A discussion on benchmarking unconventional configurations with conventional aircraft: the box-wing study case

This article is intended to introduce an alternative approach to comparative analyses between innovative aeronautical technologies and established state-of-the-art references. Commonly, the tendency is to use a ‘like-for-like’ comparative approach with respect to current technologies -defined as reference benchmarks- that is, to evaluate the possible incremental improvements that can be achieved by introducing a specific technological innovation. However, when innovations that potentially introduce step improvements or new functions compared to the state of the art are evaluated, typically referred to as ‘breakthrough’, this approach may not be the most formally sound one, and it may introduce bias and misjudgements. In the field of aircraft design, using the same top-level requirements and figures of merit as those used for conventional aircraft to initialise and steer the design of unconventional configurations, could undermine the exploitation of their operating and functional potential. The soundness of the comparative approach is of paramount importance, especially in the very early stages of the development of disruptive technologies and unconventional aircraft configurations. In this paper, with the supporting example of the application of the box-wing configuration to medium-range transport aircraft, a general discussion is offered on the necessity of leaving aside the ‘like-for-like’ benchmark approach when investigating the potential of disruptive aircraft innovations. This argumentation does not only refer to the case study proposed as an example, but is generally extendable to aeronautical innovations that may introduce operating and functional novelties compared to current technologies.