In a surprise development, President Donald Trump has said that he wants the United States to develop a twin-engine version of the F-35 Joint Strike Fighter, which he has named the F-55. Exactly how far such a concept has progressed, at this stage, is very much open to question, but it does raise some interesting questions about the futures of both the F-35 and the F-47, the Air Force’s next-generation crewed stealth fighter.
Trump was speaking in Qatar today, where he also visited U.S. forces stationed at Al Udeid Air Base. The U.S. president’s Qatar visit also coincided with Boeing securing its biggest-ever deal for widebody airliners, Qatar Airways ordering 160 777X and 787 jets worth $96 billion.
On the F-35, Trump said, “We’re doing an upgrade, a simple upgrade, but we’re also doing an F-55. I’m going to call it an F-55, and that’s going to be a substantial upgrade, but it’s going to be also with two engines because the F-35 has a single engine. I don’t like single engines.”
In response to our questions about the F-55, a Lockheed Martin spokesperson said: “We thank President Trump for his support of the F-35 and F-22 and will continue to work closely with the administration to realize its vision for air dominance.”
While we will return to the “simple upgrade” later, the big development here is the idea of a twin-engine F-35, something that has not been previously touted on a serious level since the Joint Strike Fighter program was launched.
While Trump pointed to the safety advantage of having two engines rather than one, this is just one aspect of such a configuration. Having more thrust would also increase performance, including potentially the aircraft’s speed and altitude, as well as boosting the aircraft’s payload. Range could be enhanced or reduced, depending on the design tweaks that would go along with such a configuration change.
Engine options for such an aircraft might well include those being developed under the Next Generation Adaptive Propulsion (NGAP) program, which has been focused primarily on developing new engines as part of the Next Generation Air Dominance (NGAD) initiative, leading to the new F-47 next-generation stealth fighter. There has long been speculation that NGAP might also feed into other advanced aviation programs. In January of this year, the Air Force increased the value of NGAP contracts with General Electric and Pratt & Whitney, giving them both a ceiling of $3.5 billion.
Previously, the Pentagon looked at the option of re-engining the F-35 as part of the Air Force’s Adaptive Engine Transition Program (AETP). In 2023, the Air Force announced its intention to cancel AETP in favor of upgrading the existing Pratt & Whitney F135 engine currently used on all variants of the F-35. Nevertheless, Congress subsequently authorized additional funding for AETP. Work on AETP has also been leveraged in the NGAP designs from General Electric and Pratt & Whitney, known as the XA102 and XA103, respectively. It’s also possible that such a change could incorporate existing engine core designs.
At the same time, a twin-engine F-35 would be heavier and more expensive, and it would bring with it an increased burden in terms of support and maintenance. Regardless, it will require an extensive redesign of the F-35 airframe and numerous subsystems to accomplish.
In the case of the short takeoff and vertical landing (STOVL) F-35B, there would appear to be no realistic option of creating an equivalent twin-engine version of the F-55.
On the other hand, there are some compelling arguments for a twin-engine aircraft in the class of the conventional takeoff and landing (CTOL) F-35A and the carrier-capable F-35C.
The Navy, in particular, would value the benefits that a twin-engine F-35 would bring, with these advantages becoming even more pronounced when operating from a carrier deck. Here, safety margins are even more critical, and the ability to carry a heavier payload is especially prized. Still, there have been no known major complaints about the F-35C’s single engine and no aircraft have been lost from carriers due to engine failures.
It’s notable that China’s J-35, which is a broad equivalent to the F-35, and which is frequently described as a ‘clone’ of the U.S.-designed jet, has featured twin engines from the outset. It, too, is intended for carrier operations.
Returning to the U.S. Navy, there is a possibility that Trump’s words today might reflect developments in the service’s F/A-XX sixth-generation stealth fighter program. Earlier this week, TWZ reported on how this program is still being reviewed by the Pentagon, the White House, and Congress.
This came after a published report that a contract award for F/A-XX, potentially worth hundreds of billions of dollars, could be delayed by as much as three years. There is also the possibility that this could lead to cancellation or further postponement.
