For those that have read or consulted the text: How to Design, Build and Test Small Liquid-Fuel Rocket Engines (Rocketlab/China Lake). Otherwise, see steps 10-13 here: https://risacher.org/rocket/example.html
I am currently designing an amateur rocket engine of my own. I am working through the book's calculations before I calculate dimensions for my own design. When calculating the gap for the water (coolant) there seems to be a mistake. The book displays: D2=(.0151)^(1/2)=0.123 ft = 1.475 inch, but I have done the calculation over and over again and continue to get D2=(.0139)^(1/2)=0.118 ft = 1.416 inch. I have used the books values and convert from inches to ft when appropriate. Do you know what's going on here? Does D2=0.123 ft = 1.475 inch (which is what the book says), or is this a mistake?
For those of you that have read this text, there seem to be various other discrepancies, rounding errors, and overlooked items that I have questions about as well.