Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2012. / Cataloged from PDF version of thesis. / Includes bibliographical references (p. 110-112). / Performance Based Navigation (PBN) is a key element of the Federal Aviation Administration's (FAA) NextGen Program. In order to increase National Airspace System (NAS) capacity and efficiency, PBN routes and procedures are being developed, including Area Navigation (RNAV) and Required Navigation Performance (RNP) procedures. RNAV enables aircraft to fly directly from point-to-point on any desired flight path using groundor spaced-based navigation aids. RNP is RNAV with the addition of onboard monitoring and alerting capability. Both RNAV and RNP procedures allow aircraft to fly accurate routes without relying on ground-based navigation aids. RNAV and RNP procedures facilitate more efficient design of airspace and procedures, offering significant safety improvements and flexibility to negotiate terrain, as well as improving airspace capacity and operational efficiency. The initial implementation of RNAV and RNAV (RNP) procedures has raised several human factors issues. RNAV (RNP) Instrument Approach Procedures (IAP) and RNAV Standard Instrument Departures (SID) and Standard Terminal Arrivals (STARs) often have more waypoints, altitude constraints and other elements than conventional procedures, resulting in charts being cartographically complex. Thus, a chart review was conducted to objectively understand the procedure elements that contributed to increased information density and high levels of visual clutter. A total of sixty-three approach, fifty-two departure, and fifty-four arrival procedures were analyzed. Primary findings were that the factors associated with high levels of visual clutter included having multiple flight paths per page for approach and departure procedures, and having complex altitude constraints for arrival procedures. Multiple waypoints per path was also a factor for both arrivals and approaches. In addition, having RF legs were additional factor contributing to visual clutter for approach procedures. One method to mitigate the increased information density and visual clutter on the RNAV and RNP procedure depiction is to reduce the number of flight paths shown on a single page by separating the depicted paths to multiple pages. However, there are a number of drawbacks to this clutter mitigation technique. Example drawbacks include having more paper to carry in the flight deck and more time spent searching for the correct page within a set of separated pages. An experiment was conducted to determine the effect of reducing the number of paths depicted on single-page "Modified" charts. FAA AeroNav Products and Jeppesen created versions of the Modified chart in their standard cartographical conventions. The experiment was conducted to evaluate whether these Modified charts would impact information retrieval time and accuracy compared with the "Current" charts being used now. Current FAA AeroNav Products and Jeppesen charts were used as the baseline condition. Six procedures were studied, including three RNAV departure procedures from Dallas/Fort Worth, Las Vegas, and Salt Lake City airports, and three RNAV (RNP) approach procedures from Boise, Bozeman, and Palm Springs airports. During the experiment, pilots were shown the same procedure in Current and Modified chart formats. All charts were displayed electronically on a high-resolution computer monitor. Pilots were asked information retrieval questions associated with each chart. Pilot response time and accuracy with which pilots answered the information retrieval questions were recorded. Pilots completed the task in two blocks, one for approaches and one for departures. The Current and Modified charts within each block were presented in random order, and the order of the two blocks was counterbalanced. Each block began with six practice questions. Each session took approximately one hour to complete. Data were collected from 28 commercial airline pilots and 19 corporate pilots with average flight experience of 11,484 hours. Fourteen pilots used FAA AeroNav charts, and 33 pilots used Jeppesen charts. Pilots were found to answer questions faster using Modified charts than Current charts. This effect was statistically significant with a p-value less than 0.01. For approach procedures, the mean response time for Current charts was 16.9 seconds, compared with 10.6 seconds for Modified charts. For departure procedures, the mean response time for Current charts was 16.2 seconds, compared with 13.2 seconds for Modified charts. Response times were also significantly faster for Modified charts than for Current charts when analyzed for each airport, chart manufacturer (Jeppesen and FAA AeroNav Products), and pilot type (Corporate and Airline). Overall question response accuracy for all 47 participants was 99.5%. There were no statistically significant differences found for the response accuracy between Modified and Current chart use. / by Abhizna Butchibabu. / S.M.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2001. / Includes bibliographical references (p. 175-179). / by Olivier Mongrard. / S.M.

