BY JOHN FENG ON 7/21/21 Newsweek
A team of researchers in northwestern China have reportedly designed a prototype drone that has successfully operated both in the air and underwater thanks to special hardware.
The project is led by a group from the School of Mechano-electronic Engineering at Xidian University in Xi'an, Shaanxi province, according to a report Wednesday by Hong Kong's South China Morning Post.
The team is expecting its hardware to have civilian uses in rescue operations, but governments may be eyeing similar "transmedium" hardware to gain an upper hand in future naval warfare, the paper said.
A research paper about the specially designed drone was published in bimonthly journal Flight Dynamics. The journal contains a wide collection of studies related to unmanned aerial vehicles—many for military applications.
According to the report, the researchers were able to successfully fly the drone in and out of water seven times during their tests, which lasted 90 seconds. Currently a proof of concept, the prototype has a maximum flight time of 20 minutes and can carry a payload of up to 500 grams, or just over 1 pound.
In creating the hardware, the researchers overcame challenges including vast differences in density while underwater. This determines the speed at which a drone's rotors must spin to avoid being damaged while submerged.
The one engineered in Xi'an came with two kinds of blades, one of which spins at 3,600 times per minute in water to generate thrust. Research has shown the blades of a typical small commercial multirotor drone can reach between 4,000 and 6,000 revolutions per minute.
"The cross-medium UAV is designed to expand the operating environment and application range of existing aircraft, and can make full use of stealth underwater and high maneuvrability in the air," lead researcher Zhang Shuxin said.
Another challenge is the need for additional communication equipment for use underwater, where radio waves do not travel far, the report said.
Zhang and his team expect the transmedium drone technology to have a wide range of applications in civilian life, such as for lifeguards who might use the device to deliver equipment to drowning victims, the paper noted.
The newspaper says China is developing transmedium drones to be released from submarines for purposes including "airborne surveillance, communication or attack."
"Chinese military scientists are also developing some high-speed, long-range missiles that can jump in and out of water like a flying fish to evade the defense system of a warship or aircraft carrier," Wednesday's report added.
While China is yet to openly announce the deployment of such technologies, it has the potential to change the dynamics of naval strategy, The Post concluded.
