Constant force on 2Drigidbodys

I have a 2D game with a plane. I want this plane to be affected by gravity and have a max speed. right now I'm just using AddForce() and it makes the sprite accelerate indefinitely. I also want to move forward based on the rotation of the sprite. Here's what I have so far:

 using UnityEngine;
 using System.Collections;

 public class PlaneScript : MonoBehaviour {
     public float maxSpeed = 10f;
     public Vector2 thrustForce = new Vector2(0, 100);

 // Use this for initialization
 void Start () {
 
 }
 
 // Update is called once per frame
 void FixedUpdate () {
     //checks inputs
     bool move = Input.GetButton ("Thrust");
     float Yrotate = Input.GetAxis ("Horizontal");



     //adjust thrust forward
     if (move) {
         rigidbody2D.AddForce( thrustForce );
             }

     //rotates plane based on A & D keys
     rigidbody2D.transform.Rotate (0,0,(Yrotate- (2 * Yrotate))*maxSpeed);

 
 }
 }  

Any help would be greatly appreciated.