RedKraken Posted December 25, 2018 Share Posted December 25, 2018 5 minutes ago, DDE said: Gwynne’s engineers really outdid themselves on the “brutal simplicity” front. It’s beginning to sound like an actual workhorse. Michail Timofeevich would be proud. Its a shame that the grand old men of soviet rocketry could not live to see what spacex is doing now. Korolev, Glushko, Mishin, Chertok and many others. I'd like to think they would have been thrilled. (Glushko may have been surprised (or maybe not) to find his engines powering american rockets.) Quote Link to comment Share on other sites More sharing options...
CatastrophicFailure Posted December 25, 2018 Share Posted December 25, 2018 28 minutes ago, DDE said: Booger hook off the bang switch, yeesh! Quote Link to comment Share on other sites More sharing options...
sh1pman Posted December 25, 2018 Share Posted December 25, 2018 (edited) 8 hours ago, NSEP said: So, it looks like they went for active cooling, removing the heat shield. Their new stainless steel alloy may indeed survive the reentry if actively cooled, but what about everything else? Wouldn’t it fry everything inside? Edited December 25, 2018 by sh1pman Quote Link to comment Share on other sites More sharing options...
MinimumSky5 Posted December 25, 2018 Share Posted December 25, 2018 That's kind of the point of the active cooling? I'm guessing that at least some of the methane gets vented overboard to expell heat, and the reflective alloys will seriously cut down on the amount of absorbed heat. Quote Link to comment Share on other sites More sharing options...
Xd the great Posted December 25, 2018 Share Posted December 25, 2018 20 minutes ago, MinimumSky5 said: That's kind of the point of the active cooling? I'm guessing that at least some of the methane gets vented overboard to expell heat, and the reflective alloys will seriously cut down on the amount of absorbed heat. Hmm. Expelling methane into ionized oxygen. Hmmmmmmm. Quote Link to comment Share on other sites More sharing options...
DDE Posted December 25, 2018 Share Posted December 25, 2018 3 hours ago, sh1pman said: Wouldn’t it fry everything inside? In order to survive in deep space, the interior would be insulated from the outer shell. Ditto for entry. 4 hours ago, RedKraken said: grand Mishin Nope! Quote Link to comment Share on other sites More sharing options...
DDE Posted December 25, 2018 Share Posted December 25, 2018 Hey, while the topic is Red, do you think this hull would be weldable to allow in-situ repairs? We might get the chance to take Vulcan out for a spin. Quote Link to comment Share on other sites More sharing options...
cubinator Posted December 25, 2018 Share Posted December 25, 2018 6 hours ago, Xd the great said: Hmm. Expelling methane into ionized oxygen. Hmmmmmmm. Hmmmm indeed. I think you could pump the methane around under the skin, negating the need to expel any precious fuel into the open air. Quote Link to comment Share on other sites More sharing options...
DDE Posted December 25, 2018 Share Posted December 25, 2018 1 hour ago, cubinator said: Hmmmm indeed. I think you could pump the methane around under the skin, negating the need to expel any precious fuel into the open air. Probably won’t work. Risks evaporating most offyour propellant before it makes it into the preburner injectors. Quote Link to comment Share on other sites More sharing options...
tater Posted December 25, 2018 Share Posted December 25, 2018 Something just occurred to me. SpaceX has been messing with Stage 2 recovery for years now. Not testing actual recovery, but via instrumentation on S2, and looking at what the actual forces are on the vehicle during reentry. Forget S2 recovery, and think of what data they could glean from this work. They typically do a deorbit burn, and also vent excess props, right? They can vary the entry profile. They can vary the mass of the vehicle (and hence ballistic coefficient). The mass difference is also in this case an amount of cryogenics in the tanks, which changes the thermal behavior of the vehicle during reentry. There has been talk of various active cooling techniques that could be used on Starship (inside the tanks). Makes me wonder what they might have learned playing with S2... Quote Link to comment Share on other sites More sharing options...
