This work describes a theoretical and experimental study of combustion instability in hybrid rocket motors. Results are highlighting that the parameter (pressure drop between tank and chamber scaled by average chamber pressure) plays an important role in the oscillatory characteristics of the chamber pressure. By modifying the feed-system-coupled instability theory, a combustion time lag model has been developed; using this a new general analysis criterion is proposed. Results show good

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... t with the experimental data and suggest that the combustion time delay of the liquid oxidizer is more important than the response time of solid fuel boundary layer.