December 27, 2022: Taiwan has developed a new SEAD (Suppression of Enemy Air Defenses) loitering munition called Chien Hsiang (Rising Sword). This is a compact 1.2x2 meter (47 x 79 inch) propeller driven UAV that weighs 6 kg (13 pounds). Cruise speed is 185 kilometers an hour, endurance is five hours and max range is 900 kilometers. Its guidance system consists mostly of electronic sensors that can identify signals for specific radars or any other system that emits an electronic signal on a continuous basis. In addition there is a video system that uses a library of images to spot a specific system to be attacked. This is done by Chien Hsiang going into a dive and hitting the target at speeds of up to 600 kilometers an hour. This is sufficient to destroy or disable antennas or radars.

Chien Hsiang is stored and launched from a box shaped container that is part of a 3x4 configuration mounted on a trailer, a fixed location or a ship. The UAVs can be launched individually or in rapid succession to form a swarm. The guidance system takes care of swarm management and coordination. This enables multiple UAVs to search an area and, when a target is found, several or all members of the swarm will attack. Mass production of Chien Hsiang won’t begin until 2024 because of the time required to perfect the guidance system software. While Chien Hsiang is relatively slow, it is small and emits little noise and no electronic signals. That makes it jamming proof and difficult to spot and shoot at.

Chien Hsiang appears similar to a 1990s Israeli SEAD Uav called Harpy. This one is still in use, especially the updated versions like Harpy 2 (or Harop). This is 2.5 meters (8 feet, 2 inches) long, has a 3-meter (9 feet, 10 inches) wingspan and weighs 135 kg (298 pounds). Top speed is 185 kilometers (115 miles) per hour. Harop was exported to India, Turkey and Germany. Unlike the original Harpy design, which was primarily designed to operate autonomously on SEAD missions, the Harop was designed to either operate autonomously (like many UAVs) or under remote control. When operating autonomously it cannot be jammed and it is sent out to detect and home in on radar signals from specific types of enemy air defense radars. In this respect it is like the classic HARM anti-radiation missile, using an anti-radar homing system to cripple enemy air defenses. Unlike Harpy, Harop can also be remotely controlled. This enables the operator to find and select static or moving targets using an onboard vidcam or FLIR (Forward Looking Infrared) heat-sensing camera. While under remote control targets can be hit whether their radar is on or not. The remote-control operation uses line-of-sight communications that are effective at up to 150 kilometers from the operator. That range can be extended using another aircraft or UAV to relay the control signals farther.

Even when sent out with a warhead Harop can return and land if it did not find a target and be reused. Harop also has a stealthy design which, in addition to its small size and quiet engine, makes it very difficult to detect by radar or infrared (heat detecting) sensors. This stealth feature was meant mainly for SEAD missions because most air defense systems have sensors meant to detect approaching hostile aircraft. If these sensors detect an approaching unidentified aircraft the radar can be promptly turned off to avoid a HARM missile or other SEAD airstrike. Modern HARM missiles get around that by capturing the location of a radar signal and then homing in on where it came from, not the signal itself.

Chien Hsiang is similar in appearance to Harpy but lighter, not reusable and with a more capable sensor-based guidance system. Taiwan plans to produce several hundred Chien Hsiangs by 2025 and more after that if the system performs well. There are already plans to produce a version of Chien Hsiang optimized to be a decoy. Chien Hsiang was designed specifically for Chinese radars and other types of transmitters that are land-based or carried by ships.