As powered flight expands to include electric propulsion technologies, aeronautics designers need to understand the electrical, aerodynamic, and structural characteristics of these systems. Therefore, researchers at NASA’s Armstrong Flight Research Center have developed a modular test stand to conduct extensive measurements for efficiency and performance of electric propulsion systems up to 100 kW in scale.
The test stand helps engineers understand subsystem interactions as well as efficiencies of different batteries, motors, controllers, and propellers. It offers opportunities to determine effective test techniques for this emerging technology. The test stand’s large suite of sensors gathers extensive data on:
- Torque (±1,800 lbf-in)
- Thrust (±500 lbf)
- Motor speed (0 to 20,000 rpm)
- Vibration/acceleration (±50 g, 0.5 Hz to 2 kHz)
- Motor, inverter, and battery voltages and currents (±500V AC/DC, ±500A)
- Temperatures of motor, inverter, and batteries (–40 °C to +125 °C)
- Ground plane acoustics (20 Hz to 16 kHz)
- Atmospheric conditions (e.g., ambient temperature, static/dynamic pressures, wind speed, humidity)
The data acquisition system offers high-speed sampling rates — up to 2.5 million samples per second per channel — enabling the test stand to provide accurate efficiency measurements. Developers can use these measurements to characterize new electric propulsion technologies, refine simulation models, and develop best practices through lessons learned.
- A key feature of this innovation is its modularity, allowing researchers to test a variety of motors, controllers, batteries, and a wide range of parameters. For example:
- The test stand can accommodate different motors, up to 100kw, through the use of motor adapter plates.
- The software reduces reconfiguration time as sensor suites are easily added or removed.
- The top section of the test stand can be quickly removed, enabling easy transport indoors to protect test articles from adverse weather without dismantling the setup.
- The test stand can be mounted onto a truck to perform dynamic testing.
- Modular wiring and test structure allows components to be switched out with minimal changes to the instrumentation and data acquisition system. It also allows certain configurations of the test stand to be easily changed without having to create completely new cabling.
Safety considerations were of paramount importance for NASA Armstrong during the design of this test stand. Remote command and monitoring allows test operations to be conducted from a safe location. Furthermore, software and hardware implementations of emergency shutdowns and lockouts reduce the risk of injury and asset.
NASA Armstrong’s electric propulsion test stand represents a step toward establishing best practices for measuring the performance and efficiencies of these cutting-edge systems.