>Why are we on a another engine redesign?

Just looking at it should tell you a lot about why:

https://www.metal-am.com/wp-content/uploads/sites/4/2024/08/...

It’s cheaper and faster to make in volume. It doesn’t require nearly as much shielding, because it’s less fragile, which saves a lot of weight. The engine itself is lighter. And on top of that, it develops more thrust, at higher fuel efficiency.

The net result is cheaper and lifts significantly more mass to space, which significantly drops the cost per kg to orbit.

It already worked, they’re making it much better, and getting it ready for a level of mass production that we’ve never seen anything close to in the space industry, even from SpaceX. They are much more ambitious than I think people who haven’t been watching them closely understand. The US grid is 1.4 TW of generation, they’re aiming to put up 1 TW of AI compute every year. Maybe they’ll stop well short of that, but their stated goal is insanely ambitious.