Streamlining — Form Drag vs Friction Drag Three shapes in the same wind. The round rod (top) can’t keep the flow attached round its back; it drags a wide, dark wake and most of its drag is that suction — form drag. The teardrop strut (middle) is the same thickness but eases the flow back together, so its wake is a sliver and its drag is mostly skin friction. The strut’s total drag equals that of a bare wire one-tenth its thickness (bottom). The journey: total drag = pressure over the body + shear over the body. Delay separation and the pressure term collapses — the whole point of a fairing. The bars on the right split each body’s drag into form and friction.