Stratospheric flying opportunities for high-speed propulsion concepts
The stratosphere is the highest layer in the atmosphere where aircraft can still fly. Nevertheless, it is presently rarely exploited for commercial aviation. As Europe’s Vision for Aviation predicts globally a six-fold increase in passenger by 2050, flight levels above the troposphere become attractive and maybe the only way to realize this. 

While the lower stratosphere could still be reachable for classical aircraft, the higher altitudes would demand for higher speeds. Various technologies, systems and novel aircraft concepts related to high-speed transport have progressed rapidly over the last 20 years showing their technical feasibility and readiness up to TRL-3. Technology roadmaps elaborated by industrial and research teams indicated their readiness-level can easily be brought up to TRL-6 by 2035 provided the related application can be shown to be commercially exploitable.

The first project goal covers the multi-functional integration of propulsion, aerodynamics, airframes and on-board systems across various disciplines to define and detail a high-speed aircraft configuration enabling long-haul travels.
However, Europe should have simultaneously a directive which flight altitudes are environmentally sustainable on the basis of fuel type and emission rates. This parametric mapping of the stratospheric climate impact covers the second goal of the project.

Last but not least, the potential of stratospheric flight relies also on economic viability. Apart from potential routes, aircraft capacity and performance, development and exploitation costs… the third goal will also consider human factors, social acceptance, implementation and noise issues. 

The present proposal will, contrary to regular viability studies, perform a bottom-up approach. The validity will follow a sound technical and scientific approach and shall demonstrate environmental and economic compatibility. This enables then a formulation of regulatory, technological and socio-economic barriers.