As you can see, the F-117 has its leading edges and upper fuselage and tails covered in the mirror-like coating very similar to the one seen on the F-22 that has been flying out of Nellis. This is not the first time the F-117 has worn a similar exotic mirror-like skin. As we wrote in December, back in the early 1990s, a mirror-like metallic finish was tested on an F-117 under the SENIOR SPUD program. That program looked at ways to significantly reduce the Nighthawk's infrared signature and was likely a progenitor of what we are seeing today. Now, nearly 30 years later, the 'Black Jet' is back in a silver skin again.

The F-35, on the other hand, has never been seen in such a scheme. The fact that the aircraft in question is an F-35C from Air Test and Evaluation Squadron Nine (VX-9), one of the Navy's major test units out of Naval Air Weapons Station (NAWS) China Lake, means this coating program is in some ways a joint operation, or at least both services are testing it independently. This would make sense as we first saw this treatment on a Model 401 'Son of Ares' test jet flying over NAWS China Lake.

The shots below that show the VX-9 F-35C in the treatment were taken by aviation photographer Elijah Delgadillo, who goes by @eli_aviation on Instagram, on January 20, 2022. Here is a little from the photographer about how and where he snapped the dramatic images:

The general layout of the metallic coating on this F-35C is nearly identical to what we have seen on the F-22, including the scalloped edges mid-way across the wing. These new images do show one thing new — that the coating appears to be translucent, allowing the markings on the jet to show through below the coating, but only from certain angles. This makes sense considering how the coating goes from polished to matte to somewhat shiny looking depending on the aspect you are viewing it from.

You can see in the photos above and the one below how the roundel marking on the wing literally disappears as the aircraft passes perpendicularly then reappears again. It is actually transitioning to looking dark to light, almost becoming a negative of itself. Also, the nose markings are fully visible as is the VX-9 logo on the tail. Another photo we have examined from another photographer of this jet on the same day also shows this, with the entire aircraft looking polished from the quartering head-on aspect, but the logos showing through as dark outlines. It's also possible that the logos were applied as part of this coating and act similar to it as a result.

Like the F-22, the F-35's radar-absorbent material coating plays a very important role in the aircraft's ability to drastically reduce the range at which radars — especially those associated with fire control — can detect and track them. When we broke the Nellis-based 'mirrored Raptor' story, we noted that the finish is clearly quite unique, made up of a mosaic of small custom-fitted tiles in some places and large sheet-like areas in others, that act more as a coating than a cladding. 

We have speculated as to this treatment's purpose before and the Air Force actually gave us a direct comment on it, although it was extremely vague. But by most accounts, this material is thought to reduce the infrared signature of the aircraft from the frontal and side hemispheres. This would reduce the effectiveness of infrared search and track (IRST) systems, of which advanced types are proliferating around the globe and are present on most of the fighter aircraft peer adversaries are flying today.

IRSTs are totally passive sensors and an aircraft's ability to negate radar detection through stealth technology has zero effect on them. You can read all about advanced IRSTs from the best source around in this past feature of ours. Although stealthy aircraft, including the F-22, F-117, and F-35, all have measures built into their designs to help reduce their infrared signature, this is a very tough proposition with high-performance fighters, especially when it comes to hiding from increasingly advanced IRSTs that are fully integrated into an aircraft's combat system and networked with other aircraft. 

The USAF and Navy are just now in the process of fielding their first advanced IRSTs in years, initiatives that have, and continue to, require a lot of testing and tactics development work. This includes flying all types of aircraft against the sensor in many conditions. The Air Force is even looking to procure an IRST-like capability for the F-22, which lacks any type of long-range infrared sensor.

It's also important to note that IRSTs will play a major role in the services' unmanned air combat future, with multiple drones carrying IRSTs while linked together via datalink providing targeting information for manned and unmanned assets. There is a secretive program underway that appears to focus on producing a stealthy drone for this role specifically and General Atomics' Avenger drones have been proving the concept during real exercises. 

The big thing is that we now know this is, at least up until now, a coating that is exclusive to low-observable designs. In other words, we have not seen it on the F/A-18E/F Super Hornet or F-16C/D Viper, for instance. This could be because testing is being prioritized for aircraft that would push the farthest forward in combat — basically operating in the most high-risk areas. This is a stealthy aircraft's domain over the modern battlefield. If that's the case, this coating must be designed to maintain as much of the aircraft's radio-frequency stealth capability while also minimizing its IR signature, if indeed that is what it is being used for. It is also possible that this is a new RF stealth coating that just happens to appear like this, although that seems less likely. If it is transparent to most radar waves, clearly this would be a huge advantage as it would provide IR signature reduction without compromising the aircraft RF signature reduction measures. 

It's also possible that the fact that 4th generation fighters without stealth technology, or in which it was not a primary driver of their design, are already readily detectable by radar, so reducing their infrared signature is not as much of a priority. 

The coating could also be used to test new IRST or other sensor systems going into service. This alone made a lot of sense until the F-35 showed up with it on. Having both 5th generation fighters wear it, along with the F-117 and Son Of Ares, just to test sensors doesn't make all that much sense. That is unless both are supporting IRST development for each service independently. We know the Navy and USAF IRST programs are largely compartmentalized even though they use the same base sensor technology, so this is a possibility.