tater Posted July 19, 2017 Share Posted July 19, 2017 Just now, CatastrophicFailure said: This is seeming like a disappointing day for SpaceX. Any reason why the difficulty with the D2 landing legs? Not needed for commercial crew, and with a sub scale BFR/BFS in the works, they will put propulsive landing on that biconic stage 2 anyway. Why work the issue twice? Quote Link to comment Share on other sites More sharing options...
TheEpicSquared Posted July 19, 2017 Share Posted July 19, 2017 Nobody asked about the BulgariaSat-1 landing? Quote Link to comment Share on other sites More sharing options...
tater Posted July 19, 2017 Share Posted July 19, 2017 Quote Link to comment Share on other sites More sharing options...
CatastrophicFailure Posted July 19, 2017 Share Posted July 19, 2017 19 minutes ago, tater said: Not needed for commercial crew, and with a sub scale BFR/BFS in the works, they will put propulsive landing on that biconic stage 2 anyway. Why work the issue twice? Seems like a good sub-scale testbed... Wait, what?! Red Dragon is dead, just like that?? Quote Link to comment Share on other sites More sharing options...
KSK Posted July 19, 2017 Share Posted July 19, 2017 27 minutes ago, CatastrophicFailure said: Seems like a good sub-scale testbed... Wait, what?! Red Dragon is dead, just like that?? Hard to do Red Dragon without a propulsively landing Dragon. The rational part of my brain is trying hard to persuade me that this is a good thing. Trim the wild fancies for now, double-down on clearing that launch backlog and keep the money coming in, build a stepping stone to a fully fledged BFR... The rest of my brain is completely ignoring all that rationality and is definitely having one of these moments... Quote Link to comment Share on other sites More sharing options...
CatastrophicFailure Posted July 19, 2017 Share Posted July 19, 2017 @KSK man, you said it. At this rate, nevermind even the static fire, just raising the FH upright is gonna be a nail biter! Elon could prolly assuage some of today's dreariness if he released that BulgariaSat footage... just sayin'... Quote Link to comment Share on other sites More sharing options...
tater Posted July 19, 2017 Share Posted July 19, 2017 I liked the idea of D2 propulsively landing from ISS for cargo, and this doesn't mean they could not mess with it (land on an air bag) at some point. I think it shows that SpaceX is not falling for the sunk cost fallacy. 1. The vehicle will work for the customer as it is. 2. They were planning on an entirely new vehicle as a focus once their NASA obligations are fuffilled anyway. 3. BFR and BFS were always way over the top. Many have suggested an interim step anyway. Given those points, I think using an interim vehicle does everything needed, and the dev timeline is probably much easier to deal with. Quote Link to comment Share on other sites More sharing options...
CatastrophicFailure Posted July 19, 2017 Share Posted July 19, 2017 4 minutes ago, tater said: Given those points, I think using an interim vehicle does everything needed, and the dev timeline is probably much easier to deal with. To heck with you and your rationality and logic! I want my 1960's Buck Rogers fantasy! Quote Link to comment Share on other sites More sharing options...
tater Posted July 19, 2017 Share Posted July 19, 2017 (edited) Elon specifically said the moon should happen first. This is really novel for him, and I think important to absorb. Shotwell also said they were not using ITS as a name internally any more. Because it is not primarily for that function now is my guess. I imagine a smaller BFR will be used for LEO as he stated, and possibly for the moon---with refueling. This allows operational use of a biconic vehicle as well as being a platform to test on orbit refueling. Such a vehicle is still huge, btw. Edited July 19, 2017 by tater Quote Link to comment Share on other sites More sharing options...
tater Posted July 19, 2017 Share Posted July 19, 2017 Merlin 1D is under a meter in diameter. A full scale raptor would be around twice that. That nominally means a 9 raptor falcon would be about 8m in diameter. That's bigger than NG, and basically SLS. Quote Link to comment Share on other sites More sharing options...
TheEpicSquared Posted July 19, 2017 Share Posted July 19, 2017 33 minutes ago, tater said: Merlin 1D is under a meter in diameter. A full scale raptor would be around twice that. That nominally means a 9 raptor falcon would be about 8m in diameter. That's bigger than NG, and basically SLS. That would pack quite a punch. Quote Link to comment Share on other sites More sharing options...
Spaceception Posted July 19, 2017 Share Posted July 19, 2017 So what will BFRs little sibling look like? 3 hours ago, tater said: SO, could the subscale BFR replace the FH? Or would it just be a step up from that? Quote Link to comment Share on other sites More sharing options...
tater Posted July 19, 2017 Share Posted July 19, 2017 https://twitter.com/elonmusk/status/887782904360816640 https://twitter.com/elonmusk/status/887782904360816640 The mobile version of this forum stinks. Quote Link to comment Share on other sites More sharing options...
