We have developed a preliminary design method for commercial aircraft in academic perspective. There are four main phases in this design method. They are (1) determining design objectives and requirements, (2) statistically estimating of takeoff weight, required sea level static (SLS) thrust, and wing reference area, (3) performing a trade study to locate the optimal design point and the design region, and (4) conceptualizing the model based on the optimal design point.
Based on historical data of jet transports and the Federal Aviation Regulation (FAR) rules, we established a guideline to determine the design objectives and requirements for a commercial aircraft. We also used the historical data to formulate statistical equations to estimate the takeoff weight, the require SLS thrust, and the wing reference area. We utilized the knowledge of aircraft flight mechanics into a comprehensive comparison among the design requirements in order to sketch the design region and to locate the optimal design point. Finally, we used computer aid design (CAD) softwares to conceptualize the model based on the optimal design point.
We implemented the method into designing a wide-body commercial aircraft. Inspiring by the blended-wing-body (BWB) concept, we designed jet transport whose fuselage was shaped by the MS(1)-0317 airfoil and was blended with an Eppler 407 wing. The aircraft was sized for 200 passengers and to cruise at Mach 0.85 at the initial cruise altitude (ICA) of 38,000 ft over a 3,000-nmi range. The results show that the vehicle has an overall lift-to-drag ratio of 24, a takeoff weight of 203,096 lb, a required SLS thrust of 38,759 lb per engine, and a wing reference area of 2,338 ft2. Through the design of this aircraft, we learned that the improvement in fuel consumption of an aircraft through enhancing its aerodynamic efficiency is remarkable. From the practical perspective, this type of wide-body concept has more potential to be developed into production than the current BWB concept.