Definition
In an aircraft engine, aspiration refers to the method by which air is drawn into the cylinders for combustion. A naturally aspirated engine relies on atmospheric pressure alone to push air into the cylinders during the intake stroke, while a turbocharged or supercharged engine forces air in under higher pressure.
Plain English
How the engine gets air into its cylinders so it can burn fuel. Either the engine simply breathes in air on its own, or a pump is used to push extra air in.
Context Anchor
Seen in fuel-system and engine discussions, especially when explaining how air and fuel get into a piston engine before burning.
Derivation
From the Latin 'aspirare', meaning 'to breathe upon' or 'to breathe in'. The aviation use keeps that original sense: the engine is breathing in air, and the question is whether it breathes on its own or with help.
Why Pilots Care
Naturally aspirated engines lose power as altitude increases because thinner air reduces the amount of oxygen available for combustion.
Analogy
Aspiration is like taking a breath before speaking or running. The engine needs its own breath of air before it can burn fuel and make power.
Grounding Statement
When the piston moves down, air is drawn into the cylinder; that drawing-in action is aspiration.
Intuition Check
Do not read aspiration here as a medical term about accidentally inhaling liquid. In this fuel and engine context, it means the engine drawing in air, or an air-and-fuel mixture, for burning.
Example Sentence 1
The Cessna 172 has a naturally aspirated engine, so its climb performance falls off noticeably above 8,000 feet.
Example Sentence 2
At high density altitudes, reduced aspiration limits the power output of a naturally aspirated engine.