Demographics and economics in the next 20 years are being examined. They reflect a significant GDP growth and with this a strong demand for commercial aircraft not only in the US and Europe but across Asia and the Middle East. The demand will focus on more fuel efficient and more environmentally friendly vehicles. Significant progress is being made with the new regionals, narrow-body, and wide-body aircraft between now and the year 2020. Looking beyond, the world will examine new airplane architectures, new changes in propulsion systems, and higher thermal and propulsion efficiencies. Distributed propulsion options will come into play. With them, higher operating pressure gas generators will be developed and great attention will have to be ...