China’s upgraded heavy fuel CH-4 UAV achieves first flight

An improved version of the Cai Hong 4 (Rainbow 4, or CH-4) armed reconnaissance medium-altitude long-endurance unmanned aerial vehicle (MALE UAV) equipped with an indigenously manufactured heavy fuel engine (HFE) has completed its maiden flight, its manufacturer China Aerospace Science and Technology Corporation (CASC) announced on 17 August.

Industry sources told AMR on 18 August that the flight occurred in north-western China earlier in July.

The company did not provide details of new engine that was integrated to the CH-4, but sources indicated that the powerplant is the 150hp class turbocharged four-stroke Lark HFE unit developed by the Wuhu-based Anhui Haery Aviation Power (Haery Power). A representative example – designated DB416 – was earlier displayed alongside a full-scale CH-4 UAV at the 2021 edition Airshow China in Zhuhai.

According to company specifications, the Lark HFE is a liquid-cooled engine with a dry weight of 98kg and includes features such as a high-pressure common-rail (HPCR) fuel system, full-authority digital electronic control (FADEC), and a mean time before overhaul rating of 2,000 hours.

Developed by the China Academy of Aerospace Aerodynamics (CAAA) subsidiary of CASC, the CH-4 UAV has a maximum take-off weight (MTOW) of 1,330 kg and payload capacity of 345 kg. The air vehicle is powered by a 100hp-class piston engine in its standard configuration, which drives a three-bladed variable pitch pusher propeller and enables it to achieve a maximum claimed flight endurance of up to 30 hours.

It is understood that the Lark HFE-equipped CH-4 variant can stay aloft for up to 42 hours at cruise speeds, a 40% increase in endurance from the type’s baseline performance.

The new and more powerful engine would also lower fuel consumption by around 20% and significantly reduce the air vehicle’s take-off distance, which in turn enhances its ability to operate in challenging environments such as austere airfields where usable runway space is limited.

Production of CH-4 UAVs for domestic and international customers have surged in recent years, prompting CAAA to expand its production capabilities with a new automated manufacturing facility in the eastern city of Taizhou.

The new facility, located in the Taizhou Bay Circular Economy Industrial Agglomeration Zone, was commissioned in December 2019. The first batch of air vehicles produced in Taizhou – specifically configured for airborne survey and geospatial mapping operations – were delivered to the Zhejiang Department of Natural Resources.

by Jr Ng