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Robotbeat🗽 ➐ Profile picture
Robotbeat🗽 ➐
@Robotbeat
“Only we are Earthseed. And the destiny of Earthseed is to take root among the stars.” —Octavia Butler (tweets don't reflect employer policy)
Yomi Shishio Profile picture 1 subscribed
Sep 5, 2023 • 45 tweets • 8 min read
@pronounced_kyle In a basic rocket engine, your combustion chamber can't exceed your injector pressure. Your injector pressure would, in turn, have to be lower than your tank pressure. So your tank pressure would have to be super high. Tank pressure is proportional to tank mass. 2/n @pronounced_kyle That is a PRESSURE fed rocket engine, however. They have a fundamental trade-off between tank mass and operating pressure. The higher operating pressure, the higher the performance (i.e. the higher the thrust for a given mass of propellant used & rocket engine throat area)... 3/n
Aug 28, 2022 • 24 tweets • 5 min read
I like Stephenson, but hard disagree on this. We have tried other methods. They all suck. The specific power of a rocket engine is just absurdly higher than virtually everything else (especially lasers & microwaves), at orders of magnitude lower cost. The efficiency is good, too. And you have physics fighting against you given the elements we have. You want to use beamed lasers or nuclear to make a higher Isp thermal rocket? Well you have to use hydrogen but effectively as inert gas, & the input energy to make hydrogen is 10 times methalox per kg!
Sep 5, 2019 • 21 tweets • 6 min read
My plan on clean power:
1/n stop coal. All coal burning must stop within 12 months of entering office. Conversion to gas is okay, with the understanding that...
2/ No new gas plants. Anything below 50% LHV efficiency phased out in 5yrs. Everything else phased out within 7 unless: 3/ Carbon capture and permanent geological sequestration would be allowed on super high efficiency natural gas plants.
4/ Coal exports stopped immediately. Met coal allowed domestically but must transition to non-fossil alternatives within 7 years (HEAVY subsidy for this).
Aug 31, 2019 • 7 tweets • 2 min read
How to create near-constant multi-terawatt electricity on Mars: millions of solar sails operating as mirrors in areosynchronous orbit, deflecting sunlight to a 100km by 100km solar array on the surface, quadrupling the light intensity and illuminating it night and day. Solar cells are currently as cheap as 8.5 cents per Watt. ~$130billion worth of cells with 2000W/m^2 illumination gives you about 3 terawatts over a 100km by 100km array (a little less if it's circular).