I am trying to make a realistic flight model, and I need to know what direction the object is moving so I can accurately create drag. I am looking for something like the yellow marker on the nav ball in Kerbal Space Program. Any help would be much appreciated.
A quick Google search can find this information for you but I believe you just need this.
var velDir = transform.InverseTransformDirection(rigidbody.velocity);
You should then have velDir.x,y,z