Batch 2018-batch-02

4 grains 80mm long for 54mm cases, with 0.5 inch cores

The is a test batch in preparation for doing a demo for college students on Monday. Since I have a total of 8 casting bases and such for 54mm, doing 4 now and 4 then ensures I can demo even if the grains aren't quite cured enough to pull coring rods by then.

The simulator says we need 200g of fuel per grain, so the batch size will be 800g (plus a bit for the pan made up by re-melting previous scraps):

• 65% KNO3, 520g
• 35% Sorbitol, 280g
• 1% red iron oxide, 8g, added after melt
• 12 drops Polystep-B1, added before pour using eye dropper

This formula is completely fluid with 225F indicated on the Presto Multicooker, but viscosity is noticeabley lower making for easier pouring at 250-275F.

Grain fill lines 73.6mm from the bottom of the casting tube.

These grains were cast on 2018-12-15.

Results

Forgot to weigh casting tubes, using average from the next couple batches instead. Grain 2 visibly under-filled.

• Grain 1, 195.5g gross, 5.8g casting tube, 189.7g net propellant
• Grain 2, 192.6g gross, 5.8g casting tube, 186.8g net propellant
• Grain 3, 195.3g gross, 5.8g casting tube, 189.5g net propellant
• Grain 4, 201.6g gross, 5.8g casting tube, 195.8g net propellant