It's long been accepted that the smoother the surface, the lower the aerodynamic drag. That turns out not always to be the case. https://www.wired.com/story/a-fundamental-principle-of-aeronautical-engineering-has-been-overturned/?utm_brand=wired-science&utm_campaign=aud-dev&utm_medium=social&utm_social-type=owned&utm_source=voante-science