: The movement of liquid fuel can drastically shift the center of mass and introduce new vibrational modes.

The interaction between the air flowing over the vehicle and the elastic deformation of the hull.

| Concept | Description | |---------|-------------| | | Decomposition of elastic deformation into a sum of mode shapes (from finite element analysis) with time-varying generalized coordinates. | | Mean Axes | A reference frame attached to the rocket that minimizes coupling between rigid and elastic motions. | | Slosh Dynamics | Propellant moving inside tanks modeled as spring-mass-damper systems or equivalent mechanical analog. | | Pogo Oscillation | Longitudinal vibration coupled with propulsion system pressure fluctuations. | | Flutter | Aeroelastic instability involving bending/torsion modes. | | Control–Structure Interaction | Sensors (gyros, accelerometers) measure body motion + elastic deflection; actuators (thrust vector control) may excite modes. |

: Timothy M. Barrows (Draper Laboratory) and Jeb S. Orr (Mclaurin Aerospace). Publisher : Academic Press (an imprint of Elsevier).

The ultimate purpose of these complex dynamic models is to design a robust control system. The simulation environment allows engineers to test "Notch Filters" and "Bending Filters." These are control algorithms designed to filter out the specific frequencies of the structural bending modes so that

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