Recently three NASA-sponsored conceptual design studies considered the feasibility of using advanced turbofan engines to power civil two-seat trainer and four-seat utility-type aircraft. The first of these studies was performed by an engine manufacturer, Garrett Corporation, who developed conceptual turbofan engine models of appropriate design and cycle. Garrett also produced several preliminary airplane designs, including a two-seat trainer and a four-seat utility airplane. Subsequent studies were performed by two general aviation airframe manufacturers, Cessna Aircraft Company and Gates Learjet Corporation. Each airframe manufacturer developed a preliminary airplane configuration (either two or four place) designed to be powered by one of Garrett's conceptual turbofan engines.The purpose of this paper is to summarize and compare the configurations which emerged, from these studies. Emphasis is placed on identifying the sensitivities of each design to performance constraints, aerodynamic assumptions, and weight estimation techniques.