Loss-of-control resulting from airplane upset is a leading cause of worldwide commercial aircraft accidents. One of the upset prevention and recovery strategies currently being considered is to provide pilot upset recovery training using ground-based flight simulators. However, to simulate the large amplitude and highly dynamic motions seen in upset conditions, both the flight model and the simulator motion need improvement. In this thesis, an enhanced flight model is developed to better represent the aircraft dynamics in upset conditions. In particular, extension is made to the aerodynamic database of an existing Boeing 747-100 (B-747) model to cover large angle of attack, sideslip and angular rates. The enhanced B-747 model is then used to conduct a set of upset recovery experiments in a flight simulator without motion. The experimental results can be used to identify and potentially correct major motion cueing errors caused by the conventional motion drive algorithm in upset conditions.

Loss-of-control resulting from airplane upset is a leading cause of worldwide commercial aircraft accidents. One of the upset prevention and recovery strategies currently being considered is to provide pilot upset recovery training using ground-based flight simulators. However, to simulate the large amplitude and highly dynamic motions seen in upset conditions, both the flight model and the simulator motion need improvement. In this thesis, an enhanced flight model is developed to better represent the aircraft dynamics in upset conditions. In particular, extension is made to the aerodynamic database of an existing Boeing 747-100 (B-747) model to cover large angle of attack, sideslip and angular rates. The enhanced B-747 model is then used to conduct a set of upset recovery experiments in a flight simulator without motion. The experimental results can be used to identify and potentially correct major motion cueing errors caused by the conventional motion drive algorithm in upset conditions.

An examination of historical changes in technical efficiency in the U.S. air transportation industry and trends in relative factor prices reveals a relationship that is consistent with the economic theory of production. The study attempts to show the extent to which this relationship reflects causality. Average factor productivities for selected aircraft introduced between 1948 and 1972 were calculated on an ad hoc basis to document the particular events that established the overall trends in technical efficiency. Those aircraft and innovations that had characteristics consistent with prevailing factor price incentives were identified and the circumstances surrounding their introduction analyzed to determine whether factor proportions had been set in accordance with these incentives. It is found that exogenous technological developments and considerations related to the improvement of quality of output had just as great an influence in establishing trends in technical efficiency as considerations related to the maximization of economic efficiency. The influence of the military, oligopolistic interdependence in the aircraft manufacturing industry, and the effects of speed on quality of output created problems of identification. Possible effects on past events of a higher relative price for energy were examined. It is shown that this modification of factor price conditions would quite likely have had a significant impact on the historical pattern of technological development. / Graduate and Postdoctoral Studies / Graduate

As fuel prices soar ever higher, aircraft manufacturers and their airline customers demand that the next generation of engines used on their aircraft push the limits of efficiency and capability. This study consists of a computational examination of two currently accepted methods of axial compressor performance improvement in terms of surge margin and efficiency, rotor casing treatments and stator land seals.ADPAC and Fluent CFD solvers were used in the analysis of circumferential groove casing treatments and two types of stator seals, one typical of a front stage stator and one typical of a rear stage stator. The computational solutions and visualizations allowed for greater understanding of the complex flows inherent in each of these features. It was found that rotor tip vortex control plays a large part in the surge margin gains from a circumferential groove casing treatment. The efficiency gains of knife seals were dependent primarily on the gap size of the seals.

This work has the approach for how an electric motor controller should be designed. In aircraft applications it is important that the system has a high power density, and that it is reliable. The target was to find out what is possible with technology of today, and with possibilities of tomorrow. The target is to be able to compare hydraulic systems with electrical ones. The type of controllers that was studied was controllers for permanent magnetized synchronous machines (PMSM). The reason for that choice is that PMSM has a high efficiency. Different transistor technologies were evaluated. Discrete IGBT was found to be the best option. Of the evaluated transistors has IRG4PSH71U operating with a SiC freewheeling diode the best efficiency. The benefit with discrete components is that they are easy to cool, for example if they are distributed on an aluminium heatsink with forced air cooling. To minimise losses and gain controllability on the motor should the inverter be controlled with some kind of vector control, such as DTC (Direct Torque Control). / I det här arbetet studerades hur en elmotorstyrning i ett flygplan bör konstrueras. I flygapplikationer är det viktigt att systemet är lätt i förhållande till effekten, och att det är tillförlitligt. Målet var att ta reda på vad man kan uppnå med dagens teknik, och även med kommande teknik. Syftet är att kunna jämföra hydrauliska system med elektriska. Det som undersöktes var motorstyrningar till permanentmagnetiserade synkronmaskiner (PMSM), eftersom dessa motorer har en hög verkningsgrad. Olika transistortekniker utvärderades. Diskreta IGBT fanns vara det bästa valet i en sådan applikation. Av de transistorer som jämfördes har IRG4PSH71U tillsammans med en frihjulsdiod av SiC den bästa totala verkningsgraden. Det vill säga att summan av ledningsförluster och switchförluster är lägst för den kombinationen. Fördelen med diskreta transistorer är att de har en lägre termisk resistans och kan spridas på en kylfläns, vilket underlättar kylningen, t.ex. med en aluminiumkylfläns med forcerad luft kylning. För att minimera förluster och öka styrbarheten på motorn bör växelriktaren styras med någon typ av vektor kontroll exempelvis DTC (Direct Torque Control).

