U.S. Navy Carves Independent Path For Future Fighter Design

The new carrier-based fighter sought by the U.S. Navy will be affordable, versatile and independent of such Air Force-funded technologies as an adaptive-cycle turbofan engine, yet it still faces fiscal pressures that could delay fielding, a top Navy official tells Aviation Week in a rare, exclusive interview about the secretive project.

Coming during a source selection among Boeing, Lockheed Martin and Northrop Grumman for the F/A-XX contract, the comments by Rear Adm. Michael Donnelly, director of the air warfare division in the Office of the Chief of Naval Operations, further distance the replacement for the Boeing F/A-18E/F and EA-18G from the Air Force’s paused acquisition process for the Next-Generation Air Dominance (NGAD) platform.

The Navy previously confirmed that the F/A-XX required a different airframe than the Air Force’s next fighter, ending speculation about a multiservice program. But naval officials never clarified whether the F/A-XX would share a propulsion system with the NGAD platform. The service once appeared interested in adaptive-cycle technology, participating in the Air Force’s early development work and investing in its own Variable-Cycle Advanced Technology program.

• U.S. Navy carves independent path for future fighter design
• F/A-XX program avoids adaptive engine technology
• Design focuses on strike mission with multirole flexibility

In the past decade, however, propulsion plans for the Air Force and Navy have diverged, Donnelly says. The Air Force continues to develop Next-​Generation Adaptive Propulsion (NGAP), the only one of five new technologies confirmed to be funded by the NGAD program. But the industry proposals submitted for the F/A-XX contract are based on older engines that lack the variable bypass flow of adaptive engines.

“We’re looking at more of a derivative-type engine solution,” Donnelly says. “That’s just one example where we probably are different in many ways from the Air Force. In totality, they are two unique programs from an acquisition point of view and also going forward, so we’re relatively independent of each other at this point.”

The Navy’s approach leaves the Air Force’s NGAD platform as the only known potential customer for NGAP engine technology. The Air Force alone has spent more than $4 billion since 2006 to prepare adaptive cycle engines to power future long-range fighters, promising a generational leap in fuel efficiency without compromising acceleration performance. But the Defense Department rejected a proposal in 2023 to reengine the Lockheed Martin F-35 with the GE Aerospace XA100 or Pratt & Whitney XA101 adaptive turbofans. The NGAP program now is preparing the GE XA102 and Pratt XA103 engines as candidates for the NGAD platform.

The Navy’s independent path could help shield the F/A-XX program from the impact of any decisions about the Air Force’s next fighter.

This summer, the Air Force paused the source selection process to review the relevance of the costs, threats and requirements. On Nov. 1, Air Force Secretary Frank Kendall affirmed that the review is still in progress, saying the original technology for the NGAD platform is unaffordable without major changes. Kendall previously estimated the new fighters would cost hundreds of millions each. In September, he called for a reimagined aircraft design that would cost less than a Lockheed Martin F-35A, which is currently about $95 million.

By contrast, Navy officials remain confident in their original assumptions about the suitability and affordability of the F/A-XX fighter. The Navy started working on plans for a new fighter several years before the Air Force. The first market survey released to industry for F/A-XX concepts came out in 2012. A Milestone B decision to launch an engineering and manufacturing development stage remains on track for the end of fiscal 2025, Donnelly says.

“We have to have an affordable platform to make it relevant to our force structure and force design, so we’ve got that in mind,” he says. “We think we’ve got an affordable solution that supports our force structure of the future.”

The Air Force put the NGAD platform on pause after the mandatory pre-Milestone B review, but the Navy harbors no second thoughts about the performance requirements for the F/A-XX.

“We feel really good through the concept development that we’ve got the right bracket for those requirements and the attributes we need to deliver the capability,” Donnelly says. “We’ll continue to look at that as we go through the next phases of the acquisition process and make smart decisions.”

The NGAD platform and F/A-XX are on separate paths but face similar fiscal pressures. For the Air Force, rising costs to field a new intercontinental ballistic missile are putting a pinch on other priorities, including ramping up Northrop Grumman B-21 production, launching development of new tankers and the costs of the NGAD platform. The Navy, meanwhile, is simultaneously developing a nuclear submarine, a new destroyer and a next-generation fighter while dealing with capacity shortfalls within its current fleet.

Fiscal pressures already risk slowing the pace of F/A-XX development. The Navy’s fiscal 2025 request slashed planned spending on the new fighter 67% between fiscal 2025 and 2028, resulting in a projected budget of $3.3 billion instead of $10.3 billion.

Senate appropriators voted to restore about $450 million to the fiscal 2025 budget—but even if passed in a final spending bill, the change would represent a 59% cut compared with last year’s spending plan. The fiscal 2025 defense appropriations bill remains in limbo in the wake of the U.S. presidential election on Nov. 5.

“Any time we are causing budget perturbations,” Donnelly explains, “we’ve got to consider what that does to schedule.”

Without revealing details about the impact of the proposed spending cuts, Donnelly says the Navy in general can decide to accept delays based on changes in threat evaluations and financial resources. Those decisions could be reversed in future budget plans.

“But obviously the later we wait, the more challenging it is to continue to pull that [schedule to the] left,” he says, referring to the delivery date for the F/A-XX.

The Navy traditionally divides its fighters into carrier air wings between  two primary missions: air-to-surface and air-to-air. The former, also referred to as long-range strike and sea control, is  performed primarily by the Lockheed Martin F-35C. The F/A-XX, however, is slated to replace the F/A-18E/F first. The latter entered service with the long-range strike role but switched to air superiority, also known as fleet defense, as the F-35C arrived and the F/A-18C/D retired.

With the Navy expected to select an F/A-XX design next year, officials are looking for another fighter that is optimized for air-to-surface strike roles but still capable of fleet defense.

“The central focus of its design is to be able to conduct long-range fires, sea control and those types of missions,” Donnelly says. “Inherent in its design is its ability to participate in fleet defense.”

That means a future carrier air wing of F-35C and F/A-XX fighters will be composed solely of strike mission-optimized, multirole aircraft, a makeup that Donnelly says will be a strength over separate mission-specific fleets.

“We can’t afford to have a break-glass capability or a really unique single-mission or single-phase-of-operation focus,” he says.

The Navy’s multirole fleet strategy still draws critics. The Navy retired the 2,380-nm range Grumman A-6E Intruder in 1997 without a direct replacement, having canceled the General Dynamics-McDonnell Douglas A-12 Avenger II six years earlier. Despite its “long-range” description, it is not clear if the F/A-XX will have the range for the A-6E’s deep-strike capability, leaving a possible gap in the carrier’s power projection, says Jerry Hendrix, a retired Navy captain and senior fellow at the Sagamore Institute.

“My concern is the continued pursuit of a jack-of-all-trades, master of none,” Hendrix tells Aviation Week. “I think that has diminished the effectiveness of the carrier air wing, and continuing to pursue this approach suggests a growing weakness in the carrier air wing going forward.”

Early concepts of the F/A-XX released by contractors pointed to an optionally crewed platform, but the Navy requirements settled on a different approach. The aircraft will be designed to be controlled by a human, but the onboard systems will be able to work collaboratively with uncrewed partners, starting with the Boeing MQ-25 Stingray.

“F/A-XX is intended to be a manned platform,” Donnelly says, noting that the “F/A-XX will really be our pivot point from a manned air wing to a hybrid future, with a manned-unmanned air wing.”