You probably are. The Barrowman "equations" are just arithmetic (no algebra, let alone anything advanced). There's a lot of arithmetic for anything more than an nFMT, but if you can to basic +-×÷ and follow directions, then you can use them.

I've done the Barrowman calculations for CP on a couple of different rockets, mainly to see how close it came to OR's CP calculation. Both times the two CPs were within .125" of each other, which tells me that I can indeed rely on OR.

My comment to

@Ez2cDave —"If I were proficient [...]" was admittedly a little sarcastic (sorry, Dave), but intended to underscore the point that while it may be possible to do that calculation on paper, as well as all the other calcs that OR does on-the-fly, why would I want to spend the time required by manual calculations when OR is completely reliable?

In other words:

Calculating stability and performance for every permutation of every component mass, size, shape, and placement throughout design, and simulating every design in various wind, elevation, launch angle, etc. conditions is so time consuming that I can't take seriously the claim that anyone is doing this by hand as thoroughly as a simulator can, nor thoroughly enough not to be a safety issue in high performance flights.

That's about as salient as one can get, and hits the nail on the head.

Finally—and quite apart from OR's ability to predict rocket performance

*based on the data it's given*—the ability to design a rocket in OR and see how changes in materials, sizes and weights of components, and motors, all affect performance as the build progresses, is invaluable to me.

That said, I completely understand Dave's desire to 'own' his rocket design by doing the math, however rigorous it might be, and, in the end, be able to say, "I did this!" (Every last bit of it.) Frankly, my hat's off to him for his ability and tenacity.

In the end, if we can't do basic math with a pencil and paper—even in our heads, in many cases—as so many schoolkids these days can't, we're screwed if calculators, computers and software ever go by the wayside. And not just for building rockets.