Servo - March 2016

Goblins to Gremlins

Way back in 1947, McDonnell Aircraft introduced the XF-85 Goblin: a prototype fighter designed to drop out of a B- 36 bomber to defend it from enemy interceptors. Not only was it one of the ugliest aircraft ever built, it wasn’t really capable of fending off enemy jet fighters, so only two were built before the program was terminated.

The concept of employing such “parasitic” fighters has been reincarnated a few times, with pretty much the same degree of success.

However, the Defense Advanced Research Projects Agency (DARPA) believes that is has it right this time in the form of its Gremlins program, which seeks “to show the feasibility of conducting safe, reliable operations involving multiple air-launched, air-recoverable unmanned systems.” In other words, they want to launch groups of Gremlin UASs from bombers, transport aircraft, fighters, and other small fixed-wing aircraft before they encounter adversary defenses. When the Gremlins complete their mission, a C- 130 transport aircraft would grab them out of the air and carry them home, where ground crews would prepare them for redeployment within 24 hours. Each one could be used up to 20 times. Rather than farming everything out to the usual huge defense contractors, DARPA “strongly encourages participation ... by nontraditional performers, including small businesses, academic and research institutions, and first-time government contractors.” So, feel free to offer proposals at www.darpa.mil. Artist’s concept of low cost, air-retrievable Gremlin unmanned air systems. by Jeff and Jenn Eckert Robytes

Printing on Air

When we think of 3D printing, we generally picture a mechanism in a box that produces little plastic things. However, in the Netherlands, a company called MX3D ( mx3d.com) is thinking (literally) outside the box with a different kind of print technology. According to the company, “Our robots print sustainable materials such as metals and synthetics in virtually any size or shape. Our engineers, craftsmen, and software experts bring together digital technology, robotics, and traditional industrial production.” The MX3D Metal unit is a multi-axis industrial robot combined with a welding machine and software (provided by Autodesk) that drives the combination. It can print with a variety of metals, including steel, stainless steel, aluminum, bronze, and copper. The MX3D Metal doesn’t even need external support structures, as it adds small layers of molten metal to print things in mid air.

Proof of concept is apparent in a footbridge that will span a canal in downtown Amsterdam. The company declined to offer specifics about cost, but did note that it is cheaper than the more traditional selective laser melting process. “In the future,” it was predicted, “you might even see torch-carrying robot arms building bridges for cars or trains. The bots could also be useful at sea to fix offshore oil rigs, or in space to repair broken satellites.” For vids, just search MX3D on You Tube.