Aeronautics faces new and increased challenges in the 21st century. These include climate change, long-term fuel supply, traffic congestion, and noise pollution. Radical technological steps will be demanded of the industry in order to maintain a sustainable transportation system.

In setting out its ideas for a Sonic Cruiser, Boeing has recently acknowledged that there is a need to look beyond the high-aspect-ratio wing with separate fuselage and podded engine configuration, which it pioneered at the start of the Jet era.

This paper sets out the case for the broad delta including its advantages as a basis for achieving higher transonic cruising speeds, with very long range and large payloads, while providing progressive and significantly improved environmental impact. The work is based on concept designs drawing on flight and weight data from the Vulcan bomber and the Concorde aircraft – both pioneering designs, by no means at the end of their technical potential.

A broad delta is taken to mean an aircraft of aspect ratio in the range 2 to 4. Not only does such a planform have application to many sizes of airliner, cruising at various high subsonic speeds, but also it is inherently well suited to later application of laminar flow. Wing surfaces undisturbed by flaps and slots and unhampered by very thick wing skins, together with favourable engine inlet locations, could be a basis for improved overall aerodynamic efficiency.

Airliners designed for operation in the region of Mach 1 are likely to pose more difficult problems for the aerodynamicist. Designs must cater for both cruise and maximum design speeds, which may encompass the Mach 1 condition.