Definition
The high-velocity column of air pushed rearward by a propeller, which strikes the wing and tail surfaces behind it at a higher speed than the surrounding free airstream. On a multi-engine airplane, the wing area immersed in this faster-moving air produces more lift than the wing area outside it, which becomes important when one engine fails and only one wing is still receiving the accelerated flow.
Plain English
The blast of air thrown back by a spinning propeller. It hits the wing right behind the engine and makes that part of the wing produce more lift than the rest of the wing.
Context Anchor
Seen in multiengine training when explaining why an airplane becomes harder to control after one engine fails.
Derivation
Slipstream means the stream of air slipping past a moving object. Accelerated means sped up. So an accelerated slipstream is simply the airflow that has been sped up — in this case, by being pulled through the propeller disc.
Why Pilots Care
The extra airflow over the vertical stabilizer improves rudder effectiveness, which directly lowers VMC and affects how much rudder is needed to maintain directional control after an engine failure.
Analogy
Think of a fan blowing across only one side of a light object. The side in the fan’s airflow behaves differently from the side without that airflow.
Grounding Statement
Picture the operating propeller throwing fast air over one wing while the other wing no longer has that extra airflow.
Intuition Check
Do not read “slipstream” as just air sliding past the whole airplane. Here it means the faster air driven backward by a propeller. “Accelerated” does not mean the airplane itself is speeding up; it means the air behind the propeller is moving faster.
Example Sentence 1
With the left engine failed, the right engine's accelerated slipstream continued to produce lift on the right wing, rolling the airplane to the left.
Example Sentence 2
The pilot noted that at lower airspeeds the accelerated slipstream effect diminished, requiring greater rudder deflection to counteract yaw.