NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Preliminary Characterization of the Altair Lunar Lander Slosh Dynamics and Some Implications for the Thrust Vector Control DesignThis paper describes a conceptual design of the Thrust Vector Control (TVC) system and preliminary modeling of propellant slosh, for the Altair Lunar Lander. Altair is a vehicle element of the NASA Constellation Program aimed at returning humans to the moon. Guidance, Navigation, and Control (GN&C) is the measurement and control of spacecraft position, velocity, and attitude in support of mission objectives. One key GN&C function is the commanding of effectors that control attitude and impart delta V on the vehicle, utilizing both reaction control system (RCS) thrusters and throttling and TVC gimbaling of the vehicle main engine. Both the Altair descent and ascent modules carry fuel tanks. During thrusting maneuvers, the sloshing of liquid fuels in partially filled tanks can interact with the controlled system in such a way as to cause the overall system to be unstable. These fuel tanks must be properly placed, relative to the spacecraft's c.m., to avoid any unstable interactions. Following this will be a discussion of propellant slosh modeling work performed for the present vehicle configuration, including slosh frequency and participatory fluid mass predictions. Knowing the range of slosh mode frequencies over mission phases, the TVC bandwidth must be carefully selected so as not to excite the slosh modes at those frequencies. The likely need to increase the damping factor of slosh modes via baffles will also be discussed. To conclude, a discussion of operations procedures aimed at minimizing TVC-slosh interactions will be given.
Document ID
20150008899
Acquisition Source
Jet Propulsion Laboratory
Document Type
Conference Paper
External Source(s)
Authors
Lee, Allan Y.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Strahan, Alan
(NASA Johnson Space Center Houston, TX, United States)
Tanimoto, Rebekah
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Casillas, Arturo
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Date Acquired
May 26, 2015
Publication Date
August 2, 2010
Subject Category
Spacecraft Propulsion And Power
Meeting Information
Meeting: AIAA Guidance, Navigation, and Control Conference 2010
Location: Toronto, Ontario
Country: Canada
Start Date: August 2, 2010
End Date: August 5, 2010
Sponsors: American Inst. of Aeronautics and Astronautics
Distribution Limits
Public
Copyright
Other

Available Downloads

There are no available downloads for this record.
No Preview Available