Abstract The main objective of this thesis was to develop a method than can be used to approximate the pressure forces on air vehicles traveling at hypersonic speed (Mach number > 5). The aerodynamic forces such as lift and drag were calculated from the pressure values on the surface of the airplane. Pitching moment was also tabulated. This work was initiated based on the idea of developing a flow solver proficient and capable of providing aerodynamic data (lift and drag look-up tables) for hypersonic air vehicles that can be fed to a flight simulator (used by the Aviation Systems Department) at the University of Tennessee Space Institute. Several approximation methods are used to solve hypersonic such as shock expansion method. Based on different studies, Computational Fluid Dynamic (CFD) proved to produce very accurate results; however, it is a difficult technique to use. In this thesis work Newtonian Method was adopted as a technique to approximate the aerodynamic forces and hence the performance of hypersonic airplanes, therefore, a computer program (Hyper-N) has been developed for aerodynamic analysis of three dimensional geometries airplane. The program is designed to read in a previously configured list of plates and compute the aerodynamic forces and moments for hypersonic free stream conditions. Programming was completed using MatLab language. The results obtained from the Hyper-N program were for the experimental airplane X-43A which were found to match the results when the shock expansion method is used for the same airplane, [1]. Because of the difficulties involve in using CFD or the complete Navier Stocks equation to obtain the aerodynamic forces on bodies traveling at hypersonic speeds, the Newtonian method is considered to be the most efficient technique to use for preliminary evaluation of the performance of hypersonic airplanes. Modified Newtonian theory and the computational requirement of the code are described. A number of geometric configurations, including the X-43A (experimental hypersonic) airplane, are provided as examples of applications of the Hyper-N program.

In this study, loss and loading characteristics of compressor tandem blades are evaluated. Whole study was focused on change of the total camber so called turning angle. Effects of camber change were investigated in terms of loss and loading characteristics. Methodology was increasing overall camber first by aligning angular positions of blades and second, if required, using more cambered airfoils. 2-dimensional cascade flow CFD analyses were performed to obtain loss-loading information of different tandem blade combinations. Acquired results were compared with the classical axial compressor blades&rsquo / loading and loss characteristics which were obtained from literature. Results showed that most of the time tandem blade configuration performed better than the single blade counterpart in 2-dimensional cascade flow. Lastly, to clarify the benefit of the study and present the gained performance in numbers, only one cascade flow CFD analysis was performed for a classical single compressor blade. Loss and loading results were compared with the tandem blade counterpart where single and tandem configurations both having the same degree of camber. It was clearly seen that tandem blade performed better again.

The anti-torque mechanism of a NOTAR helicopter is a complex system including vertical tail and pressurized tail boom which provides air ejection used for both circulation control around the boom and creating directed jet air at the end of the boom. This thesis targets the modeling of this mechanism and integrating it to a helicopter simulation model. Flight tests are performed on the MD 600N helicopter to verify the results. Finally, the simulation is compared with flight test data.

ITC/USA 2013 Conference Proceedings / The Forty-Ninth Annual International Telemetering Conference and Technical Exhibition / October 21-24, 2013 / Bally's Hotel & Convention Center, Las Vegas, NV / Multipath interference continues to be the dominant cause of telemetry link outages in low-elevation angle reception scenarios. The most reliable and universally applicable solution to this problem is in the form of equalization. Previous work in this area has considered the Constant modulus algorithm (CMA) equalizer operating in a blind adaptive mode. To the extent that knowledge of the multipath channel improves the performance of CMA and related equalizers and permits the use of other equalization techniques, data aided equalizers are of interest. Channel knowledge is obtained by comparing the received samples with the samples corresponding to a known bit pattern (called a pilot block) periodically inserted in the telemetry data stream. The main objective of this research is to evaluate the performance of a modified CMA equalization algorithm, which has the property of automatically resolving the phase of the QPSK modulated symbol, and to determine its suitability for use with SOQPSK-TG by taking into account the capability of exploiting the presence of a periodically inserted pilot block. As an initial effort in that direction, this paper provides simulation results of the error performance of the blind linear combination of CMA and alphabet matched algorithm (AMA) equalizer as compared to that of pilot assisted equalization with SOQPSK modulation over aeronautical channel.

