A waverier is a hypersonic aircraft design that improves its supersonic lift-to-drag ratio by producing a lifting surface built out of the shock waves being generated by its own flight, a technique known as compression lift. To date the only aircraft to use the technique is the Mach 3 supersonic XB-70 Valkyrie, which was waverider-like with its drooping wingtips. The waverider remains a well-studied design for high-speed aircraft in the Mach 5 and higher hypersonic regime, although no production design has used the concept to date. An effective Waverider craft requires an extremely characteristic shape, and this has made the concept a popular design for craft in science fiction[dubious – discuss].