Compared to any version of Raptor, the RS-25 is a fairly low-performance engine. Raptors operate at a chamber pressure that is 70% higher than the RS-25’s. The sea level thrust of a Raptor 3 is 60% higher than an RS-25’s, it weighs less than half as much and its sea level T/W ratio at nominal throttle is 3.25 times better – 183.5 vs 56.

Trying to remember when the last time a SSME blew up…like Raptors

https://www.youtube.com/watch?v=jd0O4JQCMiE

The short answer to his question, by the way, is “It’s a big pain to be open.” And it is! ITAR compliance alone is a nightmare. But I think SpaceX has shown how the pain paid off for them.

One other note about the patents: As Eager Space reminds us, Elon Musk is notoriously disdainful of patents, and yet he discoveres that SpaceX has filed 87 patents, which is more than twice as many as ULA! But as it turns out, 85 of these patents are related to Starlink design. Apparently he has decided that they have value for staellite design and manufacture in way that they simply don’t for rockets.

Phil Metzger: I was just notified the US Patent Office awarded this patent on a lunar construction technology. It is a method to reduce the energy for sintering lunar soil into a concrete-like material. My hypothesis was that magnetic and microwave susceptibilities should be correlated, since magnetic loss tangent is one of the mechanisms of microwave absorption in minerals.

https://x.com/DrPhiltill/status/1955829518171554108

US Patent 12,384,730 B2
12 AUG 2025

Other materials
https://www.secretprojects.co.uk/threads/what-new-materials-are-there.18181/page-25#post-821838