The engine—linked to the WS-19 or an advanced WS-15 derivative—completed both ground and simulated high-altitude trials by late 2025. Developed by the Aero Engine Corporation of China (AECC), it uses variable bypass airflow to shift seamlessly between efficiency and power, marking China’s first verified adaptive-cycle success.

Triple-Bypass Prototype Completes Rigorous Testing

AECC’s prototype, featuring a triple-bypass configuration, passed ignition, mode-switching, and thermal endurance checks at its Shaanxi Province high-altitude test center, operational since 2024.

Engineers simulated Mach 4 conditions (about 4,900 km/h at 20–30 km altitude) using vacuum and steam-injection systems.

The engine switched from high-bypass cruise to low-bypass combat mode in under 0.5 seconds without thrust disruption—a key performance metric for sustained maneuvering in contested airspace.

Mode Shifts Without Thrust Loss

The VCE leverages adjustable vanes, flow diverters, and bypass valves to reroute air dynamically between the core and outer streams.

Under full afterburner, it maintained turbine stability at 1,850–1,900 K inlet temperatures, avoiding blade failure issues seen in early WS-15 iterations.

AECC sources described the trials as validating “stable transitions and full-load reliability,” setting up 2026 in-flight mode-switch tests.

Performance Gains Over WS-15

Compared with the WS-15’s 18–20 tons of thrust (40,000 lbf) and fixed bypass ratio of 0.25–0.3, the VCE is projected to deliver 20–22 tons with a variable bypass of 0.2–1.5. Specific thrust rises by roughly 47%—from 320 to up to 470 N/(kg/s)—while fuel consumption drops 37.5%, extending combat radius from 2,000 to over 2,600 km.

The triple-bypass design diverts about 30% of airflow for cooling, a feature essential for directed-energy systems and hypersonic heating control.

Matching Western Adaptive Engines

The VCE’s reported 30–50% range improvement exceeds the 25% boost seen in General Electric’s XA100 under U.S. Next Generation Air Dominance (NGAD) testing.

Analysts view this as Beijing’s clearest propulsion leap since WS-15 serial production began for the J-20.

The new engine could equip future platforms such as the twin-seat J-20S or the rumored J-36, and power “loyal wingman” drones using shared architectures.

Strategic Context and Remaining Hurdles

The breakthrough aligns with China’s 2028–2030 sixth-generation fighter roadmap, integrating AI-assisted control, hypersonic weapons, and adaptive stealth.

Yet experts caution that Mach 4 simulations cannot fully replicate operational stress, and field integration remains unproven.

Past issues—oxidation and turbine fatigue—still shadow AECC programs, though the firm’s output has expanded to 10-ton-class WS-19 variants for lighter airframes.