ITC/USA 2012 Conference Proceedings / The Forty-Eighth Annual International Telemetering Conference and Technical Exhibition / October 22-25, 2012 / Town and Country Resort & Convention Center, San Diego, California / The goal of this paper is to implement a model of multipath fading in a radio channel simulator for aeronautical applications. When developing a wireless communications system, it is useful to perform simulations of the radio context in which the system has to operate. A radio link is substantially composed by three parts: transmitting segment, transmission channel and receiving segment. We focus our attention on the radio channel propagation. We proposed two geometrical models of a territory corresponding to a determined flight area and, after importing the data needed to estimate our parameters, we compared our results with the channel soundings in literature, obtaining comparable values.

The deployment of unmanned aerial vehicles (UAV) in military applications increased the research about them and the importance of them. The unmanned helicopters are the most agile and maneuverable vehicles among the unmanned aerial vehicles (UAV). The ability of hovering and low speed cruise makes them even more attractive. Such abilities supply more areas to deploy the usage of the unmanned helicopters like search &amp / rescue, mapping, surveillance. Autonomy is the key property for these vehicles. In order to provide autonomy to an unmanned vehicle, the guidance and the autopilot units are designed in the first step. Waypoints are used to track the desired trajectories. The line of sight guidance is used to reach an active waypoint. In order to realize the guidance commands controllers are designed by using LQR. In addition, position and heading controllers are designed by root-locus method. The trimming and linearization are implemented in order to extract linear models used for controller design. Keywords: Helicopter, control, guidance

Thesis (M.S.)--Ohio University, June, 2004. / Includes bibliographical references (p. 136-138).

Thesis (M.S.)--Ohio University, June, 2004. / Title from PDF t.p. Includes bibliographical references (p. 136-138)

Thesis (M.S.)--Ohio University, November, 2006. / Title from PDF t.p. Includes bibliographical references.

This thesis describes a framework for the high level control of an autonomous unmanned spacecraft. Greater autonomy than currently exist is required for unmanned spacecraft to enable missions to distant planets and bodies. One reason for this is that the signal return time is too long to accommodate real-time control from the ground. A second reason is that spacecraft travelling to bodies where little is known of the environment (e.g. asteroids) must have the capability to respond to unplanned events. In addition, autonomy can help reduce mission operations costs, a very important factor in the current climate where more is expected from space missions at a lower cost. The thesis proposes a novel architecture for an autonomous unmanned spacecraft, based on Distributed Artificial Intelligence (DAI), and more specifically based on the multi-agent paradigm. The proposed model for spacecraft control is decentralised. In this architecture, the spacecraft is made up of agents; the traditional ground-based controller is one agent. The spacecraft is goal-driven; it receives high level goals from the ground. The planning and scheduling of activities to achieve these goals is carried out on-board the spacecraft. The spacecraft is also event-driven; it reacts to events that occur on-board the spacecraft as well as in the environment. A DAI architecture requires a co-ordination mechanism, and a communication structure. Also, distributed versions of algorithms must be provided. In this thesis, co-ordination with and without explicit communication and distributed scheduling were investigated, and a framework proposed for both these issues. An autonomous spacecraft must have inference capability for on-board decision making to enable it to respond to unplanned events. Probabilistic reasoning in the form of Bayesian networks was used to provide the spacecraft with the capability for on-board decision making. Situations may arise where the spacecraft must make decisions with uncertain or incomplete information. The issue of decision making with uncertain or incomplete knowledge (e.g. co-ordination without explicit communication) was investigated using domain specific scenarios. Spacecraft resources are typically very limited in capacity. On-board resource management should result in more efficient use of resources. A framework for an on-board resource manager was defined and implemented using reinforcement learning. A distributed version of the scheduling algorithm using reinforcement learning was developed. Thus, this thesis describes and investigates an architectural framework for a multi-agent approach to spacecraft control.