sh1pman Posted December 25, 2018 Share Posted December 25, 2018 17 minutes ago, tater said: Something just occurred to me. SpaceX has been messing with Stage 2 recovery for years now. Not testing actual recovery, but via instrumentation on S2, and looking at what the actual forces are on the vehicle during reentry. Forget S2 recovery, and think of what data they could glean from this work. They typically do a deorbit burn, and also vent excess props, right? They can vary the entry profile. They can vary the mass of the vehicle (and hence ballistic coefficient). The mass difference is also in this case an amount of cryogenics in the tanks, which changes the thermal behavior of the vehicle during reentry. There has been talk of various active cooling techniques that could be used on Starship (inside the tanks). Makes me wonder what they might have learned playing with S2... I think that a subscale test version of starship would be the right way to go. Just a shiny stainless steel fuel tank with fins that can be placed on top of a flight-proven S1, with just enough fuel to get to orbit and then deorbit. Allows them to test regenerative cooling, fins, reentry profile, everything else. Much more relevant data than just S2 deorbit. Since it has no payload, they can add a lot of parachutes to land the thing, and actual propulsive landing can be tested with the Grasshopper they’re currently building. Quote Link to comment Share on other sites More sharing options...
CatastrophicFailure Posted December 25, 2018 Share Posted December 25, 2018 (edited) 49 minutes ago, tater said: There has been talk of various active cooling techniques that could be used on Starship (inside the tanks). Makes me wonder what they might have learned playing with S2... Yup. There’s this impression out there that the place rises and falls on the whims of Elon Musk and his flights of fancy, but that’s just not true. All of these changes we’re seeing now have no doubt been in the pipes for a very long time, Musk has made a bigger habit of surrounding himself with some very smart people. There’s a method to this madness, and none of these decisions have been made lightly. 21 minutes ago, sh1pman said: I think that a subscale test version of starship would be the right way to go. Just a shiny stainless steel fuel tank with fins that can be placed on top of a flight-proven S1, with just enough fuel to get to orbit and then deorbit. Allows them to test regenerative cooling, fins, reentry profile, everything else. Much more relevant data than just S2 deorbit. Since it has no payload, they can add a lot of parachutes to land the thing, and actual propulsive landing can be tested with the Grasshopper they’re currently building. I think this is more or less what we’re going to see “in June” as Musk has said, re: S2 recovery attempts for data logging. Something like a hybrid S2/Starship, probably more conventional construction, that drops off a few Starlinks (since either way it’d be pretty radical changes to risk on a customer’s payload) then tests all the reentry stuff. Combine that with the data that will be flowing back from the hopper tests going on at the same time, and all the data they’ve gathered so far and this fantastic ginormous fully-reusable launch vehicle starts to sound more and more reasonable. Heck, even their timelines don’t sound all that unfeasable with that. Edited December 25, 2018 by CatastrophicFailure Quote Link to comment Share on other sites More sharing options...
magnemoe Posted December 26, 2018 Share Posted December 26, 2018 9 hours ago, DDE said: Probably won’t work. Risks evaporating most offyour propellant before it makes it into the preburner injectors. This will require hull, piping for coolant, insulation and finally tank. They might simply heat up gas in the large tank while the liquid fuel is in the small return tanks. you would need to either vent or burn over-pressure in the trusters. At least for the composite version it was an single hull for the tanks. Quote Link to comment Share on other sites More sharing options...
DDE Posted December 26, 2018 Share Posted December 26, 2018 (edited) 6 hours ago, magnemoe said: This will require hull, piping for coolant, insulation and finally tank. They might simply heat up gas in the large tank while the liquid fuel is in the small return tanks. you would need to either vent or burn over-pressure in the trusters. At least for the composite version it was an single hull for the tanks. A lot with regards to tankage configuration depends on how they plant to vacuum-start the Raptor. You know what that white ball is? A supply of evaporated hydrogen fuel for the TLI restart sequence. The Merlin, in contrast, uses an external, finite helium tank to spin up the turbopump. So a lot of hot gas might be handy. I also recall a major engine that solved ullage by using a smaller initial tank that had either some sort of a positive displacement system, or capillary retention of liquid, rather than needing a shove from the RCS. I’ll skim through Sutton during lunch break. Edit: Agena, and it were pistons. Damn, that’s a lot of nifty features for an early space tug. Surface tension was used on LK’s Block E. Edited December 26, 2018 by DDE Quote Link to comment Share on other sites More sharing options...
