Posts
Nick Wijngaards
@nickwijngaards · Jun 10, 2020
I’m curious to see new test footage or specs improvements of the raptor engine. SN1 vs SN20 🚀
Elon Musk
@elonmusk · Jun 10, 2020
Hundreds of improvements in manufacturability primarily (this is by far the hardest problem), mass down, thrust up, Isp up. Current improvement list continues past SN50. As the saying goes, it’s 1% inspiration & 99% perspiration …
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Just A. Tinker
@John_Gardi · Jun 10, 2020
Folks don't realize the mass penalty using hydrogen as rocket fuel.
The Space Shuttle's External Tank carried about four time the volume of liquid hydrogen than its liquid oxygen. Hydrogen is light but takes room that equates to larger tanks. Liquid methane takes much less room.
Elon Musk
@elonmusk · Jun 10, 2020
Also, insulation of a deep cryogen( which I’d call anything that liquifies nitrogen aka 78% of air) is heavy & prone to heat leaks. H2 is hell.
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Elon Musk
@elonmusk · Jun 10, 2020
After which they are recycled
Elon Musk
@elonmusk · Jun 10, 2020
Tesla factory workplace safety is 5% better than industry average for manufacturers & improving fast
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Elon Musk
@elonmusk · Jun 10, 2020
We could never reach 380 Isp with RP/kerosene. CH4 has higher Isp potential on paper, but even better in practice. With CH4, you can reach >99% of max theoretical combustion efficiency, but RP is ~97% on a good day & requires desooting of turbines between flights.
Elon Musk
@elonmusk · Jun 10, 2020
Important technical note: due to higher O/F of CH4 vs RP1 (oxygen is dense) & significant density increase of subcooled CH4 (plus no common dome insulation needed), plus cryo strength bump of CH4, tank mass of CH4/O2 stage is almost same as RP1/O2.
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Everyday Astronaut
@Erdayastronaut · Jun 10, 2020
I know you’d never add unecessary complexity in the manufacturing line, but I’m still surprised you never made a closed cycle Merlin Vacuum to get closer to that 380 mark. Especially with SpaceX’s experience with ox rich preburners now with Raptor 🚀
Elon Musk
@elonmusk · Jun 10, 2020
We could never reach 380 Isp with RP/kerosene. CH4 has higher Isp potential on paper, but even better in practice. With CH4, you can reach >99% of max theoretical combustion efficiency, but RP is ~97% on a good day & requires desooting of turbines between flights.
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Elon Musk
@elonmusk · Jun 10, 2020
Tesla batteries are lasting much longer than 200k miles / 320k km
Elon Musk
@elonmusk · Jun 10, 2020
After which they are recycled
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Elon Musk
@elonmusk · Jun 10, 2020
Moreover, energy produced by Tesla solar deployments far exceeds energy used in our factories
Elon Musk
@elonmusk · Jun 10, 2020
Tesla batteries are lasting much longer than 200k miles / 320k km
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Elon Musk
@elonmusk · Jun 10, 2020
Electric cars produce *much* less CO2 than fossil fuel cars, taking both electricity emission & vehicle production into acount
Elon Musk
@elonmusk · Jun 10, 2020
Moreover, energy produced by Tesla solar deployments far exceeds energy used in our factories
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Elon Musk
@elonmusk · Jun 10, 2020
Elon Musk
@elonmusk · Jun 10, 2020
Electric cars produce *much* less CO2 than fossil fuel cars, taking both electricity emission & vehicle production into acount
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Elon Musk
@elonmusk · Jun 10, 2020
Posting Tesla Impact Report, this time with summary points & charts in my reply tweets tesla.com/ns_videos/2019…
Elon Musk
@elonmusk · Jun 10, 2020
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Elon Musk
@elonmusk · Jun 10, 2020
Posting Tesla Impact Report, this time with summary points & charts in my reply tweets
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venus 🧜♀️
@VENUS__6942 · Jun 10, 2020
I'm reading📖
Elon Musk
@elonmusk · Jun 10, 2020
Haha. Will post summary.
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Elon Musk
@elonmusk · Jun 10, 2020
Quite a piece! I should credit Soviet/Russian engine work in the 80’s as being a factor in deciding to switch from H2 to CH4. They demonstrated excellent performance on test stands, with Isp up to 380 secs.
Elon Musk
@elonmusk · Jun 10, 2020
Combined with SpaceX deep subcooling of propellants to near liquefaction temp of N2, use of common dome (CH4 & O2 liquid at similar temps) & higher T/W of engines enables de facto higher delta-V than an H2/O2 stage
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Eric Berger
@SciGuySpace · Jun 10, 2020
This English translation of Dmitry Rogozin's comments on Crew Dragon is something. My favorite part is his comparison of Soyuz to Renaissance artists. "In the same manner the paintings by Leonardo da Vinci, Michelangelo, and Titian are priceless..."
en.roscosmos.ru/21511/
Elon Musk
@elonmusk · Jun 10, 2020
Quite a piece! I should credit Soviet/Russian engine work in the 80’s as being a factor in deciding to switch from H2 to CH4. They demonstrated excellent performance on test stands, with Isp up to 380 secs.
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Elon Musk
@elonmusk · Jun 10, 2020
Wort reading the whole thing
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Elon Musk
@elonmusk · Jun 10, 2020
Replying to @Jg305
We shall see …
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Elon Musk
@elonmusk · Jun 10, 2020
Replying to @flcnhvy
Maybe I should retweet the top four or five point. What caught your eye the most?
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Elon Musk
@elonmusk · Jun 10, 2020
Replying to @flcnhvy
Good point!
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James Stephenson
@ICannot_Enough · Jun 10, 2020
Is the leaked semi production email legit?
Elon Musk
@elonmusk · Jun 10, 2020
Yes
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Ross Gerber
@GerberKawasaki · Jun 10, 2020
Dear @elonmusk and @Tesla - your sustainability report was amazing and thorough. With such a huge direct impact on #ClimateChange so clearly represented in the report... it’s surprising none of the findings were covered in the media. $tsla
Elon Musk
@elonmusk · Jun 10, 2020
(Formerly) mainstream media has systemic negative & political bias about almost everything. Reading major newspapers makes you feel sad & angry. That’s why they’re being crushed by @joerogan. Likes/retweets of old media are extremely low. Ironic article:
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