After previously teasing an under-development hybrid-electric demonstrator but revealing only sparse programme details, Sikorsky has shared its vision for a tiltwing vertical take-off and landing (VTOL) aircraft called Hex.

During a 27 February press briefing at the Heli-Expo show in Anaheim, Sikorsky president Paul Lemmo said the company is “not confined to rotor blades” as it prepares with partner GE Aerospace to build, test and eventually fly a testbed for its autonomous flight and hybrid-electric propulsion systems.


Source: Sikorsky

Hex is intended to be the first in a series of large VTOL aircraft featuring “varying degrees of electrification”, Sikorsky says 

“What we want to look at is how well a turboshaft engine combined with a 1MW class generator and associated power electronics save on fuel, reduce emissions and optimise engine performance,” Lemmo says.

“We also want to look at how this architecture will provide quieter flight experiences, save on production and operating costs and improve the safety of flight.”  

Sikorksy disclosed that it was developing the demonstrator during last year’s Heli-Expo show but did not share details of the aircraft’s architecture. The Lockheed Martin company chose to pursue a tiltwing design for several reasons, says Lemmo. 

“First is the flexibility to test a range of integrated system dynamics,” he says. “Second, we want the ability to validate the benefits of electrification, and then finally the opportunity to explore new configurations enabled by electrification.”

Tiltwing and tiltrotor concepts have existed for decades, Lemmo acknowledges, but “I’ve always said they make a lot of sense when you can electrify them”. 

Additionally, Sikorsky’s customers have related that range and speed are top priorities for next-generation aircraft, he says, “but they also still need the ability to do the missions that traditional helicopters do”. 

Sikorsky is hoping to achieve a range exceeding 500nm (926km) “at high speed” with the Hex demonstrator, which will have a maximum gross take-off weight of 4,800kg (9,000lb). 

The aircraft itself is not intended to become a commercial product but rather to inform the development of a future family of advanced air mobility vehicles, including rotorcraft and fixed-wing aircraft. ”We envision a family of systems that are safer, more reliable, easier to maintain and can fly farther and faster at a lower cost,” Lemmo says. 

Hex will be equipped with the company’s Matrix technology, enabling it to fly autonomously, he adds: “As we experiment with the aircraft, it will be flown by a pilot but it will have the capability to be autonomous.”

Sikorsky and GE Aerospace are finalising designs for a hybrid-electric systems testbed powered by a 600kW electric motor, which the companies say is the first step in evaluating Hex’s hover performance. 

Flights of a sub-scale proof-of-concept aircraft have already taken place, adds Lemmo, which could pave the way for the Hex to get airborne by 2026.