What is Boom's current plan to make the engines that they need? How is that going? IIRC, the last news was that Rolls-Royce noped out of that (1), which is an

What is Boom's current plan to make the engines that they need? How is that going? IIRC, the last news was that Rolls-Royce noped out of that (1), which is an indicator that it's either not technically or commercially feasible. Are they still planning to design the engines in-house? I'm not an expert, but this seems like it's on the critical path to success, and also high chance of failure. i.e. Without engines, they have nothing, and if Rolls-Royce can't do it, then who can? 1) https://www.space.com/boom-supersonic-rolls-royce-engine-split https://www.space.com/boom-supersonic-rolls-royce-engine-spl...