China Aerospace Science and Technology Corporation (CASC) is developing a new variant of its Cai Hong 4 (Rainbow 4, or CH-4) armed reconnaissance medium-altitude long-endurance unmanned aerial vehicle (MALE UAV), which will feature an indigenously manufactured heavy fuel engine (HFE), company sources confirmed with Jane's on 21 December.
Produced by CASC's flight technology division, China Academy of Aerospace Aerodynamics (CAAA), the baseline CH-4 has a carbon fibre-based composite airframe with an 8.5 m-long fuselage and 18 m wingspan. The UAV has a maximum take-off weight (MTOW) of 1,330 kg and payload capacity of 345 kg.
The baseline air vehicle is currently powered by a 100-hp piston engine, which drives a three-bladed variable pitch pusher propeller and enables it to achieve cruise and maximum speeds of up to 180 km/h and 230 km/h, and a maximum endurance of up to 30 hours. It typically performs its missions at altitudes of 9,800-19,600 ft (3,000-5,000 m), although it can operate up to a service ceiling of 23,600 ft.
CAAA has also developed two other variants of the CH-4 platform: the CH-4A, which has a MTOW of 1,260 kg and is configured primarily for reconnaissance missions with a flight endurance of 30 hours; and the strike-oriented CH-4B, which can carry a 345 kg payload but has a shorter flight endurance of 14 hours.
A new variant, the CH-4C, is also being developed based on operational data and customer feedback that the company accumulated since the CH-4 family entered the market in 2014. New features include an improved load-carrying ability and electrical power generation capacity, as well as an updated data processing and electronic architecture. The air vehicle's build quality and flight-control systems have also been upgraded to improve its ability to operate in adverse weather conditions.
CAAA is planning to install an indigenous HFE propulsion system to further push the CH-4's flight envelope and performance.