tater Posted March 16 Share Posted March 16 14 minutes ago, DAL59 said: I have a really stupid idea, whats the mass of the Blue Origin lander fully fueled? Could the easiest Artemis architecture just be putting the Blue Origin lander on a lunar trajectory with an expendable Starship launch? Says ">45t." Dry mass supposedly ~16t. If the Be-7 has an Isp of 450s, then it needs to be at least 56t wet to make a RT from Gateway. In short, it could easily be sent to gateway with an expended SS—with Orion docked to it in LEO. And a huge orital hab module in between for comfort (can be left at Gateway—undock lander, Orion installs module to Gateway, lander docks to module, Orion docks to another Gateway port. Quote Link to comment Share on other sites More sharing options...
grawl Posted March 16 Share Posted March 16 3 hours ago, tater said: Says ">45t." Dry mass supposedly ~16t. If the Be-7 has an Isp of 450s, then it needs to be at least 56t wet to make a RT from Gateway. In short, it could easily be sent to gateway with an expended SS—with Orion docked to it in LEO. And a huge orital hab module in between for comfort (can be left at Gateway—undock lander, Orion installs module to Gateway, lander docks to module, Orion docks to another Gateway port. That would be a spectacular example of cooperation towards a common goal, between seemingly concurrent industrials ! I'd find it wonderful for SpaceX and Blue Origin and Boeing to fit together this way. One launches, the other lands, and the last one returns. Everyone has a piece of the cake this way. BUT, one other thing I'm REALLY looking forward to hear about if this ever happens, is the reaction of Musk and Bezos when they'd be announced NASA said "now, kiss" Quote Link to comment Share on other sites More sharing options...
tater Posted March 16 Share Posted March 16 4 hours ago, grawl said: BUT, one other thing I'm REALLY looking forward to hear about if this ever happens, is the reaction of Musk and Bezos when they'd be announced NASA said "now, kiss" SpaceX has a couple Kuiper launches, don't they? Quote Link to comment Share on other sites More sharing options...
Exoscientist Posted March 16 Share Posted March 16 7 hours ago, tater said: Says ">45t." Dry mass supposedly ~16t. If the Be-7 has an Isp of 450s, then it needs to be at least 56t wet to make a RT from Gateway. In short, it could easily be sent to gateway with an expended SS—with Orion docked to it in LEO. And a huge orital hab module in between for comfort (can be left at Gateway—undock lander, Orion installs module to Gateway, lander docks to module, Orion docks to another Gateway port. Thanks for that. Considering just how low cost the expendable SH/SS is, the same as the Falcon Heavy but at 3 to 4 times the payload, an expendable SH/SS has advantages for being able to conduct single launch missions to the Moon or Mars, assuming you have a separate lander(NOT landing the entire Starship on the surface.) Bob Clark Quote Link to comment Share on other sites More sharing options...
Flavio hc16 Posted March 16 Share Posted March 16 (edited) 1 hour ago, Exoscientist said: Thanks for that. Considering just how low cost the expendable SH/SS is, the same as the Falcon Heavy but at 3 to 4 times the payload, an expendable SH/SS has advantages for being able to conduct single launch missions to the Moon or Mars, assuming you have a separate lander(NOT landing the entire Starship on the surface.) Bob Clark So, math time ( again). Let's say 17 tons of dry mass for the BO lander and 3 tons of payload to the moon. For a trip from NHRO, to land, and back to NRHO you need around 3.9 km/s of DV, with margin let's say 4km/s. Let's say that the B3U has 410s of ISP, quite high performance but not insane. With a total mass "usable" of 20 tons and 35 tons of props, so total mass of 55 tons you have 4.1 km/s of DV. How do we throw 55 tons to NRHO? We need to give this payload around 4km/s from LEO. A single raptor vacuum with 380 of ISP, and 25 tons of dry mass between tankage and engine ( wayyyy too heavy, but I want to be conservative), with 170 tons of props gives yoo 4.2 km/s. So a launcher that can loft into orbit 250 tons can get a fully fueled Blue moon lander to NRHO, so it can go and do his mission happily If the dry mass of the raptor stage is 15 tons you get down to 210 tons into orbit. If the B3U has a 450s Isp the mass of the lander goes to 50 tons, and the total stack needed into orbit is 200 tons.... We might actually arrive at a point were you can launch a Blue moon lander fully fueled with a reusable Starship. The world is not ready. Edit, ok I used the wrong data ( direct transfer), so all above works for an Apollo style, not for Artemis Edited March 16 by Flavio hc16 Quote Link to comment Share on other sites More sharing options...
tater Posted March 16 Share Posted March 16 useful NASA chart for considering cislunar operations. Gateway/surface RT is 5.5 km/s. A 100% propulsive Gateway/LEO RT is 7.3 km/s. Quote Link to comment Share on other sites More sharing options...
tater Posted March 16 Share Posted March 16 Quote Link to comment Share on other sites More sharing options...
