The U.S. Air Force is interested in adding an active electronically-scanned array (AESA) radar to its X-62A test jet. The radar is part of larger plans to acquire a new modular sensor suite to further expand the capabilities of the uniquely modified F-16, which has already assumed a key role in advanced exploratory work for autonomous air combat drones. Following the announcement that the X-62A had taken part in a first-of-its-kind artificial intelligence-driven dogfight earlier this year, The War Zone highlighted how uninterrupted 360-degree situational awareness will be essential for truly making autonomous close-in air-to-air combat a reality.
Air Force officials at Edwards Air Force Base first put out a call for information about potential AESA radar options for the X-62A back in August, but only stopped taking submissions last Friday. Also known as the Variable Stability In-flight Simulator Test Aircraft (VISTA), the jet is assigned to the U.S. Air Force Test Pilot School (USAF TPS) at Edwards.
“The potential radar upgrade is for the X-62 Variable In-Flight Simulator Test Aircraft (VISTA) in support of a Mission Systems Upgrade (MSU),” the contracting notice explains. “The upgraded radar will be part of a set of modular components that can be used individually or together to provide sensory input to aircraft.”
“At the end of the mission systems upgrade, the aircraft will be capable of processing raw data from the AESA radar in an autonomy enclave that can use machine learning to process the data and directly control the sensors using either the existing modes available via the radar OFP [operational flight program] or via experimental modes and experimental combinations of modes inaccessible or unachievable by human use,” the notice adds.
The notice also lays out a number of core requirements for an AESA to go onto the X-62A, including that it not weigh more than 200 pounds, be air-cooled, and have a startup time of under two minutes. It “must be an AESA radar that can [be] operated in an unclassified mode” and “be one that “possess both an Air to Air and Air to Ground modes.”
“Raw AESA data must be available for computation external to AESA processing unit,” the contracting notice adds.
The air-cooled requirement notably precludes the potential use of Northrop Grumman’s AN/APG-83 AESA radar, also known as the Scalable Agile Beam Radar (SABR), which hundreds of operational Air Force F-16s are in the process of receiving. The SABR, which you can read more about here, is a liquid-cooled design.
There are other AESAs on the market now could meet the stated requirements for installation on the X-62A. Raytheon’s PhantomStrike, which is an air-cooled type that also weighs around 150 pounds, and is otherwise designed to be compact to help ease integration on a wide array of crewed and uncrewed aircraft, is one example. The ELM-2052 from ELTA, a subsidiary of Israel Aerospace Industries (IAI), is another compact AESA that has been growing in popularity, including as an upgrade option for existing aircraft types, though it’s not immediately clear if it meets the cooling and weight stipulations.
It’s unclear what radar the X-62A has now, but the two-seat Block 30 F-16D on which it is based would have come standard with a mechanically-scanned pulse-doppler AN/APG-68. In general, AESAs offer improved range, as well as greater precision and fidelity of tracks even when it comes to smaller or stealthy objects, compared to mechanically-scanned types. They are also more reliable and offer increased resistance to electronic warfare jamming.
As such, a new AESA would give the X-62A valuable new capabilities, as well as better overall situational awareness. This, in turn, could be extremely useful for future autonomy testing work, including more advanced mock air-to-air engagements. After the ground-breaking dogfight earlier this year, the Air Force disclosed that the X-62A’s systems had been directly exchanging position and other “state information” with the crewed F-16 it was dueling with, primarily for safety reasons.
As The War Zone has previously explored in detail, data-linking the X-62A to the crewed F-16 also made sense for practical reasons, but underscored significant challenges to overcome to truly demonstrate autonomous air-to-air combat capability against a completely unknown threat. The addition of a more modern radar is not enough by itself to address the issues at hand. As we wrote:
“Despite over a century of military aviation advancements, dogfighting remains a visual affair where a human pilot’s on-the-spot judgment, intuition, and stereo vision are critical. An aircraft’s sensor suite, including radar, electro-optical and infrared cameras, and electronic warfare and support measures systems, can provide a wealth of data about enemy contacts. However, their utility steadily diminishes, if it does not largely collapse, as the distance to the target closes to very close-in maneuvering range. A radar in the nose of an aircraft, for instance, can only ‘see’ what’s in a cone-shaped area in front of it. Even existing 360-degree camera systems have two-dimensional limitations and can be hampered by environmental conditions. Datalinked information from external sources can be extremely valuable for building situational awareness or even guiding weapons, but it also has limited in fidelity. External tracks of the enemy and friendly fighters can merge together at very close range.”
