Abstract: Engines and methods for operating the engines are provided. The engine includes a means for limiting overspeed in flow communication with a turbine section flowpath, wherein the means for limiting overspeed is adapted to block a first portion of an airflow received along a first direction vector from flowing into an exhaust section flowpath and to redirect a second portion of the airflow received along the first direction vector or a portion of the blocked first portion of the airflow to flow along another direction vector that is closer to parallel with a longitudinal axis than the first direction vector.

Abstract: Methods for maintaining a constant electrical output frequency in a turbogenerator with increased electrical loads are provided. The methods comprise biasing adjustable guide vanes of a compressor and/or a compressor bleed valve in response to the increased electrical load. A dual schedule system for carrying out the methods of the present invention is also provided.

Abstract: An electronic controller maintains the operating temperature of a cryopump by controlling a heater coupled to the cryopump. The heater is coupled to a cryopumping surface of the cryopump. The controller can control the operation of the heater in response to feedback from temperature sensors coupled to the cryopump. The controller can cause the heater to shut-off if a temperature sensor reads out of its normal temperature range.

Abstract: A start circuit controlled by an electronic control unit for providing power from one or both of a battery and TRU in parallel to a starter motor coupled to a gas turbine engine. The circuit includes contactors between the TRU and battery and a junction where the current from the TRU and battery combine. The circuit further includes two additional contactors in series between the junction and the starter motor. Voltage sensors and contactor position sensors are employed for diagnostics. A novel method of starting the engine using the start circuit contemplated by the present invention is also descibed. In this method, the start is initiated with power only from the battery. After a period of time power from the TRU is added. This method reduces the amplitude of the start motor inrush current, which has a beneficial reliability effect on the components of the start circuit.