KSK Posted July 19, 2017 Share Posted July 19, 2017 (edited) 2 hours ago, tater said: Elon specifically said the moon should happen first. This is really novel for him, and I think important to absorb. Hah - I expect all those scary Mars bacteria put him off. The moon does seem more aligned with Blue Origin's - and possibly NASA's plans - which might be useful for finding new business. Plus any serious mission profile that uses on-orbit refuelling would be very interesting, to put it mildly. It also sounds very SpaceX somehow, as in, it would be potentially transformative for spaceflight, it's not a new concept in itself but it's not one that people have started bending serious metal for until now. Of course it'll probably also turn out to be Falcon Heavy levels of hard and be developed on about the same schedule. All the same though, my Buck Rogers brain is feeling mollified! Edited July 19, 2017 by KSK Quote Link to comment Share on other sites More sharing options...
CatastrophicFailure Posted July 19, 2017 Share Posted July 19, 2017 13 minutes ago, KSK said: Hah - I expect all those scary Mars bacteria put him off. The moon does seem more aligned with Blue Origin's - and possibly NASA's plans - which might be useful for finding new business. It will probably be good for actual progress towards something instead of just pretty CGI, yet I am unable to shake this mental image of Elon hanging from a weather vane while Jeff Bezos thrusts a hand out... "join me, and with our combined strength, we can end this destructive conflict, and bring order to cis-lunar space! Together, we can rule as Baldy and Hair!" Quote Link to comment Share on other sites More sharing options...
tater Posted July 19, 2017 Share Posted July 19, 2017 I have issues with Mars past the cool factor of flags and footprints because I think it's a money sink with no possible RoI. I think dragging asteroids nearby has possible implications for new business, I suppose. Such a capability (once robust) also addresses most of Musk's stated concerns about security vs extinction events. I'll add (again?) that I think that smallifying (lol) BFS makes it far more likely in a timeframe that my life fits inside. Quote Link to comment Share on other sites More sharing options...
DDE Posted July 19, 2017 Share Posted July 19, 2017 https://arstechnica.com/science/2017/07/spacex-appears-to-have-pulled-the-plug-on-its-red-dragon-plans/ Quote ...during a speech Wednesday at the International Space Station Research and Development Conference, Musk confirmed that the company is no longer working to land Dragon propulsively for commercial crew. (Although initially the company had moved to water landings, SpaceX had maintained that in future crew contracts with NASA, it would use Dragon's thrusters to land on land.) But no longer. "Yeah, that was a tough decision," Musk acknowledged Wednesday with a sigh. It had to be a somewhat humbling one, too, after Musk bragged during the Dragon 2 reveal in 2014 that this vehicle showed how a 21st century spacecraft should land—not with parachutes in the water. "The reason we decided not to pursue that heavily is that it would have taken a tremendous amount of effort to qualify that for safety for crew transport," Musk explained Wednesday. "There was a time when I thought the Dragon approach to landing on Mars, where you've got a base heat shield and side mounted thrusters, would be the right way to land on Mars. But now I'm pretty confident that is not the right way." Musk added that his company has come up with a "far better" approach to landing on Mars that will be incorporated into the next iteration of the company's proposed Mars transportation hardware. Musk laid out an initial version of this "Interplanetary Transport System" in 2016, but he has said an updated architecture is coming soon, perhaps at the 2017 International Astronautical Conference in Adelaide, Australia. The event will be held from September 25 to 29. Quote Link to comment Share on other sites More sharing options...
_Augustus_ Posted July 19, 2017 Share Posted July 19, 2017 *sniffle* Quote Link to comment Share on other sites More sharing options...
tater Posted July 20, 2017 Share Posted July 20, 2017 They're not ditching retropropulsion, the dracos are still there, and the capsule could still land... they are ditching the landing gear. Skipping red dragon to do a smaller BFS, instead. Quote Link to comment Share on other sites More sharing options...
tater Posted July 20, 2017 Share Posted July 20, 2017 As I said about this same subject in the spacex thread, I think this is a good thing. 1. it shows that SpaceX is agile, and changes to better designs without sunk cost notions. 2. I think it means that they think they can do a larger craft quicker without wasting effort of the marginal return on propulsive landing on D2. 3. He said they might revisit the idea later---perhaps once they have a D2 near end of service, they add gear, and give it a test on a cargo return. Quote Link to comment Share on other sites More sharing options...
