XB-70A Posted July 31, 2018 Share Posted July 31, 2018 Nice sight. Quote Link to comment Share on other sites More sharing options...
Wjolcz Posted July 31, 2018 Share Posted July 31, 2018 47 minutes ago, XB-70A said: Nice sight. So they took the legs off to transport it? Or is it that first B5 that they wanted to inspect? Quote Link to comment Share on other sites More sharing options...
tater Posted July 31, 2018 Share Posted July 31, 2018 Quote Link to comment Share on other sites More sharing options...
CatastrophicFailure Posted July 31, 2018 Share Posted July 31, 2018 Quote Link to comment Share on other sites More sharing options...
tater Posted July 31, 2018 Share Posted July 31, 2018 Quote Link to comment Share on other sites More sharing options...
DAL59 Posted August 1, 2018 Share Posted August 1, 2018 On 7/27/2018 at 6:31 AM, cubinator said: They might even consider building giant nuclear or electric space tugs at that point. Its hard to say. They could make it wider, to 12 meters, like the ITS, and then add some nuclear gas core engines. 30-50 km/s of deltavee. Quote Link to comment Share on other sites More sharing options...
Xd the great Posted August 1, 2018 Share Posted August 1, 2018 3 hours ago, DAL59 said: They could make it wider, to 12 meters, like the ITS, and then add some nuclear gas core engines. 30-50 km/s of deltavee. Thats a ssto. Quote Link to comment Share on other sites More sharing options...
cubinator Posted August 1, 2018 Share Posted August 1, 2018 3 hours ago, DAL59 said: They could make it wider, to 12 meters, like the ITS, and then add some nuclear gas core engines. 30-50 km/s of deltavee. You can do some serious orbital assembly with even a 9 m ship, and that might be cheaper if the rockets are ~100x reusable. Might even save dry mass on the space tug. Going back to 12 m ITS design would be a sound step either way once the 9 m BFR is flying frequently. 2 minutes ago, Xd the great said: Thats a ssto. TWR ASL is probably way too low to take off, though. Quote Link to comment Share on other sites More sharing options...
Bill Phil Posted August 1, 2018 Share Posted August 1, 2018 20 minutes ago, Xd the great said: Thats a ssto. BFS is already an SSTO, the question is how much payload. Probably around as much to LEO as F9... Quote Link to comment Share on other sites More sharing options...
sevenperforce Posted August 1, 2018 Share Posted August 1, 2018 The problem with nuclear engines is about the same in real life as in KSP -- abysmal atmospheric thrust. They also have the added problem of fluffy deep-cryo propellant and potentially radioactive exhaust. An air-augmented nuclear turborocket (with optional LOX injection for vertical liftoff, or without for horizontal takeoff) can SSTO pretty easily and have good margins for recovery, but you have to play fast and loose with environmental hazards. Quote Link to comment Share on other sites More sharing options...
Bill Phil Posted August 1, 2018 Share Posted August 1, 2018 3 hours ago, DAL59 said: They could make it wider, to 12 meters, like the ITS, and then add some nuclear gas core engines. 30-50 km/s of deltavee. Gas core has a host of problems, and at this point is probably further away than fusion. Quote Link to comment Share on other sites More sharing options...
sevenperforce Posted August 1, 2018 Share Posted August 1, 2018 5 minutes ago, Bill Phil said: Gas core has a host of problems, and at this point is probably further away than fusion. Open-cycle gas core is not too far from fragment fission, from a materials science standpoint. It could be done. Damn the fallout. Closed-cycle gas core is unobtainium-powered science fiction. A rotating pebble-bed reactor with either liquid methane or liquid hydrogen (depending on what flight profile you choose) as coolant will be able to nearly match a closed-cycle gas core without all of the nasties. Quote Link to comment Share on other sites More sharing options...
