The Pegasus engine was
developed from funding by the US Mutual Weapons
Development Team (MWDT) and without it there would be no
Harrier.
The front nozzles (cold)
direct fan bypass air through them at 800 knots and the rear
nozzles (hot) use pure exhaust that exits at 1,200
knots with the engine burning 250 lbs. per minute
of fuel during hover.