Definition
The single combined velocity that results when two or more separate velocities act on the same object at the same time. In the context of P-factor, it is the combined velocity seen by a propeller blade, made up of the blade's rotational speed plus the aircraft's forward airspeed.
Plain English
When something is moving in more than one way at once, the resultant velocity is the overall speed and direction you get when you add those motions together.
Context Anchor
Seen in discussions of P-factor and asymmetric propeller loading, especially when explaining why one side of the propeller can produce more thrust than the other.
Derivation
From Latin 'resultare' meaning 'to spring back' or 'to follow as a consequence.' In physics it came to mean the single value that 'results' from combining several. That fits the aviation use: one combined velocity that follows from adding the separate ones together.
Why Pilots Care
It determines the true angle of attack on each propeller blade, explaining why the descending blade produces more thrust and creates left yaw.
Grounding Statement
Picture a propeller blade swinging downward while the aircraft is also moving forward. The blade's actual path through the air is the combination of those two motions, and its speed along that path is the resultant velocity.
Intuition Check
Do not read resultant velocity as just airspeed or just propeller speed. It means the combined speed and direction the propeller blade actually feels.
Example Sentence 1
At a high angle of attack, the descending blade has a greater resultant velocity than the ascending blade, which is why the aircraft yaws left under high power.
Example Sentence 2
The pilot compensates for the yaw created by uneven resultant velocities across the propeller disk with right rudder.