F-55: Trump’s Vision Meets Air Force Reality

In the high-stakes realm of military aviation, where every design choice carries colossal implications for national security and taxpayers alike, a recent pronouncement from former President Donald Trump sent ripples of bemusement and outright disbelief through the defense establishment.

On May 15, 2025, during a business meeting in Doha with the chief executives of Boeing and GE Aerospace, Trump declared plans for a twin-engine variant of the F-35 Joint Strike Fighter — a hypothetical “F-55” — contingent, he noted, on the price being right.

It was a statement that, for many, underscored a familiar disconnect between grand political vision and the stark realities of aerospace engineering.

The immediate reaction from within the U.S. Air Force was, to put it mildly, incredulous.

Air Force Secretary Frank Kendall was quick to dismiss the notion, telling Breaking Defense, “It’s an option that was never presented and that we never considered, to my knowledge.”

Kendall’s understated dismissal speaks volumes: the idea of grafting a second engine onto the F-35 isn’t just an upgrade; it’s a fundamental reimagining, a complete overhaul that would not only balloon the Air Force’s budget but also derail meticulously planned strategic initiatives.

Trump’s rationale for this twin-engine preference was straightforward: a disdain for single-engine jets, advocating for the redundancy and perceived safety of multiple powerplants.

While the appeal of a backup engine is intuitively understandable, particularly in the unforgiving skies of combat, the engineering complexities and strategic implications of such a modification to the F-35 are anything but simple.

Experts quickly lined up to underscore the sheer impracticality of the concept.

Richard Aboulafia, an aerospace analyst with AeroDynamic Advisory, bluntly labeled the F-55 as “not feasible.”

His reasoning is rooted in the inescapable physics of aircraft design: a twin-engine F-35 would necessitate such a radical redesign that it would effectively become a new aircraft, indistinguishable in size and cost from the F-47 – the very sixth-generation fighter jet currently under development.

J.J. Gertler, a senior analyst with the Teal Group, offered an even more vivid analogy, explaining that re-engineering the F-35 for two engines would create an entirely new machine, much like declaring “a mansion is an upgraded bungalow.”

The current F-35 airframe simply lacks the inherent space and structural integrity for a second engine.

To accommodate double the thrust, the entire airframe would need to be bigger and stronger, requiring a complete rethinking of the wing, tail, and air intakes.

Perhaps the most critical hurdle, and one that highlights the fundamental misunderstanding inherent in the F-55 proposal, is the F-35’s defining characteristic: its stealth.

The aircraft is meticulously designed to evade detection, a feat achieved through precise shaping, materials, and internal componentry.

Introducing a second engine and the requisite structural alterations would demand an entirely new set of complex calculations to ensure that the stealth signature remains intact.

This isn’t merely adding parts; it’s recalculating an intricate balance of aerodynamics, heat signatures, and radar cross-section, a project so monumental it borders on the absurd when considering the existing F-35 platform.

The irony of Trump’s F-55 musings is particularly sharp given the Air Force’s actual, and incredibly ambitious, plans for its future air superiority.

Even as Trump spoke, the F-47 Program, a sixth-generation fighter jet developed by Boeing under the Next-Generation Air Dominance (NGAD) initiative, had just been announced.

This is the true successor to the F-35 and other fifth-generation jets, a project born of a recognized strategic imperative to maintain air superiority against rapidly advancing adversaries like China.

The F-47 is designed from the ground up for improved capabilities and upgraded technology, with a single unit estimated to cost around $300 million and an Engineering and Manufacturing Development (EMD) contract valued at a staggering $20 billion.

This is where the Air Force’s focus, resources, and strategic foresight are genuinely directed.

The Pentagon’s decision to delay the U.S. Navy’s F/A-XX program to prioritize the F-47 underscores the critical importance placed on this next-generation capability.

Meanwhile, the existing F-35 fleet, still one of the most advanced fighter jets in the world, is not being ignored.

The Air Force is actively pursuing upgrades, focusing on enhancing engine power and adding new capabilities to its current F-35s.

Lockheed Martin CEO Jim Taiclet has even floated the idea of a “fifth-gen plus” version, designed to deliver 80% of the F-47’s capabilities without requiring the acquisition of an entirely new airframe.

Noticeably absent from any of these upgrade discussions, however, is any mention of adding a second engine.

Ultimately, the consensus among defense experts is clear: Trump’s vision of a twin-engine F-35, or F-55, will almost certainly remain confined to the realm of political rhetoric.

The immense technical hurdles, the prohibitive costs, and the Air Force’s established, forward-looking strategic programs — particularly the F-47 — render the concept a non-starter.

In the intricate dance of modern military aviation, engineering reality and strategic necessity continue to hold far more sway than even the most powerful political pronouncements.