Propellant characterization and motor ballistics is a passion of mine.
I get almost as much of a thrill from testing a motor on the stand and having the results match the simulation as flying the motor in a rocket! Almost.
The spreadsheet below is used to get the burn rate exponent (n) and burn rate coefficient (a) from a set of burn rate / pressure data points.
A minimum of 3 data points must be used. More is better.
The test data is acquired through the use of a test motor.
The design I use is a simple end burning 3 inch motor with interchangeable nozzles and a pressure transducer.
I may write up an article on its design and use for Extreme Rocketry magazine, or I may just post plans here.
For now, please enjoy the spreadsheet.
To make use of this data, please download a free trial of my motor simulation software, BurnSim.
BurnSim allows you to design your motor and simulate its results, as well as exporting the results to a .eng file for use in various rocket simulation programs.
The spreadsheet is in Microsoft Excel, and you will need to have that installed to use it.
The spreadsheet uses some advanced features in Excel to match the data points to a curve and provided the necessary values.
If you have any questions please dont hesitate to contact me.
Click here to download Characterization.xls, a 25kb Microsoft Excel file. Right click the link and choose 'Save Target As...' to download the file to your machine.