Lockheed Martin is proposing a “5+” version of the F-35, incorporating advanced engines, enhanced stealth capabilities, and modernized weaponry. Washington is studying this option.
Summary
Lockheed Martin is working on an improved version of the F-35 Lightning II, described as “fifth generation plus.” This version, for which there is still no official contract, would incorporate elements developed as part of US studies for a sixth-generation aircraft. The concept is based on three main areas: a modernized engine inspired by the AETP program, enhanced stealth to reduce radar and infrared signatures, and the integration of more powerful weapons. The U.S. Department of Defense has expressed strategic interest in this project, which would extend the competitiveness of the F-35 until the 2060s. This proposal is based on budgetary and industrial considerations: maintaining a modernized fleet while delaying a complete transition to a new generation, which would be more costly and risky. Lockheed Martin’s approach therefore aims to offer an intermediate, pragmatic, and technologically credible solution.
The concept of the “fifth generation plus” F-35
Lockheed Martin presents the “F-35 5+” version as a natural evolution of the current F-35 Lightning II. The aim is to introduce technologies derived from work on the future sixth generation program (Next Generation Air Dominance – NGAD). Rather than waiting for a new aircraft to become available around 2040, this version would improve the existing platform.
The F-35 is already at the heart of US and allied air power, with more than 1,000 aircraft delivered worldwide. Projections estimate a total of more than 3,000 aircraft by 2045. A major upgrade would extend the operational life beyond the 8,000 flight hours planned per airframe and maintain a technological lead over Chinese and Russian competitors.
This approach is reminiscent of past upgrades to the F-16, some of whose Block 70/72 versions incorporated capabilities comparable to those of later-generation aircraft. The F-35 5+ would follow this logic of incremental evolution, but with a more significant leap in propulsion, stealth, and weaponry.
The advanced engine: an expected breakthrough in performance
One of the major aspects concerns the engine. The current F-35 uses the Pratt & Whitney F135, which provides approximately 191 kilonewtons of maximum thrust with afterburner. However, this engine is considered limited in view of the growing need for electrical power and sensor cooling.
The US Adaptive Engine Transition Program (AETP) has enabled General Electric and Pratt & Whitney to develop prototypes capable of generating up to 25% more thrust and 30% more energy efficiency. These adaptive engines have a third airflow, optimizing fuel consumption during cruise and thrust during combat.
Integrating this type of engine into the F-35 5+ would offer an increased range of nearly 30%, which would correspond to approximately 400 km more on a basic range of 1,100 km. It would also extend the operating time of sensors and future energy weapons, such as close-range defense lasers.
This development is considered crucial by the US Air Force, which has reported an urgent need for more powerful propulsion to support future Block 4 upgrades to the F-35.
Planned stealth improvements
The stealth capabilities of the F-35 Lightning II are based on an optimized aerodynamic design, absorbent materials, and a specific surface treatment. However, the proliferation of low-frequency radars and passive networks is calling into question its long-term effectiveness.
The F-35 5+ project incorporates new radar-absorbing coatings that are less expensive to maintain and more effective in low frequency ranges. In addition, the airframe’s thermal management would be improved to reduce its infrared signature, a key factor in countering modern air-to-air missiles equipped with advanced sensors.
These developments aim to maintain an advantage in a sensor-saturated environment, particularly in the face of the rise of Chinese AESA radars and European passive systems. The stealth improvement would also have the advantage of reducing maintenance costs, currently one of the F-35’s weak points.
Integration of new weapons
The F-35 5+ would be designed to integrate a larger and more powerful arsenal. Among the priorities are long-range air-to-air missiles such as the AIM-260 JATM, designed to replace the AIM-120 AMRAAM by 2030.
On the air-to-ground side, the aircraft could carry compact hypersonic weapons and new-generation guided bombs. The internal space of the F-35, limited to around 2,600 kg, currently restricts the integration of certain munitions. Lockheed Martin engineers are working on compact systems that will allow more weapons to be stored in the cargo hold while maintaining stealth.
Block 4 of the F-35 already provides for the gradual integration of 17 new weapons. Version 5+ would serve as a test bed to integrate them more quickly and prepare for the transition to sixth-generation weapons.
The interest of the US Department of Defense
The Pentagon has shown interest in Lockheed Martin’s proposal. The idea of an F-35 5+ is appealing because of its flexibility: it allows the current fleet to be maintained at the highest level without waiting for the NGAD, whose estimated cost per aircraft would exceed €250 million.
The F-35 5+ would cost much less than developing a completely new fighter. Currently, the unit price of an F-35A is around €80 million, but its full cost per flight hour is nearly €33,000. Improvements to the engine and stealth systems could reduce these maintenance costs, strengthening the economic argument.
However, no contract has yet been signed. The Department of Defense is studying the various options, between maintaining a modernized F135 engine and adopting a completely new engine.
Strategic and industrial consequences
The introduction of an F-35 5+ would have repercussions beyond the United States. Many allied countries, such as the United Kingdom, Italy, Japan, and Poland, depend on the F-35 for their future air defense. A move to a 5+ version could require major upgrades to existing fleets.
Industrially, this would provide additional work for Lockheed Martin, Pratt & Whitney, and General Electric. It would also strengthen the consistency of the F-35 program by avoiding technological fragmentation among users.
Finally, strategically, the 5+ option would maintain a credible lead over the Russian Su-57 and Chinese J-20, until the NGAD becomes operational.
Reflections on the future of American aeronautics
The F-35 5+ concept raises a key question: is it better to extend an existing platform indefinitely or to invest heavily in a technological breakthrough? The United States seems to want to take a two-pronged approach: on the one hand, financing the NGAD for the long term; on the other, modernizing the F-35 to maintain a large and competitive fleet in the meantime.
This strategy illustrates a budgetary and political constraint: the need to reconcile innovation with cost control. The coming months will tell whether the Pentagon gives the green light to this interim project. One thing is certain: the battle for air superiority will not be fought solely on sixth-generation aircraft, but also on the ability to effectively upgrade those already in service.
War Wings Daily is an independant magazine.