NASA X-57 Maxwell

SCEPTOR: Scalable Convergent Electric Propulsion Technology and Operations Research


NASA New Aviation Horizons Initiative

Distributed Electric Propulsion (DEP) is a new technology frontier, enabling ultra-high efficiency, low carbon emissions, low community noise, and low operating costs.When coupled with the autonomy technology frontier, will enable transformative high-speed On-Demand Mobility10 Year, $4 Billion Initiative to Return NASA to X-Planes




  • Goal: 5x Lower Energy Use (Compared to Original P2006T @ 175 mph)
  • IC Engine vs Electric Propulsion Efficiency changes from 28% to 92% (~3.3x)
  • Synergistic Integration (~1.5x)


  • ~30% Lower Total Operating Cost
  • Zero In-flight Carbon Emissions


  • 15 dB Lower community noise
  • Flight control redundancy and robustness
  • Improved ride quality
  • Certification basis for DEP technologies


Distributed Electric Propulsion Wing High-Lift Impact

Lift Coefficient at 70 mph Takeoff Velocity (with/without 220 kW power into distributed propellers)


SCEPTOR Wing Sizing Impact


  • Same Takeoff/Landing Speed
  • Large Reduction in Wing Area
  • Decreases the Friction Drag
  • Allows Cruise at High Lift Coefficient
  • Less Gust/Turbulence Sensitivity


Cruise Motors

  • Air cooled, direct drive outrunner
  • Replaces 100 HP Rotax 912S engine with 60 kW Joby motor
  • Expected cruise operating point between 42 and 45 kW
  • Tailoring FAA engine design acceptance testing (Part 33) for NASA flight qualification
  • Electrodynamics, thermal and control modeling and prototyping underway


Battery Module Configuration

  • Electric Power Systems design
  • Organized into 8 battery modules per aircraft, split into two packs, each with 4 battery modules and a control module
  • Cooling analysis will drive module spacing, cells spaced at 4mm
  • Nickel Cobalt Aluminum 18650 cells selected; provides sufficient energy density and discharge rate for SCEPTOR mission. Cells arranged in 20p32s modules with BEP between series halves.
  • Each pack is 20p128s; 47 kWh useful capacity, 461 VDC nominal (416 to 525 across SOC range), peak discharge of 132 kW
  • Will comply with flight environment, including 18 g crash loads, -5 to +45 °C operating environment



We’re at the beginning of a 30-50 year propulsion revolution

Electric propulsion is not merely about propulsion, it’s about being able to apply a scale-free technology to fundamentally change how we design vehicles. Synergistic integration of Distributed Electric Propulsion will transform aircraft, and the missions they perform, and potentially society
The age of on-demand services is about to lead to On-Demand Mobility