Thesis: S.M., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2017. / Cataloged from PDF version of thesis. / Includes bibliographical references (pages 211-214). / Satellites at geosynchronous orbital altitudes are highly valuable for national defense, but are also difficult to access and monitor. Uncrewed inspection spacecraft could supervise various essential defense platforms and deter covert rendezvous by adversaries with malicious intent. 'Neighborhood watch' satellites tasked with this situational awareness mission should be designed and operated in such a way as to maximize their lifespan and efficacy. Motivated by this requirement, this thesis explores the prolonged medium- to close-range spacecraft proximity operations problem from the perspective of continuous optimal trajectory control. A numerical optimization framework is presented for developing and analyzing fuel-, energy-, and time-optimal trajectories with multiple phases using Gauss pseudospectral collocation software. Emphasis is placed on energy efficiency during inspection, for which accurate dynamical models play a critical role in formationkeeping fuel consumption. Various scenarios are analyzed for minimum-energy solutions, such as tactical phasing and insertion into periodic trajectories, avoidance of 'no-fly' zones, inclusion of coupling attitude dynamics, and operations with highly-eccentric targets. This thesis focuses primarily on proximity operations carried out in geosynchronous orbital regimes and neglects orbit perturbations, instead determining the pure cost of linearizing Keplerian gravity using the Hill-Clohessy-Wiltshire model. Error in relative position, angular rate of circumnavigation, and fuel use to enforce linearized periodic trajectories are characterized. It was determined that proximity operations utilizing low-thrust high-specific-impulse solar electric propulsion are well-suited to minimum-energy trajectory optimization with this method. While the contributed analysis tool is not suitable for on-board optimal trajectory generation, it provides a framework to perform useful pre-mission analyses. / by Zachary K. Funke. / S.M.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1988. / Includes bibliographical references. / by Dana Rae Lindquist. / M.S.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2008. / Includes bibliographical references (p. 104-108). / As unmanned aerial vehicles (UAVs) become increasingly autonomous, current single-UAV operations involving multiple personnel could transition to a single operator simultaneously supervising multiple UAVs in high-level control tasks. These time-critical, single-operator systems will require advance prediction and mitigation of schedule problems to ensure mission success. However, actions taken to address current schedule problems may create more severe future problems. Decision support could help multi-UAV operators evaluate different schedule management options in real-time and understand the consequences of their decisions. This thesis describes two schedule management decision support tools (DSTs) for single-operator supervisory control of four UAVs performing a time-critical targeting mission. A configural display common to both DSTs, called StarVis, graphically highlights schedule problems during the mission, and provides projections of potential new problems based upon different mission management actions. This configural display was implemented into a multi-UAV mission simulation as two different StarVis DST designs, Local and Q-Global. In making schedule management decisions, Local StarVis displayed the consequences of potential options for a single decision, while the Q-Global design showed the combined effects of multiple decisions. An experiment tested the two StarVis DSTs against a no DST control in a multi-UAV mission supervision task. Subjects using the Local StarVis performed better with higher situation awareness and no significant increase in workload over the other two DST conditions. The disparity in performance between the two StarVis designs is likely explained by the Q-Global StarVis projective "what if" mode overloading its subjects with information. This research highlights how decision support designs applied at different abstraction levels can produce different performance results. / by Amy S. Brzezinski. / S.M.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2003. / Includes bibliographical references (leaves 197-201). / by David Joe Willis. / S.M.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2012. / CD-ROM contains files in .m and .xls formats. / Cataloged from PDF version of thesis. / Includes bibliographical references (p. 243-257). / Robotic planetary surface exploration, which has greatly benefited humankind's scientific knowledge of the solar system, has to date been conducted by sedentary landers or by slow, terrain-limited rovers. However, there are other types of vehicles which can conduct planetary surface exploration. One of these is hopping vehicles, which do not require fluid contact or ground contact in order to move, but instead propulsively balance thrust from their engines against gravity to propel themselves over the surface. Hopping vehicles are still a nascent technology, however, and no spaceborne hopping vehicles have yet flown. In order to bring hopping vehicles into the decision space for planetary surface exploration missions, in this thesis we provide a framework to understand hopping vehicles' key characteristics and advantages, as well as a tradespace model to size hopping vehicles based on mission characteristics. The tradespace model takes user-input mission requirements, including target planetary body, scientific payload, and a detailed flight profile, and produces a subsystem-level model of a hopping vehicle which can complete the mission. Information on the operational profile and lifecycle costs of the hopping vehicle is also produced. The tradespace model also permits users to capture results from one model run and compare them to other model runs, or to results produced by other models. In this thesis, the tradespace model is described, and initial tradespace investigation is performed using the model. Finally, lessons learned are summarized and suggestions are offered for future research. The thesis closes with a summation of the potential offered by hopping vehicles for planetary surface exploration missions in the decades to come. / by Phillip M. Cunio. / Ph.D.

