Improved Strand Burn Rate Reproducibility Using a New Preparation Methodology for Paint-Based Inhibitors

摘要

Small-scale ballistic characterisation of composite rocket propellants is a critical step in the development of rocket motors and is achieved by measuring linear strand burning rates determined using the Crawford strand burning technique. To utilise this technique, the propellant strands must burn with an end-burning configuration, which is achieved through the application of a water-based acrylic paint as an inhibitor. To be effective, the inhibitor needs to be of such a quality that the resultant coating on the propellant strands will be defect-free. If the inhibitor coating contains defects, erroneous and irreproducible burn rate data can result, a problem that has been evident at this facility in the past To improve the strand burn rate reproducibility, a series of paint/water compositions, ranging between 65 and 78%(v/v) paint/water, were prepared using a modified preparation methodology. Of the inhibitor compositions investigated, a 70%(v/v) paint/water ratio was found to be optimal. Using this inhibitor composition, coupled with the introduction of a more rigorous inhibitor preparation methodology, a 60% reduction in erroneous burn rate data and a 32% improvement in burn rate reproducibility was achieved.