Stealth has long been a staple of the U.S. Navy’s most important national security operations. As such, many of these operations take place underwater, where submariners can discreetly eavesdrop on enemy forces and carry out missile strikes if necessary.
But things are changing, and crewed submarines are being replaced by drones.
Technology has disrupted just about every industry over the last couple of decades, and warfare is no exception: the U.S. government is now pouring significant resources into the development and deployment of unmanned undersea drones. And that comes as no surprise, considering the ubiquity of unmanned aerial vehicles (UAVs).
The Need for UUVs
Unmanned underwater vehicles (UUVs) are set to transform the way the U.S. military operates at sea — and the same goes for the 12+ other countries currently working on similar technology.
In an interview with the Christian Science Monitor, Deputy Defense Secretary Robert Work discussed the high cost to staff, maintain, and replace manned submarines, predicting that we’ll see fewer and fewer in operation in the years ahead. “You can’t buy as many manned subs, so UUVs will be a means by which the U.S. will be able to maintain its undersea dominance even with a smaller number of manned submarines,” he said.
What will these underwater drones look like? A team of Singapore researchers led by Jianxin Xu recently revealed an eel-like design prototype that may have serious potential.
One drone the U.S. Navy is looking at is the Slocum Glider, which resembles a torpedo. While that shape works well for missiles, the Slocum’s rigid, inflexible design and rear-facing propellers leave much to be desired for an unmanned vehicle. What happens when it runs into obstacles like underwater reefs? What if it needs to react quickly, make a sharp turn, or back up with little notice?
Nature is pretty good at figuring things out. Millions of years of natural selection have shaped marine life into what it is today, so every species tends to be an expert in its particular environment. With that in mind, you can see why researchers are looking to nature in their quest to design the ultimate UUV.
By mimicking the agility of an eel, Xu’s drone would be able to maneuver seamlessly through small spaces (like reefs, underwater landscapes, and other obstacles). And, thanks to eel-like noiseless propulsion, it would be less detectable and consume less energy than previous models as well.
Anguilliform Locomotion: The Eel’s Secret Weapon
The Navy is looking at a wide range of animal-based design options including jellyfish, eels, and fish—but many experts agree that eels make the most sense and could become the most effective unmanned underwater vehicles.
What’s so special about the eel? Its swimming style.
Anguilliform locomotion (from the Latin anguilla for eel) involves a wave-like motion of the body that pushes water out of the way from side to side. Researchers writing for Nature in 2000 found that European eels can migrate from Europe to the Seagasso Sea with very little food, which demonstrates just how energy-efficient anguilliform swimmers (like eels and sharks) are.
This particular swimming style has stealth advantages as well. It displaces water evenly, making it smoother and less detectable than its predecessors—an essential trait for military use.
But perhaps most importantly, an eel drone could be amphibious. The same movement that propels eels through water could move a drone forward on land, much like a snake. So, should it need to leave the water, it could do so without much trouble.
What Could Eel Drones Do?
Eel bots would be ideal for exploring reefs and underwater geological formations that submarines and other drones wouldn’t be able to access. They could serve many of the functions that today’s submarines perform at a much lower cost and perhaps more effectively.
The applications aren’t limited to the military, though. Marine biologists and explorers could use eel drones to study the uncharted depths of the ocean. Humans have yet to explore 95 percent of the underwater world, but the right UUV could help us lower that percentage significantly.
NASA could also use eel drones on space missions, Space.com reports:
“The connection between the robot and the rover also means that the snake robot will be able to assist the vehicle if the latter gets stuck,” said Pål Liljebäck, a researcher with the Foundation for Scientific and Industrial Research in Norway.
“In such a situation, the robot could lower itself to the ground and coil itself around a rock, enabling the rover to pull itself loose by means of the cable winch, which the rover would normally use to pull the snake robot towards the rover.”
As you can see, there are limitless real-world applications for eel drones. They’re set to change underwater military operations in big ways, but they also have a lot to add to sea and space exploration as well.
What do you think of Jianxin Xu’s eel drone? Can you think of any other applications for this technology? Let us know in the comments below!