The F-35 Joint Program Office expects a modernized propulsion system for the Joint Strike Fighter will take between five to seven years to develop, a JPO spokesman told Inside Defense , a timeline that would see a new engine for the Lightning II by 2031 as the military services stand poised to choose an upgrade for the fighter's powerplant. The timeline was confirmed by JPO spokesman Chief Petty Officer Matthew Olay in response to questions about a pre-solicitation notice released...