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C-Slot motor Kn ratios

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solrules

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Well, I decided to try my hand at making an excel spreadsheet that calculates the Kn ratio of a C-slot grain. My answers are reasonable, but I get a big drop after the width of the grain burns through. This seems reasonable, but when I sim it with burnsim, the Kn peaks in about the same area, but there is no huge drop.

The file is at

http://www.amberwesterman.com/sol/cslot.xls

Note: I could not figure out how to do one part of the ends burning, but that number is pretty insagnificant compared to all the other area burning.

I am seeking all the math geeks/intuativeness of all the TRF members to see what I did wrong (or right!)

Note #2: this spreadsheet works best if you keep the slot height and width the same, otherwise it may explode. However, I may have fixed the problem by simply putting an ABS() in front of some negative answers.... seems to work OK with AT 29/40-120 c-slot grains, giving about the same Kn and in the same place as in burnsim.
 

solrules

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If you are wondeing, "what the heck is *insert weird calculation here*?" here are some of my scrawlings, if it helps any. Below shows the basic burn regression



And below is what I mean by "Ends2 Triangle". It is used to calcualte the sliver still burning in the motor after the width was burned up.

 
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