No description available.

No description available.

Thesis (M.App.Sc.) - Carleton University, 2002. / Includes bibliographical references (p. 112-122). Also available in electronic format on the Internet.

Thesis (M.App.Sc.) - Carleton University, 2006. / Includes bibliographical references (p. 195-200). Also available in electronic format on the Internet.

Thesis (M.S. in Operations Research)--Naval Postgraduate School, June 2009. / Thesis Advisor(s): Brown, Gerald ; Carlyle, Matthew. "June 2009." Description based on title screen as viewed on July 13, 2009. Author(s) subject terms: optimization, math programming, helicopter planning, assault support. Includes bibliographical references (p. 41). Also available in print.

No description available.

The current state of international civilian (General Aviation) helicopter flight safety was perceived to be poor and without focus on the potential application of low-cost digital data acquisition devices to increase the quantity of flight data available for analysis, which could help identify issues leading to common incident and accident scenarios. The research project undertook a review of some of the common incident and accident scenarios, performed an analysis of the composition of the worldwide helicopter fleet and explored the interaction of operators, pilots, missions, and national aviation authorities, in order to understand and define the context for this study. Two radically different types of digital flight and event data recorders were then developed, which were considered appropriate for use in the most common small to medium sized helicopter types identified, in order to determine if reliable low-cost digital data acquisition was achievable. Also developed were software tools for extracting the recorded data sets and their processing/analysis. The proof of concept devices were flight tested, in a variety of environments by a number of helicopter operators and manufacturers in Europe and North America, in order to determine whether such simple devices actually returned useful flight data and in doing so contribute to improving flight safety by highlighting the occurrence of common issues. During the flight trials a number of real safety critical events were captured or observed, despite being flown for only a fraction of the time that would statistically elapse between incidents. Examination of the data sets revealed an abundance of information about pilot behaviour, which it will be argued substantiates the widely held belief that most accidents are caused by pilot error or negligence. It will be asserted that these results demonstrate that real improvements in training and flight safety can be achieved through the wide spread use of such proof of concept devices and their associated software tools. The international helicopter community has subsequently expressed a strong desire for such devices to become common place in small to medium sized helicopters.

Approved for public release; distribution is unlimited / Usage Monitoring requires accurate regime recognition. For each regime, there is a usage assigned for each component. For example, the damage accumulated at a component is higher if the aircraft is undergoing a high G maneuver than in level flight. The objective of this research is to establish regime recognition models using classification algorithms. The data used in the analysis are the parametric data collected by the onboard system and the actual data, consisting of the correct regime collected from the flight cards. This study uses Rpart (with a tree output) and C5.0 (with a ruleset output) to establish two different models. Before model fitting, the data was divided into smaller datasets that represent regime families by subsetting using important flight parameters. Nonnormal tolerance intervals are constructed on the uninteresting values; then these values in the interval are set to zero to be muted (e.g. excluded). These processes help reduce the effect of noise on classification. The final models had correct classification rates over 95%. The number of bad misclassifications were minimized (e.g. the number of bad misclassifications of a level flight regime as a hover regime was minimized), but the models were not as powerful in classifying the low-speed regimes as in classifying high-speed regimes. / Outstanding Thesis

In this research, a laboratory platform which has 2 degrees of freedom (DOF), the Twin Rotor MIMO System (TRMS), is investigated. Although, the TRMS does not fly, it has a striking similarity with a helicopter, such as system nonlinearities and cross-coupled modes. Therefore, the TRMS can be perceived as an unconventional and complex "air vehicle" that poses formidable challenges in modelling, control design and analysis and implementation. These issues are the subject of this work. The linear models for 1 and 2 DOFs are obtained via system identification techniques. Such a black-box modelling approach yields input-output models with neither a priori defined model structure nor specific parameter settings reflecting any physical attributes. Further, a nonlinear model using Radial Basis Function networks is obtained. Such a high fidelity nonlinear model is often required for nonlinear system simulation studies and is commonly employed in the aerospace industry. Modelling exercises were conducted that included rigid as well as flexible modes of the system. The approach presented here is shown to be suitable for modelling complex new generation air vehicles. Modelling of the TRMS revealed the presence of resonant system modes which are responsible for inducing unwanted vibrations. In this research, open-loop, closed-loop and combined open and closed-loop control strategies are investigated to address this problem. Initially, open-loop control techniques based on "input shaping control" are employed. Digital filters are then developed to shape the command signals such that the resonance modes are not overly excited. The effectiveness of this concept is then demonstrated on the TRMS rig for both 1 and 2 DOF motion, with a significant reduction in vibration. The linear model for the 1 DOF (SISO) TRMS was found to have the non-minimum phase characteristics and have 4 states with only pitch angle output. This behaviour imposes certain limitations on the type of control topologies one can ado·pt. The LQG approach, which has an elegant structure with an embedded Kalman filter to estimate the unmeasured states, is adopted in this study. The identified linear model is employed in the design of a feedback LQG compensator for the TRMS with 1 DOF. This is shown to have good tracking capability but requires. high control effort and has inadequate authority over residual vibration of the system. These problems are resolved by further augmenting the system with a command path prefilter. The combined feedforward and feedback compensator satisfies the performance objectives and obeys the constraint on the actuator. Finally, 1 DOF controller is implemented on the laboratory platform.

The dissertation investigates helicopter trim and stability during level bank-angle and diving bank-angle turns. The level turn is moderate in that sufficient power is available to maintain level maneuver, and the diving turn is severe where the power deficit is overcome by the kinetic energy of descent. The investigation basically represents design conditions where the peak loading goes well beyond the steady thrust limit and the rotor experiences appreciable stall. The major objectives are: 1) to assess the sensitivity of the trim and stability predictions to the approximations in modeling stall, 2) to correlate the trim predictions with the UH-60A flight test data, and 3) to demonstrate the feasibility of routinely using the exact fast-Floquet periodic eigenvector method for mode identification in the stability analysis. The UH-60A modeling and analysis are performed using the comprehensive code RCAS (Army's Rotorcraft Comprehensive Analysis System). The trim and damping predictions are based on quasisteady stall, ONERA-Edlin vi (Equations Differentielles Lineaires) and Leishman-Beddoes dynamic stall models. From the correlation with the test data, the strengths and weaknesses of the trim predictions are presented. / by Ranjith Mohah. / Thesis (Ph.D.)--Florida Atlantic University, 2012. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2012. Mode of access: World Wide Web.