Barry Jenakuns
@jenakuns.bsky.social
New profile new Akin Law:
"Capabilities drive requirements, regardless of what the systems engineering textbooks say."
"Capabilities drive requirements, regardless of what the systems engineering textbooks say."
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Superheavy you were supposed to be the good part of Starship; not join the dark side of failing press tests. No more clean transition; all bets are off. (aside from betting against Elon I guess)
Superheavy you were supposed to be the good part of Starship; not join the dark side of failing press tests. No more clean transition; all bets are off. (aside from betting against Elon I guess)
November 21, 2025 at 10:53 PM
:((((((((((((((((
Superheavy you were supposed to be the good part of Starship; not join the dark side of failing press tests. No more clean transition; all bets are off. (aside from betting against Elon I guess)
Superheavy you were supposed to be the good part of Starship; not join the dark side of failing press tests. No more clean transition; all bets are off. (aside from betting against Elon I guess)
Come on they're 535kg each; that's not a cubesat. They're smaller than most Mars missions, but that's still a lot of sat for a $82M budget mission. And it's notable, because the substantial amount of delta V they have is enabling this out of window launch.
November 9, 2025 at 4:55 AM
Come on they're 535kg each; that's not a cubesat. They're smaller than most Mars missions, but that's still a lot of sat for a $82M budget mission. And it's notable, because the substantial amount of delta V they have is enabling this out of window launch.
NASA has had multiple $B's new launch vehicle development become massive white elephants due to a lack of this. All the technology and money in the world is useless if you can't produce a design/market you can execute on and that is probably the primary success of SpaceX.
October 26, 2025 at 4:03 AM
NASA has had multiple $B's new launch vehicle development become massive white elephants due to a lack of this. All the technology and money in the world is useless if you can't produce a design/market you can execute on and that is probably the primary success of SpaceX.
From the SpaceX side of things, Merlin 1D, ASDS VTVL, Raptor are genuine excellent and technical marvels. But it is the lean manufacturing, vertical integration and flat management that makes the capital/IP in their hands valuable.
October 26, 2025 at 4:03 AM
From the SpaceX side of things, Merlin 1D, ASDS VTVL, Raptor are genuine excellent and technical marvels. But it is the lean manufacturing, vertical integration and flat management that makes the capital/IP in their hands valuable.
Going to PICA, the decision to in-house was driven by a NASA SME, but then enabled by the structure of SpaceX to great ends.
"According to Mueller, SpaceX’s material, called PICA-X, is 10 times less expensive than the original, “and the stuff we made actually was better.”"
youtu.be/P06X2TZUKZU?...
"According to Mueller, SpaceX’s material, called PICA-X, is 10 times less expensive than the original, “and the stuff we made actually was better.”"
youtu.be/P06X2TZUKZU?...
Dan Rasky: SpaceX's Collaborative Design Approach
YouTube video by Knowledge @ NASA (ARCHIVED)
youtu.be
October 26, 2025 at 4:03 AM
Going to PICA, the decision to in-house was driven by a NASA SME, but then enabled by the structure of SpaceX to great ends.
"According to Mueller, SpaceX’s material, called PICA-X, is 10 times less expensive than the original, “and the stuff we made actually was better.”"
youtu.be/P06X2TZUKZU?...
"According to Mueller, SpaceX’s material, called PICA-X, is 10 times less expensive than the original, “and the stuff we made actually was better.”"
youtu.be/P06X2TZUKZU?...
This is great. NASA being able to drive government R&D/talent and milestone based funding through an efficient management structure which is then able to tap private capital/markets substantially increases the amount NASA achieves. SpaceX is not an antagonist to NASA; it is their greatest success.
October 26, 2025 at 4:03 AM
This is great. NASA being able to drive government R&D/talent and milestone based funding through an efficient management structure which is then able to tap private capital/markets substantially increases the amount NASA achieves. SpaceX is not an antagonist to NASA; it is their greatest success.
There's still plenty of tech transfer. For example friction stir welding and Al-Li alloys; developed for Shuttle external tank, were used to great effect with Falcon 9. These technologies, combined with pragmatic ideas resulted in stages with fantastic mass fractions that were cheap to make.
October 26, 2025 at 4:03 AM
There's still plenty of tech transfer. For example friction stir welding and Al-Li alloys; developed for Shuttle external tank, were used to great effect with Falcon 9. These technologies, combined with pragmatic ideas resulted in stages with fantastic mass fractions that were cheap to make.
