This thesis focuses on CFD analysis of the Aircar 5.0 flying car prototype. The theoretical part covers basic information about the connection between the aerodynamics of airplanes and cars as well as cars themselves. The computational part begins with the calibration of the mathematical model, continues with the CFD simulations, which have the role to determine basic aerodynamic characteristics of the Aircar in vehicle mode. There are several configurations tested to find out their influence on aerodynamic stability and their advantages and disadvantages are summed up in the conclusion chapter.

<p> Prototypes of the recently developed periscopter, a flying platform tethered to a ground station, are presently extremely difficult to fly. Tests conducted by the Defence Research Board of Canada in Valcartier, Quebec, and by Westinghouse of Canada near Hamilton, have led to several crashes. Possible causes for the lack of flying qualities are: unbalanced aerodynamic forces and moments; inadequate controls; and poor inherent stability characteristics. </p> <p> In this investigation, the system of counter-rotating lifting rotors used in the present periscopters is examined with a view to improvement of the flying qualities. The aerodynamic theory of helicopter rotors is considered as a background. </p> <p> The blades of the present periscopter rotors neither flap nor feather. The feasibility of using either articulated (flapping) blades or rigid feathering blades is examined. It is found that flapping blades are not feasible mainly because of associated stability and control problems. Also the two counter-rotating rotors would tend to strike against each other. A rigid rotor system featuring feathering blades is found to be feasible. Such a system is therefore examined in detail by computing all relevant aerodynamic parameters. It is shown that the feathering system can provide all required control moments. Its introduction would therefore eliminate the present bail mechanism. </p> <p> An analysis of the stability characteristics of a periscopter featuring a rigid feathering rotor system is developed. However, when hovering in still air, such a periscopter is shown to be unstable. The possibility of rendering it stable by the use of rotor controls is demonstrated. No attempt is made to suggest a specific design for the control system to be used. </p> <p> The effect of various operational parameters on the flying qualities of the periscopter is investigated. </p> / Thesis / Master of Engineering (ME)

In this dissertation the linearized dynamics and stability of a two-craft Coulomb tether formation are investigated. With a Coulomb tether the relative distance between two satellites is controlled using electrostatic Coulomb forces. A charge feedback law is introduced to stabilize the relative distance between the satellites to a constant value. Compared to previous Coulomb thrusting research, this is the first feedback control law that stabilizes a particular formation shape. The two craft are connected by an electrostatic virtual tether that essentially acts as a long, slender near-rigid body. Inter-spacecraft Coulomb forces cannot influence the inertial angular momentum of this formation. However, the differential gravitational attraction can be exploited to stabilize the attitude of this Coulomb tether formation about an orbit nadir direction. Stabilizing the separation distance will also stabilize the in-plane rotation angle, while the out-of-plane rotational motion remains unaffected. The other two relative equilibriums of the charged 2-craft problem are along the orbit-normal and the along-track direction. Unlike the charged 2-craft formation scenario aligned along the orbit radial direction, a feedback control law using inter-spacecraft electrostatic Coulomb forces and the differential gravitational accelerations is not sufficient to stabilize the Coulomb tether length and the formation attitude. Therefore, hybrid feedback control laws are presented which combine conventional thrusters and Coulomb forces. The Coulomb force feedback requires measurements of separation distance error and error rate, while the thruster feedback is in terms of Euler angles and their rates. This hybrid feedback control is designed to asymptotically stabilize the satellite formation shape and attitude while avoiding plume impingement issues. The relative distance between the two satellites can be increased or decreased using electrostatic Coulomb forces. The linear dynamics and stability analysis of such reconfiguration are studied for all the three equilibrium. The Coulomb tether expansion and contraction rates affect the stability of the structure and limits on these rates are discussed using the linearized time-varying dynamical models. These limits allow the reference length time histories to be designed while ensuring linear stability of the virtual structure. Throughout this dissertation the Coulomb tether is modeled as a massless, elastic component and, a point charge model is used to describe the charged craft. / Ph. D.

