Korea works on stratospheric drone

By Lee Min-hyung

A state-run aerospace research body is pushing to develop a stratospheric drone that could stay airborne more than a week, in a move to enhance the nation’s telecommunications and meteorological research capabilities.

The Korea Aerospace Research Institute (KARI) developed the solar-powered EAV-3 drone in 2013. The unmanned aircraft comes with a flight time of 24 hours. It falls short of its overseas counterparts such as Zephyr from England, which can fly two weeks on a single charge.

“The EAV-3 can conduct more research activities only when it can fly at least a week in the stratosphere,” a KARI senior researcher said.

He pointed out the organization needs a long-running battery to achieve its goal.

“A lithium-ion battery used for drones can carry 250 watt-hours per kilogram (Wh/kg), but the capacity is not enough for aeronautical research,” he said. “A lithium-sulfur battery, however, comes with 350 Wh/kg. But only a few battery manufacturers across the globe can develop lithium-sulfur batteries, as they are not commercially used as of now.”

Sion Power from the United States is one of the leading battery companies securing rechargeable lithium-sulfur battery technologies. The company is on track to develop a 650 Wh/kg battery, but is unwilling to sell the product to overseas companies amid concerns over possible technology outflow, according to the researcher.

“The technology is very limited, and other existing battery giants are reluctant to jump into the lithium-sulfur battery industry due to its narrow usage,” he said.

KARI started developing the EAV series in 2010, setting out to design the EAV-3 in 2013 by using Panasonic’s leading lithium-ion battery. The EAV-3 weighs 53 kilograms, flying at up to 43 kilometers per hour.

Last year, the unmanned aerial vehicle stayed at an altitude of 18.5 kilometers for 90 minutes. This was the third time an unmanned aircraft stayed in the stratosphere following Zephyr as well as Helios from U.S.-based firm AeroVironment which supplies tiny drones to the country’s military.

To compete with such leading aerospace vehicle manufacturers, the government should encourage more firms to join the aviation battery industry, the KARI researcher said.

“We are not a battery manufacturer, so we have had to use high-end batteries sold on the local market,” he said. “Backed by the government’s support, however, KARI believes it can join hands with battery firms here and abroad to develop batteries with higher storage used for unmanned aerial vehicles.”