A university in Singapore has conducted one of the first practical flights of a solar-powered quadcopter drone.

The prototype has flown as high as 10 meters (about 33 feet) in test flights using solar power with no battery or other energy storage on board, according to the National University of Singapore (NUS), which announced that an engineering team had conducted the test flight.

“Rotary winged aircraft are significantly less efficient at generating lift compared to their fixed wing counterparts [so] a viable 100 per cent solar rotary aircraft that can take-off and land vertically remains a major engineering challenge to date,” the university said in a statement.