Japan launched a public-private council for aircraft decarbonization in 2022. This manuscript provides the overview of UK FlyZero projects and its 25 open reports and invite readers to consider Japanese strategy.

For the comprehension of the shock wave velocity modulation mechanism, one-dimensional numerical simulation and the theoretical analysis of the Riemann problem was conducted. From the numerical simulation, the shock wave velocity mechanism was summarized as the following four hypothesizes. 1) The shock wave can be accelerated in the temperature increasing region, and decelerated in the temperature decreasing region. 2) The shock wave velocity can be smaller than the initial velocity even at the region just recovered to the initial temperature due to the interaction with the reflected waves. 3) The multi-reflected shock wave generated between contact surfaces can be converged with repeating reflection. 4) The shock wave gradually accelerated due to the overtake effect of the multi-reflected shock waves and can reach the converged state. From the theoretical analysis, the above hypothesizes were confirmed. Based on these analyses, the shock wave velocity modulation mechanism can be explained due to the interaction with the waves generated at the contact surfaces.