WASHINGTON — The idea behind DARPA’s Gremlins program is simple: Turn cargo aircraft like the tried-and-true C-130 into motherships capable of launching and retrieving swarms of small drones. But a recent test proves execution of that goal may be easier said than done.
During a series of flight tests that started Oct. 28, the Defense Advanced Research Projects Agency made nine attempts to recover three X-61A Gremlins Air Vehicles in flight. Each failed, the agency said in a news release, which characterized the effort as “just inches from success.”
The tests marked the first time DARPA has attempted to recover the Gremlins drones — made by Leidos subsidiary Dynetics — via a capture device mated to the same C-130 that deployed the air vehicles. During a successful recovery, the C-130 would lower a docking bullet that helps stabilize each vehicle from the turbulence generated by the C-130. Once in place, an engagement arm would grab the X-61A and drag it into the C-130′s cargo bay.
However, during the October tests, the Gremlins drones were never able to mechanically engage with the docking station because the “relative movement was more dynamic than expected and each GAV, ultimately, safely parachuted to the ground,” DARPA stated.
DARPA’s program manager Scott Wierzbanowski sounded an optimistic note about the tests, saying the challenges encountered were not insurmountable.
“All of our systems looked good during the ground tests, but the flight test is where you truly find how things work,” Wierzbanowski said. “We came within inches of connection on each attempt but, ultimately, it just wasn’t close enough to engage the recovery system.”
Not everything went wrong during the recent demonstrations, DARPA said. Over three flights, each X-61 flew for more than two hours, allowing DARPA to further validate the drone’s ability to operate autonomously. The agency also collected “hours of data” that will help it to understand aerodynamic interactions between the Gremlins drone and the capture device, which program officials will study to understand how the system needs to be modified.
DARPA will then attempt to fly and recover the Gremlins drones this spring.
“We made great strides in learning and responding to technological challenges between each of the three test flight deployments to date,” said Wierzbanowski. “We were so close this time that I am confident that multiple airborne recoveries will be made in the next deployment. However, as with all flight testing, there are always real world uncertainties and challenges that have to be overcome.”
This isn’t the first time there have been anomalies during Gremlins tests. When DARPA first launched the Gremlins aircraft from a C-130A during a November 2019 demo held at Dugway Proving Ground, Utah, an X-61A flew almost two hours while the test team completed every objective, including testing the air vehicle’s data links and deploying the docking station.
But when the time came to recover the drone, one of its two parachutes didn’t deploy, leaving the vehicle to crash to the ground.
Eventually, DARPA wants to demonstrate that it can safely and reliably launch and recover four Gremlins drones within 30 minutes.
Meeting that goal would open up a world of possibilities to the military, allowing the services to deploy swarms of small, inexpensive, reusable drones with different sensors and payloads from legacy aircraft — a capability the Defense Department currently lacks. Those swarms could move closer to adversary airspace and do tasks such as gathering imagery or providing a communications relay without having to endanger human aircrew.