STIRLING!
STIRLING!
STIRLING!
        Okay, my bad.  I've been talking about AIP [Air Independent
Propulsion] systems for submarines, using 'sterling' engines.
Well, I just figured out that they're spelled STIRLING!  Duh.... <g>
        Of course, I was spelling (and pronouncing) "tetrahedron"
(as in "tetrahedron kite") as "tetrahedon" for a long time, too....
-Allan