derega16 Posted August 12, 2020 Share Posted August 12, 2020 (edited) I'm wonder more which centaur? One on atlas V i'm not sure this one still on product tion in 2030's or one on Vulcan with 4 RL-10 or resurrecting G' or T. Edited August 12, 2020 by derega16 Quote Link to comment Share on other sites More sharing options...
RCgothic Posted August 12, 2020 Share Posted August 12, 2020 If Persephone insists on using those low g limits then actually Starship probably wouldn't be suitable as an alternative launch vehicle. I would like to see a refueled starship send a 56t probe to the outer planets with a raptor kick stage some day though, that would be rad. Quote Link to comment Share on other sites More sharing options...
Hannu2 Posted August 13, 2020 Share Posted August 13, 2020 On 7/9/2020 at 7:23 AM, kerbiloid said: According to wiki, that's 4 / 153 * 25 ~= 0.65 bln in the Apollo-time prices. So, if compare it to Saturn V + Apollo, they were probably even more expensive. Maybe, but political situation was completely different on those days. Apollo was a propaganda project for cold war between superpowers. It had so high share of state's budget that nothing even near is possible in foreseeable future. Unfortunately space exploration is now low cost low interest science project for nerds and budgets compete with tardigrade investigations and ancient languages of disappeared cultures. SLS could fit in Apollo -like situation but several billions per launch ruin all current scientific space projects immediately. If administration of USA does not give crazy level of funding for example manned moon operations no one is able to buy SLS launch, which cost about as much as whole flagship class planetary mission. And I do not see such funding very realistic. Quote Link to comment Share on other sites More sharing options...
Space Nerd Posted August 14, 2020 Share Posted August 14, 2020 On 8/12/2020 at 9:36 PM, RCgothic said: I would like to see a refueled starship send a 56t probe to the outer planets with a raptor kick stage some day though, that would be rad. Would using RL-10 on the kick stage be better? Or the TWR would be too low? Quote Link to comment Share on other sites More sharing options...
RCgothic Posted August 14, 2020 Share Posted August 14, 2020 19 minutes ago, Space Nerd said: Would using RL-10 on the kick stage be better? Or the TWR would be too low? Depends on the payload mass relative to the stage mass. For a 56t payload, yes, RL10 would be better if you're staging shortly after the main launch vehicle has burned from the parking orbit. For a 1.3t payload like Persephone, a raptor stage would be better than a Centaur because for small payloads better mass fraction trumps better ISP. TWR isn't really important to vacuum stages already in orbit. Quote Link to comment Share on other sites More sharing options...
tater Posted August 14, 2020 Share Posted August 14, 2020 23 hours ago, Hannu2 said: SLS could fit in Apollo -like situation but several billions per launch ruin all current scientific space projects immediately. Can't really do anything Apollo-like, it's the wrong size given Orion. Quote Link to comment Share on other sites More sharing options...
RealKerbal3x Posted August 14, 2020 Share Posted August 14, 2020 1 hour ago, tater said: Can't really do anything Apollo-like, it's the wrong size given Orion. SLS/Orion is basically Saturn V/Apollo, but the launch vehicle is too small and the spacecraft is too big Quote Link to comment Share on other sites More sharing options...
RCgothic Posted August 17, 2020 Share Posted August 17, 2020 Wow. SLS isn't even necessarily compatible with clipper. Quote Link to comment Share on other sites More sharing options...
tater Posted August 18, 2020 Share Posted August 18, 2020 Quote Link to comment Share on other sites More sharing options...
wumpus Posted August 19, 2020 Share Posted August 19, 2020 maneuvering On 8/14/2020 at 3:58 AM, RCgothic said: TWR isn't really important to vacuum stages already in orbit. TWR isn't completely unimportant in orbit. First, if your fuel is hydrogen you don't want it to boiloff before being burned. Second, unless you plan on taking your time and using pressure-fed hypergolics like Mangalyaan (the spacecraft that brought "pe kicking" to real life) you can easily lose out on the Oberth effect. Scott Manley points out that while the Shuttle maneuvering system may have been fine for the last bit of delta-v needed to circularize the shuttle's orbit, it would have been less effective for achieving escape velocity: https://www.youtube.com/watch?v=5mIRFxYYaC0 That said, the important thing is that this only means that thrust still has advantages in orbit, not that it is absolutely required as in early rocket stages. If your spacecraft can survive the Van Allan belts, ion engines are more than ready to take you anywhere in the solar system from orbit, even if it takes months to spiral away from Earth. Quote Link to comment Share on other sites More sharing options...
