The US Army isn't just looking to giving soldiers a hand, but a whole extra arm. At the Aberdeen Proving Grounds in Maryland, the US Army Research Laboratory (ARL) is testing a prototype passive support system called Third Arm, which evenly distributes the weight of heavy weapons, allowing soldiers to use them with less fatigue and greater accuracy.

In the 1986 sci-fi classic Aliens, one of the signature props was the fictional M56 Smartgun, which was a dressed up MG42 machine gun stuck on a steadicam mount. This mount, which in reality connects a hand-held cine-camera to the operators body to stabilize it, made for some very cool action scenes and has now apparently inspired a real-life counterpart.

Mechanical engineer Dan Baechle has come up with a more advanced, more articulated, militarized version of the steadicam mount that can take the weight of a weapon off a soldier's arms. Third Arm is an unpowered, articulated frame made of composite materials that helps to distribute the weapon's weight while allowing enough range of motion to be practical on the battlefield.

"We've actually tested it with the M249 and M240B machines guns," says Baechle. "The M240B weighs 27 lb (12.2 kg), and we were able to show that you can take the weight of that weapon completely off of the soldiers' arms."

According to Baechle, the Third Arm is still in the early prototype stage and is undergoing a number of changes as feedback from users comes in. Recently, the rig was worn by a sergeant with an M4 type weapon. The latest iteration allowed him to aim the weapon with greater accuracy and dive into a prone position from a sprint.

The Third Arm is part of the Army's modernization program that includes a greater interest in exoskeletons that improve soldiers' load-bearing, shooting, movement, communications, protection, and sustainment in the field with less fatigue. Third Arm has already been subject to live-fire trials and Baechle is working to improve the design and make it capable of carrying heavier weapons.

"It falls in line with the direction that the Army wants to be heading in the future," says Baechle. "We get comments from Soldiers who tell us different things about the way it feels on their body … about the way it redistributes the load. Some like it, some give us tips about the ways it could be improved, and we're using that input to improve the device and improve the design so that it not only works well, but it also feels good."

The video below discusses the Third Arm project.

Source: US Army

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