Key Points –The F-35 Lightning II’s combat radius of approximately 670 nautical miles, while not critically short, is increasingly viewed as a limitation, especially compared to the 1000+ nm range targeted for next-generation fighters like the F-47.
-This range constraint stems from the F-35’s origin as a compromise design intended to fulfill diverse roles for three US military services, a multi-mission approach that necessitated design trade-offs.
-Furthermore, persistent issues with its F135 engine, derived from the F-22’s F119, have impacted performance and contributed to low aircraft availability rates, arguably a more pressing concern than range alone for the widely deployed stealth fighter.
The F-35 Range Problem That Won’t Go Away
As more nations line up to procure the F-35, there are also more frequent inquiries as to whether the aircraft’s range is a limiting factor. F-35’s range is not critically short. As pointed out in a previous report, the aircraft’s combat radius is slightly less than that of the longest-ranged fighter in the US Air Force (USAF) inventory, the F-15EX.
But there are multiple answers to the question about the F-35 and its 670 nautical mile (nm) range. One would be yes if the soon-to-be optimal range for a USAF fighter is 1000nm—one of the major design drivers for both the US Air Force’s F-47 Next-Generation Air Dominance (NGAD) and the US Navy’s forthcoming (someday) F/A-XX replacement for the Boeing F/A-18E/F Super Hornet—then F-35’s range is not enough for some missions.
It is not enough to the level that it would be better for the aircraft’s combat radius to be 50 percent greater than it is. However, one should remember why the aircraft was designed and what customer profile it was intended for. A 1000nm range was never a major requirement.
A Replacement For Too Many Mission Roles
As a long-time colleague and aviation journalist who has written extensively on the F-35’s trials and tribulations has pointed out multiple times to me, “If you employ Old Testament genealogy, the A-12 [US Navy attack aircraft program] ‘begat’ the F-35. When that ill-fated program was cancelled in 1991 , it did not cancel the requirement. The Navy still had to have something to replace the mission of the famous A-6 Intruder.”
Immediately, the combat aviation world saw a flurry of “A-X” design concepts to fill that void created by the A-12 cancellation. At the same time, the USAF was still going to need something in the 21st century to provide to its squadrons and those of its allies to replace the F-16. The US Marine Corps also had to find a next-generation platform for AV-8B Harrier Vertical/Short Take-Off and Landing (VSTOL) fighters.
There is an old saying. Two products you never want to see being made are sausage and procurement decisions taken inside the Pentagon. The F-35 is a classic example of the latter. The final solution was to replace all by building one aircraft in three variants to carry out those three disparate combat roles. The rest—including a less-than-maximum range performance—as they say, is history.
This is one of the reasons more than one of the service branches wishes they could go back in time and reconsider. Simply put, there is no shortage of people in the defense policy-making community who will tell you, “We are never going to do that—buy one aircraft in three versions for multiple missions—not ever again.”
Propulsion Woes
But to be fair, the F-35’s range limitations are not entirely to blame for its ending up as a program that tries to be all things to all its users. Range limitations are today assessed as a symptom of a larger problem: the aircraft’s engine would never deliver the desired or required performance.
Bryan Clark, a Senior Fellow at the Hudson Institute and Director of the Hudson Center for Defense Concepts and Technology, testified last summer on the F-35’s growing problems and blamed the architects of the entire project for much of them, not the competence of the contractors running the program.
He concluded that the F-35’s design problems “reside in its origin more than its execution.”
Some propulsion experts say one of those origins was adapting the F-119 engine that powers the twin-engine F-22 fighter into the F-35’s F135 engine. The two engines are not the same but utilize a set of common core elements. The common core was a fateful decision made to short-circuit the development cycle.
The result has been a series of engine defects, one of the most vexing of which has been excess vibration, or “harmonic resonance,” which caused failures in other parts of the engine. This prompted the F-35’s Joint Program Office (JPO) to order the entire fleet of aircraft to be retrofitted with an engineering fix to address the issue.
“Range is one issue, yes,” said the aviation journalist who has followed the program for years. “But the greater headache now is the availability rate. It matters less how far the aircraft can fly and still have enough in the gas tank to return if no more than 50 percent of them are even able to take-off at any one time.”
About the Author:
Reuben F. Johnson is a survivor of the February 2022 Russian invasion of Ukraine and is an Expert on Foreign Military Affairs with the Fundacja im. Kazimierza Pułaskiego in Warsaw. He has been a consultant to the Pentagon, several NATO governments and the Australian government in the fields of defense technology and weapon systems design. Over the past 30 years he has resided in and reported from Russia, Ukraine, Poland, Brazil, the People’s Republic of China and Australia.
