Definition
The mixture of vaporized fuel and air drawn into an engine cylinder during the intake stroke, which is then compressed and ignited to produce power. The term refers specifically to the combined fuel-and-air content delivered to the cylinder for one combustion cycle.
Plain English
The blend of fuel and air that gets pulled into the cylinder, ready to be squeezed and lit so the engine can fire.
Context Anchor
Seen in piston-engine combustion discussions, especially when describing how the engine takes in mixture, burns it, and turns that burning into power.
Derivation
Charge' here comes from the older sense of 'a load' or 'an amount put in' — the same sense used when 'charging' a firearm with powder. So a fuel-air charge is simply the load of fuel and air put into the cylinder for each firing.
Why Pilots Care
The correct ratio in the fuel-air charge determines engine power, smoothness, and safety; wrong mixtures can cause overheating or damage.
Grounding Statement
For each power-producing cycle, the engine receives a fresh fuel-air charge, ignites it, and uses the expanding gases to make power.
Intuition Check
“Charge” does not mean an electrical charge here. It means the amount of fuel-and-air mixture loaded into the engine to be burned.
Example Sentence 1
On the intake stroke, the piston moves down and the fuel-air charge flows into the cylinder through the open intake valve.
Example Sentence 2
The pilot adjusts the mixture control to keep the fuel-air charge at the right proportion for efficient combustion.