That the F-35 Lightning II has been prohibited from flying anywhere near lightning is ironic. That the F-35 has been under development since 1994 and that the Pentagon “doesn’t have a path forward” to fix the F-35 is unforgivable.
That a plane that’s supposed to be the foundation of American air supremacy has an Achilles heel so easily exploitable is a glaring example of how our military procurement system wastes taxpayer dollars while failing to provide the weapon systems needed to meet our national security needs.
Yes, the F-35, the aging “wunder plane” that the U.S. Air Force and Lockheed Martin have been assuring us for decades is just that one fix away from being ready for full-rate production, isn’t allowed to fly within 25 miles of a thunderstorm.
So far, the indefinite restriction has been publicly announced as applying “only” to the Air Force’s F-35A. But given the F-35 Joint Program Office’s history of hiding and “managing” bad news, it would not be at all surprising to find out that the same restrictions are in place for the Marines’ F-35B and the Navy’s F-35C, but have not yet been made public. That having this unpublicized policy in place could make sense was demonstrated in July 2021 when two F-35Bs flying out of their airbase in Japan were forced to execute emergency landings after they both suffered millions of dollars worth of lightning damage in the same storm.
This restriction is even more crippling than the F35’s restrictions on supersonic flight, as not being able to fly within 25 miles of potential lightning activity will allow an enemy to use lightning proximity as cover for air, ground, and sea operations knowing that the F-35s will not be flying overwatch or be able to be scrambled to areas where lightning threatens them. That this is the plane that’s slated to be the replacement for F-16s, A-10s, AV-8B Harriers, F/A-18E Hornets, and F/A-18F Super Hornets is a decision that needs to be re-evaluated.
On the face of it, it seems as if it shouldn’t be that hard to design a plane to do what planes have been doing for many decades. Each year commercial aircraft worldwide are struck tens of thousands of times by lightning. And every commercial plane is struck about once or twice a year on average. As is the case with commercial aircraft, military aircraft, while instructed to avoid thunderstorms if possible, are expected to be able to fly through them as necessary. And they’re expected to be able to take lightning strikes and complete their missions with no problem. For example, a single 1950s-era jet fighter, an F-106B Delta Dart, was struck over 700 times by lightning while flying test flights for NASA and maintained flight worthiness. Of course, that’s an extreme example, but it does demonstrate that lightning strikes need not cripple or destroy a fighter.
So, why was the most expensive airplane/weapons system development program in the history of the world unable to come up with a plane able to do what pretty much any other plane can do? We don’t really know, because the F-35 Joint Program Office won’t reveal the problem specifics due to “operational security reasons.” But by looking at the F-35’s design history and the basics of lightning protection for aircraft, we can come up with a couple of possibilities.
Possibility one comes out of the fact that planes with composite skins, such as that of the F-35, rely much more heavily on their on-board inert gas generating system (OBIGGS) to keep their fuel tanks from blowing up than do planes with metal skins.
The OBIGGS pumps nitrogen into a plane’s fuel tanks as they empty to ensure that the oxygen content in the tanks never reaches a level that will support combustion (about 9 percent). That way, even if lightning does arc through the fuel tanks, the fuel vapor will not have enough oxygen to combust, and the plane doesn’t blow up.
So, if the F-35 OBIGGS can’t generate enough nitrogen and or evenly distribute that nitrogen through all the F-35 tanks, the F-35 would be vulnerable to a lightning strike. Still, one would think that properly sizing an OBIGGS unit would be a no-brainer for F-35 designers. However, the F-35 isn’t your typical airplane, and since the beginning of its development, it has been dealing with severe weight problems, and in 2004 it went through what many would describe as a draconic weight-cutting exercise.
Did the F-35 design team, in their eagerness to drop weight, perhaps cut it too close in estimating just how much oxygen the OBIGGS system would have to deal with for a plane with truly massive fuel tanks and a super big fuel fraction? And did they take into account just how much dissolved oxygen would be forced out of the fuel when it heated up as it provided cooling for electronics, avionics, and radar equipment—far more cooling than for which it was initially specificationed? This could be the case, but the other possibility that has yet to be mentioned publicly is even more insidious.
The other possibility is that the F-35 is so stuffed full of sensitive electronics gear that the foil/mesh embedded in its composite skin isn’t thick enough to effectively conduct lightning strikes around the exterior of the plane. Hence a lightning strike could damage the sensitive electronics housed in the interior.
This vulnerability may also have stemmed from a design process in which every ounce mattered, and that the weight of metal embedded in the F-35 skin necessary to conduct the lightning ended up being inadequate for the task of protecting more electronics than was ever before crammed into a single-engine fighter, or any fighter for that matter.
That this could be the issue jibes with the previously cited incident in which F-35Bs damaged by lightning didn’t blow up but did suffer severe enough damage to require landing immediately. Of course, the exact nature of the damage was never revealed, but if it was the electronics that were damaged, that would be very bad news as a fix would almost certainly be prohibitively expensive.
Either both, or one of the above, or maybe even none of the above, could be why the F-35 has to avoid lightning. As the Pentagon is keeping the specifics secret, we don’t know for sure. Regardless, having our main source of future airpower unable to fly in rough weather is flat-out unacceptable, and unless this critical problem can be remedied, continuing to move forward with the F-35 is actually damaging, not enhancing our national security.