Scaled Composites’ Mysterious Stealthy Jets Spotted Working With High-Flying Proteus (Updated)

The highly unique aircraft flew between China Lake and Mojave Air and Space Port in what appears to have been an aerial test.

byTyler Rogoway|
U.S. Homeland photo


Scaled Composites' mysterious Model 401 demonstrators flew together yesterday along with the company's Proteus high-altitude test platform in what appears to have been some sort of test operation not far from their home base at Mojave Air and Space Port. The flight was captured from the ground by one of our readers, aerospace enthusiast Hans Friedel. 

According to Hans, on June 9th, 2020, the following occurred:

"I noticed on ADSB-Exchange that the Northrop/Rutan Proteus was flying an irregular pattern out over Lake Isabella. There was also a Northrop/Rutan Model 401 circling around the Ridgecrest/China Lake area. Both the Proteus and Model 401 were circling around 24,000 feet... Around noon, the Proteus and the Model 401 joined up over lake Isabella and flew in my direction towards Mojave. I pulled over to see if I could see them and to my surprise both Model 401s were in formation with the Proteus high overhead... I don't think there are any photos of any of these planes together in formation. 

When I looked closer at ADSB, I noticed that the two 401s had been there all along, flying identical paths in formation. I'm wondering if the 401s were involved in some sort of loyal wingman test. The Proteus and at least one 401 recovered to Mojave Air and Space Port - not sure if both did."

Formation of Proteus and both model 401s and the earlier flight track of the 401s in formation. , Hans Friedel/
Note, N401XD appears to be working out of NAWS China Lake. ,

Proteus first flew in 1998 and has since become one of the legendary aerospace design and manufacturing firm's most successful vehicles. It has been used to prove many technologies and concepts of operation, with its ability to carry outsized payloads in central gondola-like pods to high altitudes—up to 65,000 feet—for the better part of a day. These payloads have included everything from rockets, to NASA scientific payloads, to dummy bombs, to the Global Hawk's newest radar system. Proteus' design also influenced the company's 'White Knight' mothership aircraft that haul their suborbital manned spaceships up tens of thousands of feet for launch. Proteus, which hit is 1,000th flight back in 2017, is one of kind, with no other examples of the test platform ever being built. 


The Model 401, also known internally as 'Son Of Ares,' is far more of a mystery. While their existence has not been a secret and they do fly and operate in the open, their exact purpose and even who they were built for remains unknown. The War Zone has kept maybe the closest eye on this intriguing program and we have been able to discover some information about the aircraft and its unique lineage, but an overall idea of the program and its objectives remains a question mark. 

Last we wrote about the Model 401, it was headed to NAS Patuxent River for some sort of trials. We later received indications that this visit was likely to test the stealthy design's radar cross-section in laboratory-like conditions. Although not 'very low observable' in nature, the design has well-established low-observable features that definitely reduce its radar and infrared signature. Being built from composite materials only helps in terms of the type's radar profile when viewed from different aspects and at various wavelengths. 

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There has been some speculation as to what these aircraft are meant to do, especially in terms of being possible surrogates for unmanned combat air vehicles (UCAVs) or that they may even be optionally manned themselves. Some sort of loitering reconnaissance platform and light attack role has also been floated. The design has large ventral bays that could hold sensor turrets and other systems and their wings are canted upward providing a better line-of-sight to the horizon while orbiting over an area. 

Scaled Composites

So, with all this in mind, Hans's comment about a possible loyal wingman test isn't without its merits. A similar concept was envisioned using a version of Proteus as a central player over a decade ago as part of what eventually was coined in the press as the Hunter-Killer unmanned aircraft project. A militarized and strictly unmanned variant of Proteus, known as the Model 395, was eyed to be procured in conjunction with that program's goals. 

With the B-21 Raider coming online in the not so distant future, an aircraft that is primed to work as a centralized command and control and networking platform for swarms of unmanned combat air vehicles, using Proteus and the Model 401 demonstrators to test the building blocks of such a capability, and the communications architecture that will underpin it, would make sense. The B-21 will likely have a high operational ceiling that will give it long line-of-sight connectivity, something that Proteus could emulate in follow-on testing as the B-21 works towards its first flight. It's also worth noting that the Scaled Composites is owned by Northrop Grumman, the manufacturer of the B-21 Raider.

If the two types were indeed working together, as they seem to have been, a sensor Proteus was carrying could have been tested against the low-observable Model 401s. The Global Hawk's new Multi-Platform Radar Technology Insertion Program (MP-RTIP) radar, which has been tested extensively on Proteus, has a latent air-to-air capability that hasn't been developed, but that could be changing especially as low-observable threats are proliferating around the globe. There are plenty of other larger airborne sensors in development that would need flight trials, including the B-21's future radar system. 

Proteus with MR-RTIP radar system that is now flying on the Block 40 Global Hawk. , Scaled Composites

As such, the Model 401s may be used as flying low radar cross-section targets in a similar manner as to how the retired F-117s have been used, working as something of a flying control variable to benchmark sensor systems. Of course, this very well could be just one of their uses and not even their primary reason for existing. And maybe they were up to something totally different, we just don't know. For instance, there are plenty of initiatives ongoing in the artificial intelligence-infused air combat space alone that will need surrogate aircraft. An optionally manned one may be highly attractive at least for some of those tests. 

Like so many of Scaled Composites' unique designs, the Model 401 aircraft could have multiple purposes, some of which will emerge as time goes on and technology moves forward. In fact, that is the story of their namesake, Ares, which started life as a gun-toting very light battlefield interdiction demonstrator and went on to work in many developmental roles, including acting as an unmanned aircraft surrogate and more. 

Ares early in its career as a gun-slinging close air support demonstrator and later as a surrogate testbed. , Scaled Composites

We formally inquired about the Model 401 as recently as last month, but nothing more about the program was released to us. With both demonstrators hard at work, maybe we will find out more about them in the not so distant future. We will certainly keep an eye out for future missions with Son of Ares flying in conjunction with Proteus, as well. 


The three aircraft flew again today, and like the day before, one of Model 401s appears to be working out of NAWS China Lake. Apparently, F-117s were also up today and flew into China Lake at around the same time. They could be part of the test, as well. An EA-18G Growler appears to also be involved in some manner. Hans mentioned it was also present on June 9th, but it wasn't clear how involved it was. It actually ended up landing at Mojave on that day.

Here are the flight tracks from today:

If the F-117s were involved, this would point to this being a sensor test against low radar cross-section aircraft, with Proteus flying the sensor aloft. The EA-18G could test the sensor's resistance to electronic attack while trying to spot the stealthy targets. 


Images of F-117s leaving Tonopah Test Range Airport (TTR) yesterday before flying to Edwards AFB for approaches and eventually landing at NAWS China Lake. Images courtesy of Matt McRae. Check out more of his shots on Instagram @west.coast.aviation

According to Matt: 

"We were out at TTR, saw one jet takeoff and do a full 180 pointed south, then it did another 180 north and joined with a second jet. Then they joined up flew for a bit then broke off..." 

After leaving the TTR area they headed west to Edwards AFB.

Matt McRae
Matt McRae
Matt McRae

We will continue to update this post when more information comes available. 

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