Dont display on screen, but do it in background

Hi. I am having a little problem with my RPG arrow. I have to rotate it to get a nice movement direction… Here is the code. Hope someone knows how to do this :confused:

var projectile : Rigidbody= Instantiate(bullet, muzzlePoint.transform.position, muzzlePoint.transform.rotation); 
      projectile.rigidbody.isKinematic= false;

 // have to hide this part 

try this

   if( projectile.rotation.eulerAngles.x >= 85   ||  projectile.rotation.eulerAngles.y >= 25){
    projectile.renender.enabled = false;

this will help me probably. just have to figure out when to disable, and when to enable rendering for my arrow. Thank You.