# Test 11 # Our first attempt at making 54mm grains with sorbitol. Grain length 3.25", core diameter 0.5" (only mandrels on hand). Casting tubes from [ARR](http://www.alwaysreadyrocketry.com/), machined a new set of hardwood casting stands on our CNC router, drilled PVC pipe caps for upper mandrel centering. The formula used is the same we've been using with sorbitol, but in an 875g batch this time: * 65% KNO3, 568.75g * 35% Sorbitol, 306.25g * 1% red iron oxide, 8.75g, added after melt * 10 drops Polystep-B1, added before pour using eye dropper Robert noted that tamping down the material in the grains required a tweak to his process for 38mm, since the larger casting tubes and greater propellant mass meant having to hold everything together more solidly. We also noted that there was some variation (a mm or so?) in my casting tube lengths, so getting them uniformly filled was a bit fiddly. These grains were cast on 1 September 2015. ## Results ## * Grain 1, ?g net * Grain 2, ?g net * Grain 3, ?g net * Grain 4, ?g net ## Observations ##