Complex sentence: By 2015 the aircraft had gone through a redesign, with an enlarged cockpit and a new wing design added, but by the end of 2015 the company website was taken down and the company seemed to be out of business.
Split into simpler sentences: By 2015 the aircraft had gone through a redesign, with an enlarged cockpit and a new wing design added. By the end of 2015 the company website was taken down and the company seemed to be out of business.