Original challenge by @keptin First thread of this challenge  by @Mjp1050 Kerbal Express Airlines is in need of updating its aging fleet of regional jets and turboprops. It's a big client, operating at hundreds of airports around Kerbin, and that means big fleet sales. Does your aircraft company offer the right kind of aircraft for the job?   Kerbal Express wants profitable aircraft. They're looking for aircraft that meet or exceed their requirements for fuel efficiency, spee