Helix, the Milton Keynes–based specialist in ultra power-dense electric motors and inverters, has teamed up with Californian aerospace startup Astro Mechanica to power a new generation of hybrid-electric supersonic engines. The collaboration centres on Duality™, Astro Mechanica’s proprietary dual‑use propulsion system designed to tackle the biggest economic barrier to supersonic flight: fuel efficiency.
At the heart of the current Duality prototype sit four Helix SPX242‑94 motors. Each unit weighs just 31.3kg yet can deliver 400kW of peak power and up to 470Nm of torque, with 300kW and 286Nm available continuously. Working as part of the propulsor unit, the motors drive a two‑stage compressor and give the system the power density needed to shrink hardware size and weight while maintaining serious thrust capability.
Duality separates the propulsion unit from the turboshaft core using a power‑dense hybrid-electric layout. A gas turbine drives two motors as a turbogenerator to produce electrical power, which then feeds the four Helix machines in the propulsors to control both fan and compressor. This architecture lets the engine behave like a turbofan at subsonic speeds, a turbojet at lower supersonic speeds, and transition towards ramjet-like operation at very high supersonic flight. The result is a combined‑cycle turboelectric adaptive engine that stays efficient from take‑off right through to beyond Mach 3, especially when integrated with Astro Mechanica’s advanced airframe designed for true transpacific range.
Helix is already developing bespoke hardware for the fifth generation of Astro Mechanica’s propulsion system. The new custom motors are designed to power the full‑scale turbogenerator and will each weigh 61.5kg while delivering 900kW of continuous power in both generator and propulsion modes. Peak output is targeted at 950kW at up to 20,000rpm, with maximum torque of 575Nm, and a new isolation system tailored for extreme‑altitude operation.
Thanks to Helix’s radial‑flux motor technology and its focus on power density, the turbogenerator and propulsor can operate at the efficiency levels Duality demands. The partnership brings together Helix’s experience at the sharp end of electric propulsion — from Formula E and record‑breaking hypercars to aerospace and marine projects — with Astro Mechanica’s ambition to make on‑demand supersonic passenger and cargo travel as accessible and economical as today’s commercial aviation.
Astro Mechanica is currently testing the fourth‑generation engine prototype and is targeting a first flight within three years. Over the next decade, the company plans to roll out adaptable, high‑speed systems for government and commercial operators, while deepening its collaboration with Helix as they push the frontier of high‑speed, low‑emissions aviation.