On Feb 20, 2023, at 6:18 PM, Rick Maschek <dmarc-noreply@xxxxxxxxxxxxx> wrote:
The case was approximately 12 inch by 9 feet long, quarter inch wall oil pipeline steel pipe.24 grade 8 half inch bolts in two rows holding the quarter inch wall steel retaining ring.The forward bulkhead was a steel plate welded in the motor case.5 grains of KNSB propellant 20 inch long with the cores varying from 2.5 inches at the bulkhead to 4 inches at the nozzle We used aluminum motor cases as our mandrels covered in silicon sheet and greased for release.The nozzle grain weighed in at 124 pounds with the others slightly heavier because of smaller cores. The nozzle had a 94% ideal density, normal density for me is 96-98%
I was up all night Thursday and much of Friday night helping student teams so I left soon after our 12 inch test.Not sure what caused the anomaly, lots of speculation and guessing. I'm still investigating the cause.We had two previous successful 12 inch KNSB sugar tests, one with 2 grains and one with 3 grains.
This test had five grains and was designed to be progressive to test our three piece safety nozzle.Design pressure at start up was higher than the two previous 12 inch tests.