Well ****.... Now I am done.
For cripes sake man. Chalk it up as a learning experience as long-necked motors are a REALLY big challenge to get right in any diameter even with a cool burning mixture. Hang in there!
Try some shorter motors and work your way up. If anyone around there in your area is known to be a mixer, go to them or their club.
I learned a lot of stuff in a TRA club (now defunct because the prefect died) that did a lot of communal mixing. Bring your "stuff" casting tubes, chems and such and have at it. We'd figure out what recipe to use and did the "ball and pack" routine as there were plenty of members who'd show up to help out even if they weren't able to bring chems to the mixes. Suffice it to say the prefect made sure anyone who helped out, got some grains in what size the participant would like whether the person brought "stuff" or not. Those were heady days for me. We guys had a lot of fun too.
I saw others misfortunes and learned from them too. Burnsim is a tool that is not absolutely perfect. Good but not perfect. The posted "numbers" A and N one has to trust whomever ran them on whatever equipment they used if using a borrowed mix formula. Use them as a starting point. The longer one uses it (Burnsim) and compares it to their test burns, the better they will become at testing motors and determining motor length and how to "step" grain cores. (To a degree mind you because if one steps over the line of too high an L/D ratio there may be nothing that can help them if they go too far.)
I think I might have had the prediction right in #46 above.
"That might burn pretty hot and destroy the case with a 12 inch long end burn grain. I'd bury it in the ground to be honest with you. Case could melt. If nozzle fails with the end grain still burning like a flare, the heat soak (if it doesn't melt the case in two) will probably severely compromise the strength of the case."
The longer one does this, the better they will get at making predictions and it makes it that much more fun!
Soooooooooo, have at it and keep going.
Kurt Savegnago