Mitchz95 Posted July 20, 2017 Share Posted July 20, 2017 We already have a SpaceX discussion thread here. Quote Link to comment Share on other sites More sharing options...
kerbiloid Posted July 20, 2017 Share Posted July 20, 2017 (edited) At last here is a clear answer to the question about D2 delta-V. (For me, it was expectable). If a launchpad abort test (6 g * 6 s) had exhausted its inner tank (and there is no outer one), this means dV ~300..400 m/s. Orbital operations usually require 300..400 m/s (including 100-150 m/s to deorbit). Landing with free fall speed ~150 m/s requires also ~300 m/s (free-fall speed itself + gravitational losses due to the continuous burn). So, with 400 m/s in total, was it going to reach the ISS or to land? Now we can see, that the former. The next question: if it will spend its fuel in orbit and land with chutes, that means the SuperDraco battery is not a landing engine, but a reusable built-in LES tower. It's greatly overpowered in orbit, so has no other usage except launch escape and landing. So, the question is whether it's indeed useful to carry a liquid-fueled reusable LES to orbit rather than drop a powder rocket, when every flight burns dozens of such rockets equivalent. Of course they need no more landing legs, as without the landing engines they can't kill the horizontal speed. So the legs + chute = guaranteed overturn and crashed legs. Also they now need just a simple heatshield without mechanics. As the Dragon v2 shape is vertical, droplet-like, they would anyway overturn every landing without engines. Now probably they need to make it lower. Let me guess that the next step we'll see. Dragon v2 will be just Dragon v1, painted white, with seats and windows, and with simple LES tower instead of the SuperDraco Malfoy bunch. P.S. Interesting, will PTK NP project react in some way. Say, remove the legs. P.P.S. Single-use LES can be spent with pleasure if make it fireworks + .piñata Edited July 20, 2017 by kerbiloid Quote Link to comment Share on other sites More sharing options...
Streetwind Posted July 20, 2017 Share Posted July 20, 2017 (edited) 12 hours ago, CatastrophicFailure said: This is seeming like a disappointing day for SpaceX. Any reason why the difficulty with the D2 landing legs? The statement given was "landing legs extending from the heat shield turned out unworkable". In other words, they couldn't find a way to safely seal the gaps against the force of reentry. I'm fairly sure this is what ultimately killed the plan. Elon isn't afraid of a little showmanship as long as it works, so even if there were other difficulties with software and control, he'd make his engineers push through it. To cancel the project, it would take something that's literally unsolvable without completely rolling up a major part of the whole company's development history. And it seems like the heatshield technology is such a thing. They've been dead set on their chosen material even before Dragon V2 was announced. And before someone suggests it: landing legs extending from the side hull of the Dragon V2 would also require such a rollback at this stage of development. The vehicle is practically finished, and spacecraft don't generally have excess space or structural mounting points like that. Edited July 20, 2017 by Streetwind Quote Link to comment Share on other sites More sharing options...
magnemoe Posted July 20, 2017 Share Posted July 20, 2017 (edited) The statement given was "landing legs extending from the heat shield turned out unworkable". In other words, they couldn't find a way to safely seal the gaps against the force of reentry. I'm fairly sure this is what ultimately killed the plan. Elon isn't afraid of a little showmanship as long as it works, so even if there were other difficulties with software and control, he'd make his engineers push through it. To cancel the project, it would take something that's literally unsolvable without completely rolling up a major part of the whole company's development history. And it seems like the heatshield technology is such a thing. They've been dead set on their chosen material even before Dragon V2 was announced. And before someone suggests it: landing legs extending from the side hull of the Dragon V2 would also require such a rollback at this stage of development. The vehicle is practically finished, and spacecraft don't generally have excess space or structural mounting points like that. I wonder if it wather resistance rather than reentry who is the main issue, Space shuttle had no issues with the landing legs, some capsule designs even had hatches in heat shield. Edited July 20, 2017 by magnemoe Quote Link to comment Share on other sites More sharing options...
kerbiloid Posted July 20, 2017 Share Posted July 20, 2017 (edited) 4 minutes ago, magnemoe said: If so the downside would just be the superdrako themselves, leaving you with lots of orbital dV. dV stays the same (maybe even greater, if they remove 8 heavy engines). 6 minutes ago, Streetwind said: In other words, they couldn't find a way to safely seal the gaps against the force of reentry. Unlikely TKS VA was happily floating in a pool with a doorway in the heatshield. They just don't need legs if can't kill horizontal speed. Edited July 20, 2017 by kerbiloid Quote Link to comment Share on other sites More sharing options...
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