DARPA Wants Millions To Design An Unmanned ‘Flying Gun’ Under Its New Gunslinger Program

Budget documents describe a gun-armed “missile” that would be able to engage multiple targets, either on the ground or in the air.

byJoseph Trevithick|
U.S. Homeland photo


Tucked away inside the Defense Advanced Research Projects Agency's most recent budget proposal is a request for millions of dollars to explore what one could best describe as an unmanned flying gun capable of engaging airborne and ground-based targets. This comes around a year and a half after DARPA first announced it was working on what it called a "Flying Missile Rail." The system would carry its own air-to-air missiles and would be launched like a drone from under the jet's wing, after which they would fly off and engage aerial targets with their missiles. 

DARPA is asking for $13.27 million in its budget request for the 2021 Fiscal Year for the flying gun effort, which it has dubbed Gunslinger. The budget documents say that this is a new program and it is in no way related to the U.S. Navy and Marine Corps program of the same name, which developed a system to detect incoming hostile gunfire.

"Gunslinger program will develop and demonstrate technologies to enable an air-launched tactical range missile system capable of multi-mission support," the Gunslinger entry in DARPA's budget proposal says. "This system will utilize the high maneuverability of a missile system coupled with a gun system capable of scalable effects and engagement of multiple targets."

The section does not give any specifics as to the overall size of the weapon system DARPA is envisioning or what type or types of guns it might be capable of carrying. It also does not say what types of aircraft would be capable of carrying these gun-armed "missiles" in the future, though it says that the plan would be to ultimately transition the project to the Air Force and the Navy. 

The entry on Gunslinger from DARPA's 2021 Fiscal Year budget request., DARPA

"These mission sets addressed [by Gunslinger] will include counter-insurgency (COIN) operations, close air support (CAS) and air-to-air engagements," the budget documents add. "The program will address the system and technology issues required to enable development of a robust missile system considering (1) vehicle concepts possessing the required aerodynamic, propulsion, and payload capacity for a wide operational envelope, (2) the algorithms that support maneuvering and target recognition to enable expedited command decision making for selecting and engaging targets and (3) approaches to incorporating modularity of design to reduce cost throughout the design and development process."

The funding that DARPA is seeking the 2021 Fiscal Year would go specifically to "trade studies, to include propulsion, munitions, sensors, GPS and communication," as well as conceptual design work and modeling and simulating potential concepts of operation for employing the weapon system. 

It's not entirely clear what the driving factors behind this program are from its description in the budget documents. The use of the word "missile" to describe it strongly implies that DARPA is treating this as an expendable weapon, like any other missile or bomb, rather than a recoverable, reusable drone. The section on Gunslinger does say that it would have the ability to "loiter" over a part of the battlefield, engaging multiple targets. Loitering munitions, which Israel pioneered and that are something of a hybrid of traditional missiles and unmanned aircraft, are seeing increasing use within the U.S. military.

It's certainly true that aerial guns typically offer the ability to focus fire on much smaller targets, which is especially valuable if the threat is situated very close to friendly forces or innocent bystanders. This is something that is very likely to occur in dense urban areas, which the U.S. military increasingly sees as a likely environment for future conflicts.

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With a sufficiently large ammunition magazine, guns can also readily engage multiple targets and rapidly shift focus from one to another, things that a single traditional missile or bomb cannot achieve. Ammunition loads can also be tailored to specific target sets.

One possible concept of operations could involve a high-flying bomber-type aircraft, or some or form of future "arsenal plane," launching these flying gun pods over a target area, where they could offer a more persistent and precision means of engaging targets on the ground or in the air. When it comes to close air support, U.S. Air Force bombers have increasingly been called upon to perform that mission, but lack any functional way of providing this particular kind of direct fire. It's worth remembering that Boeing received a patent for a ventral gun system for the B-1B Bone bomber in 2018, but there has been not been any clearly articulated reason why the company pursued that project in the first place since then.