Multiple poor experiences with space vendors is what led to the drive for vertical integration.
With Merlin 1C, the pumps were brought in house, although still based on the initial Fastrac 1.
However over the course of Merlin dev, the pumps have 4x'd their original horsepower; think pump of Theseus.
With Merlin 1C, the pumps were brought in house, although still based on the initial Fastrac 1.
However over the course of Merlin dev, the pumps have 4x'd their original horsepower; think pump of Theseus.
![The Merlin engine itself has undergone a number of improvements, including reducing the number of parts and increasing its power and efficiency. According to Mueller, the 140,000-pound-thrust Merlin 1D, designated the production model for Falcon 9, has the highest thrust-to-weight ratio of any rocket engine ever made.
Significantly, the Merlin engines—like roughly 80 percent of the components for Falcon and Dragon, including even the flight computers—are made in-house. That’s something SpaceX didn’t originally set out to do, but was driven to by suppliers’ high prices. Mueller recalls asking a vendor for an estimate on a particular engine valve. “They came back [requesting] like a year and a half in development and hundreds of thousands of dollars. Just way out of whack. And we’re like, ‘No, we need it by this summer, for much, much less money.’ They go, ‘Good luck with that,’ and kind of smirked and left.” Mueller’s people made the valve themselves, and by summer they had qualified it for use with cryogenic propellants.
“That vendor, they iced us for a couple of months,” Mueller says, “and then they called us back: ‘Hey, we’re willing to do that valve. You guys want to talk about it?’ And we’re like, ‘No, we’re done.’ He goes, ‘What do you mean you’re done?’ ‘We qualified it. We’re done.’ And there was just silence at the end of the line. They were in shock.” That scenario has been repeated to the point where, Mueller says, “we passionately avoid space vendors.”](https://cdn.bsky.app/img/feed_thumbnail/plain/did:plc:rgctb5bjolcv5ixg3rz6ajbo/bafkreid6vrnzs6xno7mkzrdvlzzcea57kzn6o7j344gts5vdlnhcaxydqq@jpeg)
October 26, 2025 at 4:03 AM
Multiple poor experiences with space vendors is what led to the drive for vertical integration.
With Merlin 1C, the pumps were brought in house, although still based on the initial Fastrac 1.
However over the course of Merlin dev, the pumps have 4x'd their original horsepower; think pump of Theseus.
With Merlin 1C, the pumps were brought in house, although still based on the initial Fastrac 1.
However over the course of Merlin dev, the pumps have 4x'd their original horsepower; think pump of Theseus.
Going back to the initial days of SpaceX, one of the initial ideas was horizontal integration. The Fastrac turbopumps made by Barbel Nichols were bought and used for the Merlin 1A. This did aid with development timelines and helped them get a vehicle to pad.
spacenews.com/web-entrepre...
spacenews.com/web-entrepre...
October 26, 2025 at 4:03 AM
Going back to the initial days of SpaceX, one of the initial ideas was horizontal integration. The Fastrac turbopumps made by Barbel Nichols were bought and used for the Merlin 1A. This did aid with development timelines and helped them get a vehicle to pad.
spacenews.com/web-entrepre...
spacenews.com/web-entrepre...
I just don't like using the limited amount of extremely scientifically valuable volatiles for something as commoditized as propellant, so I'm not a fan of full H2/LOX ISRU. And oxygen is by mass 40% of the Moon and everywhere, so it's substantially easier to work with.
October 26, 2025 at 12:48 AM
I just don't like using the limited amount of extremely scientifically valuable volatiles for something as commoditized as propellant, so I'm not a fan of full H2/LOX ISRU. And oxygen is by mass 40% of the Moon and everywhere, so it's substantially easier to work with.
With a 3.1 days/launch cadence, these V2 mini sats and a 5yr replacement time, it implies a max constellation size of ~15,000. This gives them the ability to triple their current capacity which currently supports 7 million users and an annual revenue of ~$10B with some B$ amount of profit.
October 26, 2025 at 12:29 AM
With a 3.1 days/launch cadence, these V2 mini sats and a 5yr replacement time, it implies a max constellation size of ~15,000. This gives them the ability to triple their current capacity which currently supports 7 million users and an annual revenue of ~$10B with some B$ amount of profit.
