I am a space enthusiast and am intrigued mostly by rockets. I recently found a book HOW to DESIGN, BUILD and TEST SMALL LIQUID-FUEL ROCKET ENGINES and have been fiddling around with rocket engine calculations and calculated a theoretical engine. Now, this book/PDF has a lot of useful calculations and many other tips and tables in it. And the tables are what I want to know about. In the document, there are calculated performances for many fuels at different pressures, mixture ratios, and many graphs of how the performance (or some "part" of it) is affected by other variables. I also found many sites with this kind of graphs, like the site from Robert A. Braeunig and more precisely this site with these charts again. So the question is: How can I calculate these graphs with my "totally" random variables or at least where could I find this knowledge. I'm basically interested just in the graphs shown on the "more precise" link. Thank you for your answers and for sharing your knowledge with me.

Disclaimer: I have no intention of building a real rocket engine as I do not have manufacturing knowledge nor tools to make it (so even if I wanted to I could literally).