Rejish Jesudasan

1. Introduction Shape optimisation of aircraft wings, turbomachinery blades, or automotive ducts has become a widely used technique over recent decades. While early studies in shape optimisation used gradient-free approaches, more recent work in the past decade has firmly established gradient-based approaches as the method of choice given their superior efficiency for the large number of design variables that are often required [1].

1. Introduction Aviation industry is entering a new era with great interest in developing revolutionary aircraft technology to meet the strict regulations for reducing CO 2 and NO x emissions by 2050 [1]. This opens up opportunities to look back at aircraft concepts that showed great potential in terms of efficiency and were abandoned due to lack of technological progress.