Xd the great Posted December 26, 2018 Share Posted December 26, 2018 (edited) How does a merlin engine run a fuel rich open cycle with RP-1? Edited December 26, 2018 by Xd the great Quote Link to comment Share on other sites More sharing options...
MinimumSky5 Posted December 26, 2018 Share Posted December 26, 2018 By using a gas generator cycle? Are you asking how that cycle works, or why it was chosen? Quote Link to comment Share on other sites More sharing options...
SaturnianBlue Posted December 26, 2018 Share Posted December 26, 2018 (edited) Has there been any news or new information about the solar panels that will be used on the Starship? To my knowledge, aside from an appearance in the DearMoon video, there has been very little about them, not even estimates of power output. Edited December 26, 2018 by SaturnianBlue Quote Link to comment Share on other sites More sharing options...
Xd the great Posted December 26, 2018 Share Posted December 26, 2018 9 hours ago, MinimumSky5 said: By using a gas generator cycle? Are you asking how that cycle works, or why it was chosen? Rp-1 would be very sooty and has deposits on the cycle right? Quote Link to comment Share on other sites More sharing options...
Mad Rocket Scientist Posted December 27, 2018 Share Posted December 27, 2018 44 minutes ago, Xd the great said: Rp-1 would be very sooty and has deposits on the cycle right? I don't think it is any worse than on the nozzle, since the gas generator doesn't need to burn extremely fuel or oxidizer rich. Plus, the RS-27A, F-1, and RD-107 engines all use RP-1 and the gas generator cycle. Quote Link to comment Share on other sites More sharing options...
DDE Posted December 27, 2018 Share Posted December 27, 2018 (edited) 18 hours ago, Xd the great said: How does a merlin engine run a fuel rich open cycle with RP-1? Because American rocketeers are afraid of superheated oxygen, which would be the other option. Also, random Internet quote: Quote A fuel-rich gas generator mixture ratio produces better engine specific impulse than an oxidizer-rich mixture ratio due to higher specific heat capacity of the turbine gas That explains a lot: the Soviets were obsessed with staged combustion. I’ve found only one oxidizer-rich GG engine (NK-9); Sutton claims there was only one storeable propellant fuel-rich engine, and naturally you have the fuel-rich hydrolox designs. 7 hours ago, Xd the great said: Rp-1 would be very sooty and has deposits on the cycle right? Being able to deal with those deposits is part and parcel of using a hydrocarbon fuel. This is exactly why X-15 opted for ammonia instead. Edited December 27, 2018 by DDE Quote Link to comment Share on other sites More sharing options...
KSK Posted December 27, 2018 Share Posted December 27, 2018 On 12/24/2018 at 11:13 AM, DDE said: Shiny. Gorram shiny. Quote Link to comment Share on other sites More sharing options...
tater Posted December 27, 2018 Share Posted December 27, 2018 Quote Link to comment Share on other sites More sharing options...
sh1pman Posted December 27, 2018 Share Posted December 27, 2018 New architecture, meaning steel hull? Quote Link to comment Share on other sites More sharing options...
ThatGuyWithALongUsername Posted December 27, 2018 Share Posted December 27, 2018 9 minutes ago, sh1pman said: New architecture, meaning steel hull? Yeah. Changing one's mind in 2 months is still a bit more than a few hours. This is the new architecture. Quote Link to comment Share on other sites More sharing options...
Ultimate Steve Posted December 27, 2018 Share Posted December 27, 2018 2 hours ago, ThatGuyWithALongUsername said: Yeah. Changing one's mind in 2 months is still a bit more than a few hours. This is the new architecture. *Starship is on the pad ready for first test flight *At T-10 Elon cancels liftoff and announces extensive changes to the architecture Quote Link to comment Share on other sites More sharing options...
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