NSEP Posted August 1, 2018 Share Posted August 1, 2018 26 minutes ago, Bill Phil said: BFS is already an SSTO, the question is how much payload. Probably around as much to LEO as F9... Somewhere between absolutely nothing and 15 tons. I don't think a BFS would be able to send much stuff to LEO. Quote Link to comment Share on other sites More sharing options...
wumpus Posted August 1, 2018 Share Posted August 1, 2018 (edited) 15 minutes ago, sevenperforce said: Open-cycle gas core is not too far from fragment fission, from a materials science standpoint. It could be done. Damn the fallout. Closed-cycle gas core is unobtainium-powered science fiction. A rotating pebble-bed reactor with either liquid methane or liquid hydrogen (depending on what flight profile you choose) as coolant will be able to nearly match a closed-cycle gas core without all of the nasties. From a quick look at the wikipedia explanation of "gas core", I don't think there's much difference between a 1970s NTR and anything with a pebble bed (except the 1970s designed worked better and at least had the possibility of shutting down for a second burn). You also need to look at how Isp is defined. The moment you switch from hydrogen to methane, you might as well be using hydrolox. If you have any uranium in your exhaust, forget about having any Isp (you can't afford to be throwing the heavy stuff away). Note that for any temperature that doesn't melt the pebbles (why being cooled with the exhaust hydrogen), don't expect much Isp. The other issue with pebbles is avoiding a meltdown when you stop ejecting the cooling hydrogen. [back to spacex] Note that even starting a nuclear R&D program requires being on good terms with the military industrial complex (possibly civilian types in less nuclear armed nations, but that isn't a realistic option for spacex). This might take awhile and I suspect that BO has the inside track on MIC friends. Obviously this wouldn't be a problem for ULA, but they aren't going to do anything like this. Edited August 1, 2018 by wumpus "back to spacex" note Quote Link to comment Share on other sites More sharing options...
Wjolcz Posted August 1, 2018 Share Posted August 1, 2018 46 minutes ago, NSEP said: Somewhere between absolutely nothing and 15 tons. I don't think a BFS would be able to send much stuff to LEO. Wasn't the BFS tanker supposed to be the SSTO? There's no point in making it SSTO since the rocket is supposed to be 100% recoverable anyway. Could Nautilus-X be assembled with FH/F9 only? Quote Link to comment Share on other sites More sharing options...
NSEP Posted August 1, 2018 Share Posted August 1, 2018 3 minutes ago, Wjolcz said: Could Nautilus-X be assembled with FH/F9 only? Nautilus X has a few components that won't fit inside the fairing, so they would need to either redesign Nautilus-X construct some of the components in orbit. Maybe they can even make specialized 'Dragon Shuttle' for the Falcon fleet but i doubt it would happend. BFR could probably construct the Nautilus in one or two launches though. Quote Link to comment Share on other sites More sharing options...
tater Posted August 1, 2018 Share Posted August 1, 2018 Use NG in a few years. Quote Link to comment Share on other sites More sharing options...
Wjolcz Posted August 1, 2018 Share Posted August 1, 2018 50 minutes ago, NSEP said: Nautilus X has a few components that won't fit inside the fairing, so they would need to either redesign Nautilus-X construct some of the components in orbit. Maybe they can even make specialized 'Dragon Shuttle' for the Falcon fleet but i doubt it would happend. BFR could probably construct the Nautilus in one or two launches though. Hm. But then these two BFS's could simply be tied together for artificial gravity. Quote Link to comment Share on other sites More sharing options...
NSEP Posted August 1, 2018 Share Posted August 1, 2018 36 minutes ago, tater said: Use NG in a few years. Yeah, New Glenn is a better option for pre-BFR 'cool projects' 2 minutes ago, Wjolcz said: Hm. But then these two BFS's could simply be tied together for artificial gravity. Yes, BFR could probably upscale the Nautilus project, and pretty much any project by alot. BFR could scale everything up 10x. Quote Link to comment Share on other sites More sharing options...
tater Posted August 1, 2018 Share Posted August 1, 2018 Huge version: https://farm2.staticflickr.com/1835/42840169205_8b486529b0_o.jpg Quote Link to comment Share on other sites More sharing options...
