Projetil rotation in straight line trajectory

Good evening, I would like a help in a script, with a 2D game TopDown, I wish the enemies could throw arrows, straight line, but fowards the player, however, I could not make the arrow sprite spin on its axis Without affecting the straight trajectory. Tips to incorporate?

using System.Collections; using System.Collections.Generic; using UnityEngine;

public class Blast : MonoBehaviour {

 public float speed;
 public GameObject player;
 private Rigidbody2D myRigidbody;
 private Animator anim;
 public Vector3 vDirection;
 public float angle;
 // Use this for initialization
 void Start () {
     myRigidbody = GetComponent<Rigidbody2D>();
     anim = GetComponent<Animator>();
     vDirection = player.transform.position - gameObject.transform.position;
     vDirection = vDirection.normalized;
 }

 void Update () {
     player = BlasterAttack.PlayerT;
     myRigidbody.velocity = transform.TransformDirection (vDirection * speed);

}