Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2002. / Includes bibliographical references (p. 119-121). / The Perching Unmanned Aerial Vehicle (PUAV) is a 9-inch diameter ducted vertical takeoff and landing reconnaissance vehicle with the capability of fast-forward cruise flight. Currently in the development stage, the program is envisaged to yield a man-portable craft that a foot soldier can use to provide over-the-hill observation. Several prototypes have been constructed and tested, with mixed results. Concerns regarding duct aerodynamics led to the proposal for further aerodynamic study to investigate effects of inlet lip radius and surface area, diffuser area ratio, blade tip clearance and rotor position on thrust, power and efficiency. This report covers the theory of rotorcraft and ducted propeller aerodynamics, and outlines the tests performed and results obtained. It also presents specifications of the test vehicle and methods that can be used in future ducted aircraft studies. Large angle diffusers tested showed reduced thrust and efficiency and increased power compared to smaller diffusers, contrary to theory. Reverse flow within the core appears to disrupt uniform exit flow and yields a conically divergent turbulent wake. Results of this study will be used in the redesign of a duct core fairing, which will act to control the airflow and reduce the tendency for reverse flow at the center where blade thrust is absent. Future studies will also consider twisted, cambered and tapered rotor blades in an effort to better address spanwise thrust distribution and optimized airflow. The test apparatus and methods developed for this report, in addition to results of initial testing, will be instrumental to further development of small ducted UAVs. Findings and methods are not limited to exact duplicates of PUAV-like aircraft, but can be used in a wide range of applications including lift and thrust-producing ducts. / by Kyrilian Dyer. / S.M.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1961. / Includes bibliographical references (leaves 105-106). / by Norbert Andrew Durando. / M.S.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2009. / This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections. / MIT Institute Archives copy: with CD-ROM; divisional library copy with no CD-ROM. / Includes bibliographical references (p. 93-98). / Rising world oil prices and advanced oil recovery techniques have made it economically attractive to rehabilitate abandoned oil wells. This requires guiding tools through well junctions where divergent branches leave the main wellbore. The unknown locations and shapes of these junctions must be determined. Harsh down-well conditions prevent the use of ranged sensors. However, robotic tactile exploration using a manipulator is well suited to this problem. This tactile characterization must be done quickly because of the high costs of working on oil wells. Consequently, intelligent tactile exploration algorithms that can characterize a shape using sparse data sets must be developed. This thesis explores the design and system architecture of robotic manipulators for down-well tactile exploration. A design approach minimizing sensing is adopted to produce a system that is mechanically robust and suited to the harsh down-well environment. A feasibility study on down-well tactile exploration manipulators is conducted. This study focuses on the mature robotic technology of link and joint manipulators with zero or low kinematic redundancy. This study produces a field system architecture that specifies a unified combination of control, sensing, kinematic solutions for down-well applications. An experimental system is built to demonstrate the proposed field system architecture and test control and intelligent tactile exploration algorithms. Experimental results to date have indicated acceptability of the proposed field system architecture and have demonstrated the ability to characterize geometry with sparse tactile data. / (cont.) Serpentine manipulators implemented using digital mechatronic actuation are also considered. Digital mechatronic devices use actuators with discrete output states and the potential to be mechanically robust and inexpensive. The design of digital mechatronic devices is challenging. Design parameter optimization methods are developed and applied to a design case study of a manipulator in a constrained workspace. This research demonstrates that down-well tactile exploration with a manipulator is feasible. Experimental results show that the proposed field system architecture, a 4 degree-of-freedom anthropomorphic manipulator, can obtain accurate tactile data without using any sensor feedback besides manipulator joint angles. / by Daniel Terrance Kettler. / S.M.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2011. / This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections. / Cataloged from student submitted PDF version of thesis. / Includes bibliographical references (p. 101). / The New York airspace is the most congested in the U.S. air transportation network. Increasing capacity in this area is critical to ensure the balanced growth of traffic across the U.S. This study compares the total measured runway capacity at the New York airports with the achieved throughput of the New York airspace. The comparison is performed for six airspace configurations representing operations under different wind conditions, visibility and relative arrival and departure demand. The comparison shows that in all cases the capacity of the system of airports is lower than the total capacity of the airports considered individually by approximately 20%. This finding suggests that air traffic throughput in the New York area is constrained by shared airspace resources. If these constraints could be removed, these funding suggest that capacity could be increased approximately 20% without any airport infrastructure or procedure changes. An examination of procedures close to the airports is performed to identify fixed constraints. The impact of these constraints is not captured by the empirical analysis because these constraints are always present. This analysis identifies cases where new navigation technologies could be used to reduce the interactions between airports. The greatest potential for improvement is found to be in the lower performing configurations. Therefore procedural changes close to the airports may provide more benefit in reducing the variability of capacity between different configurations, rather than providing large increases in maximum capacity. / by Alexander David Donaldson. / S.M.

