Hi Ken ...
I haven't read the entire topic yet, but it looks like you are using TGEA on this (?)
back in 2001-2002 I talked to Jeff Tunnell about doing flight sim , however the original TGE didn't have the ability to do large terrains, among other restrictions at the time ..
.dts and .dml ... ha ha dml = Dynamix Material List ...
if you want a website for this .. I can provide very solid hosting, with every feature you could possibly want, including a forum (PHPBB or Simple Machines Forum) ... likely for free .. and could do website work for nearly free .. domain name would only be $10 per year
I host a few RB3D sites, including my own www.flybert.net (still 1999 design ...lol ...), www.redbaronplayers.net (better design) , and host/maintain www.swwisa.net and host www.vonhelton.com
very interested in your project ... shoot me an email .. flybert@sbcglobal.net