The F-35C’s Radar-Absorbent Skin Is Looking Pretty Rough After Months At Sea

F-35Cs have become covered in rusty-looking deposits on their first operational carrier cruise.

byThomas Newdick and Tyler Rogoway| UPDATED Jan 29, 2022 7:09 PM
The F-35C’s Radar-Absorbent Skin Is Looking Pretty Rough After Months At Sea
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The U.S. Navy’s F-35C stealth fighters, one of which has recently grabbed unwanted attention after a landing mishap aboard the aircraft carrier USS Carl Vinson

sent it into the sea, are also showing some fairly significant wear and tear on their debut operational cruise. Radar-absorbent skins are historically made of materials that are notoriously sensitive to environmental conditions. While it is known that significant leaps in the maintainability of radar-absorbent materials (RAM) were integrated into the F-35 design, recent images from the F-35C's inaugural cruise raise potential questions about the ease of maintaining the jet's coatings in the demanding maritime environment.

Photos that appeared recently on the Pentagon’s Defense Visual Information Distribution Service, or DVIDS, website reveal the extent of the weathering that’s affected the F-35Cs of Strike Fighter Squadron 147 (VFA-147), the “Argonauts,” aboard the Nimitz class carrier USS Carl Vinson (CVN-70). These pictures were all taken while the carrier was underway in the Philippine Sea earlier this month.

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Unlike their Air Force counterparts, the jets appear covered in reddish-brown streaks and splotches over most of their upper surfaces, including the center fuselages, wings, and tail surfaces. In fact, the aircraft almost look as if they have a case of rust, which is not altogether unheard of for the Navy, but as with most things related to the F-35, the reality is likely much more complex.

After all, rust only affects ferrous metals like iron or steel and the F-35's largely composite airframe wouldn’t rust, although its RAM — which has already been through a couple of iterations — may very well show similar signs after significant exposure to the harsh saltwater environment. While what makes up the F-35's RAM — some of which is supposedly baked directly into the aircraft's skin panels themselves — is a closely guarded secret, Iron is a known ingredient of radar-absorbent coatings going back to the dawn of stealth technology.

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So, while there’s no doubt the F-35Cs are looking a little rough after around six months at sea, the cause of the brown stains may not have an impact on the airframe itself and the oxidization effect on the skin of the jets might not even significantly affect its stealth qualities. It's worth noting that past stealthy aircraft like the B-2 and F-22 have their low observable treatments degrade over time, then once they hit a certain threshold or operational concerns demand it, repairs are done to bring them back up to an optimal state. Exposure to the elements, like high humidity and heat, could accelerate that degradation. 

It’s also worth bearing in mind that the resilience of the jet’s skin was one of the issues that were raised during preparations for this first operational carrier deployment by the F-35C variant. While caring for a stealth jet’s finicky skin is one thing when operating from a well-appointed land base, it’s more complicated when critical maintenance tasks have to be undertaken at sea, where spares, maintenance experts, and specialized tools are less likely to be available in significant quantities. On top of that, space on a carrier is at a premium and low-observable maintenance shops have traditionally been fairly elaborate dedicated facilities.

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The F-35Cs are also walked all over by maintainers and crews and are constantly blasted with jet exhaust and saltwater spray when embarked aboard the carrier. In addition, oils like hydraulic fluid tend to get on everything. For all we know, any one of those factors could have resulted in the rough appearance of the USS Carl Vinson's F-35Cs. Even the hardiest of aircraft will show signs of corrosion after long periods at sea, but deploying 5th generation stealth fighters to the carrier environment for months at a time remains a new endeavor, especially on a supercarrier with its high-tempo operations.

The radar-absorbent material that coats the F-35 is also just one element of its enhanced survivability, which also includes composite construction, and especially its carefully aligned edges and radiused contours tailored to deflect enemy radar, especially against radar bands used by threatening fire control radars hitting the jet from the forward hemispheres. These features, as well as drastically increased situational awareness via advanced sensors, data fusion, and networking, combined with electronic warfare, unique tactics, and carefully planned mission profiles based on the latest intelligence, allow for the jet to survive in highly contested airspace. In other words, some degradation in the aircraft's RAM does not mean it becomes totally vulnerable to threatening radars, if that were indeed the case.

USS Carl Vinson transits the Philippine Sea, January 22, 2022., U.S. Navy/Mass Communication Specialist Seaman Sophia Simons

The Navy, for its part, boasts in its F-35C factsheet that the jet “combines lessons learned from previous aircraft with technology breakthroughs to produce a fighter that retains its stealthy advantage with minimal low observable maintenance, even in the harshest shipboard conditions.” 

Long before an F-35C was operating from a carrier, Lockheed claims it used a model to simulate the effects of “extensive damage” on the jet, representing the cumulative effect of more than 600 flight hours of operations. The all-important radar cross-section (RCS) measurements, in this case, showed that the jet’s stealthy signature remained intact, the company said.

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As long ago as 2012, the Navy was developing processes required to undertake repairs on the F-35C’s low-observable coatings aboard the carrier and without specialized facilities. On the other hand, the U.S. Air Force’s accounts of maintaining its F-35As often stress the labor-intensive nature of this highly specialized work.

Air Force F-35As feature several panels that have to be frequently removed or opened on the flight line for routine maintenance, as well as more than 5,000 fasteners that keep these panels in place. “All of these, when worn, can potentially limit the jet’s stealth capabilities,” the service has said in the past and the same would seem to apply to the carrier-based F-35C.

Maintainers with the 421st Fighter Generation Squadron perform maintenance on an F-35A at Hill Air Force Base, Utah. , U.S. Air Force/R. Nial Bradshaw.

“Maintaining [the] radar-absorbent coating on the surface of the F-35 is a job that takes very detail-oriented, sometimes tedious work — masking every small area, properly mixing chemicals, applying them precisely, smoothing, and assessing the smallest imperfections. It’s time-consuming, but it’s vital to get it right,” Master Sgt. Francis Annett, 388th Maintenance Squadron Fabrication Flight Noncommissioned Officer-in-Charge explained in an Air Force release.

The F-35C is still at the very beginning of its operational career and the manufacturer and the Navy will be learning how best to operate it and maintain it as it becomes a more familiar presence at the center of the future carrier air wing. In the meantime, we have reached out to the Navy for more information on what we can see happening to the F-35C’s stealthy coatings.

Contact the author: thomas@thedrive.com

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