---------------------------------------------------------------------------
   Find the equilibrium state of the engine.
---------------------------------------------------------------------------
   Form:
   x = ACEngEq( d, v, r )
---------------------------------------------------------------------------

   ------
   Inputs
   ------
   d                     Aircraft data
   v              (3,1)  Velocity
   r              (3,1)  Position

   -------
   Outputs
   -------
   x                     Equilibrium engine state

---------------------------------------------------------------------------