Sikorsky Cranks Up HEX Hybrid System on the Ground

Sikorsky activates hybrid-electric testbed for HEX tiltwing VTOL, with full uncrewed demonstrator flights targeted for 2027

15 Apr 2026

Sikorsky has fired up the Power Systems Test Bed for its HEX hybrid-electric tiltwing VTOL at its Stratford, Connecticut facility. The ground rig completed its first run in December 2025 and is now in active testing, pushing the aircraft's 1.2-megawatt drivetrain toward readiness ahead of two full uncrewed demonstrator flights targeted for 2027.

At its core, HEX pairs a GE Aerospace CT7 turboshaft engine with Sikorsky-developed electric motors in a series-hybrid configuration. The turboshaft drives a generator, which feeds power to electric motors that turn proprotors mounted on a tilting wing. That wing rotates between vertical and horizontal positions, giving the aircraft helicopter-style takeoff capability and efficient high-speed cruise. Sikorsky is targeting a range beyond 500 nautical miles, a figure that places HEX in a different class entirely from the battery-only eVTOL concepts currently chasing FAA certification.

The Power Systems Test Bed is a wire-frame ground rig stripped of its airframe, built specifically to run the drivetrain in isolation. The logic is straightforward: find integration problems early, validate performance on the ground, and avoid surprises when a 9,000-pound aircraft is actually airborne. Two complete HEX air vehicles with aerodynamically finished composite airframes are already taking shape in assembly. First flights are expected in 2027, roughly six to eight months behind the testbed program, with exact timing contingent on what the current ground runs reveal.

Autonomy is baked in alongside propulsion. HEX integrates Sikorsky's Matrix autonomous flight controls, making it pilot-optional by design. That dual emphasis positions the demonstrator as a foundation for future aircraft serving both military logistics and commercial air mobility.

For the US advanced air mobility sector, the test bed activation is a signal worth paying attention to. Hybrid-electric propulsion for long-range, high-speed VTOL has spent years as a roadmap slide. Right now, it is running on the ground in Connecticut, and the sky is next.