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2000. / Includes bibliographical references (p. 215-223). / A new concept for retrofitting a reconfiguration module to an existing control law is reported in this thesis. The concept is motivated by the need for low cost, add-on modules that improve air safety in the existing fleet of civil air transport vehicles. A direct adaptive approach that accommodates control surface nonlinearities is adopted, which uses a slowly adapting model of the closed-loop aircraft as the reference model. The motivation, benefits, and components of the architecture are presented. In addition, the issues of control surface magnitude and rate saturation are addressed. A proof of stability is outlined for input-error adaptation when position and rate saturation are present. The reconfiguration architecture is demonstrated using an F/A-18 and a generic transport nonlinear simulator. General issues associated with commercial transport reconfiguration are highlighted. In both the longitudinal and directional axes, the control surfaces are not well balanced from a reconfiguration viewpoint. As a result, a novel reconfiguration control allocation scheme was devised that blends in all the control effectors in a given axis to perform the reconfiguration task. The simulation results revealed that the reconfiguration architecture does provide reconfiguration functionality for a wide variety of control surface failures. The reconfiguration potential is illustrated through comparisons of post-failure performance with and without reconfiguration via non-linear simulations. Additionally, comparisons between post-failure performance and nominal performance are made through non-linear simulations, closed-loop frequency responses, and aircraft handling qualities. For all of the failure scenarios illustrated, the simulation results showed that the aircraft without reconfiguration departs; with reconfiguration, nominal performance is achieve provided that adequate control authority exists post-failure. / by Jerry M. Wohletz. / Ph.D.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2004. / Includes bibliographical references (p. 117-119). / In recent years, high altitude unmanned aerial vehicles have been used to great success in combat operations, providing both reconnaissance as well as weapon launch platforms for time critical targets. Interest is now growing in extending autonomous vehicle operation to the low altitude regime. Because perfect threat knowledge can never be assumed in a dynamic environment, an algorithm capable of generating evasive trajectories in response to pop-up threats is required. Predetermination of contingency plans is precluded due to the enormity of possible scenarios; therefore, an on-line vehicle trajectory planner is desired in order to maximize vehicle survivability. This thesis presents a genetic algorithm based threat evasive response trajectory planner capable of explicitly leveraging terrain masking in minimizing threat exposure. The ability of genetic algorithms to easily incorporate line-of-sight effects, the inherent ability to trade off solution quality for reduced solution time, and the lack of off-line computation make them well suited for this application. The algorithm presented generates trajectories in three-dimensional space by commanding changes in velocity magnitude and orientation. A crossover process is introduced that links two parent trajectories while preserving their inertial qualities. Throughout the trajectory generation process vehicle maneuverability limits are imposed so that the resultant solutions remain dynamically feasible. / (cont.) The genetic algorithm derived provides solutions over a fixed time horizon, and is implemented in a receding horizon fashion, thereby allowing evasion of threat areas of arbitrary size. Simulation results are presented demonstrating the algorithm response for a rotorcraft encountering several different threat scenarios designed to evaluate the effectiveness of the algorithm at minimizing risk to the vehicle. / by Ryan L. Pettit. / S.M.

Thesis: S.M., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2018. / Cataloged from PDF version of thesis. / Includes bibliographical references (pages 111-112). / The increasing use of renewable energy sources necessitates power-generating gas turbines capable of frequently and rapidly starting up to supplement the energy supply when renewable sources alone cannot meet demand [1], [21. This makes the off-design performance of such gas turbines more important as they spend more of their operational life off the design point. Currently off-design performance cannot be estimated with high fidelity until late in the gas turbine compressor design process at which point the design is largely fixed and only limited changes can be made. This thesis presents a Non-Uniform Radial Meanline method for multistage axial compressor off-design performance estimation, capturing the transfer of radial flow non-uniformity and its impact on compressor blade row performance. This method enables the high-fidelity characterization of blade row performance and the stage matching of multistage compressors with non-uniformity effects included. A new representation of non-uniform radial flow profiles using orthonormal basis functions was developed to provide a compact representation suitable for inclusion in a one-dimensional performance estimation method. The link between radial flow non-uniformity and compressor blade row performance was characterized using three-dimensional embedded stage calculations. An initial implementation of the Non-Uniform Radial Meanline method was demonstrated for different compressor inlet non-uniformities. The computations show that the new approach provides an effective means of incorporating radial flow non-uniformity into a one-dimensional compressor performance estimation method. / by David Andrew Birkenheier. / S.M.