Rotate Slightly With Torque

Hello,

I am working on a pretty basic flight simulator, using a helicopter model taken from the asset store. I wrote a basic movement script for it. It will move the helicopter using AddForce along all axis, but remaining in the same direction. My question is how to use torque to rotate the helicopter slightly, to make it look more realistic. My current code is as follows:

 using UnityEngine;
 using System.Collections;
 
 public class HeloFlight : MonoBehaviour {
 
     private Rigidbody rigidbody;
 
     // Use this for initialization
     void Start () {
         rigidbody = GetComponent<Rigidbody> ();
     }
     public int vertspeed = 0;
     public int horspeed = 0;
     public int lrspeed = 0;
     public int torque;
     public bool lightstate = false;
 
     // Update is called once per frame
     void Update () {
         if (Input.GetKey(KeyCode.Q))
             vertspeed++;
             Debug.Log("Increasing Vertical Speed");    
             //Enact Movement
 
         if (Input.GetKey(KeyCode.E))
             vertspeed--;
             Debug.Log("Decreasing Vertical Speed");
             //Enact Movement
 
         if (Input.GetKey (KeyCode.W))
             horspeed++;
             Debug.Log ("Increasing Horizontal Speed");
             //Enact Movement
 
         if (Input.GetKey (KeyCode.S))
             horspeed--;
             Debug.Log ("Increasing Horizontal Speed");
             //Enact Movement
 
         if (Input.GetKey (KeyCode.A))
             lrspeed--;
             Debug.Log ("Increasing Right Speed");
             //Enact Movement
 
         if (Input.GetKey (KeyCode.D))
             lrspeed++;
             Debug.Log ("Increasing Left Speed");
             //Enact Movement
 
         if (Input.GetKey (KeyCode.X))
             rigidbody.useGravity = true;
             
         if (Input.GetKey (KeyCode.Y))
             rigidbody.useGravity = false;
                 
 
 
 
         if (!Input.GetKey (KeyCode.D) && !Input.GetKey (KeyCode.A)) {lrspeed = 0;}
 
         if (!Input.GetKey (KeyCode.Q) && !Input.GetKey (KeyCode.E)) {vertspeed = 0;}
 
         if (!Input.GetKey (KeyCode.W) && !Input.GetKey (KeyCode.S)) {horspeed = 0;}    
     
 
         rigidbody.AddForce (lrspeed * Vector3.right);
         rigidbody.AddTorque (torque * Vector3.right);
         rigidbody.AddTorque (torque * Vector3.left);
         rigidbody.AddForce (horspeed * Vector3.forward);
         rigidbody.AddTorque (torque * Vector3.forward);
         rigidbody.AddTorque (torque * Vector3.back);
         rigidbody.AddForce (vertspeed * Vector3.up);
         rigidbody.AddTorque (torque * Vector3.up);
         rigidbody.AddTorque (torque * Vector3.down);
 
     }
 }

As you can see I have rigidbody.AddTorque but it does absolutely nothing. Ideas? Thanks in advance.