Adding curve to a frisbee in virtual reality

Hi there, I am currently building a daydream vr game for frisbee throwing. I have the frisbee throwing mechanics working quite well, but even when using the controller to throw the frisbee at an angle, the frisbee did not curve around as in real life, it just flies straight. I'd like to add this curve effect and have already seen an answer on this in unity answers but it does not take into account this is a vr app using the daydream controller. Here is my code, specifically relevant is the ThrowFrisbee() function. Thanks, Duncan

 public class ControllerManagerScript : MonoBehaviour {
 
 public GameObject ballSpawn;
 public GameObject Frisbee;
 
 private Vector3 ballAccel;
 private Vector3 ballLastVelocity;
 // Use this for initialization
 void Start () {
 ballSpawn.SetActive(false);
 ballAccel = new Vector3 (1f, 1f, 1f);
 }
 
 // Update is called once per frame
 void Update () {
 
 if (GvrController.ClickButtonDown) {
 // show ball as visible to start throw
 ballSpawn.SetActive(true);
 }
 
 ballAccel = (ballSpawn.transform.position - ballLastVelocity) / Time.fixedDeltaTime;
 ballLastVelocity = ballSpawn.transform.position;
 
 if (GvrController.ClickButtonUp) {
 ThrowFrisbee ();
 ballSpawn.SetActive(false);
 }
 
 }
 
 void ThrowFrisbee () {
 GameObject ballObj = (GameObject) Instantiate (Frisbee);
 ballObj.transform.position = ballSpawn.transform.position;
 ballObj.transform.rotation = ballSpawn.transform.rotation;
 Rigidbody rb = ballObj.GetComponent ();
 
 rb.AddForce (ballAccel.x * 2.0f, ballAccel.y * 2.0f, ballAccel.z * 2.0f, ForceMode.Impulse);
 }
 }