Myriad reports of UFO sightings exist and are well documented in the literature of the study of UFOs. This field is widely known as ufology. The history of UFO sightings and their socio-political context and consequences constitutes the broad subject of this study and provides a site for analysis of how scientists address, both publicly and privately, anomalies that appear to pertain to science. The Condon Report, the Scientific Study of Unidentified Flying Objects, commissioned by the Air Force in 1968, provides a complex case for the exploration of how the outcome and conclusions of the study were influenced by all that had gone on before in ufology.AB / Master of Science

Thesis (Ph.D.)--University of Wyoming, 2008. / Title from PDF title page (viewed on Dec. 4, 2009). Includes bibliographical references.

Approved for public release; distribution is unlimited. / This thesis done in cooperation with the MOVES Institute. / Despite data indicating more human error accidents occur during NVG flight than in any other flight mode, there are very few simulation tools available to aviators at the unit level that aid them in learning or practicing NVG flight tasks. This thesis examines the potential for a Chromakeyed Augmented Virtual Environment (ChrAVE), consisting only of Commercial-Off-The- Shelf (COTS) hardware, to be used as an NVG flight training platform. It also examines whether or not physically-based light calculations are necessary to produce adequate visual representation of simulated NVG imagery. Twelve subjects performed simulated low-level NVG flight navigation tasks in the ChrAVE. Treatments included questionnaires, vision tests, variation of the physics-based component of the NVG imagery, and performance of an evaluation task that compares standard thresholds between day and NVG navigation. Analysis of data and subject feedback indicate that the ChrAVE has potential as an NVG flight training device, and that physically-based calculations may not be necessary to achieve simulated NVG imagery that is adequate for training. The data also supports the existence of a substantial difference in the subjective evaluation standard between navigation performances based on flight condition. / Captain, United States Army

Master of Science / Department of Architectural Engineering and Construction Science / Kimberly Kramer / The flying buttress is one of the most prominent characteristics of Gothic architecture. Understanding stress distribution from the upper vaulted nave (high vault) to the flying buttress system would contribute greatly to preservation efforts of such iconic structures. Many investigations have emphasized structural analysis of Gothic flying buttresses, but only limited research how architectural design affects load distribution throughout the Gothic members exist. The objective of this investigation was to inspire engineers and architectural preservationists to develop further research in Gothic structural analysis and restoration by increasing understanding how architectural design of flying buttresses affects the load path being transmitted from the main superstructure to the lateral force resisting system. Several flying buttress designs under similar analytical parameters were compared in order to understand how member geometries affect stress distribution. Because Gothic design is architecturally complex, finite element analysis method was used to obtain member stress distribution (regions of compressive and tensile stresses). Architectural elevation schematics of the flying buttresses of prominent Gothic cathedrals were referenced when modeling the structural members to a computer software program (RAM Elements).

