The Pentagon is continuing to invest in developing next-generation propulsion technologies, even as the future of a new sixth-generation fighter is in question.
The US Air Force (USAF) on 27 January announced billions of dollars in additional funding for the Next Generation Adaptive Propulsion (NGAP) programme, which aims to develop an engine solution for “future air-dominance platforms”. Those funds will be split between the USA’s two main suppliers of military turbofans – Pratt & Whitney and GE Aerospace.
Both engine makers scored increases to earlier NGAP contracts, with each company now eligible for up to $3.5 billion in research and development funding. The modifications add a potential $2.5 billion to the $975 million already earmarked for both firms by the USAF in 2022, when the service launched the NGAP effort.
Those initial contracts saw $4.8 billion in funding split equally across five companies: Boeing, GE, Lockheed Martin, Northrop Grumman and P&W. Now, it appears only the two traditional engine makers are advancing in the programme.
The latest awards are meant to support early development of a next-generation engine and associated technologies, according to the Pentagon, including initial design work, rig testing, prototype fabrication and eventual integration.
However, the air force may still be taking a wait-and-see approach when it comes to targeting its R&D dollars toward a new propulsion solution. The 27 January contract announcements note that none of the additional funds have yet been obligated to either GE Aerospace or Pratt & Whitney.
Speaking to FlightGlobal on background, officials from one of the manufacturers say they understand the NGAP programme to have a total of $3.5 billion available to invest in the prototyping phase, rather than $3.5 billion for each company, with that amount being divvied up at some later date, presumably based on the promise of each design.
USAF headquarters did not immediately respond to a request for clarification on the matter.
In whatever form it takes, the fresh investment in developing advanced propulsion systems comes as support within the USAF for a new sixth-generation fighter has waned somewhat.
Former air force secretary Frank Kendall paused development of the Next Generation Air Dominance (NGAD) programme in late 2024, citing concern about the cost per aircraft. Based on classified prototypes – believed though not confirmed to be developed by Boeing and Lockheed – Kendall estimated each NGAD fighter would cost the equivalent of multiple Lockheed F-35s.
The USAF currently pays around $80 million for a new example of the conventional take-off and landing F-35A variant.
Last December, prior to stepping down as USAF secretary ahead of Donald Trump’s inauguration, Kendall deferred a decision about whether to advance NGAD design proposals.
“Regardless of where NGAD is… we’ve continued to develop our NGAP solution,” said Chris Calio, chief executive of P&W parent company RTX, during a 28 January earnings call.
Though he declines to reveal details about the classified effort, Calio says P&W has been engaged in “rigorous testing” since the programme launched in 2022 and that company is “very pleased” with the latest round of financial support.
“This funding will help us continue to drive down any risks on the key requirements that are there,” Calio says. “We think we’re going to have a very competitive offering.”
Little is known about two prototype engines, other than their names. P&W has designated its NGAP prototype XA103, while GE dubs its design XA102. Both prototypes have passed key design reviews in the past year – GE’s XA102 in late 2023 and P&W’s XA103 in early 2024.
”We are excited about the progress our team continues to make on our XA102 adaptive cycle engine, a key component of the Next Generation Adaptive Propulsion programme,” GE Aerospace said on 28 January.
Both firms spent years developing the prototype adaptive engine for the F-35 under the separate Adaptive Engine Transition Program (AETP). Although the air force ultimately shelved those designs, both P&W and GE Aerospace say technology developed under the AETP will feed into NGAP work.
The companies describe adaptive engines as combining the performance of conventional fighter engines with the cruising fuel efficiency of commercial jet powerplants. GE claimed its XA100 offered 20% more thrust and 30% greater range compared to the F-35’s P&W F135 powerplant.
The USAF has since opted to pursue a core upgrade for the F-35’s F135 engine, rather than a replacement, with a goal of addressing a need for more onboard power generation.
Further decisions on both NGAP and NGAD will fall to the next air force secretary. President Donald Trump has nominated Troy Meink, a former Boeing KC-135 navigator and acquisitions official at the agency managing the USA’s spy satellites, to that role. The position requires Senate confirmation.
Story modified 29 January to reflect a clarification of NGAP funding amounts provided industry officials
