I think article could have more mentions of previous developments of rotation detonation engines. Navy experimented with it (for efficiency, not rockets) since

I think article could have more mentions of previous developments of rotation detonation engines. Navy experimented with it (for efficiency, not rockets) since 2012. E.g here's overview with images: https://www.sciencedirect.com/science/article/pii/S1000936115002356 https://www.sciencedirect.com/science/article/pii/S100093611...