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Aeneas Profile picture
Aeneas
@Phrankensteyn
Space & Energy Numbers Nerd
Jul 3, 2024 • 14 tweets • 4 min read
My more important threads about mostly rocket science listed here.

Disclaimer: keep the posting date in mind. Things might be outdated by now.

And: Keep criticising! I'm happy to learn! Discussing rocket development with focus on Starship:

Jun 16, 2024 • 9 tweets • 3 min read
Remember @SpaceX's ITS image? Impressive Isp, isn't it? Currently, a lot of us would be glad, if Raptor sea-level (SL) achieves at least 341 s and RVac 363 s. But what needs to change to achieve 361 s for Raptor SL and 382 s for RVac?
(1/9) Image Some time ago, I made this study. Showing the ridiculous result of increasing thrust but not enlarging the bell due to spacing issues. You leave a lot of valuable vacuum Isp on the road. But, due to construction tooling and OLM, widening Ship & Booster would be expensive.
(2/9) Image
Aug 11, 2023 • 16 tweets • 5 min read
Aeon R thread: Remember the open cycle thread? Yeah, I'm still not a big fan of that cycle. But, @thetimellis once sad, @relativityspace will run Aeon R at a surprisingly high main chamber pressure. That got me thinking. What could that value be? 1/ https://t.co/5bSZWE175H
Image At first: Why is high pressure useful?
When burning the propellant to increase temperature, the gas particles gain speed. Keep in mind, temperature is a measure for average kinetic energy per particle. But those particles fly chaotically. Not useful for directed thrust. 2/
Jun 2, 2023 • 20 tweets • 6 min read
FFSC/Raptor thread: Recently, Musk reported that @SpaceX achieved 350 bar chamber pressure for Raptor 3. Impressive. Though, is there a limit to the maximum pressure? Or will this go up indefinitely? Does it make sense to further increase that value? 1/ Image Last question first: Increasing chamber pressure (MCCp) is generally good and should be only limited to physical restrains. At some point, plumbing might get too heavy but we're faaar away from that point. Higher MCCp allows higher expansion ratio (ER) with same sized bell. 2/
May 14, 2023 • 11 tweets • 3 min read
Open cycle engine thread: Those engines are a bit tricky if you want to understand their efficiency a bit better. The problem is the gas generator. Usually you don't know the combustion temperature and even then, finding the associated oxidizer-to-fuel ratio (O/F) is hard. 1/x Image Luckily, on Wikipedia it is stated that the F-1 had a max temp of ~820 °C. That's quite on the edge of finding the O/F with RPA (which is possible to a degree). The value is 0.2. That's 0.2 parts oxygen for 1 part RP-1. Stochiometric would be 3 to 1! 2/x