[Solved] Getting relative torque from mass and set turn rate?

I've come across a bit of a frustration with the space game I'm working on.

Currently, turning is done by addrelativetorque. It works fine for fighters, but capital ships with higher mass on their rigidbodies do not seem to like it.

Currently, I have to tune all of the ships individually to get the turning speeds I want out of them by plugging in a raw torque value that works with the mass of the ship and hope it turns out the way I like. Any adjustment to mass forces me to have to retune all of the numbers again. Tuning capital ships this way has been stressful because they either end up as agile as starfighters or steer so slowly it isn't even visible to the human eye despite the AI trying to steer as hard as it can. I have been trying to make sure the capital ships have enough mass that they will not be moved when a fighter crashes into them, but Unity's physics do not seem to like high mass values.

What I want to know is if there is an equation to convert a specific turn speed (as degrees per second) and ship mass into the appropriate amount of torque to apply to the rigidbody in question.

Or is there a better way to smoothly rotate a gameobject at a set rate regardless of mass?