The X-61A Gremlins Air Vehicle (GAV) program being developed by the US Defense Advanced Research Projects Agency (DARPA) completed its second test flight in late August.

Developed by Leidos subsidiary Dynetics, Gremlins is a demonstration program designed to demonstrate the concept of a multiple unmanned aerial systems that can be launched and retrieved in flight from a large transport aircraft.

The 132-minute flight was part of a series of tests focused on risk reduction and system and subsystem performance verification that had been delayed due to COVID-19 restrictions. The X-61A was released from a wing hardpoint of the C-130 mothership, and then rendezvoused with and flew in formation 125 feet from the C-130 using artificial intelligence.

Although the C-130 had deployed its Gremlins Autonomous Docking System (GADS) with a view to retrieving the X-61A, it was decided to not dock and defer that part of the test to a later flight, and the air vehicle was recovered using a parachute.

“The air vehicle performed beautifully from launch through mission modes, and the consistency between the flight tests in November and July increases confidence in the X-61A,” Scott Wierzbanowski, the Gremlins program manager in DARPA’s Tactical Technology Office said in a DARPA statement.

In a Leidos company statement, Dynetics Gremlins team program manager, Tim Keeter said, “We have taken a major step forward towards accomplishing airborne recovery, and we are ever so close to achieving it. Our second GAV flown to date performed very well, which increases our confidence in the X-61A. And for the first time, we rendezvoused and flew in close formation with the recovery C-130 multiple times using the GADS. 

“Multiple captive tests were also conducted for the first time, with actively-controlled GAVs attached to the stabilised towed docking device,” he added. “This demonstrated the ability of the recovery system to safely reel in and stow GAVs once they have docked. The data collected from these tests will provide the necessary information to perform final tuning of GADS.”

Dynetics X-61A chief engineer, Brandon Hiller added, “While we successfully tested both the GAV and recovery system, we decided during the mission to stop short of docking. We now have additional data, which will help us tune the system and further validate our models. These results are encouraging and present higher confidence to achieve airborne recovery in our next flight.”

DARPA says that “mission flexibility and affordability” are the key goals of the Gremlins development program. If successful, it would see multiple UASs with up-to 150kg of sensors or weapons launched from multiple aircraft types while the launch aircraft remain beyond the range of adversary defences. Once the Gremlins complete their mission, the transport aircraft would retrieve them in mid-air and return to base for quick turnaround. The recovery system is designed to be easily modified and compatible with different transport aircraft and weapons systems

Dynetics’ industry team on the X-61A includes Kratos Unmanned Aerial Systems, Williams International, Applied Systems Engineering, Kutta Technologies, Moog, Sierra Nevada Corporation, Systima Technologies, and Airborne Systems.

A DARPA video of the X-61A’s first flight can be viewed here.