tater Posted May 2, 2020 Share Posted May 2, 2020 They can move tanks around. Also, something occurred to me just now that I would do differently. The legs still bug me for the Moon. I'd take at least the 3 legs that don't have RCS on them and keep the shape, but reimagine them as F9 booster legs. They flip out the same way as those, but have not much clearance, matching the smaller legs in that respect. That would massively increase the footprint on the ground. Quote Link to comment Share on other sites More sharing options...
CatastrophicFailure Posted May 2, 2020 Share Posted May 2, 2020 (edited) 8 hours ago, Shpaget said: Half an hour of setting time would be too fast. Do we have any concrete specialists here? What cement like vacuum resistant concoction can we pour on Moon to fix the surface? Concrete. Fast curing time could be an advantage, you’d just need a machine that creeps slowly along laying down a strip of concrete that’s set (but not fully cured) when it comes out the back end. Make multiple passes back and forth and voila, landing pad. These machines actually exist already, would just need to be modified for moon use. this line from that article tho... Quote ...the application of a vacuum to the surface concrete results in a large amount of a vacuum to the surface of the concrete... Um... Edited May 2, 2020 by CatastrophicFailure Quote Link to comment Share on other sites More sharing options...
zolotiyeruki Posted May 2, 2020 Share Posted May 2, 2020 Maybe vacuum bag the concrete to prevent the water from evaporating into space while the concrete sets up and cures? Except that doesn't make sense, since vacuum bagging only works if you have an atmosphere present... Quote Link to comment Share on other sites More sharing options...
RCgothic Posted May 2, 2020 Share Posted May 2, 2020 The water has to be allowed to come out of regular concrete. It sweats as it cures. Quote Link to comment Share on other sites More sharing options...
sevenperforce Posted May 2, 2020 Share Posted May 2, 2020 3 hours ago, magnemoe said: Yes they probably keep the header tanks, they are nice for matching trajectory with gateway or other stuff. Header tank is for supplying Raptors, not for RCS. RCS is gas-gas, pressure-fed from boiloff and autogen press of the main tanks. 3 hours ago, magnemoe said: As cargo is lighter you might shorten the tanks for lunar SSTO operation it still need to do any sort of moon missions including polar. You still need full tank volume. dV for single-stage from LEO to the lunar surface and back again is immense. 1 hour ago, RCgothic said: The water has to be allowed to come out of regular concrete. It sweats as it cures. IIRC the water doesn't come out of the concrete; it reacts with the concrete mix to create the concrete. Quite exothermically, I believe. Quote Link to comment Share on other sites More sharing options...
RCgothic Posted May 2, 2020 Share Posted May 2, 2020 19 minutes ago, sevenperforce said: IIRC the water doesn't come out of the concrete; it reacts with the concrete mix to create the concrete. Quite exothermically, I believe. However it happens it sure is damp. For a project we had to build up a temporary concrete plinth and line it with anti-dust compound and aluminium plate to take an air-skate. Contractor: "Don't paint this for at least two months." Us: "Unfortunately we have to have to use this within a fortnight." Contractor: "Well." Six months later our aluminium liner is curling up at the edges and the anti-dust paint is still tacky from the moisture. Us: "Well." Quote Link to comment Share on other sites More sharing options...
tater Posted May 3, 2020 Share Posted May 3, 2020 Quote Link to comment Share on other sites More sharing options...
tater Posted May 3, 2020 Share Posted May 3, 2020 Looks like they are tanking it up. Quote Link to comment Share on other sites More sharing options...
CatastrophicFailure Posted May 3, 2020 Share Posted May 3, 2020 1 hour ago, tater said: Looks like they are tanking it up. Think they quit or paused, EMS escorted a car over to the area a minute ago. Man, who ever thought a fueling test could be so captivating. Quote Link to comment Share on other sites More sharing options...
kerbiloid Posted May 3, 2020 Share Posted May 3, 2020 Spoiler 8 hours ago, sevenperforce said: 10 hours ago, RCgothic said: The water has to be allowed to come out of regular concrete. It sweats as it cures. IIRC the water doesn't come out of the concrete; it reacts with the concrete mix to create the concrete. Quite exothermically, I believe. No water, no problem. Spoiler Spoiler Methalox... Methane... Natural gas... Shale. They need a lunar shale. Quote Link to comment Share on other sites More sharing options...
CatastrophicFailure Posted May 3, 2020 Share Posted May 3, 2020 Testing shut down for the night, but... Quote Link to comment Share on other sites More sharing options...
RealKerbal3x Posted May 3, 2020 Share Posted May 3, 2020 I'm probably very wrong, but isn't the higher expansion-ratio engine bell one of the only differences between the sea-level and vacuum Raptor variants? The bell will need more propellant pumped through it for regenerative cooling because it's bigger but otherwise RVac is very similar to the SL version. Quote Link to comment Share on other sites More sharing options...
RCgothic Posted May 3, 2020 Share Posted May 3, 2020 (edited) Edited May 3, 2020 by RCgothic Quote Link to comment Share on other sites More sharing options...
