Chinese companies and institutions are developing a range of helicopter unmanned air vehicles for military and civilian applications.

Some of the UAVs and models of conceptual aircraft were on display at the Aviation Expo/China 2011 trade show in Beijing.

One of the systems, the Sunward Tech SUV200, has a 200kg (441lb) payload capacity, and was ostensibly built for the monitoring of power lines. However, a video also showed it being used for military applications, such as firing rockets and delivering supplies to soldiers.

Dennis Fetters, a freelance UAV designer who worked with Sunward on the project, said the SUV200 will have its first flight in three months. The aircraft has a 75hp (55kW) engine, and an endurance of up to 3h.

Sunward plans to sell two units and a ground control station for yuan 10 million ($1.6 million). The aircraft can carry a range of weapons and sensors, and has two small internal storage compartments.

Other helicopter UAVs on display included the Beijing Youtaishuncheng Technology Development M28, with contra-rotating blades, and several others using a conventional helicopter layout.

"The big advantage of helicopter UAVs is that they can deliver cargo," said Fetters.

The China Aerospace Science & Industry Corporation also displayed an animated video of three UAV concepts. These included the WJ-600, a full-sized model of which appeared at last year's Air Show China in Zhuhai.

In the video, the WJ-600 operates over both land and sea, attacking moving land targets and ships with missiles. It is also depicted blinding the sensors on warships with an electronic warfare capability