KNSU Rocket Motor Test with 3D Printed Nozzle Mold

I successfully fired a static test of a KNSU propellant motor. I had it set up to measure the resulting thrust with a load cell and FubarinoSD.

The only problem was I forgot to plug the load cell into the amplifier for the final test. So the CSV file saved on the Fubarino's SD card just contained 1kHz samples of noise. Oh well, it was still a successful test.

This motor used PourStone for the nozzle and bulkhead material that was cast in place using a 3D printed mold. Cutting the fired motor in half revealed minor burns to the casing around the nozzle and bulkhead. Nothing serious, though.

Motor cut open.

 The throat eroded from 0.142" to 0.23". Steel inserts (washers) to limit throat erosion will be required on future motors. Note that much on the nozzle mold is still intact on the convergent section of the nozzle. It is orange ABS.

Significant throat erosion.

 The 3D printed bulkhead cover also survived.

Bulkhead with thin orange cover.

Next time I will be using KNSB fuel and I will be sure to get some thrust data.