In recent years unconventional aircraft configurations, such as Blended-Wing-Body (BWB) aircraft, are being investigated and researched with the aim to develop more efficient aircraft configurations, in particular for very large transport aircraft that are more efficient and environmentally-friendly. The BWB configuration designates an alternative aircraft configuration where the wing and fuselage are integrated which results essentially in a hybrid flying wing shape. The first example of a BWB design was researched at the Loughead Company in the United States of America in 1917. The Junkers G. 38, the largest land plane in the world at the time, was produced in 1929 for Luft Hansa (present day; Lufthansa). Since 1939 Northrop Aircraft Inc. (USA), currently Northrop Grumman Corporation and the Horten brothers (Germany) investigated and developed BWB aircraft for military purposes. At present, the major aircraft industries and several universities has been researching the BWB concept aircraft for civil and military activities, although the BWB design concept has not been adapted for civil transport yet. The B-2 Spirit, (produced by the Northrop Corporation) has been used in military service since the late 1980s. The BWB design seems to show greater potential for very large passenger transport aircraft. A NASA BWB research team found an 800 passenger BWB concept consumed 27 percent less fuel per passenger per flight operation than an equivalent conventional configuration (Leiebeck 2005). The purpose of this research is to assess the aerodynamic efficiency of a BWB aircraft with respect to a conventional configuration, and to identify design issues that determine the effectiveness of BWB performance as a function of aircraft payload capacity. The approach was undertaken to develop a new conceptual design of a BWB aircraft using Computational Aided Design (CAD) tools and Computational Fluid Dynamics (CFD) software. An existing high-capacity aircraft, the Airbus A380 Contents RMIT University, Australia was modelled, and its aerodynamic characteristics assessed using CFD to enable comparison with the BWB design. The BWB design had to be compatible with airports that took conventional aircraft, meaning a wingspan of not more than 80 meters for what the International Civil Aviation Organisation (ICAO) regulation calls class 7 airports (Amano 2001). From the literature review, five contentions were addressed; i. Is a BWB aircraft design more aerodynamically efficient than a conventional aircraft configuration? ii. How does the BWB compare overall with a conventional design configuration? iii. What is the trade-off between conventional designs and a BWB arrangement? iv. What mission requirements, such as payload and endurance, will a BWB design concept become attractive for? v. What are the practical issues associated with the BWB design that need to be addressed? In an aircraft multidisciplinary design environment, there are two major branches of engineering science; CFD analysis and structural analysis; which is required to commence producing an aircraft. In this research, conceptual BWB designs and CFD simulations were iterated to evaluate the aerodynamic performance of an optimal BWB design, and a theoretical calculation of structural analysis was done based on the CFD results. The following hypothesis was prompted; A BWB configuration has superior in flight performance due to a higher Lift-to-Drag (L/D) ratio, and could improve upon existing conventional aircraft, in the areas of noise emission, fuel consumption and Direct Operation Cost (DOC) on service. However, a BWB configuration needs to employ a new structural system for passenger safety procedures, such as passenger ingress/egress. The research confirmed that the BWB configuration achieves higher aerodynamic performance with an achievement of the current airport compatibility issue. The beneficial results of the BWB design were that the parasite drag was decreased and the spanwise body as a whole can generate lift. In a BWB design environment, several advanced computational techniques were required to compute a CFD simulation with the CAD model using pre-processing and CFD software.

The purpose of this thesis is to design and study an aircraft which implements the Co-Flow Jet (CFJ) airfoil concept, as well as to study the CAARC standard highrise building. The design concept is verified mainly by the use of a Computational Fluid Dynamics (CFD) package. A thorough methodology for geometry and mesh generation is developed, and subsequently applied to the two cases. The first case studied is that of the CFJ Airplane (CFJA). It consists of a threedimensional, highly blended, ying wing geometry implementing the Co-Flow Jet airfoil concept. Though a thorough comparison to a baseline geometry, it is shown that usage of the CFJ airfoil cross-section greatly improves aircraft performance by increasing lift, reducing drag, and providing a source of thrust over the operational range of angles of attack. A steady state CFD simulation is used for this case, as the air ow around an airfoil cross-section is inherently steady for attached ows. CFD results are used to support the Engineless Aircraft" concept, where the CFJ airfoil is used as the sole form of propulsion. The second case studied consists of a rectangular high-rise building undergoing a wind condition with Mach number of 0:1 and a Reynolds number of 160000. Due to the non-streamlined geometry of the building cross-section, aerodynamic instabilities due to uid separation are present, and therefore an unsteady CFD analysis is necessary to fully resolve all of the ow phenomena. Preliminary steady state results are presented, and a plan is laid down for the future study of this highly complex case. Results are presented for a variety of angles of attack in the case of the CFJA, and for the main ow direction in the case of the CAARC building. Results are compared with baseline geometry in the case of the CFJ Airplane. The CFJ Airplane case is simulated using a 3rd order steady state scheme, which is sufficient to achieve valid results for the ow regime. The CAARC building, which has inherent ow separation, requires the use of high order schemes.

Thesis (M.S. in Mechanical Engineering)--Naval Postgraduate School, December 2003. / Thesis advisor(s): Garth V. Hobson, Max F. Platzer. Includes bibliographical references (p. 83). Also available online.