[areoform]

I appreciate and respect your enthusiasm. I wish more people were as passionate about spaceflight as you.

Raptor shares the pintle-type injector, which was designed for the LEM and was part of the technology transfer to SpaceX as a part of their participation in the overarching COTS/CRS programs. The engine's design was partly funded by the USAF, and is a part of a rich history of alternate engine designs that all learn/share from one another.

SpaceX in general has leveraged NASA's rich history and high open-ness to integrate this history into their work, https://historycollection.jsc.nasa.gov/JSCHistoryPortal/hist...

Raptor is one of the few advanced engine concepts that have gone from the test stand to near-use, and that's an amazing achievement.

I would be remiss if I didn't point out that Raptor wasn't the first full flowed staged combustion engine. Being the first doesn't change what Raptor has done, taken several technologies from the test-stand phase to flight testing.

Autoland was de-emphasized due to demands for greater control by the astronaut corps. There was also the incident with STS-3. However, the Shuttle was designed from the ground up with GNC that was meant for full-scale autopilot, including landing. They were hoping for long-term space habitation and to send vehicles uncrewed and then return with crews from the Moon, Mars, and perhaps beyond. It was felt that the astronauts would be rusty and weak after continued microgravity exposure so autoland was emphasized during the design process. For its time, the STS had extremely advanced GNC and displayed mission capabilities that hadn't been displayed before. https://ntrs.nasa.gov/citations/19760024058

One of the RS-25 engines was used 22 times. This was engine SN-2012. Another was used 19 times, SN-2019. They were designed to be flown and re-flown 50+ times, each. https://www.researchgate.net/publication/226730434_Reusabili...

BO has performed multiple suborbital flights using the same booster, and have taken scientific payloads for these flights.

Steel is heavier than Al and most other aerospace materials. It was chosen for Starship as a part of a novel Thermal Protection System, without that mission role, it is mass inefficient.

I am happy to hear your palpable excitement. I hope this comment helps you adjust your mental model to a better picture of the industry.

[simonh]

All of these points are well known and understood. Frankly, so what? Musk has been effusive in his praise of NASA’s help at SpaceX and many times has said he couldn’t have done any of it without their help. We know that. What actual point are you trying to make, other than list mainly irrelevant facts.

Yes some Musk fans ridicule NASA for past failures or lost opportunities and that’s a shame. It’s also widely understood in the community that this is mainly due to political interference and constraints forced on the organisation. But none of that has anything to do with your ‘criticisms’.

Take the points about steel. That matters on a non reusable system because you’re wasting weight for no mission relevant purpose, but if it allows you to reuse the vehicle rather than not, is it really still an inefficient choice? What point are you even trying to make? If that even is a criticism, it’s just not relevant. If you genuinely think it’s a bad choice, just say so and say why. But you don’t actually give any explanation of why any of these points matter.

[greedo]

>I hope this comment helps you adjust your mental model to a better picture of the industry.

I hope you realize that not only are you getting downvoted for factual inaccuracies, style of writing etc, but this passive aggressive coda at the end does you no favors...

[valuearb]

I could also appreciate your enthusiasm if you could get your facts right.

1. Raptor does not use Pintle injectors (invented at Caltech), it uses coaxial swirl injectors.

2. Raptor was designed and developed completely by SpaceX for six years before the USAF gave it small contracts to develop specific versions for their potential needs.

3. Raptor is the first full-flow staged combustion rocket engine ever flown. Flying is a lot more important than the lab. And a lot harder given vibration and acceleration effects.

4. The Shuttle autoland system was incomplete when first implemented, it could not land the Shuttle. Even when “completed” NASA never trusted it or allowed its use . The Russians did land Buran with their system.

5. While it’s technically true that RS-25 engines were re-used, they were also required to be completely torn down and rebuilt between flights. At some point you’ve replaced so many parts it’s basically a new engine, and it was an extremely expensive maintenance requirement that entirely negated the value of reuse.

6. BO has never made an orbital flight, which is the key first step for any space travel. It’s never risked a human life in its mini rocket, nor ever flown a paid cargo. It’s still behind the 2006 version of SpaceX, which was attempting orbital flights and succeeding in 2009.

7. Without a thermal protection system your flights are one way and everything is “mass inefficient”. The inefficiency of throwing away a complete launch system every flight is the only inefficiency that matters.

SLS is designed to put 100 tons of payload in orbit. Not including development costs, each launch will cost roughly $1B, with development costs it will be over to $4B per launch. Every bit of that hardware will be destroyed every launch. It’s payload cost per pound will be over $40,000.

The Starship stack is designed to put 110+ tons of cargo in orbit, inside a 120 ton Starship. It’s launch mass will be nearly double the SLS. So on paper it’s actual payload mass percentage is about half the SLS.

But none of the Starship stack is destroyed at launch, it’s all reused. Cost of fuel for each flight is around $500K. It’s launch cost will be less than $50M, eventually maybe $5M. That means it’s payload cost per pound starts at $200/lb and could drop as low as $20/lb.

Sure, build a Starship out of aluminum or carbon fiber if you never want to be able to land it on earth again, or want to land on Mars with far smaller payloads without the massive fuel savings from Aerobraking.

NASA isn’t paying SpaceX to develop Starship. SpaceX is actually getting paid to design a lunar only version of Starship that won’t need thermal protection. Perhaps they’ll custom build NASAs versions out of lighter materials to increase their lunar landing payloads.

But they won’t do that for Starships in general because it makes them too inefficient for their planned missions. Starships efficiency cones from in-orbit refueling, which is how the same Starship can take the same 110+ ton payload to earth orbit, and on to land it on Mars.