Posted for "Douglas W. Johnson, MD" <Lancair1@bellsouth.net>:

 I used tungsten and DU in my IVP rudder.  With a specific gravity of around
 20, as opposed to around 10 for lead, the smaller denser material could be
 shifted more anterior (away from the fulcrum point) in the counterweight
 cavity.  This in turn allowed me to shave off several pounds from the
 counterweight.  The overall lighter tail moved my CG forward to the point
 that, coupled with the Hartzell prop, there is NO configuration in which I
 can load the plane to aft CG within its weight envelope.
 
 Just another idea...
 Doug Johnson
 LIVP 654DM
 770hrs and counting...