ment18 Posted August 1, 2018 Share Posted August 1, 2018 (edited) 2 hours ago, wumpus said: From a quick look at the wikipedia explanation of "gas core", I don't think there's much difference between a 1970s NTR and anything with a pebble bed (except the 1970s designed worked better and at least had the possibility of shutting down for a second burn). You also need to look at how Isp is defined. The moment you switch from hydrogen to methane, you might as well be using hydrolox. If you have any uranium in your exhaust, forget about having any Isp (you can't afford to be throwing the heavy stuff away). Note that for any temperature that doesn't melt the pebbles (why being cooled with the exhaust hydrogen), don't expect much Isp. The other issue with pebbles is avoiding a meltdown when you stop ejecting the cooling hydrogen. [back to spacex] Note that even starting a nuclear R&D program requires being on good terms with the military industrial complex (possibly civilian types in less nuclear armed nations, but that isn't a realistic option for spacex). This might take awhile and I suspect that BO has the inside track on MIC friends. Obviously this wouldn't be a problem for ULA, but they aren't going to do anything like this. Nuclear lightbulb is feasible, they had tested the quartz that the bulb was made of. Your statement about methane ntrs is completely false. In a normal solid core you still get 650s isp, about 200 more then hydrolox. You get a high density propellant that can actually be stored for long duration missions. It requires less water, which and is the main limit for Martian ISRU. The exhaust of a solid core engine is not radioactive. Nearly all nuclear engines info I've seen has very good atmospheric isp, usually like 80% of vacuum, which is better then hydrolox. Shutting down these engines are all relatively simple. Insert control rods, then taper off the flow of propellant as the engine cools. Simple math problem. And spacex already has a nuclear project, it might not have nuclear material yet though. A nuclear powered methane BFS could ssto 100t to leo with the same hull shape. Edited August 1, 2018 by ment18 Quote Link to comment Share on other sites More sharing options...
kerbiloid Posted August 1, 2018 Share Posted August 1, 2018 (edited) Spoiler Not really about SpaceX, but in whole. If a reusable heavy rocket puts into orbit hundreds tonnes, then is it really important if it is SSTO rather than TSTO? The first stage works from 0 to 50 km, then separates and returns back to the launch field. The second stage gets into orbit, separates the payload, performs 1-2 turns and lands on the launch field. Yes, you have to stack them again, but anyway you have to do this with its heavy cargo. Edited August 1, 2018 by kerbiloid Quote Link to comment Share on other sites More sharing options...
Bill Phil Posted August 1, 2018 Share Posted August 1, 2018 2 hours ago, sevenperforce said: Open-cycle gas core is not too far from fragment fission, from a materials science standpoint. It could be done. Damn the fallout. Closed-cycle gas core is unobtainium-powered science fiction. A rotating pebble-bed reactor with either liquid methane or liquid hydrogen (depending on what flight profile you choose) as coolant will be able to nearly match a closed-cycle gas core without all of the nasties. We haven't even built a gas core reactor on the ground. Flight articles are basically out of the picture for the foreseeable future. I also don't think much research is being dedicated to it, and even though fusion isn't being researched as much as it should be it's still likely getting more resources. Gas core seems like something that won't happen. Quote Link to comment Share on other sites More sharing options...
sevenperforce Posted August 1, 2018 Share Posted August 1, 2018 3 hours ago, NSEP said: Somewhere between absolutely nothing and 15 tons. I don't think a BFS would be able to send much stuff to LEO. BFS as SSTO does not have enough fuel reserves to re-enter and land, and it does not have enough TWR to lift off at sea level when fully loaded without running the Raptor Vacs, which is not recommended. Quote Link to comment Share on other sites More sharing options...
NSEP Posted August 1, 2018 Share Posted August 1, 2018 5 minutes ago, sevenperforce said: BFS as SSTO does not have enough fuel reserves to re-enter and land, and it does not have enough TWR to lift off at sea level when fully loaded without running the Raptor Vacs, which is not recommended. Yes. BFS SSTO will likely not be usefull for anything, BFS would have to be modified in order to works as a functional SSTO. Maybe remove some of the Vacuum engines and use that extra space for extra Sea Level engines, and use the spacious cargo bay for extra fuel. They can probaby use the regular passenger BFS for continental hops. Quote Link to comment Share on other sites More sharing options...
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