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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In this paper, a new nonlinear control allocation method is presented for a distributed electric propulsion (DEP) aircraft. As the electric propellers can be used actively for control, in addition to the control surfaces, the DEP aircraft is over-actuated. This freedom in control effectors can be exploited with an appropriate control allocation method. All control effectors are, therefore, captured in the incremental nonlinear control allocation (INCA) method, which allows taking into account effector nonlinearities and interactions introduced by the propellers. The INCA method is based on a real-time updated Jacobian model of the control effectiveness, thereby solving an efficient linear control allocation problem. This paper reformulates the original INCA method to optimize the control allocation for minimal propeller power, resulting in more efficient flight. A model predictive control (MPC) controller is added as an actuator dynamics compensation method. This ensures that the commanded control inputs from the INCA controller are achieved. The new controller is compared to a standard incremental nonlinear dynamic inversion (INDI) controller with a translational and rotational loop. It is shown in simulation that by combining INCA with MPC, the tracking performance is improved and efficiency increased by 6.1%.@en