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Full-Text Articles in Physical Sciences and Mathematics
Empirical Modeling Of Tilt-Rotor Aerodynamic Performance, Michael C. Stratton
Empirical Modeling Of Tilt-Rotor Aerodynamic Performance, Michael C. Stratton
Mechanical & Aerospace Engineering Theses & Dissertations
There has been increasing interest into the performance of electric vertical takeoff and landing (eVTOL) aircraft. The propellers used for the eVTOL propulsion systems experience a broad range of aerodynamic conditions, not typically experienced by propellers in forward flight, that includes large incidence angles relative to the oncoming airflow. Formal experiment design and analysis techniques featuring response surface methods were applied to a subscale, tilt-rotor wind tunnel test for three, four, five, and six blade, 16-inch diameter, propeller configurations in support of development of the NASA LA-8 aircraft. Investigation of low-speed performance included a maximum speed of 12 m/s and …
Emergency Diesel-Electric Generator Set Maintenance And Test Periodicity, Stephen John Fehr
Emergency Diesel-Electric Generator Set Maintenance And Test Periodicity, Stephen John Fehr
Engineering Management & Systems Engineering Theses & Dissertations
Manufacturer and industry recommendations vary considerably for maintenance and tests of emergency diesel-electric generator sets in emergency standby duty. There is little consistency among generator sets of similar technology, and manufacturers and their representatives often provide contradictory guidance. As a result, periodicity of emergency diesel-electric generator set maintenance and tests varies considerably in practice. Utilizing the framework proposed and tested by Fehr (2014), this research developed a parametric regression survival model of the reliability of modern diesel-electric generator sets in emergency standby duty as a function of maintenance, age, and cumulative run hours. A survival regression technique leveraging Cox’s (1972) …