Moving a movieclip in a certain direction

if you chose your transform points wisely, you can use the tanks rotation property to direct your missile.  but don't attach to the missile to the tank.  that will be problematic for more than 1 reason.

so you would usually look something like the following in a loop (eg, enterframe) and you may need to adjust the tanks rotation if its default rotation of 0 fails to point towards the position x axis.:

missile.x+=speed*Math.cos(Math.PI*tank.rotation/180);

missile.y+=speed*Math.sin(Math.PI*tank.rotation/180);

eg,

var m:Missile;

var speed:int=whaTEVER;

var tankW:Number = tank.width;

function bF(e:KeyboarEvent):void{

m=new Missile();

this.addChild(m);

m.rotation=tank.rotation;

m.x = tank.x+tankW/2*Math.cos(tank.rotation*Math.PI/180);

m.y = tank.y+tankW/2*Math.sin(tank.rotation*Math.PI/180);

m.addEventListener(Event.ENTER_FRAME,enterframeF);

}

function enterframeF(e:Event):void{

e.currentTarget.x+=speed*Math.cos(Math.PI*e.currentTarget.rotation/180);

e.currentTarget.y+=speed*Math.sin(Math.PI*e.currentTarget.rotation/180);

if(e.currentTarget.x>stage.stageWidth||e.currentTarget.y>stage.stageHeight||e.currentTarget.x<0||e.currentTarget.y<0){

this.removeChild(MovieClip(e.currentTarget));

e.currentTarget.removeEventListener(Event.ENTER_FRAME,enterframeF);

}

}