A schematic of Boeing's notional ventral gun system for the B-1B Bone bomber that would fit inside the bomber's rear bomb bay., USPTO
A schematic of the gun system itself., USPTO

There has been something of a move away from gun-armed aircraft by the U.S. military, in general, as well. The Navy and Marine Corps versions of the F-35 Joint Strike Fighter do not have a gun installed by default, though they can carry an external gun pod. However, that system, as well as the internal 25mm GAU-22/A gun on the Air Force's F-35A variant, have limited ammunition capacities. The F-35A carries 180 rounds for the GAU-22/A, which fires at approximately 3,300 rounds per minute, giving the aircraft enough ammunition for roughly 3 three seconds of continuous fire. 

Though nowhere near this extreme, other U.S. military combat jets equipped with internal guns also have relatively limited ammunition capacities. The F-16C/D Vipers and F/A-18E/F Super Hornets carry 511 and 412 rounds of 20mm ammunition for their M61 Vulcan cannons, respectively. That gun has a rate of fire of around 6,000 rounds per minute, giving Viper pilots just over five seconds of continuous fire and aviators flying Super Hornets a little more than four seconds of trigger time.

Advocates of retaining the venerable A-10 Warthog ground-attack aircraft often cite its iconic 30mm GAU-8/A Avenger cannon and ammunition load of 1,174 shells as a key reason for keeping those aging aircraft in service as long as possible. Proposals for A-10 replacements in the past, such as the experimental Scaled Composites Agile Responsive Effective Support (ARES) aircraft, focused heavily on gun armament. General Electric also offered the GPU-5/A gun pod for a time, which contained a lightened derivative of the GAU-8/A, the GAU-13/A, in a failed attempt to give other aircraft the A-10's awesome firepower.

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The Air Force's most recent budget request for the 2021 Fiscal Year calls for the retirement of 44 Warthogs, 15 percent of the remaining fleet. The service also still wants to eventually replace them all with F-35As.

So, DARPA may be looking into Gunslinger as potential alternative means of providing an aerial gun capability in the future that would also not necessarily require a dedicated aircraft. The gun-armed "missile" would also provide a system that a stealth aircraft could carry internally while remaining its most low-observable configuration. It could even fly into high-threat areas without putting the launching aircraft at risk. It could also bridge a gaping chasm between the capabilities of high-flying bombers and low-flying close air support capable fast jets when it comes to providing close air support. 

It's also entirely possible that this will turn out to be a more academic exercise with benefits that may not necessarily be directly tied to the performance of the weapon system. For instance, DARPA's tangential Flying Missile Rail project also focused heavily on exploring rapid prototyping and manufacturing processes. You can read more about that in this past War Zone story. The U.S. military, as a whole, is increasingly interested in these types of developments to help reduce the ever-growing costs of both procuring and sustaining high-end systems, such as stealth aircraft. 

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At the same time, DARPA's 2021 Fiscal Year budget request also asks for $22 million to continue work on a program called LongShot, another new effort, but one that sounds very much like an evolution of the Flying Missile Rail effort with a more operational focus. "LongShot will explore new engagement concepts for multi-modal, multi-kill systems that can engage more than one target," the budget documents say.

The entry on LongShot from DARPA's 2021 Fiscal Year budget request., DARPA

"An air system using multi-modal propulsion could capitalize upon a slower speed, higher fuel-efficient air vehicle for ingress, while retaining highly energetic air-to-air missiles for endgame target engagements," it continues. "First, the weapon system will have a much-increased range over their legacy counterparts for transit to an engagement zone. Second, launching air-to-air missiles closer to the adversary increases energy in terminal flight, reduces reaction time, and increases probability of kill."

Congress still has to debate and decide whether to approve DARPA's budget overall request, including Gunslinger, along those from the rest of the U.S. military. Maybe as those discussions, both public and private, continue, we may learn more about the ostensible objectives and driving forces behind the project.

Contact the author: joe@thedrive.com