Helix Powers Astro Mechanica’s Duality Supersonic Engine
Helix, the UK manufacturer of the world’s most power-dense electric motors and inverters, has partnered with California’s Astro Mechanica to supply electric motors for the startup’s adaptive engine concept. This collaboration positions Helix electric motors at the core of a hybrid-electric approach to supersonic flight that aims to tackle fuel efficiency, one of the primary economic barriers to viable supersonic aircraft.
Astro Mechanica currently integrates four Helix SPX242-94 motors into its proprietary dual-use propulsion system. The company designed its Duality engine and advanced airframe to support near-term military and civilian applications, including national defence, orbital launch, and long-range cargo delivery. By combining high power density with an adaptive architecture, the Duality programme targets efficient performance across demanding mission profiles and high-speed flight.
Duality uses power-dense electric motors to separate the propulsion unit from the turboshaft core. The turbogenerator relies on a gas turbine to generate electricity via two motors, then routes that power to four Helix motors in the propulsors that control the fan and compressor. This configuration gives Astro Mechanica a flexible foundation for a turboelectric adaptive engine.
This hybrid-electric architecture lets the system mimic a turbofan at subsonic speeds, a turbojet at lower supersonic speeds, and a ramjet at very high supersonic speeds. The design optimises performance across a wide range of speeds and flight profiles, and it supports efficient operation from take-off to Mach 3+. Paired with the company’s advanced airframe, this approach underpins Astro Mechanica’s ambition to develop the world’s first supersonic aircraft with transpacific capability.
Astro Mechanica places four Helix SPX242-94 motors at the heart of its fourth-generation engine prototype, where they drive the two-stage compressor of the propulsor unit. These motors deliver 400kW of peak power and 470 Nm of maximum torque. They also provide 300kW of continuous power and 286Nm of constant torque. Helix achieves this output in a compact, exceptionally power-dense package that is well-suited to high-performance aerospace electrification.
Helix now designs custom motors for the fifth generation of Astro Mechanica’s propulsion system. These motors will power the turbogenerator in a full-scale engine and should deliver 900kW of continuous power in generator or propulsion modes. The design targets 950kW of peak power at up to 20,000rpm, with a maximum torque of 575 Nm. Helix has also developed a new motor-isolation system to support extreme-altitude operations.
Helix’s radial flux motor technology provides a critical enabling capability for Astro Mechanica. Its peerless power density enables the turbogenerator and propulsor to achieve the efficiency levels required to realise the Duality engine’s step-change in aviation.
Derek Jordanou-Bailey, Aerospace Chief Engineer at Helix, said: “We are incredibly proud that our electric motors are powering Duality, given its potential to reshape aviation and aerospace. For decades, Helix has worked at the very cutting-edge of electric powertrain technology and is now a critical enabler in the electrification journey of many high-performance sectors. Astro Mechanica’s engine shows that our unrivalled power density stands to transform the engineering and economics of whole industries completely.”
Astro Mechanica continues testing the fourth generation of its engine prototype and targets a first flight within three years. Over the next decade, the company aims to make on-demand, supersonic passenger travel as accessible and affordable as commercial air travel is today. Helix and Astro Mechanica plan to deepen their partnership as they push the frontier of electric propulsion, hybrid-electric engines, and next-generation supersonic aircraft.
Helix brings strong credentials from the high-performance mobility space. With roots in motorsport, the company supplies motors, inverters, and electric propulsion units to Formula E and other racing series. Helix technology also powers record-breaking hypercars such as the McMurtry Spéirling, Lotus Evija, Czinger 21c, and Aston Martin Valkyrie. In recent years, Helix has expanded its power-dense electric systems into aerospace, defence, and marine applications, working with partners across vertical take-off and landing platforms, space launch providers, racing boats and yachts, and defence capabilities spanning land, sea, and air.