They've launched a Starlink F9 launch every 3.1 days this year. The current Starlink V2 mini optimized weigh 575kg, compared to the 260kg of V1, so they only launch max of 28 per F9, compared to the original 60 from 2020. However, V2 minis have >2x Gbps/kg capacity compared to those original V1s.
October 26, 2025 at 12:29 AM
They've launched a Starlink F9 launch every 3.1 days this year. The current Starlink V2 mini optimized weigh 575kg, compared to the 260kg of V1, so they only launch max of 28 per F9, compared to the original 60 from 2020. However, V2 minis have >2x Gbps/kg capacity compared to those original V1s.
They make Raptor Vac's. The issue here is that a gimballing R-Vac replacing the sea levels would have significant gimbal limits due to volume constraints, require a new engine section and have engine out reliability issues.
So they took the performance hit to optimise for financial metrics.
So they took the performance hit to optimise for financial metrics.
October 18, 2025 at 5:34 AM
They make Raptor Vac's. The issue here is that a gimballing R-Vac replacing the sea levels would have significant gimbal limits due to volume constraints, require a new engine section and have engine out reliability issues.
So they took the performance hit to optimise for financial metrics.
So they took the performance hit to optimise for financial metrics.
With the argument of cheap launch; SpaceX made the trade that developing a vac optimised gimballing engine wasn't worth it over just taking the performance hit from an averaged vehicle level ISP of ~345s.
Performance efficiency is one side of the coin, financial efficiency is another.
Performance efficiency is one side of the coin, financial efficiency is another.
October 16, 2025 at 11:55 PM
With the argument of cheap launch; SpaceX made the trade that developing a vac optimised gimballing engine wasn't worth it over just taking the performance hit from an averaged vehicle level ISP of ~345s.
Performance efficiency is one side of the coin, financial efficiency is another.
Performance efficiency is one side of the coin, financial efficiency is another.
300 characters get me acting unwise.
October 16, 2025 at 3:13 AM
300 characters get me acting unwise.
Mr Accelerationista stated that sea level engines can't work in a vacuum; I stated this is not accurate.
Is my previous message really all that confusing?
Is my previous message really all that confusing?
October 15, 2025 at 11:41 PM
Mr Accelerationista stated that sea level engines can't work in a vacuum; I stated this is not accurate.
Is my previous message really all that confusing?
Is my previous message really all that confusing?
God damn it I hate XKCD 386
October 15, 2025 at 3:07 AM
God damn it I hate XKCD 386
... under expansion decreases performance compared to optimum, but the engine still works fine which is glaringly obvious by the footage.
It's over expansion which causes issues at sea level with vac engines nozzles failing (although R-Vac sorta gets away with it)
It's over expansion which causes issues at sea level with vac engines nozzles failing (although R-Vac sorta gets away with it)
October 15, 2025 at 3:05 AM
... under expansion decreases performance compared to optimum, but the engine still works fine which is glaringly obvious by the footage.
It's over expansion which causes issues at sea level with vac engines nozzles failing (although R-Vac sorta gets away with it)
It's over expansion which causes issues at sea level with vac engines nozzles failing (although R-Vac sorta gets away with it)
My god these views are so excellent. Moon 2028, Mars 2030, Idk I like the cut of that jib.
Now SpaceX lets do a clean transition to V3; none of this screwing around for 4 launches.
Now SpaceX lets do a clean transition to V3; none of this screwing around for 4 launches.
October 14, 2025 at 3:21 AM
My god these views are so excellent. Moon 2028, Mars 2030, Idk I like the cut of that jib.
Now SpaceX lets do a clean transition to V3; none of this screwing around for 4 launches.
Now SpaceX lets do a clean transition to V3; none of this screwing around for 4 launches.
"WHAT DO YOU MEAN you combined lunar orbit rendezvous with earth orbit rendezvous and still have a lander and launch vehicle that's bigger our Direct proposals with more launches than von Braun Saturn 1B proposal (with a little lunar surface rendezvous just for taste)?"
September 21, 2025 at 1:24 AM
"WHAT DO YOU MEAN you combined lunar orbit rendezvous with earth orbit rendezvous and still have a lander and launch vehicle that's bigger our Direct proposals with more launches than von Braun Saturn 1B proposal (with a little lunar surface rendezvous just for taste)?"