Bye Aerospace has signed a cooperation agreement with France-based Safran Electrical & Power to equip its eFlyer 2 and eFlyer 4 aircraft with its 100 kW EngineUs electric smart motors. The motors will replace the Siemens SP70D motor, which has been used to power the eFlyer 2 prototype during development work.
The EngineUs 100 unit, which will equip the two fixed-wing all-electric aircraft, features a fully integrated motor controller. Thermal management is handled by an optimized air-cooling system jointly integrated into the airframe by the engine maker and the airframer. According to Safran, the motor will deliver a power density of 2.5 kW/kg at 2,500 rpm.
In a November 16 statement, Bye did not directly explain why it has opted to replace the Siemens motor with the Safran equipment but did hint that program timing may have been a consideration. “Bye Aerospace has concluded that Safran’s EngineUs 100 smart electric motor is the optimal production solution to meet the requirements of our rigorous FAA and EASA certification schedules,” said CEO George Bye.
Bye is working towards certification of the eFlyer 2, which is intended for the primary flight training segment, and the eFlyer 4 for air taxi and advanced training. The Colorado-based company says that it aims to have the eFlyer 2 approved under FAA Part 23 rules by the end of 2022, with the eFlyer 4 to follow around 12 months later. Safran says that it expects to complete EASA typeS certification of the EngineUs 100 in mid-2022.
Unlike the liquid-cooled Siemens motor, the EngineUs motor is air-cooled and features fully integrated power electronics systems. According to Hervé Blanc, Safran’s executive v-p and general manager of the power division, this makes the combined propulsion system more straightforward to integrate into the aircraft.
The eFlyer 2 and eFlyer 4 will have exactly the same motor, which the manufacturer said should deliver further cost savings. Safran says the motors will achieve an efficiency rate of 94 percent, meaning that no more than 6 percent of the power generated is lost before it is transformed into mechanical power. This reduced thermal loss makes air cooling possible and also simplifies the integration process for the propulsion system.
George Bye said that his team is proud of the research and development work completed with Siemens' electric motors division, which is now owned by Rolls-Royce. "For the certification and production phases of the eFlyer 2 and 4 [programs] Safran is ideal and the timing of this important agreement is significant because we now have a production backlog of 711 units [covered by purchase agrements]," he told FutureFlight.
Blanc said that Safran expects to deliver the first prototype motors to support flight testing during the second quarter of 2021. "We are working closely with Bye on the detailed specifications and we will adapt our family to meet their needs, mainly by adapting the interfaces and optimizing the integration," he explained.
According to Blanc, Safran is working with several other electric aircraft manufacturers on a confidential basis. The group, which is a major manufacturer of larger aircraft engines and other systems, is also working with power storage companies Oxis and Electric Power Systems.
