places now use sgCartToGeod() instead of rolling their own
approximation. And YASim is now using exactly the same 3D coordinate
system as the rest of FlightGear is.
Dynamics (Sim)ulator. Basically, this is a rough, first cut of a "different
take" on FDM design. It's intended to be very simple to use,
producing reasonable results for aircraft of all sorts and sizes,
while maintaining simulation plausibility even in odd flight
conditions like spins and aerobatics. It's at the point now where one
can actually fly the planes around.