CO J = 2–1 intensity weighted velocity map of the blue shifted wind from HD 163296. The purple circles show the 2012 positions of the knots, the blue and red contours show the HCO⁺J = 4–3 emission, and the two dark cyan circles in the bottom left corner show the synthesized beams of the observations, as in Fig. 2. The blue and red dashed lines delineate the double corkscrew described in the text.