Steve Baker
Senior Software Engineer (2013–present)Apr 24

Will SpaceX upgrade Starship to more than three vacuum Raptor engines?

The problem is with the space available.

Although you can fit 33 sea-level Raptors into the 9 meter diameter space at the tail end of the SuperHeavy - the vacuum optimized Raptors need a HUGE engine bell.

Just look at the difference in size (sea-level raptor on the left - vacuum-optimized on the right)…the two engines are almost identical aside from that!

It’s interesting to look at the 1st and 2nd stages of the Falcon-9. It has nine sea-level Merlin engines packed underneath the main rocket - but the second stage has the same diameter - and it’s is pretty much FULL with just one vacuum optimized Merlin!

Same exact rocket motor - but giant bell required for vacuum work.