passively Safe Rendezvous And Proximity Operations, Simon Shuster
Analytic Guidance Strategies For Passively Safe Rendezvous And Proximity Operations, Simon Shuster
All Graduate Theses and Dissertations, Spring 1920 to Summer 2023
A safety ellipse is a type of relative motion trajectory that is commonly used for unmanned rendezvous and proximity operations. As the name suggests, safety ellipses are passively safe relative motion trajectories, which means that their natural motion inherently maintains a low collision risk. The focus of this dissertation is the derivation, analysis, and application of guidance strategies that reconfigure, establish, and exit a safety ellipse. The guidance strategies consist of a set of ∆v vectors and impulse times, all written in closed form. Through applications of optimal control theory and parameter optimization, it is shown that these maneuver …
A General Approach To Lifting-Line Theory, Applied To Wings With Sweep, Jackson T. Reid
A General Approach To Lifting-Line Theory, Applied To Wings With Sweep, Jackson T. Reid
All Graduate Theses and Dissertations, Spring 1920 to Summer 2023
Lifting-line theory is one simple method of predicting the lift produced by a wing. The traditional implementation of lifting-line theory, developed in 1918, is limited to predicting the lift of traditional straight wings. In this work, lifting-line theory is extended to predict the lift produced by modern swept (or "v-shaped") wings by strategically handling the singularities inherent to the theory. The resulting formulation is shown to be both accurate and computationally inexpensive, when compared to experimental and higher-fidelity computational results, demonstrating the method's usefulness as an aerodynamic design tool. Because of the low computational cost and accuracy of the method …
Impact Of Parasitic Drag On A Family Of Optimal Lift Distributions, Austin J. Stewart
Impact Of Parasitic Drag On A Family Of Optimal Lift Distributions, Austin J. Stewart
All Graduate Theses and Dissertations, Spring 1920 to Summer 2023
Minimizing drag is a variational problem, and several minimum induced drag solutions have been found using different design constraints. The elliptic lift distribution is commonly used to minimize induced drag, but is only the optimal solution under one set of design constraints. Non-elliptic lift distributions are able to reduce induced drag, when compared to the elliptic lift distribution, by increasing the wingspan while maintaining a consistent wing–structure weight. However, these non-elliptic lift distributions are only optimal if the effects of viscous drag are neglected. In this study, numerical tools are used to estimate the total drag on rectangular wings that …
Practical Optical Survey Strategies For Near Geostationary Orbital Debris, Akhter Mahmud Nafi
Practical Optical Survey Strategies For Near Geostationary Orbital Debris, Akhter Mahmud Nafi
All Graduate Theses and Dissertations, Spring 1920 to Summer 2023
Uncontrolled space objects, more commonly known as space debris, consist of dead satellites, satellite deployment packages, and lost elements of these systems such as insulation blankets. These uncontrolled objects represent hazards to our nation’s most valuable space assets which include communication satellites, weather satellites, Earth monitoring systems, and military assets. To help mitigate this problem, this research proposes using the known astrodynamics of the near geosynchronous orbit (GEO) along with the known concentration of the uncontrolled GEO objects and observation constraints to design ground-based optical surveys that will detect uncatalogued debris. Furthermore, a scoring metric is developed to evaluate the …