The Air Force is ditching its plans to develop a new engine for its F-35 fleet and will instead upgrade the existing Pratt & Whitney engines so the planes have enough power to use future weapons.

The F-35B Lightning II ... lift fan and pivoting engine nozzle to deliver vertical landing and short takeoff capability to expeditionary airfields. The F-35 will replace AV-8B Harrier IIs in ...

a single-engine supersonic stealth fighter jet made to dominate various combat operations. The F-35 is the world's most expensive weapons program, with an expected lifetime cost of more than $2 ...