"Raptor 4" appears to be the hot topic of today. Of course we're super early on so there's not really any details on it. I would like to weigh in on at least what I would expect to see for Raptor 4 as far as design in the below annotation. Certainly not just a straight tube 🙃
Raptor 3 will probably be 2 to 4 times better than Merlin in $/ton of thrust and will exceed Merlin in thrust to weight ratio.
Raptor 4 should beat Merlin by >10X in $/ton of thrust, with further improvement in TWR and ISP.