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Aviation glossary

Compression Ratio

What is compression ratio?

Illustration related to compression ratio
Image: Marc Lacoste — CC BY-SA 4.0, via Wikimedia Commons

Compression ratio describes how much the air inside an engine is squeezed: in a piston engine it compares cylinder volume at its largest versus its smallest, and in a turbine engine it compares the air pressure at the compressor's outlet to its inlet. A higher ratio generally means more efficient combustion.

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