Describe slipstream in a propeller-driven airplane.

• A. Air from the propeller spirals around the aircraft, hits the left side of the rudder, and yaws the nose to the left.
• B. The airflow behind the aircraft causes lift to increase on the tail.
• C. It is the airflow that increases fuel efficiency by smoothing the wingtip vortices.
• D. It is the airflow above the wing that reduces drag.

Answer: (A)