Pratt & Whitney fast-tracks XA103 adaptive cycle engine for 6th generation fighter jets
September 24, 2025
Pratt & Whitney is racing to develop its XA103 adaptive-cycle engine, set to power the fighter jets of the future. Using cutting-edge digital design tools, the company has compressed development timelines to stay ahead in next-generation propulsion.
The XA103 sits at the heart of the Air Force’s Next Generation Adaptive Propulsion (NGAP) programme, which seeks to deliver engines that can dynamically shift between maximum thrust and fuel-efficient cruising.
Applications could include the US Air Force’s Boeing-built Next Generation Air Dominance (NGAD) fighter, although the propulsion for the aircraft has not yet been decided.
Pratt & Whitney says its model-based digital design environment is already cutting development timelines, lowering costs and enabling faster integration across its network of more than 100 suppliers.
Pratt & Whitney XA103 uses digital design to fast-track development for the NGAP programme
Pratt & Whitney’s XA103 team has doubled the pace at which it delivers technical data packages by distributing advanced digital models to suppliers and engineers. These packages allow rapid design iteration, easier system integration, better forecasting for manufacturing resources and faster model testing.
Jill Albertelli, president of Pratt & Whitney’s Military Engines business, said digital engineering is central to the programme’s progress: “Model-based design ties all the puzzle pieces together, fostering constant collaboration, and we are applying these learnings across our engine portfolio.”
The company has invested more than $30 million of its own funds this year to strengthen the model-based environment supporting XA103 development.
More than 1,000 engineers and over 100 domestic suppliers are engaged in the effort, working toward the next milestone – an Assembly Readiness Review – before the prototype build and ground testing later this decade.
What makes an adaptive cycle engine different from traditional fighter jet propulsion?
Traditional jet engines operate on a fixed cycle, optimised either for fuel efficiency in cruise or for maximum thrust in combat.
Adaptive-cycle engines introduce a third stream of airflow that can be opened or closed depending on mission demands. In simple terms, they can “adapt” in real time, switching between modes to prioritise efficiency or raw power.
Unlike conventional fixed-cycle engines, adaptive engines can switch between operating modes depending on mission demands. They can prioritise fuel efficiency for longer range or shift to maximum thrust for combat manoeuvres.
The XA103’s adaptive features are also designed to improve survivability and provide advanced power and thermal management. That means the engine can handle the extreme heat loads generated by 6th-generation sensors, avionics and even potential directed-energy weapons.
This step change in propulsion technology marks a leap beyond fourth- and fifth-generation engines like the F119 that powers the F-22 Raptor and the F135 used in the F-35 Lightning II.
Pratt & Whitney is leveraging nearly two million flight hours of experience from those engines to inform XA103. By combining adaptive-cycle flexibility with vast digital modelling, the company says it can provide the “persistence, range and power” NGAD will demand.
Competing designs from Pratt & Whitney XA103 and GE Aerospace XA102 under NGAP
Pratt & Whitney’s XA103 is not alone. It is competing head-to-head with GE Aerospace’s XA102 under the NGAP programme. Both engines aim to become the propulsion system of choice for NGAD.
Air dominance has always hinged on propulsion. The F-22‘s twin Pratt & Whitney F119 engines gave it unmatched agility and supercruise when it debuted in 2005.
The F-35‘s single F135 engine, meanwhile, drew heavily on F119 data, but its cooling limitations have become a bottleneck as new sensors and weapons are added.
The NGAP effort builds on earlier research under the Adaptive Engine Transition Program (AETP), where GE’s XA100 and Pratt & Whitney’s XA101 were evaluated as potential upgrades for the F-35. Those engines demonstrated the benefits of variable-cycle technology but were sized for the Joint Strike Fighter.
NGAP, by contrast, is tailored specifically to NGAD’s requirements, which include sustained supersonic cruise, longer combat radius and the ability to support power-hungry future weapons.
Boeing’s NGAD fighter F-47 to replace the F-22 Raptor
In March 2025, the Air Force awarded Boeing the contract to develop the NGAD platform, officially designated the F-47. Billed as the world’s first 6th-generation fighter, the F-47 is expected to deliver unmatched stealth, supersonic performance, range and adaptability.
