We have 3-D printed keys, guns and shoes---now a research team at the University of Virginia has created a 3D printed UAV drone for the Department of Defense.
In the works for three years, the aircraft, no bigger than a remote-controlled plane, can carry a 1.5-pound payload. If it crashes or needs a design tweak for a new mission, another one can be printed out in a little more than a day, for just $2,500. It's made with off-the-shelf parts and has an Android phone for a brain.
"We weren't sure you could make anything lightweight and strong enough to fly," says David Sheffler, who led the project. Sheffler is a former engineer for Pratt & Whitney and Rolls-Royce who now teaches at the university. After he created a 3-D printed jet engine in one of his classes, the MITRE Corporation, a DoD contractor, asked him to create a 3-D printed UAV that could be easily modified and built with readily available parts.
The first prototype, the orange and blue model seen in the video above, was based on a conventional radio-controlled (RC) aircraft made of balsa wood, which is much lighter and stronger than the ABS plastic used in the university's 3-D printers. The same plane made of plastic would have weighed five times as much as the wood version. "You're printing out of a material that's really not well-suited to making an airplane," Sheffler explains. On top of that, the way 3-D printing works---building things in layers---led to structural weaknesses in the aircraft.
To account for those downsides, Sheffler's team reworked the design. They settled on a "flying wing" design, in which the whole aircraft is basically one big wing, and called it the Razor. The latest (third) prototype is made of nine printed parts that click together like LEGO. The center of the plane is all one piece, with a removable hatch that offers access the inner cargo bay. All of the electronics live in there, including a Google Nexus 5 smartphone running a custom-designed avionics app that controls the plane, and an RC-plane autopilot that manages the control surfaces with input from the phone. The Razor's wing structure is one piece, with an aileron, winglets, and mount for the small jet engine that clip on.
>"This program was really tasked with showing what is possible."
The aircraft, with a four-foot wingspan, weighs just 1.8 pounds. Loaded with all the electronics gear, it comes in at just under 6 pounds. That lets it fly at 40 mph for as long as 45 minutes, though the team's working to get that up to an hour. An earlier prototype could top 100 mph, and the team believes the plane could hit 120 mph, at the cost of a very quickly drained battery.
It can carry 1.5 pounds, so attaching a camera to it would be no problem. The batteries take two hours to fully charge and are easily swapped out, so if you've got three or four packs on hand, the Razor can be in the air nearly continuously. The plane can be controlled from up to a mile away, or fly on its own using preloaded GPS waypoints to navigate. The team uses the Nexus smartphone's 4G LTE as well, meaning commands could be sent from much farther away, though FAA guidelines have kept them from long-distance testing.
Here's where the 3-D printing really comes in handy: The design can be modified---and reprinted---easily, to be bigger or smaller, carry a sensor or a camera, or fly slower or faster. The plane can be made in 31 hours, with materials that cost $800. Electronics (like the tablet-based ground station) push the price to about $2,500. That's so cheap, it's effectively disposable, especially since you can make another one anywhere you can put a 3-D printer. If one version is flawed or destroyed, you can just crank out another.
Though the team's research contract has run out, they're hoping to get another one next year. If Sheffler's right about how the technology will evolve, MITRE and the DoD would be wise to extend the partnership. "3-D printing is at the phase where personal computers were in the 1980s," Sheffler says. "The technology is almost unbounded."
"This program was really tasked with showing what is possible."
