Complex sentence: In 2005, Gulfstream and IAI began designing a follow-on aircraft to the Gulfstream 200, the new model, then known as the "G250" was launched in 2008.
Split into simpler sentences: In 2005, Gulfstream and IAI began designing a follow-on aircraft to the Gulfstream 200. The new model, then known as the "G250", was launched in 2008.