<p>This work has the approach for how an electric motor controller should be designed. In aircraft applications it is important that the system has a high power density, and that it is reliable. The target was to find out what is possible with technology of today, and with possibilities of tomorrow. The target is to be able to compare hydraulic systems with electrical ones.</p><p>The type of controllers that was studied was controllers for permanent magnetized synchronous machines (PMSM). The reason for that choice is that PMSM has a high efficiency. Different transistor technologies were evaluated. Discrete IGBT was found to be the best option. Of the evaluated transistors has IRG4PSH71U operating with a SiC freewheeling diode the best efficiency. The benefit with discrete components is that they are easy to cool, for example if they are distributed on an aluminium heatsink with forced air cooling.</p><p>To minimise losses and gain controllability on the motor should the inverter be controlled with some kind of vector control, such as DTC (Direct Torque Control).</p> / <p>I det här arbetet studerades hur en elmotorstyrning i ett flygplan bör konstrueras. I flygapplikationer är det viktigt att systemet är lätt i förhållande till effekten, och att det är tillförlitligt. Målet var att ta reda på vad man kan uppnå med dagens teknik, och även med kommande teknik. Syftet är att kunna jämföra hydrauliska system med elektriska.</p><p>Det som undersöktes var motorstyrningar till permanentmagnetiserade synkronmaskiner (PMSM), eftersom dessa motorer har en hög verkningsgrad. Olika transistortekniker utvärderades. Diskreta IGBT fanns vara det bästa valet i en sådan applikation. Av de transistorer som jämfördes har IRG4PSH71U tillsammans med en frihjulsdiod av SiC den bästa totala verkningsgraden. Det vill säga att summan av ledningsförluster och switchförluster är lägst för den kombinationen. Fördelen med diskreta transistorer är att de har en lägre termisk resistans och kan spridas på en kylfläns, vilket underlättar kylningen, t.ex. med en aluminiumkylfläns med forcerad luft kylning.</p><p>För att minimera förluster och öka styrbarheten på motorn bör växelriktaren styras med någon typ av vektor kontroll exempelvis DTC (Direct Torque Control).</p>

Thesis (M. Eng.)(Aeronautical)--University of Pretoria, 2004. / Title from opening screen (viewed March 18, 2005). Summaries in English and Afrikaans. Includes bibliographical references.

This thesis is concerned with an Airline Gate Assignment problem that seeks to allocate gates to aircraft at an airport, using the objective of minimizing passenger walking distances. The problem is modeled as a variant of the quadratic assignment problem with set packing constraints. The quadratic objective function is then transformed into an equivalent linearized form by applying the first-order linearization technique of Sherali and Adams [1989, 1990]. In addition to linearizing the problem, the application of this technique generates additional constraints that provide a tighter linear programming representation. A suitable solution process that exploits the structure of the linearized problem is developed. Test results are presented using realistic data obtained from USAIR. / Master of Science

This research report documents the various types of Data Acquisition Systems in use for testing jet aircraft engines. The cost trade offs and design considerations are explored for systems which employ a digital computer as the prime recording/processing element. The digital computer has revolutionized the data acquisition field, particularly in the testing of high performance jet engines. Test data can be acquired, processed, converted to engineering units, and out via high speed line printers and cathode ray tubes (CRT's). The data acquisition system operates on-line, and interleaves the random requests for data from multiple test cells by using a specially designed software system and multi-processing capability of the high speed digital computer. All test data must be traceable to The National Bureau of Standards, which required that all calibration standards also be traceable. Primary and secondary calibration methods are discussed and examples of the mathematical processes for conversion of the raw data to meaningful results are presented. Data Acquisition Systems for jet engine testing can be logically grouped into two main categories, with the determining factor being the type of test to be conducted. Production engine testing requires rapid setup, calibration, and fast data turn around, particularly for modern automated test facilities. Development engine testing requires a large number of data channels, infrequent setup, and complete software for extensive engine performance calculations. Both types of Data Acquisition Systems have been designed and built by Pratt & Whitney Aircraft and are used as examples of the techniques described in this report.

A measurement system has been developed for use on a light aircraft to measure the pressure distribution over the wing surfaces. The measurement system was developed as a low-cost alternative to existing advanced measurement systems. The system consisted of low profile, low cost pressure sensors that interfaced digitally with microcontrollers for data acquisition. The pressure sensors and microcontrollers were developed into self-contained sensor modules with all electronic components mounted on flexible circuit board that formed the base of the modules. Two types of module were developed; a module with a single pressure sensor and a module with a row of seven pressure sensors at fifteen millimetre spacing. The total cost of the sensor modules was approximately ninety dollars for a single sensor module and one hundred and forty dollars for the seven sensor module. Studies were carried out using numerical methods to predict the pressure distribution over a NACA2412 airfoil. The numerical studies were used to evaluate the effect of adding the sensor modules to the wing, and the effect of the sensor distribution on measured force coefficients. Numerical predictions were made using the XFOIL software package. This software was validated using the Hess-Smith inviscid panel method. Flight testing was carried out with the pressure distribution measurement system to confirm the operation of the system and to make preliminary measurements. The flight testing focused on the measurement of steady state pressure distributions for comparison with the numerical predictions. Good agreement was found between the measured pressure distributions and the XFOIL predictions. Integration of the pressure distributions enabled comparison of normal force, lift force and quarter chord moment coefficients. The measured force coefficients showed the expected trends with angle of attack although it was found that the limited number of sensor modules used caused large error in the quarter chord moment coefficient compared to the numerical predictions.