RealKerbal3x Posted May 3, 2020 Share Posted May 3, 2020 So Super Heavy has been redesigned again, it seems. 'Legs similar to ship' worries me. Despite their recent redesign, they're still tiny. Won't it be really easy for Super Heavy to tip over on landing? Quote Link to comment Share on other sites More sharing options...
lolkekov Posted May 3, 2020 Share Posted May 3, 2020 Interestingly, the situation with coronavirus can greatly slow down development? Will cut costs in nasa and space x? I think that funding for projects will not be as large as originally planned Quote Link to comment Share on other sites More sharing options...
mikegarrison Posted May 3, 2020 Share Posted May 3, 2020 47 minutes ago, lolkekov said: Interestingly, the situation with coronavirus can greatly slow down development? Will cut costs in nasa and space x? I think that funding for projects will not be as large as originally planned I know we're not supposed to talk politics, but it is impossible to avoid when discussing funding priorities. This really hamstrings our ability to discuss this sort of thing. Quote Link to comment Share on other sites More sharing options...
Rakaydos Posted May 3, 2020 Share Posted May 3, 2020 39 minutes ago, mikegarrison said: I know we're not supposed to talk politics, but it is impossible to avoid when discussing funding priorities. This really hamstrings our ability to discuss this sort of thing. There is an official statement from the NASA administrator that he wants to get human space flight added to any post coronavirus economic stimulus spending bill. I won't get into why space flight is considered economic stimulus, to avoid the politics. Quote Link to comment Share on other sites More sharing options...
kerbiloid Posted May 3, 2020 Share Posted May 3, 2020 Why just "NASA and SpaceX" when everywhere in the world. Quote Link to comment Share on other sites More sharing options...
Wjolcz Posted May 3, 2020 Share Posted May 3, 2020 (edited) 4 hours ago, RealKerbal3x said: So Super Heavy has been redesigned again, it seems. 'Legs similar to ship' worries me. Despite their recent redesign, they're still tiny. Won't it be really easy for Super Heavy to tip over on landing? The tiny legs do look worrisome. I don't think there's much that can be done with this design though. Maybe we're just used to seeing big spread out legs on F9. That things needs to be stable on a swaying barge though. As longs as SS has a stable and flat ground to land on it probably won't be a problem. Edited May 3, 2020 by Wjolcz Quote Link to comment Share on other sites More sharing options...
Nightside Posted May 3, 2020 Share Posted May 3, 2020 39 minutes ago, Wjolcz said: The tiny legs do look worrisome. I don't think there's much that can be done with this design though. Maybe we're just used to seeing big spread out legs on F9. That things needs to be stable on a swaying barge though. As longs as SS has a stable and flat ground to land on it probably won't be a problem. Stability is a function of width of the base and position of the center of mass. SS/SH looks to be much much wider per height than Falcon. What is the height of the Falcon first stage? (for some reason the web only want to tell me the height of the whole rocket ~70m). Quote Link to comment Share on other sites More sharing options...
tater Posted May 3, 2020 Share Posted May 3, 2020 ~44m. The F9 user guide only lists the total height, too. Quote Link to comment Share on other sites More sharing options...
Flavio hc16 Posted May 3, 2020 Share Posted May 3, 2020 (edited) 19 minutes ago, Nightside said: Stability is a function of width of the base and position of the center of mass. SS/SH looks to be much much wider per height than Falcon. What is the height of the Falcon first stage? (for some reason the web only want to tell me the height of the whole rocket ~70m). 1st stage of falcon 9: 41 meters x 3.75m of width ( finess ratio: 10.9), 1st stage of superheavy ( as of right now): 70x9 meters ( ratio 7.8) however we have to consider the legs are 10 meters long but enlarge the base of another 8 meters per side ( more or less) so at the end the width during landing is around 20 meters, so a landing finess ratio of 2.1:1 p.s. i just typed "falcon 9 first stage" and i got the answer Edited May 3, 2020 by Flavio hc16 Quote Link to comment Share on other sites More sharing options...
tater Posted May 3, 2020 Share Posted May 3, 2020 I got something similar, but it said it didn't count the interstage. Quote Link to comment Share on other sites More sharing options...
Nightside Posted May 3, 2020 Share Posted May 3, 2020 2 minutes ago, Flavio hc16 said: 1st stage of falcon 9: 41 meters x 3.75m of width ( finess ratio: 10.9), 1st stage of superheavy ( as of right now): 70x9 meters ( ratio 7.8) however we have to consider the legs are 10 meters long but enlarge the base of another 8 meters ( more or less) so at the end the width during landing is around 20 meters, so a landing finess ratio of 2.1:1 p.s. i just typed "falcon 9 first stage" and i got the answer That's what I typed too! But I just got a lot of things claiming that the height of the 1st stage is 70m, which is wrong. What we can probably only guess at is the height of the CoM, Falcon9's large legs are an asset here, but SH will have 3-4x the engines, so even with puny legs the COM will be pretty low. I would guess that the biggest difference is how much control SpaceX thinks they will have in the terminal landing phase. They may be planning on having more throttle control,which would allow for more time to correct translation. This would reduce the need for wide legs. Based on the videos of F9 Landings, many of the barge landings have been pretty sketchy, with lots of horizontal movement or hard landings, but I can't think of a onshore landing that looked very bad (I'm sure I'm forgetting something). Legs don't get you to space, so the less leg you are carrying the better. But my guess is that the SH legs will get wider as the design progresses if they don't get the level of performance out of raptor they expect. Quote Link to comment Share on other sites More sharing options...
Shpaget Posted May 3, 2020 Share Posted May 3, 2020 4 hours ago, Nightside said: SS/SH looks to be much much wider per height than Falcon. Yup, but Falcon needs to stand upright only at the end of the flight, with tanks empty. SS, would need to have enough fuel to get back from wherever, so tanks will not be empty meaning higher COG. Quote Link to comment Share on other sites More sharing options...
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