University student Frank Wang Tao spends most of his leisure time with model helicopters, and one of his hi-tech creations this summer pulled off the world's first unmanned flight around Mount Everest.
In June, Wang's helicopter swooped over lakes, glaciers and a forest in Tibet during 10-days of test flights.
While his machine looks similar to a normal remote-controlled model helicopter, it is a technological leap forward. It is equipped with the global positioning system and can fly on a pre-programmed flight path.
Battery powered, the model can fly 50 kilometres at a maximum speed of 70 km/h, but can cover 200km when powered by diesel.
A camera attached to the underside of the helicopter allows it to take photographs and videos during flights, sending live images to the user on a handheld remote control unit.
When it's not on a programmed path, the user can manually steer the helicopter by viewing images on the remote control's screen.
Wang, a postgraduate student at the Hong Kong University of Science and Technology (HKUST), started a company in Shenzhen two years ago and now has a fleet of 10 helicopters for hire by clients who want to take aerial photos of the ground.
'My clients include real estate developers who want to take videos of site landscapes or their newly completed projects,' the 29-year-old says. 'Some filmmakers also hire our helicopters ... while private companies need our help for promotional videos.'
Wang says he has been interested in model helicopters since he was a teenager, but it was not until his university years that he became serious about them.
While studying computers and electronic engineering at HKUST, he began to research the technology behind his hobby.
'Model helicopters have been my main hobby since an early age,' he says. 'But I didn't think about the possibility that I could turn an interest into my career.'
The June test-flights were a prelude to Wang's ultimate goal - landing on the 8,850-metre summit of Mount Everest. He says he is now working on upgrades to his helicopter, and will tackle the peak in one year's time. 'The peak's environment is harsh. We have to increase the helicopter's lifting power by a large degree,' he says.
At higher altitudes, the air becomes thinner and makes it more energy-costly for the helicopter to fly, Wang explains.
'The air pressure at 5,000 metres is about 50 per cent that of ground level. When you reach 8,000 metres, it drops further down to 30 per cent. The wind can also be up to 10 times the strength it is on the ground,' he says.
'We have to lengthen the rotary wings from the current 1.8 metres to 2 metres. An electric engine will replace the diesel engine because fuel consumption at that height is huge. And we have to develop a compact but high-powered battery for the electric engine.'
Besides commercial projects, Wang says his helicopters could also be used to monitor environmental changes. In one of his latest projects, his helicopters are helping Tibetan authorities to track the migration of animals on the high plateau.
One of Wang's helicopters helped in rescue and relief work after the Sichuan earthquake last year, taking photographs to help mainland authorities assess the infrastructure damage.