Falcon 9 v1.1 was the enlarged second Falcon 9 production configuration. It replaced Merlin 1C with Merlin 1D engines, lengthened both stages, adopted the compact Octaweb engine arrangement, and supported SpaceX's early controlled-descent and landing tests. Fifteen vehicles flew from CASSIOPE in September 2013 through Jason-3 in January 2016; fourteen completed their primary launch mission, while CRS-7 was lost during ascent.