Development of the D8 Transport Configuration

The D8 jet transport configuration is presented. Focus is on the aerodynamic characteristics of its distinguishing features: the wide “double-bubble” fuselage with beneficial pitching moment and carryover lift characteristics, the nearly-unswept wing and reduced cruise Mach number, and the boundary layer ingesting rear engine installation together with the twin “pi-tail” configuration. The merit of each feature is evaluated in terms of mission fuel burn, calculated via an MDO optimizer which accounts for the weight and propulsive efficiency of the design features. Evaluations via panel methods are also performed, and wind tunnel test data from a 20:1 low speed model is also presented. The calculations and tunnel data indicate that the advantages of the D8 configuration would lead to a very large 33% fuel burn reduction compared to an optimized conventional transport configuration with the same materials and engine technology.