The Caihong-4, China's top-selling unmanned combat aircraft, will soon have a more powerful engine that is expected to greatly improve its operational capability, according to its maker.

The China Academy of Aerospace Aerodynamics in Beijing, a subsidiary of China Aerospace Science and Technology Corp, said in a news release on Wednesday that a prototype equipped with a new type of heavy-fuel piston engine has recently completed all required tests to verify the drone's autonomous takeoff and landing, load capacity, flight ceiling and radius, as well as other functions.

The successful completion of the test flights confirmed that the upgraded drone is ready for operational deployment. The new version can be deployed on plateaus and islands and will also prove useful in civilian operations such as providing a signal relay in emergencies, extinguishing forest fires and obtaining data for city authorities, the academy said.

The Beijing-headquartered academy is one of China's top military drone exporters. The Caihong-4, popularly known as the CH-4, has been sold to 10 countries, making it the most popular combat-proven drone the country has exported, according to statistics from the academy.

Shi Wen, chief designer of the Caihong, or Rainbow, series, said that CH-4s now in active service are propelled by gasoline engines, while the new version runs on either diesel or kerosene.

"The new engine is the product of a private Chinese company, which owns the full intellectual property rights. It features world-class technologies, greater power, increased reliability and lower fuel consumption and can be used in tough environments," Shi said on Wednesday.

"Equipped with the new engine, the upgraded CH-4 is capable of staying longer in its target airspace, flying further and higher, and carrying more weapons and equipment," he explained.

The new CH-4 will be put on the market as early as next year.

Information from the academy shows that the current model can stay in the air for up to 30 hours on a single task. It has a maximum speed of 230 kilometers per hour, but usually operates at cruising speeds from 150 to 180 km/h.

With a maximum takeoff weight of 1.33 metric tons, it can carry nearly 350 kilograms of weapons and equipment including missiles, bombs, radars, cameras and various civilian payloads.

The drone has accumulated more than 20,000 hours of flight time from users around the world, the academy said.