In early spring to mid-summer 2006, a multi-NASA-center team led by the NASA Glenn Research Center--including the NASA Marshall Space Flight Center, the NASA Johnson Space Center, the NASA Kennedy Space Center, and industry input--conducted comprehensive thrust vector control (TVC) tradeoff studies leading to the selection of a TVC architecture for the Crew Launch Vehicle (CLV) Upper Stage (US). The NASA TVC team defined and evaluated a broad number of TVC architectures that included electric, hydraulic, and pneumatic actuation and power technologies. Quantitative and qualitative figures of merit consistent with the program mission and objectives and engineering judgment were used in selecting the TVC architecture.
Simplified TVC architecture diagram for the CLV US. GSE, ground support equipment; GH2, gaseous hydrogen; GHe, gaseous helium; PCDU, power conversion and distribution unit.
The selected TVC architecture for the CLV US is a hydraulic actuation system with a primary and backup power system (see the diagram). Hydraulic actuators are driven by two high-pressure hydraulic pumps that are powered by a turbine power assembly (TPA) or a high-voltage battery-powered electric hydraulic pump assembly (EHPA). For redundancy, both power sources are sized for full power capability for the entire ascent. The selector valve in the actuators is used to choose the primary or redundant hydraulic system. The TPA is powered by pressurized hydrogen gas supplied by the US Main Propulsion System (MPS). The gas spins the turbine with the connecting gearbox to drive the hydraulic pump. A power takeoff (PTO) from a rocket engine liquid oxygen turbopump driving a hydraulic pump or a second TPA is being considered as a potential candidate instead of a battery-powered EHPA. The hydraulic system A/B (see the diagram) transmits the source power to the actuators and absorbs the regenerative actuator power. The main components in the hydraulic system A/B are an accumulator, a reservoir, a check valve, and a filter assembly. A circulation motor-pump circulates the hydraulic fluid for thermal conditioning, and hydraulic locks are provided to lock the rocket engine in the null position during the first stage of the flight. Low-voltage power from the vehicle electric power system provides all housekeeping power to the TVC. Command for TVC actuation is through a Mil-Std1553 communication bus.
The CLV US TVC steers the launch vehicle during US ascent in the vehicle pitch and yaw or rock and tilt axes by gimbaling the rocket engine to provide thrust vectoring. Two TVC actuators are positioned 90° apart relative to each other to provide the engine’s gimbal function.
Now that the CLV US TVC architecture is selected, the detailed design and analysis of the various components within the architecture will proceed into the requirements-definition phase, leading to breadboard and engineering model hardware development and testing. An additional power tradeoff study is being conducted to decide on the second hydraulic power. Some of the assemblies will be developed under advanced development contracts, leading to a critical design review by 2009. Other components will be developed by Glenn, the overall integration activities will be performed by Glenn, and testing of breadboard and engineering model hardware will be performed at Glenn.
Glenn contacts:
Nang Pham, 216-433-6165, Nang.T.Pham@nasa.gov
Robert Tornabene, 216-433-3045, Robert.T.Tornabene@nasa.gov
Dave Frate, 216-433-8329, David.T.Frate@nasa.gov
Scott Graham, 216-977-7123, Scott.R.Graham@nasa.gov
Mark Hickman, 216-977-7105, John.M.Hickman@nasa.gov
Authors:
Nang T. Pham and David T. Frate
Headquarters program office:
Exploration Systems Mission Directorate
Programs/projects:
Constellation Systems
Last updated: December 14, 2007
Responsible NASA Official:
Gynelle.C.Steele@nasa.gov, 216-433-8258
Point of contact for NASA Glenn's Research & Technology reports: Cynthia.L.Dreibelbis@nasa.gov, 216-433-2912
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Responsible NASA Official:
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216-433-8258
Point of contact for NASA Glenn's Research & Technology reports:
Cynthia.L.Dreibelbis@nasa.gov
216-433-2912
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