Conceptual design is the starting point of an aircraft project At this stage major design changes can be brought into a design without major cost effects, but it also brings with it responsibilities. Bad structural layouts might jeopardise weight promised, the same applies for landing gear design. Aircraft conceptual design is very much about minimising risks. If you don't get the landing gear right from the beginning or neglect to find a place for it when retracted, you're in a big problem. This implies that the aircraft has to be worked through in every detail to minimise risks. As the saying is: "the devil is in the details" but on the other hand don't get lost in details and forget the big picture. This is equally important.