Comments
Burned ~0.5s prior to CATO. Forward retaining ring and forward floating closure ejected due to overpressurization. No observable damage to any motor hardware other than a ding on the O-ring gland of the floating forward closure, wear on the casing threads (still intact and mostly undamaged in appearance), and minor damage to the forward retaining ring's threads. One propellant grain was ejected and burned on the ground. Two additional propellant grains were ejected from the motor but did not ignite and only showed charring to the cardboard casting tube. The 4 remaining grains appeared to have burned inside the casing. Finally, the casing has a slight bulge with the appearance as a stress concentration where the threads are at the forward end.
During assembly, there were several points to note. The forward insulating plate came glued onto the liner, but a small chip at the liner's edge at the forward end was observed. This chip (about 0.5in around the edge) did not have any cracks or other damage stemming from it. Three propellant grains fit too snugly in the liner, so the outer layer of paper was removed from these grains, so that as each grain was glued in with Elmer's Glue All Max, they wouldn't become too tight and prevent subsequent grains from being pushed into the liner. These three grains were glued in and installed as the 3 topmost grains. Additionally, one grain spacer O-ring was omitted between the fifth and sixth grains (towards the bottom) due to the nozzle not fitting flush against the liner.
