Analysis of the Effect of Cruise Speed on Fuel Efficiency and Cost for a Truss-Braced Wing Concept

Abstract

Modern day commercial aviation has a strong incentive to pursue the design of advanced aircraft concepts, motivated both by growing environmental concerns and more challenging airline economics. In this regard, the Truss-Braced Wing concept has significant potential to achieve appreciable improvements with regard to fuel efficiency, emissions, noise, and operating cost, but without entailing as much technological risk and uncertainty as more exotic designs. The performance advantage of a Truss-Braced Wing design over a conventional cantilever wing design stems from the fact that the truss allows a wing of much higher aspect ratio, and thus higher aerodynamic efficiency, to be achieved without a correspondingly high weight penalty. In a previous investigation by the authors, a Multidisciplinary Design Optimization was performed to identify the most promising TrussBraced Wing architecture from among candidates that included a Strut-Braced Wing design in addition to one-jury and two-jury Truss-Braced Wing designs. The insights gained from that investigation are built on in this paper, which analyzes the mission-level impact of the aircraft’s cruise speed. A lower cruise speed may allow a reduction in mission fuel consumption, but this is not the only concern as airline operators must also consider the aircraft utilization. In this work therefore, consideration is given to both mission block fuel and the operating cost, and both fuel-optimal and cost-optimal designs are arrived at for a range of potential cruise speeds. The fuel and cost-optimal designs for a single aisle N+3 Truss-Braced Wing concept at the same Mach numbers were contrasted, and impact of cruise speed on operating costs was quantified.