| This research attempted to use existing shuttle test data to identify causes of the low amplitude roll-yaw oscillation of the space shuttle orbiter during reentry known as quarter-hertz motion. The nature and quantity of the data made any definite conclusions about the direct cause of the motion impossible. Previous theories regarding the quarter-hertz motion were reexamined, taking into consideration as much additional information as possible. Finally, classical control theory was applied to the orbiter system. This indicated that the quarter-hertz is probably a natural lateral-directional response frequency of the system. |
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