...
As we know, burn rate and pressure are proportional, so by doing a series of burns with different throat sizes and fitting a curve to the data, it is possible to experimentally calculate the burn rate as a function of the pressure. This is also a good way to get c*. A minor but important point is that throat diameter before and after the burn should be measured if any slag accumulates.
Lastly, there are some general data processing tasks to do. Comparing maximum and average pressure to the simulated values (so that we can check if the characterization needs to be updated), comparing real thrust trace to the simulated values (so that we can check if they match, and think about if effects like erosive burning can explain discrepancies), calculate ISP and c* (so that we can check whether they are in line with what we expect from the propellant formula).
Photo and Video Tips
We have established the fact that good firing videos can help understand so much about the firing process. Hence, we shall now consider two main tips to shoot a good firing video and also look at some example firing pictures.
Firstly, a higher frame rate is often more important than a larger resolution, but both are good to have. And secondly, trying to get as many different angles as possible is very important.
