For my aerospace engineering undergrad we also had to create a conceptual design for a new aircraft. And of course, as university projects go, we basically did it in five days. But I won't tell you how many iterations we would've had to go through until we had an optimum configuration ready to be sent to detail design
The headline makes it look like their design was a definite one. Then you actually read the article and it says it took another four years before the first one would fly. Which is actually to me the more impressive part of the story, considering the amount of time it takes aircraft manufacturers to go from concept to production these days (e.g. the A380 was first conceptualised in the 1980s and its first flight was in 2005)