ST Engineering Breathes New Life Into Wing-In-Ground Effect Craft

Credit: ST Engineering

Singapore’s ST Engineering is looking to expand beyond aircraft maintenance, repair and overhaul into something it can call its own—and setting its sights on aircraft technology made famous by the Soviet Union.

Seeing an untapped market for wing-in-ground-effect (WIG) aircraft, especially for missions in the littoral waters around Southeast Asia and beyond, the company partnered in 2023 with local player Wigetworks to form the AirX joint venture to market and scale up Wigetworks’ Airfish series.

Tan Choon Seng Leon Mark, general manager of AirX, says ST Engineering saw the potential in an untapped technology that is “faster than a ferry, safer than a helicopter and cheaper than a seaplane.” The company is entering the market hoping to apply its experience in aeronautical safety, modification and certification.

  • The company aims for Airfish 8 service entry by 2025
  • Potential regional flashpoints bring new military opportunities for aircraft

The WIG effect uses a cushion of air pressure to fly slightly above the water’s surface, resulting in stable flight with a significant reduction in drag and energy expended.

Tan says Wigetworks has proven itself, outliving the “WIG hype” of recent years and producing a product that can be commercialized and scaled quickly with conventional engines. This is in contrast to the Regent Viceroy 12-passenger WIG vehicle under development in the U.S., which will use full electric propulsion. Wigetworks’ flagship product is the 5,500-kg (12,650-lb.) Airfish 8, a 17.2-m-long (56.4-ft.) and 15-m-wide WIG aircraft that can carry a crew of two plus 1,300 kg of cargo or eight passengers.

Powered by a pair of 500-hp General Motors LS-series V-8 automobile engines driving two pusher propellers, the Airfish 8 can achieve a speed of 90 kt with a maximum operating range of 250-300 nm. On the water, it can handle up to sea state 3 (maximum wave height of 3 m) during takeoff and landing.

Unlike the short-wing concept on the Ekranoplan WIG deployed by the Soviets in the 1980s, the Airfish 8 utilizes the large reverse-delta wing design developed by Germany’s Airfoil Development, from which Wigetworks acquired patents, know-how and licenses.

ST Engineering is integrating Garmin avionics and Ray Marine maritime navigation systems into a single human-machine interface, enabling the pilot to see both conventional aircraft instruments and maritime traffic.

“Essentially, we are not looking at training a pilot, but a boat captain-plus,” Tan says. “It’s all about operating and training costs.”

Two Airfish 8 prototypes in Malacca, Malaysia, are undergoing tests and data collection for verification of the baseline design. The next steps are for the design to be cleared by testing and certification company Bureau Veritas before being certified by maritime regulators.

Certification rules for WIG aircraft have been defined clearly by the International Maritime Organization and its aviation counterpart, the International Civil Aviation Organization (ICAO). Type A certification covers only ground-effect flight. Type B includes ground-effect operation and free controlled flight up to 150 m above the surface. Anything above that altitude would fall under ICAO rules and regulations.

AirX is only seeking Type A certification for commercial operation and Type B for certain military customers that are requesting it for active flight controls. There are no near-term goals to attain any aviation type certification. 

Tan is hoping the Airfish can enter service in 2025.

ST Engineering envisions the Airfish 8 as 50% cheaper to operate than a comparable helicopter, and the company aspires to connect remote island communities more efficiently.

In the area of tourism, the WIG aircraft could find a niche among divers, for whom conventional aircraft raise pressurization concerns and ferries suffer from limited range and speed.

Other applications could include first-responder missions and oil spill cleanup, for which the Airfish 8 could arrive quickly without the need for infrastructure such as airfields. The vehicle’s cabin and doors can be modified to fit two joint modular intermodal containers or stretchers in a medevac configuration.

Tan says the company has identified a number of regional markets in which a WIG aircraft could garner traction: Australia, the Caribbean, Japan’s Okinawa and Aomori, the Maldives, Southeast Asia, Turkey’s Black Sea and the U.S. Studies show there could a market for 3,000 WIG aircraft just to replace ferries, helicopters and seaplanes.

“Taking a conservative estimate and capture of 10% of the market, we could see a production capacity of 25-50 WIG craft annually,” he adds. Each aircraft could cost $3-5 million. Although marketed as a commercial product, the Airfish 8 has garnered significant interest in recent months amid military conflicts in Eastern Europe and the Middle East, as well as flashpoints in the Asia-Pacific region.

When skimming the water’s surface, the WIG enjoys a stealth effect; its low altitude makes it hard for conventional long-range search radars to detect, while its no-wake feature makes it difficult to spot from the skies.

Tan says in addition to expected missions such as the delivery of special forces, the Airfish 8 can perform tasks like dropping sensors near borders—a mission that would be “tricky” for a helicopter. Installing a 950-liter (251-gal.) internal fuel bladder could further extend its range to 1,000 nm.

He notes that due to its expeditionary nature, the U.S. Marine Corps is one of the potential users studying the Airfish 8. The Royal Thai Navy also wrote a testimonial letter following a test flight in 2017. U.S. Special Operations Command has not reached out, but Tan hopes it is only “a matter of time as traction builds.” The military is among those requesting certification and permission to fly the Airfish 8 in so-called Type B conditions, possibly over land masses or tree lines.

ST Engineering has begun sizing studies on a new variant called the Airfish X that could seat 24-40 passengers, eyed for service entry in 2028. The company also is evaluating and incorporating technologies such as autonomous systems and considering the integration of novel electrical and hydrogen propulsion technologies. Tan says the company will be engaging established engine companies such as Yamaha and Honda—which have experience in automobile, maritime and hybrid propulsion—for future Airfish engines.

Due to fuel and fire flashpoint restrictions from maritime regulators, there are no immediate plans to integrate turbine engines onto the WIG vehicles, although Tan acknowledges it would be more efficient to use them as the craft scale up in size. 

Chen Chuanren

Chen Chuanren is the Southeast Asia and China Editor for the Aviation Week Network’s (AWN) Air Transport World (ATW) and the Asia-Pacific Defense Correspondent for AWN, joining the team in 2017.

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