The Harrier and the F-35B are masters of STOVL, but their mechanical systems for vertical lift are fundamentally different! ​The legendary Harrier relies on engineering simplicity: Its single main engine uses four rotating exhaust nozzles to vector all the hot thrust straight down. Pure, direct vectored thrust. ​The 5th-Gen F-35B Lightning II is far more complex, employing the powerful Rolls-Royce LiftSystem: ​A swiveling main nozzle (hot thrust). ​A separate, shaft-driven Lift Fan (massive cold