Originally, Boeing, Lockheed Martin, and Northrop Grumman were all in the running to develop the F/A-XX. However, Lockheed Martin was reportedly eliminated from the competition in March of this year because its proposal “did not satisfy the service’s criteria,” according to Breaking Defense, whose story cited an unnamed source with knowledge of the program.
Could it be that Trump’s F-55 comments refer to a Lockheed Martin F/A-XX contender, either one that was eliminated previously, but which may now be back in the running, or potentially a new proposal from the same company, based on a reworked, twin-engine F-35C?
At the same time, a twin-engine, land-based F-55 could be of interest to the Air Force, which has, in the past, looked at fielding some kind of cheaper crewed fighter that could operate alongside the F-47. You can read our previous analysis of what a cheaper NGAD crewed stealth fighter might look like here.
Meanwhile, the U.S. Air Force is clearly struggling to afford the programs it already has on its books, with even the F-47 increasingly being seen, at least in some quarters, as a sacrifice against other urgent needs. Even with a larger budget, it would be a challenge for the service to procure the F-55 as well. This, again, might suggest that a twin-engine F-35 development would actually be a better fit for the Navy.
Export customers, however, might look very favorably at the advantages that a land-based F-55 would offer. Indeed, Trump raising the prospect of such a fighter while on a visit to the Gulf region may have been calculated to alert local interest.
In the past, both Saudi Arabia and the United Arab Emirates have been linked with possible F-35 deals, and Washington may be looking at pitching the F-55 as a program in which one or both of those countries could invest. Notably, Qatar and Saudi Arabia played significant roles in developing versions of the Advanced Eagle, which the U.S. Air Force is now benefiting from those investments with its F-15EX.
Back in April of this year, after Lockheed president and CEO Jim Taiclet described a potential upgrade for the F-35 that he claimed could deliver 80 percent of the F-47’s capability at half its cost, using technologies developed for the F-22 and the F-47. He termed it a “Ferrari” version of the F-35, and it may well be this that Trump referred to as “a super upgrade on the F-35.” You can read all about Lockheed’s pitch on this massively up-tuned F-35 concept in our previous report here.
As to Trump’s remarks about a more modestly upgraded F-35, this could refer to one of several efforts that we already know about. As well as the latest Block 4 version of the Joint Strike Fighter, which brings a raft of new capabilities, there has been talk about a further refined jet, which has been unofficially dubbed F-35X.
Trump’s address also made reference to another “super upgrade” for the F-22 stealth fighter.
“I think the most beautiful fighter jet in the world is the F-22, but we’re going to do an F-22 Super, and it’ll be a very modern version of the F-22 fighter jet,” Trump said.
This would seem to describe ongoing Air Force efforts to update at least a portion of the existing F-22 fleet until that aircraft is finally retired, potentially in the 2040s.
A number of new capabilities are now in the pipeline for the F-22, including a new Infrared Defensive System (IRDS), as well as other additional sensors and stealthy range-extending drop tanks.
On the F-22, Trump declared that it was “the most beautiful fighter jet in the world,” before bafflingly stating that he was “not a huge believer in stealth because stealth is basically a lot of the design and the shape … So you’re going to design an ugly plane for stealth reasons.” He then accused China of copying the F-22, before noting that “they won’t be able to copy our engines so quick.”
There is also the very real possibility, and even some would argue a probability, that, with the F-55, Trump was describing an altogether non-existent program.
There is a precedent for this, with his 2018 announcement about deliveries of “F-52 and F-35” fighters to Norway. While Norway does operate the F-35, the F-52 was likely an error based on the fact that Norway ordered 52 of the Joint Strike Fighters. This is just one of many examples of Trump apparently going off script, especially when it comes to combat aircraft, including his description of “invisible” stealth fighters.
Whether the F-55 is another case of Trump misspeaking or sharing his own ideas on the fly, or whether the White House is serious about a twin-engine F-35 development remains to be seen. TWZ has reached out to the Air Force and the Navy, with the hope of bringing some more clarity to these announcements.
Contact the author: thomas@thewarzone.com