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SJessett created the topic: Sideslip
During a sideslip, why does the relative airflow come from the direction of slip, rather than from the direction opposite to motion? (on page 11.5 CPL Aerodynamics)
It does come from opposite the direction of motion, but the direction of motion is both forward and sidewards. The diagram on that page is two dimensional of course so in Fig 11.12, the arrows representing the relative airflow should be imagined to be coming, not only from the side but also from ahead of the aircraft.
If you were flying in an open cockpit such as a Tiger Moth, you would feel the airflow on your face coming from in front of you and below you and also from the side. That's opposite the direction of motion.