President Donald Trump hailed the aircraft as “the crown jewel in the Next Generation Air Dominance Family of Systems”, while Air Force Chief of Staff Gen. David Allvin stressed that it would ensure US dominance in contested skies for decades.
The F-47 is designed not just as a single aircraft but as part of a broader NGAD “family of systems”. These include Collaborative Combat Aircraft (CCA), autonomous or semi-autonomous drones flying as “loyal wingmen” and advanced command-and-control networks.
Such integration requires engines like the XA103 to deliver not only thrust but also electrical power and cooling capacity for multiple systems operating in tandem.
NGAD: America’s 6th-generation fighter jet and more
NGAD is not just another fighter jet. It is a “family of systems” centred on a 6th-generation aircraft, recently designated the F-47 after Boeing won the prime contract, that will fly alongside autonomous wingmen, or Collaborative Combat Aircraft (CCA).
The F-47 is designed to go where the F-22 cannot: deep into highly contested airspace, facing advanced Chinese and Russian air defences.
According to the Air Force, the NGAD fighter will feature extreme stealth, sustained supersonic cruise, long range, advanced sensors, and modular systems that can be upgraded rapidly. Its engines will be different in size from AETP prototypes built for the F-35, but much of the adaptive technology will “port over” to NGAP designs like the XA103.
Why propulsion is central to sustaining US air dominance in contested environments
The Air Force’s current air superiority fighter, the Lockheed Martin F-22 Raptor, entered service in 2005 and is now showing its age against rapidly advancing Chinese and Russian defences. With a combat radius of 590 nautical miles, the Raptor relies heavily on vulnerable aerial tankers.
NGAD is designed to overcome those limitations with extended range, greater payload, improved survivability and crewed-uncrewed teaming. Achieving those attributes hinges on propulsion breakthroughs. Engines like the XA103 must combine efficiency with power while managing heat and generating electricity for next-gen sensors and weapons.
A look back at how NGAD evolved from early studies to the current 6th-generation F-47
The path to NGAD began with Pentagon studies in the mid-2010s that found traditional dominance was no longer affordable in anti-access environments. Instead, the Air Force envisioned a “family of systems” with manned and unmanned aircraft, long-range sensors and advanced command networks.
By 2020, the Air Force had flown an NGAD demonstrator. Over the next five years, experimental X-planes developed with DARPA laid the foundation for 6th-generation capabilities.
Boeing, Lockheed Martin and Northrop Grumman all participated, though Northrop ultimately withdrew from the competition.
Congress has since appropriated more than $8 billion for NGAD technologies. The Air Force plans to buy more than 185 F-47s, each with a combat radius of over 1,000 nautical miles and the ability to fly faster than Mach 2.
The Congressional Budget Office has estimated that NGAD aircraft could cost up to $300 million apiece – three times an F-35 – with propulsion a major driver of expense. Pratt & Whitney’s push to cut costs through digital engineering is as much about politics as it is about technology.
The F-35 programme became the most expensive weapons project in Pentagon history, in part due to propulsion integration issues. The Air Force is determined to avoid similar pitfalls by keeping NGAP on track and competitive.
International competition with Europe and Japan on 6th-generation fighter programmes
The US is not alone in pursuing 6th-generation air dominance and propulsion. Europe’s Future Combat Air System (FCAS), led by France, Germany and Spain, and the Global Combat Air Programme (GCAP), backed by the UK, Italy and Japan, are developing their own next-generation fighters, and are also investing in adaptive-cycle engines.
The US, however, is furthest along, with XA102 and XA103 expected to deliver the first flight-ready adaptive engines for operational fighters.
Meanwhile, the US Navy is working on its F/A-XX programme.
These parallel efforts underline why propulsion breakthroughs like NGAP are crucial: the ability to adapt engines in real time could provide the decisive edge in future conflicts.
The road ahead for Pratt &Whitney XA103 and NGAD propulsion
Pratt & Whitney has completed both the preliminary and detailed design reviews for the XA103, with the next major step being prototype assembly and testing in the late 2020s. GE’s XA102 will follow a similar timeline, with the Air Force likely choosing one design for production.
Whoever wins, adaptive propulsion will underpin the F-47’s ability to project power over vast distances, support energy-hungry systems and maintain US air superiority in contested skies.
For Pratt & Whitney, the XA103 is not only about building an engine but about shaping the future of American air power.
