Helix, the UK manufacturer renowned for being a world-leader in producing power-dense electric motors and inverters, has announced a partnership with California-based
Astro Mechanica to supply electric motors for the US start-up’s adaptive engine concept. Currently, four Helix SPX242-94 motors are integrated into Astro Mechanica’s proprietary dual-use propulsion system, designed to tackle the biggest economic challenge facing supersonic flight — fuel efficiency. The company’s Duality engine, combined with an advanced airframe design, has the potential to unlock supersonic aircraft for near-term military and civilian applications, including national defence, orbital launch, and long-range cargo delivery.
Duality employs power-dense electric motors to separate the propulsion unit from the turboshaft core. A turbogenerator uses a gas turbine to generate electricity via two motors, which in turn power four Helix motors in the propulsors that drive the fan and compressor. This hybrid-electric architecture enables the system to mimic a turbofan at subsonic speeds, a turbojet at lower supersonic speeds, and transition to a ramjet at very high supersonic speeds. The adaptability optimises performance across a wide range of flight speeds and profiles, creating a combined-cycle turboelectric adaptive engine that remains efficient from take-off to Mach 3+. Paired with an advanced airframe, Astro Mechanica is developing what it claims will be the world’s first supersonic aircraft with transpacific capability.
At the heart of Astro Mechanica’s fourth-generation engine prototype are four Helix SPX242-94 motors powering the two-stage compressor of the propulsor unit. Each motor delivers 400kW of peak power with a maximum torque of 470Nm, and can sustain 300kW and 286Nm continuously, all within an exceptionally power-dense package. Helix is also designing custom motors for the fifth generation of Astro Mechanica’s propulsion system.
These motors will power the turbogenerator in the full-scale engine and are expected to deliver 900kW of continuous power in generator or propulsion modes, with peak power of 950kW at up to 20,000rpm and maximum torque of 575Nm. The new motor isolation system is engineered for extreme-altitude operation. Helix’s radial flux motors are a critical enabling technology for Astro Mechanica. Their exceptional power density allows the turbogenerator and propulsor to operate at 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 are 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 completely transform the engineering and economics of whole industries.”
Astro Mechanica is currently testing the fourth generation of its engine prototype and is targeting first flight within three years. Within a 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 will continue to deepen their partnership as they push the frontier of aviation technology.
With roots in motorsport, Helix’s motors, inverters, and electric propulsion units are well established in Formula E and other racing series. Its technology also powers record-breaking hypercars such as the McMurtry Spéirling, Lotus Evija, Czinger 21C, and Aston Martin Valkyrie. In recent years, Helix’s power-dense systems have enabled electrification across aerospace, defence, and marine sectors, with partners including VTOL aircraft developers, space launch providers, racing boats and yachts, and defence platforms spanning land, sea, and air.