SPX242 case study

Helix designed, built and tested the SPX242 Direct Drive Scalable Aerospace Electric Propulsion Demonstrator in partnership with the Midlands Aerospace Alliance and supported by the University of Nottingham’s Unlocking Aerospace Potential funding.




31.2 kg

Continuous Power


Continuous Torque



Click dots or use arrows to reveal variant data



Power peak (kW)380
Power continuous (kW)315
Torque peak (Nm)470
Torque continuous (Nm)324
Speed max (rpm)17,000
Weight (kg)31.2
Overall motor length (mm)300
Stator length (mm)94
Overall unit diameter (mm)265
Materials category5

The future of electric flight

Helix’s clients bring their most demanding requirements to X-Division, where today’s impossible becomes tomorrow’s reality, a process recently proven with the Direct Drive Scalable Aerospace Electric Propulsion Demonstrator.

Derek Jordanou-Bailey, Chief Engineer at Helix who took overall responsibility for the project, explains:

“There is an aerospace requirement for a direct-drive motor. We put a project together on that basis, supported by Midlands Aerospace Alliance funding and Aerospace UP. We wanted to design a motor with a through-shaft architecture so that it could be connected to, for example, a piston engine at one end, with the motor then augmenting the power from the engine in a parallel hybrid arrangement. Alternatively, a propeller could be driven from one end of the motor, while the other provides an auxiliary drive to generators, pumps and so on.’’

Helix Chief Engineer and project leader Derek Jordanou-Bailey

Patented cooling

The SPX242 machine provides a versatile configuration for potential customers enhanced with an integrated mechanical cooling pump. This makes it even more attractive because there is no need for a separate motor, cables, brackets and other items required for an external cooling pump. It added weight to the motor but was fault tolerant and saved on overall mass and complexity. Helix’s advanced sealing technology is incorporated too so that the patented rotor cooling is preserved in the design. The SPX242 project effectively took an existing Helix Scalable Core Technology motor and adapted it to suit a 38mm through-shaft easily connected into another motor, onto a propeller or into other driveline arrangements. This configuration provided a cost effective platform to prove several aerospace technologies under test parameters.

“We’ve proven the design for direct drive and the architecture is beneficial in lots of applications,” Jordanou-Bailey continues. “It could drive a large-diameter fan at high speed with no need for a gearbox, for example, using the shaft to provide ‘distance’ between the rotor bearings in the motor and the more robust bearing system handling the fan loads. With our seal technology the demonstrator ran up to 15,000rpm, developing high power from a relatively small package diameter. We could easily adapt it to drive a gearbox, gearing down to propeller speed. We ran it at 310kW continuous, 380kW peak – geared to drive a shaft at 2,500rpm that means huge torque suitable for driving a large-diameter propeller and a significant mass saving over a larger direct drive motor of the same power.”

Space and weight saving

Compared to a traditional piston aero engine or turbine delivering power in a similar range of 420 to 520hp, the SPX242 electric motor is lighter by around an order of magnitude, considerably smaller and virtually maintenance free. Aviation applications require high continuous power. Helix excels at designing and manufacturing motors suitable for high continuous output, arguably from the world’s most power-dense machines.

Get in touch

Thank you, your enquiry has been sent to us and we will respond to you shortly.

Please fill out the full URL incl. the https eg https://www.ehelix.com/
This site is protected by hCaptcha and its Privacy Policy and Terms of Service apply.

Copyright © 2024 Integral Powertrain Limited, Merlewood Drive, Shenley Wood, Milton Keynes, MK5 6GR

Site designed by Design Inc