What is spiraling slip-stream?

Spiraling slip-stream refers to the airflow created by a propeller as it rotates and generates thrust. This definition aligns with the correct option, which states that it is the propwash that curves towards the side of the more productive lift. As the propeller spins, it pulls air in and accelerates the airflow, creating a corkscrew-shaped pattern of airflow around the aircraft.

In a multi-engine aircraft, this phenomenon affects the lift and drag experienced by the wings, particularly during various flight maneuvers. The slipstream impacts the wing on the side of the rotating propeller more significantly, leading to enhanced aileron effectiveness on that side and affecting the aircraft's roll characteristics. This is crucial to understand during flight maneuvers, especially in configurations such as takeoff and climb.

The other options outlined do not accurately describe spiraling slip-stream. While prop wash does influence aileron effectiveness, the significant aspect of spiraling slip-stream is its curvature towards the side of greater lift. Additionally, the increase in drag on the wing does occur when discussing slipstream effects, but it is not the defining characteristic of spiraling slip-stream itself. Therefore, recognizing the relationship between the propwash and the wing performance on the more productive lift