how can i make drag and release (like pinball games) to shoot the ball with charge power in 3d mobile game

I find this script and it works with my model, but the y axis is too sensitive. how can i set a max length of the movement? if (Input.touchCount > 0) { for (int i = 0; i < Input.touchCount; i++) { currentTouch = Input.GetTouch (i); if (Input.GetTouch (i).phase == TouchPhase.Moved) { ray = Camera.main.ScreenPointToRay (Input.GetTouch (i).position); if (Physics.Raycast (ray, out rayHitInfo)) { Vector2 v2 = currentTouch.deltaPosition; Vector3 v3 = new Vector3 (transform.position.x, v2.y*Time.deltaTime/50 , transform.position.z); cube.transform.position = v3; } } } }