Burn Rate User Interface
In order to make accurate chamber pressure predictions, you need to know the coefficient and exponent in the burn rate equation for your propellant.
Propellant Burn Rate = c * (Chamber Pressure)n
Burn Rate makes that easy. You input a few data points of burn rate as a function of pressure, which you obtain from strand burners or from small test motors. Then, you simply click on the "Best Fit Data" button to get the values for the coefficient, c, and the exponent, n. You may want to bias the equation towards some data points more than others as these data points may be more accurate. To do that, you just adjust "c" and "n" until the equation fits the data the way you want it.
To bias the equation, the simplest way is to adjust the value for "n" first, until the slope of the equation matches the burn rate data. Then, adjust the value of "c", until the equation overlays the data. Once you are satisfied with the "c" and "n" values and the output from CHEM-II, you are ready to move on to FPRED and begin designing your flight motors.