bypass ratio

noun

: the ratio in an aircraft engine (such as a turbofan) of the amount of airflow that is bypassed around the engine's core to the amount that passes through the core

The bypass ratio is the amount of the air that passes through the fan—known as "cold thrust"—compared with the amount that passes through the core, or combustion chamber—"hot thrust." Typically, the higher an engine's bypass ratio, the better its fuel efficiency.

—David Noland, Air & Space Smithsonian, February/March 2008

Word History

First Known Use

1961, in the meaning defined above

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