Complex sentence: AAI Corporation followed up their RQ-2 Pioneer UAV with the similar but refined Shadow 200, and in late 1999 the army selected the Shadow 200 to fill the tactical UAV requirement, redesignating it the RQ-7.
Split into simpler sentences: AAI Corporation followed up their RQ-2 Pioneer with the Shadow 200, a similar, more refined UAV. In late 1999, the army selected the Shadow 200 to fill the tactical UAV requirement, redesignating it the RQ-7.