Batch 2019.11.23

A solid slug of KNSB propellant cast in PML 75mm coupler tube, intended to be cut into 1" long grains to be used in James' ballistic test motor. For 6 grains, thinking about saw kerfs and shrinkage, we'll try casting about a 7" length. That calculates to about 1321g.

After trying with and without RIO last year, then losing the notes on which tests were which, I'm kind of starting over. For prior with-RIO motors, I used 1% RIO and about 1.5 drops per 100g of Polystep-B1 surfactant. At this motor size, I don't think the surfactant is useful, but I do think some RIO helped with igniteability. So this time, let's try running with less RIO and no surfactant. Like 0.25% RIO.

Formula for a batch size of 1325g:

• KNO3, 859.10g
• Sorbitol, 462.59g
• red iron oxide, 3.31g

This formula is completely fluid with 225F indicated on the Presto Multicooker.

Results

These grains were cast on 23 November 2019, in the wee hours.

The actual measures of the batch (using shipping scale for primary ingredients and my 0.01g resolution scale for the RIO) were:

• KNO3, 860g
• Sorbitol, 462g
• red iron oxide, 3.4g