While the main mission of China's aerospace plants is to supply the military, they are also under pressure to make money where they can.

For managers and engineers skilled in aeronautics, that often means devising aircraft that might be sold in foreign markets or to domestic civil operators.

Lately, the most eye-catching example of that has been the so-called J-31 stealth fighter, which the Shenyang plant of combat aircraft specialist Avic Aviation Techniques presented at Airshow China in Zhuhai this month as an export product (AW&ST Nov. 19, p. 26). But in a nearby exhibition hall, national space contractor CASC revealed a medium-altitude, long-endurance UAV toting bombs and surface-to-air missiles.

At first sight the aircraft, the CH-4, looks like the Chinese military's answer to the General Atomics MQ-9 Reaper. But while CASC has developed an armed version of the CH-4, the aircraft is basically a surveillance airplane for civil use, say program officials. Indeed, they recognize a drawback in offering the CH-4 with weapons: Foreign governments may be less keen to allow airspace access to an aircraft that, for all they know, could be armed. For the same reason, some U.S. officials expect that no version of the Northrop Grumman RQ-4 Global Hawk, now used for surveillance by the U.S. Air Force, will ever be armed.

Unlike Avic Aviation Techniques, which is working on combat drones, CASC's unmanned-aircraft specialist, the China Academy of Aerospace Aerodynamics in Beijing, concentrates on surveillance types. The CH-4, fairly clearly, was not developed under a military contract, because the group has publicly exhibited it while it is still new.

The CH-4 is the largest unmanned aircraft that the group has revealed, with a span of 18 meters (59.1 ft.) and, in the heavier and armed CH-4B, a gross weight of 1.33 metric tons (2,930 lb.). The Reaper is much larger, with a gross weight of 4.76 tons.

Current sensors include a synthetic-aperture radar with a rotating antenna in a ventral radome and electro-optical and infrared cameras in a ball turret. The academy is working on integrating gravitational and magnetic sensors suitable for geological surveying. Developing an electronic system capable of working with many sensor types was the most difficult part of the program, says a designer.

Reflecting its civil origins, the CH-4 is tied to within 250 km (135 nm) of the base station that controls it because it uses a line-of-sight digital data link—even though its unarmed CH-4A version can fly for 30 hr. Dedicated military UAVs with such long endurance use satellite communications, so they range as far as their fuel allows.

Apart from attacking fixed and slow-moving targets, the CH-4 “suits such functions as border patrol, island protection, anti-terror missions and emergency communications,” says the academy, noting that the aircraft is capable of surveillance, monitoring and target localization. “The aircraft can take off and land automatically and execute programmed flight,” it says, adding that in that respect it outperforms other Chinese drones.

The structure is built mainly of carbon-fiber composite. Lift is 20.5 times drag, the academy says. The powerplant is an adapted automobile engine of 75 kw (100 hp) and fuel capacity is 325 kg (716 lb.). So far, all of CASC's publicly revealed UAVs are propeller-driven, but it would not be surprising to see the group unveil a jet soon.

CH-4 development began in 2009. CASC has moved from prototypes to building pre-production units. The aircraft is not yet in service, however.

Like other builders of unmanned surveillance aircraft, CASC adapts its products to carry weapons. The CH-4 uses the weapons-control system and interface from the earlier CASC CH-3 drone, says the designer. “This is not a complex technology for us,” he says, adding that the armed version has made weapons drops. At Zhuhai, the CH-4 was displayed carrying a pair of AR-1 laser-guided missiles and two satellite-guided bombs. Those are its only weapons.

The overtly military appearance of the CH-4 exhibition was evidently intended more to attract attention than to indicate the aircraft's primary use. The exhibition also included an animated video showing a CH-4 detecting, targeting and destroying enemy trucks.

The academy, also known as the 11th Academy, says it is China's leading base for aerodynamic research and testing and has 25 wind tunnels, “some for low-speed, high-speed, transonic and supersonic testing; some that are conventional and some that are special; some for aerodynamics and some for aerodynamic heating.” Its work extends to research and testing for space equipment and strategic missiles.

CASC's full name is China Aerospace Science and Technology Corp. The group builds space launchers, satellites and manned capsules, among other predominantly space-oriented products.

CH-4 Specifications
CH-4A CH-4B*
Span 18.0 meters 59.1 ft. 18.0 meters 59.1 ft.
Length 8.5 meters 27.9 ft. 8.5 meters 27.9 ft.
Height 3.4 meters 11.2 ft. 3.4 meters 11.2 ft.
Ceiling 8,000 meters 26,200 ft. 7,000 meters 23,000 ft.
Cruise speed 150-180 kph 81-97 kt. 150-180 kph 81-97 kt.
Max speed 235 kph 127 kt. 210 kph 114 kt.
Endurance 30 hr. 14 hr.
Operating radius (line of sight) 250 km 135 nm 250 km 135 nm
Max takeoff weight 1,260 kg 2,770 lb. 1,330 kg 2,930 lb.
Payload 115 kg 253 lb. 345 kg 761 lb.
Armament None 2 AR-1 + 2 small bombs
Source: CASC