Fluid and Constant Rotation for Space Sim?

So I made a small amateur-ish script for a fluid rotation of a "Gameobject", in this case a Spaceship. Instead of going the route of Quaternion(which frankly, the concept itself is quite complex for me to grasp wears a Dunce hat), I rather used rigidbody torque to achieve it. Here's the code for it.

 using UnityEngine;

 using System.Collections;



 public class MouseTurn : MonoBehaviour {

 

 public float pitchyawAmount = 0.5f;

    public float bankAmount = 0.5f;

 public float mouseSensitivity = 30f;

 public float angularDragAmt = 5f;    

 public float waitTime = 3f;
 

 private float horizontalaxeschange = 0f;

 private float verticalaxeschange = 0f;    

 private float angularvelocityamt = 0f;

 

 

 void Start ()

 {

     horizontalaxeschange = 0f;

     verticalaxeschange = 0f;

     angularDragAmt = 5f;        

     angularvelocityamt = 0f;

 }

 

 



 void FixedUpdate ()

 {

     Screen.lockCursor = true;

     

     if(Input.GetAxis("Horizontal") < 0){

         gameObject.rigidbody.AddRelativeTorque(0, 0, bankAmount);//transform.Rotate(0, 0, -bankAmount);

     }

         else if(Input.GetAxis("Horizontal") > 0){

         gameObject.rigidbody.AddRelativeTorque(0, 0, -bankAmount);//transform.Rotate(0, 0, bankAmount);

     }



         horizontalaxeschange = Input.GetAxis("Mouse X");// * pitchyawAmount;

         verticalaxeschange = Input.GetAxis("Mouse Y");// * pitchyawAmount;

     

     //print(angularvelocityamt);        

     angularvelocityamt = gameObject.rigidbody.angularVelocity.magnitude;



         gameObject.rigidbody.AddRelativeTorque(verticalaxeschange * pitchyawAmount, horizontalaxeschange * pitchyawAmount, 0);

     //gameObject.constantForce.torque = new Vector3(verticalaxeschange * pitchyawAmount, horizontalaxeschange * pitchyawAmount, 0);

     //transform.Rotate(verticalaxeschange * sensitivity, 0, -horizontalaxeschange * sensitivity);

     

     gameObject.rigidbody.angularDrag = angularDragAmt;

 }  

     

 void OnCollisionEnter(Collision SpaceShipHit){

     StartCoroutine("changeAngularDrag");

 }

 

 IEnumerator changeAngularDrag(){

     angularDragAmt = 10f;        

     yield return new WaitForSeconds(waitTime);        

     angularDragAmt = 5f;

 }    



 }

So my main objective here is to get a constant rotation for my gameobject when my mouse is at the edge of the screen(where my mouse should stay at all times). I did try regular rotation and also constantforce, which you can see in my code above, but they produced a very robotic/non-fluid rotation. Because of the angular drag, my gameobject comes to a halt if I stop moving my mouse. And if I decrease my angular drag, whenever I move my mouse multiple times, "AddRelativeTorque" shells out huge amount of torque, where it takes me more than a couple of mouse moves to make my gameobject stable again.

So where am I going wrong with this approach? Or is there an alternative to achieving a constant rotation with a fixed mouse cursor area?

P.S. I am using ONCollisionEnter() and subsequent coroutine to stabilize my gameobject after a collision, so that it won't go on a non stopping roll.

UPDATE: So after a through research or rigidbody and forces, I finally achieved what I was trying to do. I used ConstantForce.RelativeTorque under rigidbody to achieve a constant turn of my gameobject. If a mod sees this, they are welcome to close or delete this post if necessary. Thank You. Loving every minute of unity.

P.S For anyone looking for a X3/Black Prophecy type mouse movement, then here is a simpler version of the code I am using.

 void FixedUpdate ()

 {

     Screen.showCursor = false;

     

     float xvalue = Input.mousePosition.x;

     float yvalue = Input.mousePosition.y;

     

     int screenheight = Screen.height;

     int screenwidth = Screen.width;

     

     float xmidpoint = screenwidth/2;

     float ymidpoint = screenheight/2;



     //constantForce.relativeTorque = new Vector3(0f, (xvalue - xmidpoint) * 0.005f, 0f);



     constantForce.relativeTorque = new Vector3((yvalue - ymidpoint) * 0.01f, (xvalue - xmidpoint) * 0.005f, 0f);

     

     if(Input.GetAxis("Horizontal") < 0){

         //gameObject.rigidbody.AddRelativeTorque(0, 0, -bankAmount);//transform.Rotate(0, 0, -bankAmount);

         

         constantForce.relativeTorque = new Vector3(0f, 0f, 2f);

     }

     else if(Input.GetAxis("Horizontal") > 0){

         //gameObject.rigidbody.AddRelativeTorque(0, 0, bankAmount);//transform.Rotate(0, 0, bankAmount);

         

         constantForce.relativeTorque = new Vector3(0f, 0f, -2f);

     }

     

     

 }

Yeah took me a while to come up this this small/easy piece of code. hahaha.