Thesis: S.M., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2015. / This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections. / Cataloged from student-submitted PDF version of thesis. / Includes bibliographical references (pages 91-92). / This thesis describes a methodology to convert electrical power measurements to propulsor mechanical ow power for a 1:11-scale, powered wind tunnel model of an advanced civil aircraft utilizing boundary layer ingestion (BLI); mechanical ow power is a surrogate for aircraft fuel burn. Back-to-back experiments of BLI and non-BLI aircraft configurations to assess the BLI benet directly measured electrical power, and supporting experiments were performed in a 1x1 foot wind tunnel at the MIT Gas Turbine Laboratory to convert these measurements into mechanical flow power. The incoming flow conditions of the powered wind tunnel tests (Reynolds number and inlet distortion) were replicated. This propulsor characterization was found to convert the electrical power measurements to mechanical ow power with experimental uncertainty of roughly 1.6%. / by Nina M. Siu. / S.M.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2008. / Includes bibliographical references (p. 149-157). / Formation flying satellites offer potentially greater science returns and operational capabilities than attainable with a monolithic spacecraft. Successful control of a formation of spacecraft can be divided into two separate stages. The first stage creates a plan that meets a set of mission objectives, and the second stage implements the plan. Plans are specified as a sequence of [delta]V commands executed at specific times during an orbit. This thesis presents an online method for generating fleet-wide plans, using convex optimization techniques, that satisfy multiple objectives. The approach allows for minimum and balanced fuel usage, can position spacecraft in arbitrary configurations, and favors low-maintenance orbits that do not drift apart. Additionally, the architecture is applicable not only to formation-keeping maneuvers, but also to formation reconfigurations. Various simulations demonstrate the importance of accurately implementing plans for formation flying as well as autonomous rendezvous and docking missions. Specifically, the relationships between process error, overall fuel use, and position error are studied. Theory is put into practice with the development of a new low-level, closed-loop thrust controller for the Synchronized Position Hold Engage and Reorient Experimental Satellites (SPHERES). The controller processes measurements from accelerometers and gyroscopes to monitor thruster performance in real-time. Experiments conducted on the International Space Station (ISS) validate the controller and establish a foundation for future enhancements to the underlying algorithm. Finally, data from a series of high-fidelity formation flying simulations is presented that confirms the analysis done elsewhere in the thesis. / (cont.) The multi-objective planner is used in a closed-loop control system that guides a formation of five spacecraft through a hypothetical mission involving both reconfigurations and formation-keeping. Data from the simulations allows a straightforward, side by side comparison of the effects and relative importance of sensor error versus implementation error. / by Matthew M. Jeffrey. / S.M.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2010. / Cataloged from PDF version of thesis. / Includes bibliographical references (p. 91-93). / This thesis presents a design concept for return passages in multistage centrifugal compressors. Flow in a baseline return passage is analyzed to identify loss sources that have substantial potential for reduction. For the geometry analyzed, it is found that mismatched incidence of the return vane, separation on the hub surface at the exit of the return bend, and blockage due to separation on the shroud surface near the return bend inlet lead to losses which have such potential. Preliminary designs were developed and computationally assessed to determine effective geometries for eliminating separation on the hub at the return bend exit and for reducing losses. Then, based on assessment of the preliminary designs, other features of the loss generation were addressed. The geometry proposed includes an increased axial extent of the return bend, an increasing radius of curvature through the return bend, and lean of the return vane leading edge, mitigating the loss mechanisms identified in the baseline return passage. The three-dimensional calculations showed a cumulative loss coefficient that was 10% lower than the baseline. The design described was carried out with a fixed inlet condition, and a second return passage was thus developed to determine the potential loss reduction if the inlet geometry were modified. (The design of the impeller required to achieve the modified inlet flow was not considered.) The cumulative loss coefficient was reduced by 27% compared with the baseline, with the implication that an area for exploration is integration of the impeller and return passage flow fields. / by Benjamin W. Glass. / S.M.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1992. / Includes bibliographical references (leaves 324-330). / by Dana Keoki Jackson. / M.S.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1974. / Bibliography: leaf 103. / M.S.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2003. / Includes bibliographical references (p. 95-96). / by Vincent P. Perrot. / S.M.