411 REFERENCE · Wikibooks
Jet Propulsion/Bypass ratio
Reference material by Wikibooks contributors. This retains its source identity and is not 411 news reporting.
The ratio of turbofan bypass mass flow to the engine core mass flow in a turbofan engine.
As the name suggests, this is the ratio of the air which bypasses the engine core and flows round the outside of the engine and exits via the nozzle. In a modern, high bypass ratio engine, bypass ratios can be as high as 85%.