tater Posted September 1, 2020 Share Posted September 1, 2020 SLS has their SRB test tomorrow. Full 126 second duration burn. SRB cost is $485,000,000, so that means the burn costs ~3.85 M$ per second. It will burn ~4950kg/s of propellant during this time. If the fuel was $1 bills it would only be burning 3850kg/s, though. So it's actually burning money faster than actually burning money. Quote Link to comment Share on other sites More sharing options...
tater Posted September 1, 2020 Share Posted September 1, 2020 Live in 25 hours. Quote Link to comment Share on other sites More sharing options...
SOXBLOX Posted September 1, 2020 Share Posted September 1, 2020 1 hour ago, tater said: SLS has their SRB test tomorrow. Full 126 second duration burn. SRB cost is $485,000,000, so that means the burn costs ~3.85 M$ per second. It will burn ~4950kg/s of propellant during this time. If the fuel was $1 bills it would only be burning 3850kg/s, though. So it's actually burning money faster than actually burning money. But as we all know, this money comes from trees! Quote Link to comment Share on other sites More sharing options...
KSK Posted September 1, 2020 Share Posted September 1, 2020 2 hours ago, tater said: SLS has their SRB test tomorrow. Full 126 second duration burn. SRB cost is $485,000,000, so that means the burn costs ~3.85 M$ per second. It will burn ~4950kg/s of propellant during this time. If the fuel was $1 bills it would only be burning 3850kg/s, though. So it's actually burning money faster than actually burning money. So I make that $778 per kilogram of propellant, rounding up or $354 per pound. For comparison, Iberico ham, at 2016 prices, comes in at $140 per pound. That was the most expensive pork I could find online - but it ain't got nothing on SLS pork! Quote Link to comment Share on other sites More sharing options...
tater Posted September 1, 2020 Share Posted September 1, 2020 Yeah, the 5 seg SRB has apparently 25% more propellant than STS did (which was supposedly 1.1 million pounds). Quote Link to comment Share on other sites More sharing options...
sh1pman Posted September 2, 2020 Share Posted September 2, 2020 10 hours ago, tater said: SRB cost is $485,000,000, so that means the burn costs ~3.85 M$ per second. Things that KSP doesn’t teach: IRL you can buy several heavy-lift orbital rockets for the price of one SRB. Quote Link to comment Share on other sites More sharing options...
tater Posted September 2, 2020 Share Posted September 2, 2020 SRB test in ~20 minutes (3:05 Eastern time) Quote Link to comment Share on other sites More sharing options...
tater Posted September 2, 2020 Share Posted September 2, 2020 Nothing blew up, that's good. 3 FHe launches expended in 126 seconds. Quote Link to comment Share on other sites More sharing options...
Commodore_32 Posted September 2, 2020 Share Posted September 2, 2020 SLS SRB Test = Sucess. Quote Link to comment Share on other sites More sharing options...
sevenperforce Posted September 2, 2020 Share Posted September 2, 2020 3 minutes ago, tater said: Nothing blew up, that's good. 3 FHe launches expended in 126 seconds. That was toasty. Quote Link to comment Share on other sites More sharing options...
RCgothic Posted September 2, 2020 Share Posted September 2, 2020 (edited) Well that was fun to watch, but I still don't think SRBs should be anywhere near a crewed launch. Edited September 2, 2020 by RCgothic Quote Link to comment Share on other sites More sharing options...
tater Posted September 2, 2020 Share Posted September 2, 2020 SRBs are spectacular, no question. Quote Link to comment Share on other sites More sharing options...
Commodore_32 Posted September 2, 2020 Share Posted September 2, 2020 You can even see that they tested another one in that place. Quote Link to comment Share on other sites More sharing options...
sevenperforce Posted September 2, 2020 Share Posted September 2, 2020 Question I posed to Manley on Twitter but is worth discussing here too: Quote Link to comment Share on other sites More sharing options...
SOXBLOX Posted September 2, 2020 Share Posted September 2, 2020 That'll roast some marshmallows! Cleaned off that dirt slope, too! Beautiful! Moon, here we come! Quote Link to comment Share on other sites More sharing options...
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