I just wanted to say that whenever you are doing any calculation for a fictional thingy, as long as you are within the ball park, you are fine, it doesn't have to be exact.
So, you can use simple shapes and simple geometry to get 95% there and that is good enough.
THere is a brilliant black-and-white Twilight Zone in which an alien is visiting Earth unbeknowst to us of course. During the story, a small circle of people discover he is an alien. One of the people in this circle is a PhD Astrophysicist professor at some college. The Professor is standing in front of a board filled with equations, this board represents his life's work as he is trying to deduce some formula for something astrophysics related.
The alien looks at all the math and writes the last line of the equation, a line that has stumped the professor his entire life.
The professor looks at the solution and says, "That easy, I could do that, but that isn't a solution, it is only an approximation."
THe alien shrugs and says, "Yeah, this problem is unsolvable, but that approximation is good enough to get you across the galaxy..."
