Visitors view an unmanned armed helicopter exhibited at the 12th China International Aviation and Aerospace Exhibition (Airshow China) in Zhuhai, south China's Guangdong Province, Nov. 7, 2018. The average annual growth rate of the global unmanned aircraft system (UAS) industry will maintain at over 20 percent, and its cumulative output value will exceed 400 billion U.S. dollars in 10 years, according to a white paper released Tuesday. (Xinhua/Liang Xu)