Meecrob Posted March 16 Share Posted March 16 5 hours ago, Exoscientist said: Thanks for that. Considering just how low cost the expendable SH/SS is, the same as the Falcon Heavy but at 3 to 4 times the payload, an expendable SH/SS has advantages for being able to conduct single launch missions to the Moon or Mars, assuming you have a separate lander(NOT landing the entire Starship on the surface.) Bob Clark I get that you are trying to increase efficiency, but sometimes doing this can be counter-intuitive. I'll use austerity budgets as an example. When trying to spend money more efficiently, its easy to fall into the trap of "less money = better," but you have to look at the bigger picture. An ex of mine was a great chef, and we both had pretty low paying jobs at the time, so finding food on sale was our primary goal. We quickly realized that sometimes the sale item was not available and a comparable replacement was "too expensive" so we chose not to buy it. A few days later when she was making dinner we realized the sale item we didn't buy was needed for the dish she wanted to make. We were beat from a hard day at work so we ordered takeout instead. Total savings of -$25. All because we didnt want to pay $18 instead of $11 for one item. To bring it back to Starship, you might be able to maximize the efficiency of one launch, but the idea here is to have like 20 of these things ready to launch like an airline. Who cares what the total payload of one Starship is when we can just launch a second for all the cargo that doesn't fit on the first one. We have to move a significant amount of mass if we are going to do anything in space that isn't comm sats and experiments on the ISS. Quote Link to comment Share on other sites More sharing options...
AckSed Posted March 16 Share Posted March 16 Ooof, that ending. From that I'd conclude that it does need dedicated RCS to keep it pointed the correct attitude upon reentry, or Bad Things Happen. Maybe dig up the idea of gaseous methalox once more. Quote Link to comment Share on other sites More sharing options...
grawl Posted March 16 Share Posted March 16 6 hours ago, tater said: SpaceX has a couple Kuiper launches, don't they? True that. But, a moon landing is a bigger feat than launching a bunch of simple sats. What's happening in the mind of an egotistical billionaire (might be a pleonasm) when he needs to assess he partly failed and need the help of another billionaire that partly failed as well, is what I find interesting here. Please note I'm not saying they won't do it if needed, I guess they don't really get to choose at some point even if reluctant about it. Also, maybe the ego war Bezos and Musk are showing (I'm not sure if its still going on btw) is just fake PR and they'll willingly cooperate for the sake of science, business and collective achievement. Quote Link to comment Share on other sites More sharing options...
darthgently Posted March 16 Share Posted March 16 51 minutes ago, AckSed said: Ooof, that ending. From that I'd conclude that it does need dedicated RCS to keep it pointed the correct attitude upon reentry, or Bad Things Happen. Maybe dig up the idea of gaseous methalox once more. Super Draco thrusters have been suggested elsewhere. I wonder about some deployable drag source on the lee side that would definitely not be a standard drogue. No image is forming in my mind, but maybe inflatable and made of captan that creates more turbulence and drag on the non-tiled side Quote Link to comment Share on other sites More sharing options...
tater Posted March 16 Share Posted March 16 There's not any ego war going on to speak of. SpaceX won this campaign a long time ago. As a business, SpaceX is fighting no war—Shotwell has been asked multiple times, and she always says the same thing—everyone's dollars are good, they sell launches to customers. Amazon bought a few SpaceX launches at the very least to protect themselves legally from the claim they are fighting an ego battle at shareholder expense. Bezos in a recent interview was pretty conciliatory WRT Musk. It's important to remember that any personal issues seemed to start with the "welcome to the club" tweet by Bezos as if a suborbital vehicle is remotely comparable to an orbital vehicle. I think competition is good, and the benefit of SpaceX can only in fact be seen once someone else can actually compete. So the sooner, the better. As far as NASA is concerned, if they—the actual Artemis customer—want to fly the BO lander, and want to fly it in 1 stack—they can ask SpaceX to do that, and I they will. Quote Link to comment Share on other sites More sharing options...
