object drifts when its using rigidbody.AddRelativeForce and i rotate it

hi, im trying to make a plane simulator and im using rigidbody.AddRelativeForce to accelerate it, but when it rotates it keeps going in that direction and it slowly starts pushing it to the direction it should, making it sort og like a drift. how do i stop that?

here is the code im using:

 // acceleration
 var planeSpeed : float;
 var planeAcceleration : float = 7; 
 var planeAccelerationV : float;
 var currentPlaneSpeed : float;
 var speedSmoothDamp : float = 2;
 var maxPlaneSpeed : float = 15;
 //rotation
 
 @HideInInspector
 var xRotation : float;
 @HideInInspector
 var yRotation : float; 
 @HideInInspector
 var zRotation : float; 
 
 var maxRotation : float = 7;
 var rotSensibility : float = 7;
 
 
 function Start () {
 
 }
 
 function Update () {
 
  // acceleration
  planeSpeed += Input.GetAxis("Mouse ScrollWheel") * planeAcceleration * Time.deltaTime * 100;  
  currentPlaneSpeed = Mathf.SmoothDamp(currentPlaneSpeed, planeSpeed, planeAccelerationV, speedSmoothDamp);
  planeSpeed = Mathf.Clamp(planeSpeed, 0, maxPlaneSpeed);
  currentPlaneSpeed = Mathf.Clamp(currentPlaneSpeed, 0, maxPlaneSpeed);
  
  rigidbody.AddRelativeForce(0, 0, currentPlaneSpeed);
  // rotation 
  
  xRotation = Input.GetAxis("Vertical") * rotSensibility * Time.deltaTime;
  yRotation = Input.GetAxis("Horizontal") * rotSensibility * Time.deltaTime;
  zRotation = Input.GetAxis("Roll") * rotSensibility * Time.deltaTime;
  
  transform.Rotate(xRotation, yRotation, zRotation);
  
  if (Input.GetAxis("Horizontal") == 0){
    transform.Rotate(xRotation, 0, zRotation);  
  }
  if (Input.GetAxis("Vertical") == 0){
    transform.Rotate(0, yRotation, zRotation);
  } 
   if (Input.GetAxis("Vertical") == 0){
    transform.Rotate(xRotation, yRotation, 0);
  }
  
 }