The potential of Distributed Electric Propulsion (DEP) for future aircraft has been evaluated with Scaled Flight Testing (SFT). Scaled flight testing can contribute to a reduction of risk and cost in the development of a radically new aircraft. The flight dynamics and control of the aircraft have specifically been addressed. The validity of results of scaled flight testing for predicting the full-scale aircraft properties was addressed in a first campaign. A 1:8.5 scaled version of a typical large passenger aircraft was built, tested in the wind tunnel and was subsequently flight tested. During the flight tests an accurate flight test instrumentation system measured the scaled aircraft flight parameters, such as motion, control surface deflections and air data. Results of the scaled flight testing have been compared with full-scale test results which validates the scaled flight testing methodology. In a second campaign the methodology is applied to investigate and demonstrate the benefits of distributed electric propulsion. Aircraft with the same external shape have been used in the two test campaigns, modifying only the propulsion: the twin turbo-jet propulsion of the first campaign was replaced by propulsion with six propellers in the second campaign. This paper presents the highlights and key results of the development, manufacturing, wind tunnel tests, ground tests, taxi tests and flight tests of both campaigns.

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Within the work package radical new aircraft configuration of Cleansky2 Large Passenger Aircraft, a benefit of more than 20% in fuel consumption and CO2 emission (one of CS2 top level objectives) could be achieved by using various Distributed (hybrid) Electric Propulsion DEP architectures on different more or less radical aircraft configurations. It has therefore been identified as a disruptive technology which shall be de-risked in terms of achievable performance during wind tunnel tests and in terms of handling qualities during flight tests. The electric architecture with typical magnitudes shall also be studied in more detail. As already presented during AIAA SciTech Forum and Exhibition 2023, the D08 Distributed Electric Propulsion DEP version of the D03 Scaled Flight Demonstrator has been designed, manufactured and ground tested from 2020 to May 2023. An incident during the last ground test in May 2023 caused the total loss of this demonstrator. After its analysis, it was decided to robustify the electric architecture by improving the batteries, the wiring, the protections and the monitoring. These changes in the electric architectures lead to structural changes like the shift of the emergency parachute and bigger access hatches. The remanufacturing of the DEP-SFD2 has started in September 2023 for an exhaustive integration test campaign and taxi tests in January and February 2024. At the moment, the qualification flight tests will take place in April 2024 and the mission flight tests in May 2024.@en

In the Clean Sky 2 Large Passenger Aircraft (LPA) program the potential of innovative hybrid electric propulsion (HEP) air vehicle concepts has been investigated by the projects ADEC (Advanced Engine and Aircraft Configuration) and NOVAIR (Novel Aircraft Configurations and Scaled Flight Testing Instrumentation). In a combined effort the members of the two projects worked closely together to identify promising technologies for air vehicle concepts that utilize hybrid electric powertrains. The vehicle design studies were divided onto the three distinct teams of DLR, TU Delft/NLR (NOVAIR), and ONERA. This paper will summarize the design efforts and the results obtained from the HEP design space exploration. @en