Dispersion Reduction of a Direct-Fire Rocket Using Lateral Pulse Jets

Report No. ARL-CR-465
Authors: Thanat Jitpraphai and Mark Costello
Date/Pages: April 2001; 31 pages
Abstract: The impact point dispersion of a direct-fire rocket can be drastically reduced with a ring of appropriately sized lateral pulse jets coupled to a trajectory tracking flight control system. The system is shown to work well against uncertainty in the form of initial off-axis angular velocity perturbations as well as atmospheric winds. In an example case, dispersion was reduced by a factor of 100. Dispersion reduction is a strong function of the number of individual pulse jets, the pulse jet impulse, and the trajectory tracking window size. Properly selecting these parameters for a particular rocket and launcher combination is required to achieve optimum dispersion reduction. For relatively low pulse jet impulse, dispersion steadily decreases as the number of pulse jets is increased or as the pulse jet impulse is increased. For a fixed total pulse jet ring impulse, a single pulse is the optimum pulse jet configuration when the pulse jet ring impulse is small due to the fact that the effect of a pulse on the trajectory of a rocket decreases as the round flies down range.
Distribution: Approved for public release
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Last Update / Reviewed: April 1, 2001