131–137 of 137 posts
https://www.netflix.com/title/80119093 My rocket-science knowledge is abysmal, but I thoroughly enjoyed this article and the Netflix documentary that I have linked to was incredible. Anyone even remotely interested in rockets should check it out :).
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I really appreciate your expertise and that you're taking the time to correct the sometimes overeager amateurs in this thread. But can I suggest you tone down the unnecessary invectives? It's true that there ought to be some social penalty paid when people give confident wrong answers -- it's a pet peeve of mine -- but I think it's sufficient to just say something like "Your comment is incorrect. Here's why, in detai…
All fair, valid and noted. It’s the eve of Opportunity’s demise, and i worked on mars EDL, and the infinite tide of javascripters making statesmanly-yet-quite-mistaken proclamations on physics can feel quite disrespectful to the actual engineers who work on this stuff now, worked on the stuff on both sides in the cold war, and everyone back to goddard, tchiolkovsky and moore. But you are right. More whisky and no mor…
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This is one of the reasons SpaceX uses supercooled fuel and oxydizer (and one of the reasons for going methalox in the first place) - the tanks self-pressurize, so they can skip the Helium system. Pumps are still good because you really don't want the tanks to pressurize at the same pressure as the combustion chamber. If you do, you'll see a rapid disassembly, but your claim on it being unscheduled will be questioned…
This is completely, completely wrong. Really honestly confused nonesense. Supercooling lowers the ullage pressure, if anything increasing the need to pressurise (self or otherwise), because the self pressurisiation (the vapour pressure) is lower. So you have to do additional work to feed the pumps. The only reason to supercool is to increase the density. Your comment is quite incorrect.
https://www.netflix.com/title/80119093 My rocket-science knowledge is abysmal, but I thoroughly enjoyed this article and the Netflix documentary that I have linked to was incredible. Anyone even remotely interested in rockets should check it out :).
Unavailable for me in the UK, what's the name of the documentary?
“Benefits of the full-flow staged combustion cycle include turbines that run cooler and at lower pressure, due to increased mass flow, leading to a longer engine life and higher reliability.” TL; DR Full flow lowers turbine temperatures at the expense of parts complexity. Given turbopumps are the devil’s ass part of rocketry, this has been a sought-after technology. The pay-off isn’t so much efficiency as much as lon…
>According to SpaceX founder Elon Musk, this design was explicitly intended to achieve full reusability of all rocket stages and, as a result, "a two order of magnitude reduction in the cost of spaceflight" (wikipedia also)
And they hope to make the oxygen and methane on Mars for the return journey, using CO2 and ice found on there plus energy from solar cells.
It will be impressive if they do any of those.
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> By "many" you perhaps mean "many American". And by "many American," do you perhaps mean "pretty much just the Space Shuttle Main Engine?" Since that one, has America launched any new staged combustion engine off the ground?
I believe GP meant that not for closed cycle engines, but for all turbo-pump driven engines, which in USA mostly means open loop (gas generator) engines. In USA the tradition was to add complexity in form of gears and extra axes to get pumps running with more optimal speed, while in Russia (USSR) it was to reduce efficiency and gain in simplicity, robustness and mass.
This is an excellent article. Just curious, how much more efficient is the full-flow engine? And, what exactly is the deal with the seals the article is talking about? Anyone have more info?
A staged combustion engine is intrinsically a lot more efficient than an engine where you dump some of your fuel to power the pumps, like in a tapoff or gas-generator engine. Compared to a oxygen-rich full flow you can reach a higher pressure while having better safety margins which will allow you to re-use the engine. The higher your chamber pressure the closer the rocket's thrust at sea level is to its maximum thru…