Recognizing the attention currently devoted to the environmental impact of aviation, this three-part publication series introduces two new aircraft propulsion concepts for the timeframe beyond 2030. The first part focuses on the novel steam injecting and recovering aero engine concept. In the second part, the free-piston composite cycle engine (FP-CCE) concept is presented. Complementary to the two technical publications, this third part describes the cooperative project, which was initiated by an interdisciplinary consortium, aiming at the demonstration and the proof-of-concept of both aforementioned aero engine concepts. At the beginning of the project, simulations on propulsion, aircraft system, and test bench level will be conducted. On this basis, preliminary tests and fundamental experiments are planned in order to establish a solid basis for the demonstration. Finally, a system demonstration will be carried out at the laboratory level. Thus, the project allows for a final judgment on both the feasibility of the new concepts and the attainability of the requirements for future aircraft propulsion systems.