http://thirdwire.com/downloads_pc.htm thats the main patch DL site, with the latest patches listed
Scroll to the bottom of the page and you find
Download Archive (Old Updates) http://thirdwire.com/downloads_archive.htm
There are allindividual updates up to and inclusive May 2011, from then on there is one big patch for all SF2 series games
(Updates to Strike Fighters 2 Series) starting June 2011, this update usually requires the latest individual patch installed.
Crusader's post in line or tear in horizon - Mescalero terrain was marked as the answer