ZHUHAI, China (Reuters) - China's aerospace ambitions took centre stage on the first day of the Zhuhai air show, with COMAC announcing Air China as the first customer for its C929 widebody jet, while a model of the country's first commercial uncrewed spaceplane was on display.

China's Bayi aerobatics team, a flight of four J-20 stealth jets, and the public debut of the country's J-35A stealth fighter were among the aircraft soaring overhead as attendees strolled across the airfield tarmac.

State-owned COMAC also said its regional jet, previously known as the ARJ21, had been improved and rebranded as the C909 for better branding uniformity across its aircraft.

"After careful consideration, a long gestation and asking opinions of many involved parties, we chose to use C909 as the new commercial name to build the brand," Zhang Xiaoguang, COMAC's marketing director, told reporters.

The C909, unveiled at China's biggest airshow painted in white with a blue tail, has also reduced weight, resistance and noise as well as some improvements in flying costs compared to the ARJ21, staff at COMAC's air show booth told Reuters.

COMAC did not disclose the number of C929s that flag carrier Air China would purchase or planned delivery dates. But it announced that Hainan Airlines had placed a firm order for 60 C919 narrowbody jets and 40 C909s.

Colorful Guizhou Airlines has signed a purchase agreement for 30 C909 planes, 20 of which were firm and the remainder provisional, it added.

Airbus China CEO George Xu said his company was not deterred by competition from Chinese jets, saying: "We want to focus our resources to develop with China partners".

The company said at the air show that Chinese certification of the A330neo jet was going smoothly and that the first delivery of the widebody model in the country could come in 2025.

He added that Airbus was "very much pro-free trade" despite a dispute between the European Union and China over electric vehicles and a potential new transatlantic spat after Donald Trump won the U.S. presidential election with a pledge to impose widespread tariffs.

The model of China's first commercial uncrewed spaceplane was displayed by state-controlled aerospace company AVIC which said it was being developed to deliver cargo to China's space station.

According to the official state-run China Daily, the craft "brings a low-cost reusable cargo shuttle solution with Chinese characteristics to space exploration". The China Manned Space Agency awarded AVIC a contract for engineering flight verification of the spaceplane on Oct. 29, the paper reported.

The military's Z-20 helicopter, which experts said was being modified into many useful variants, was also on display. One version, designed to track and attack submarines, was seen as being of particular interest, as it would help the People's Liberation Army Navy operate farther from home shores.

The air show runs to Nov. 17.