Definition
A small reservoir built into the float bowl of a float-type aircraft carburetor that holds a reserve of fuel directly beneath the main discharge nozzle. When the throttle is opened suddenly, this reserve is drawn into the airstream to enrich the mixture momentarily, preventing the engine from stumbling before the main fuel system catches up with the increased airflow.
Plain English
A tiny pool of extra fuel kept ready inside the carburetor so that when you push the throttle in quickly, the engine gets the extra fuel it needs right away and doesn't hesitate.
Context Anchor
Seen in piston-engine fuel system discussions, especially when learning how a carburetor responds to quick throttle movement.
Derivation
Well' here uses its older sense of a small holding reservoir for liquid (the same sense as an inkwell). 'Acceleration' refers to the moment of throttle increase. Together: a small fuel reservoir that supports acceleration.
Why Pilots Care
Without it, rapid throttle movement can cause momentary power loss or engine stumble, which is unsafe during takeoff or go-arounds.
Grounding Statement
When the throttle opens quickly, the engine needs extra fuel for a moment; the acceleration well helps provide that fuel immediately.
Intuition Check
Do not read “well” as a hole in the ground or “acceleration” as aircraft speed alone. Here, an acceleration well is a small fuel supply inside the carburetor that helps the engine increase power smoothly.
Example Sentence 1
When the pilot advanced the throttle for the go-around, fuel from the acceleration well enriched the mixture and the engine responded smoothly.
Example Sentence 2
During the annual inspection the mechanic verified that the acceleration well in the carburetor was free of debris.