Definition
The aerodynamic drag force exerted by the air on a body moving through it, acting opposite to the direction of motion. On a propeller, air resistance opposes the rotational motion of the blades and increases as blade angle, airspeed, or rotational speed increases.
Plain English
The pushback the air gives to anything moving through it. The faster something moves, or the more it pushes against the air, the more the air pushes back.
Context Anchor
Seen in constant-speed propeller discussions when explaining how blade angle changes affect engine load and RPM.
Derivation
Resistance comes from Latin words meaning “to stand against.” That fits the aviation meaning: the air is not just empty space; it “stands against” a moving wing, airplane, or propeller blade by pushing back on it.
Why Pilots Care
The propeller governor continuously adjusts blade pitch to overcome changes in air resistance and keep engine RPM constant.
Analogy
Think of sticking your hand out of a moving car. Held flat and edge-on, the air slides past easily. Turn your palm into the wind and you feel the air pushing hard against it. That push is air resistance.
Grounding Statement
Picture a propeller blade turning through the air: the more air it has to push, the more the air pushes back.
Intuition Check
Air resistance does not mean the air is “blocking” the airplane like a wall. It means the air creates a pushing-back force whenever something moves through it.
Example Sentence 1
As the pilot increased the propeller blade angle, air resistance on the blades rose and the engine had to produce more power to hold the selected RPM.
Example Sentence 2
During a climb the thinner air reduces resistance, so the propeller automatically increases pitch to maintain the selected RPM.