The 12 point star XL motor was tested to meet the requirements for a 1st stage booster motor. Grain length was increased to 1225mm while maintaining the nozzle at 22mm. RIO was added as a burn rate modifier.
Motor provided full thrust (4200-5200N) for approximately 3 seconds. Erosive burning was minimal.
A “faster” BDO propellant was tested (66/8/2 AP, Al, CuO). Motor was ignited with 3g Mg, Al thermite, 2g BP and 7.9g APCP shavings. A 9s burn is a bit disappointing.
Post burn inspection showed a lot of slag on the nozzle. The throat was partially obstructed by this, reducing the diameter from 11.2 to approximately 7mm.
Despite a formidable flame and pressurization, the APCP grain did not ignite (3.5g BKNO3).
1.7 gram of B/KNO3 in a stainless steel mesh retainer to avoid particle expulsion.
Boron igniter test (0.5gram)
Successful test of a 12 point star core APCP motor. Relative flat thrust curve due to limited erosive burning and progressive geometry.
Because of the rain fall, a plastic bag was positioned over the nozzle.