bigyihsuan Posted March 17 Share Posted March 17 5 hours ago, tater said: Oof, that's reentry plasma directly to the engines. This will affect the Raptor performance, I think. /joke Quote Link to comment Share on other sites More sharing options...
magnemoe Posted March 17 Share Posted March 17 5 hours ago, darthgently said: Super Draco thrusters have been suggested elsewhere. I wonder about some deployable drag source on the lee side that would definitely not be a standard drogue. No image is forming in my mind, but maybe inflatable and made of captan that creates more turbulence and drag on the non-tiled side I agree, add some draco or super draco as an backup. Metalox gas thrusters is another good idea and it will be needed later anyway for moon landing and other stuff. Quote Link to comment Share on other sites More sharing options...
StrandedonEarth Posted March 17 Share Posted March 17 (edited) Methagox RCS makes the most sense, if reliable ignition isn’t an issue. The last thing they want is more complexity, especially hazardous chemicals like hypergolics. Although if that’s what they need for HLS, all bets are off… Edited March 17 by StrandedonEarth sjelling Quote Link to comment Share on other sites More sharing options...
AckSed Posted March 17 Share Posted March 17 Gravitics is developing gaseous methalox RCS for their space-station modules, with a throttle range from 5N pulsed to 40N continuous. If they wanted (nearly) off-the-shelf, it's there. Quote Link to comment Share on other sites More sharing options...
darthgently Posted March 17 Share Posted March 17 5 hours ago, magnemoe said: I agree, add some draco or super draco as an backup. Metalox gas thrusters is another good idea and it will be needed later anyway for moon landing and other stuff. Though lunar SS is going to be a very different beast, they do need to develop something and if it works for both, then great Quote Link to comment Share on other sites More sharing options...
RCgothic Posted March 17 Share Posted March 17 4 hours ago, AckSed said: Gravitics is developing gaseous methalox RCS for their space-station modules, with a throttle range from 5N pulsed to 40N continuous. If they wanted (nearly) off-the-shelf, it's there. I don't think even a cluster of 40N thrusters is going to be anything even close to powerful enough to manoeuvre a potentially 2,000,000+ kg refilled V3 ship. Quote Link to comment Share on other sites More sharing options...
Exoscientist Posted March 17 Share Posted March 17 Is it confirmed the hot gas RCS worked on the booster but not on the Starship? If so, then the propellant transfer test may have caused a fuel leak preventing the RCS from operating. Bob Clark Quote Link to comment Share on other sites More sharing options...
RCgothic Posted March 17 Share Posted March 17 (edited) No, the causes of the losses of control on both booster and ship are unconfirmed. Edited March 17 by RCgothic Quote Link to comment Share on other sites More sharing options...
Nuke Posted March 17 Share Posted March 17 control issues seems to be the major problem this time. im not even sure its strictly a thruster problem. it kind of looked like a calibration issue with the control loops. remember this is the first time we re-entered with starship and the first time the grid fins have been tested at low altitude. i saw a lot of over correcting going on. either they picked bad pid values or they were sweeping as many different values to see which ones performed the best. Quote Link to comment Share on other sites More sharing options...
CBase Posted March 17 Share Posted March 17 I am curious how SpaceX will change the ship for IFT-4. If I had this playing Kerbal, I would probably integrate an overkill of control thrusters and accept temporarly a reduced payload. Any payload to destination is better than none. When piloting is mastered, I would reduce thrust limits to see what I actually need and then refine build to match actual demand for control. Quote Link to comment Share on other sites More sharing options...
Pthigrivi Posted March 17 Share Posted March 17 17 hours ago, AckSed said: Ooof, that ending. From that I'd conclude that it does need dedicated RCS to keep it pointed the correct attitude upon reentry, or Bad Things Happen. Maybe dig up the idea of gaseous methalox once more. Im also wondering if without completing the prop transfer if the mass was actually distributed properly for reentry? Quote Link to comment Share on other sites More sharing options...
Minmus Taster Posted March 17 Share Posted March 17 Not sure if this has been posted before but: Oh boy here we go again.. Quote Link to comment Share on other sites More sharing options...
Terwin Posted March 17 Share Posted March 17 1 hour ago, Minmus Taster said: Oh boy here we go again.. I had hoped that following the flight path all the way to the end might not count as a mishap, but at least the additional hazard should be close to zero. I expect that most of the mitigation is to improve control, which SpaceX wants to do anyway. Quote Link to comment Share on other sites More sharing options...
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