bmks270 said:

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Ag_of_08 said:

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Not jyst a matter of removing mass, there's a new generation of engines on the way, as well as optimization coming along in construction.

In short yes, there is likely 50 or more tons that can be removed and/or made up for in performance.

That article is making some terrible conclusions and errors... I don't know what SLS program employee payed for it but jeez!! Seems like a hit piece designed to hand wave some of the major issues the SLS is fighting as spacex's fault

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I wouldn't say a "new generation" on the way. Raptor 1 was the big leap.

There is some optimizations to be had as they learn what makes the engines happy, and what the limits are. But there isn't going to be a huge doubling of performance, maybe just a few percent.

Raptor 2 was basically the same as Raptor 1.

Nobody knows yet what chamber pressure they will settle on, I know that's one thing Elon was pushing was higher chamber pressure. So I expect some gains there.


50 tons is a lot, you can't increase isp indefinitely with optimization. It has a theoretical limit which is dependent on the fuel.

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Raptor 2 was a bit more than a few percent increase... Raptor 3 may or may not be as big of a difference, but I'd be willing to bet that it is more than a 'few percent" increase at this point.

Taking the planned mass for flight test 3 as an absolute for production payload capacity seems pretty stupid.

From hit piece reporters to anyone biting on it.

Caliber said:

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bmks270 said:

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Ag_of_08 said:

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Not jyst a matter of removing mass, there's a new generation of engines on the way, as well as optimization coming along in construction.

In short yes, there is likely 50 or more tons that can be removed and/or made up for in performance.

That article is making some terrible conclusions and errors... I don't know what SLS program employee payed for it but jeez!! Seems like a hit piece designed to hand wave some of the major issues the SLS is fighting as spacex's fault

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I wouldn't say a "new generation" on the way. Raptor 1 was the big leap.

There is some optimizations to be had as they learn what makes the engines happy, and what the limits are. But there isn't going to be a huge doubling of performance, maybe just a few percent.

Raptor 2 was basically the same as Raptor 1.

Nobody knows yet what chamber pressure they will settle on, I know that's one thing Elon was pushing was higher chamber pressure. So I expect some gains there.


50 tons is a lot, you can't increase isp indefinitely with optimization. It has a theoretical limit which is dependent on the fuel.

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Raptor 2 was a bit more than a few percent increase... Raptor 3 may or may not be as big of a difference, but I'd be willing to bet that it is more than a 'few percent" increase at this point.

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The truth is that a lot of what gets published from space companies is aspirational, including SpaceX.

There is a difference between what gets published and what is reality. I just don't believe the differences between Raptor 1 and 2 are as large as advertised based on my conversations with people that have intimate knowledge of the program.

nortex97 said:

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bmks270 said:

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lb3 said:

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SpaceX hasn't done much weight optimization at this point.

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You think they have 50 tons worth of mass they can remove?

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The article somehow takes Elon's statement about flight 3's mass to orbit as a payload capacity for starship. He was likely referring to the (mostly empty/no payload) total mass of the upper stage which is not going to even be carrying a (simulated) payload. I don't think it's real logical to surmise he was admitting to a 50% payload/performance shortfall.

There is credible analyses they aren't really 'stretching' the Raptor 2's yet in flight tests to their capacity, which is fine, but the Raptor 3's are the real goal now anyway. Just flying and re-lighting FFSC engines is pretty damn impressive.

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Gracias.

Agreed, and I thank you for taking a bit of a contrarian/skeptical look at it. My reason for confidence in the Raptor figures is just that they have built…a LOT of them for a developmental engine that hasn't gone (fully) into orbit yet even. I don't think they'd logically keep up a charade about the performance/goals if they know it's…not going to hit the figures, and also I think data would have leaked if they aren't getting the thrust numbers advertised.

As well, the rest of the speculation is about…the vehicle/stages themselves. I don't think it makes sense to assume the increased efficiency from the hot staging is actually…decreasing payload to orbit. That's neglecting the whole rationale behind it.

Things are changing and I have no idea what to expect in July/Starship 2 etc, but I do not see any evidence from the commentariat world that Starship is actually…drastically underperforming goals, just the opposite, though there are plenty of 'clickbait' headlines I realize from, heck Marcus House, Zach Golden, Angry Astronaut you name it. They also just removed a lot of the shielding from the design I think on the booster around the engines as it's not needed, so not all changes are adding mass/decreasing payload to be sure.

Myself, it's not the engine/payload specs that worry/concern me, it's whether the catch mechanism(s) will work as advertised anytime soon...if that huge system even survives re-entry. But I'm sure enjoying the show.

I mean if you are trying to cut 50 tons to put 50 more tons up, look no farther than the Raptors to get a good start.

Thats 400kg in savings per raptor from v1 to v2. 33 in the booster is 13200kg. 9 more in Ship and you have 3600kg and you are at 15800 already. 15.8 metric tons is a start.

I bet v3 cuts another 100kg. Now you are at 20 metric tons in mass savings.

Mathguy64 said:

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I mean if you are trying to cut 50 tons to put 50 more tons up, look no farther than the Raptors to get a good start.

Thats 400kg in savings per raptor from v1 to v2. 33 in the booster is 13200kg. 9 more in Ship and you have 3600kg and you are at 15800 already. 15.8 metric tons is a start.

I bet v3 cuts another 100kg. Now you are at 20 metric tons in mass savings.

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Username checks out!