The Adaptive Versatile Engine Technology (ADVENT) program was an aircraft engine development program run by the United States Air Force with the goal of developing an efficient adaptive cycle, or variable cycle engine for next generation military aircraft; initial demonstrators were expected to be in the 20,000 lbf (89 kN) thrust class.
In 2012 the program was succeeded by the Adaptive Engine Technology Demonstrator (AETD) program; work continued in 2016 under the Adaptive Engine Transition Program (AETP), which focused on developing and testing a 45,000 lbf (200 kN) thrust class adaptive cycle engine for potential F-35 re-engining. A subsequent Next Generation Adaptive Propulsion (NGAP) program was also launched for a related 35,000–40,000 lbf (156–178 kN) thrust class engine to power the Next Generation Air Dominance crewed fighter aircraft.