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“The X-62A simply does not have any kind of organic sensor suite that would give it the uninterrupted 360-degree situational awareness that truly autonomous dogfighting would require. This is something that will have to be addressed when it comes to the development of future autonomous platforms. Arrays of small conformal radars, electro-optical or infrared cameras, and other sensors could be utilized to provide the necessary situational and spatial data, in effect working together to build telemetry for creating a solid digital three-dimensional ‘picture’ of what is going on directly around the jet during a fast developing dogfight.”
As the contracting notice about the new AESA for the X-62A notes, the radar is just one element of a planned suite of new sensors for the jet. If the Air Force uses a modular, open-architecture approach it could also help make it easier to add new and improved capabilities and functionality in the future.
“There is a plan and there is a development pathway in the future to incorporate sensing, and the complexity that that [sic] adds to the picture,” Air Force Col. James Valpiani, the commandant of the USAF TPS, told The War Zone and others at a media roundtable about the X-62A’s dogfight back in April. “Doing this in a safe and responsible way is to take it one step at a time to truly understand how each aspect works before moving on to the next problem.”
Using pilot-optional surrogates like the X-62 presents additional benefits when it comes to accelerating testing and reducing risk and eliminates bottlenecks associated with domestic U.S. airspace restrictions currently placed on completely uncrewed platforms. The War Zone recently explored all of this in more detail in the context of the new stealthy Model 437 Vanguard technology demonstrator jet from Northrop Grumman subsidiary Scaled Composites.
With this in mind, the Air Force has also been putting together a test force of six additional specially configured F-16s to further support advanced autonomy work as part of a project called VENOM (Viper Experimentation and Next-Gen Operations Mode). The VENOM jets are not being modified anywhere near to the same degree as the X-62A, but will also reportedly have AESA radars, as well as the warning sensors that go along with their electronic warfare suites.
“The VENOM aircraft are the platforms that will have the ability to sense the environment around them and do some of the things that we presently have some limitations on VISTA with,” Air Force Lt. Col. Ryan Hefron, head of the Defense Advanced Research Projects Agency’s Air Combat Evolution (ACE) program, also said at the April roundtable. “Not to say … that we won’t continue to work on [ACE using] VISTA, because we absolutely will. There are certain things that the [X-62A] aircraft is capable of performing that won’t be, I’ll say, well suited on the VENOM birds… They each have their own unique place, I’ll say, as testbeds.”
ACE is the program under which the X-62A’s artificial intelligence-driven dogfight was conducted and is among a number of efforts that are directly feeding into the Air Force’s Collaborative Combat Aircraft (CCA) drone program. The service’s plans for its CCAs are expected to evolve significantly as time goes on, but the main focus initially is on air-to-air combat in support of crewed platforms, as you can read more about in detail here. How much autonomy the first batches of CCAs might have and where humans will be in or on ‘the loop’ remain very open questions.
“We know two things about autonomy,” Andrew Hunter, Assistant Secretary of the Air Force for Acquisition, Technology & Logistics, more recently told The War Zone and other outlets at a media roundtable on the sidelines of the Air & Space Forces Association’s main annual conference last week. “One is laws of war require us to have, you know, human engagement in key decisions involving employment of weapons and other key decisions. So we have to have that. We have to have that human engagement, the ability to do that. The second is [that] we know that our ability to create systems that can operate autonomously and do missions well is something that is still maturing.”
“So, in other words, there are things that we know that we already know how to do well with autonomy, and there’s things that we know we do not know how to do well with autonomy,” Hunter continued. “So we’re going to stick to the things we know we can do well, and then have humans do the other things, and, over time, that mix is going to change… it’s not going to be static.”
The X-62A fitted with a new AESA radar and other sensors looks set to be an important part of how the Air Forces goes about defining its future autonomous air combat ecosystem.
Contact the author: joe@twz.com