Im Confused........

[starman]

Starman, actually you don't have to use the pipe radius for the CB calculation, diameters work fine. You do have to use either both radiuses or both diameters and the calculation must involve the ratio of the two volumes, as it does in a CB calculation.

For calculating c:b's, of course diameter works equally well...but I'm for offering him the real volume calculation. Many of these questioneers are young enough to never have calculated the volume of a cylinder in their lives. Why not make it a complete learning moment? and avoid possible confusion and future errors.

Learn the short-cuts after you know the fundamentals...reasonable?

[jimmy101]

Learn the short-cuts after you know the fundamentals...reasonable?

Good point. And you need the chamber volume anyway to calculate tha fuel volume if its a combustion gun.

Though once you understand, then it isn't a short-cut, it's just understanding the fundamentals of the relationship and of mathematics.

Hopefully, a noob spudder pretty quickly learns that the volumes scale as the ratio of the squares. Doesn't matter if you use radii or diameters.