Quote Originally Posted by Edmond View Post
Is there a reason they're numbered 53, 41, 63, and not 1-33?

They have blown up a lot of engines on the test stand. Full flow stage combustion engines are a challenge. None has ever been built and flown before Raptor. Soviet Union has designed them but never flown, probably due to their collapse. Once the system is mastered, the are excellent, the best engines ever. But just yesterday they blew one up again at their test site McGregor.

BTW, similar to Merlin engine development. Tom Müller, their chief engine developer told that story from early SpaceX. He had suggested a number of possible engine designs for their Falcon rocket. But Elon Musk was not happy with any of them. So Müller suggested another design, but there is a reason, why that design has never been built. He said, if they can make it work it will be cheap and reliable. But for sure many will blow up on the test stand during development. Elon said, this is what they are going to do. Result is the very reliable Merlin engine.