I was just wondering if there is a math formula of some type that tells you how far out a rocket thrust flame trail would extend from a rocket motor if you just new the amout of thrust the rock generated in lbs of thrust....or is that info of really importance to any scientists?
I can imagine the type of fuel used would be important and amount of thrust generated would be important and maybe the diameter of the rocket motor opening?
I am guessing.
Anyone heard of a formula that predicts or measures the length of a flame trail? and what it is called?
flame trail is my word because I am assuming no smoke while the rocket motor is fired in space and not sure what else to call it.
thank you.

It is infinitely long.

When the incandescent gases shoot out of the back of a rocket in space they continue glowing at ballistic trajectories. How far you would see them "glowing" would depend on how good your camera was, right? They spread out after leaving the rocket nozzle, but in theory, there should be a stream of ions extending right straight along the axis all the way to infinity, or until they get captured, hit by something, or their trajectory is altered by a magnetic field.

How long is a comet's tail?