sh1pman Posted June 27, 2018 Share Posted June 27, 2018 1 hour ago, Wjolcz said: NTO is what Dragon 2 will be using. I'd imagine it will be for in-space manouvering and LES only. Maybe for CRS2 returns as well? You can't poison the crew if there is no crew on board. Quote Link to comment Share on other sites More sharing options...
tater Posted June 27, 2018 Share Posted June 27, 2018 1 hour ago, Cassel said: what about landing with engines? This was dumped a while ago. The amount of effort and cost to make it work was not considered worth it, and since they are working on BFR, anyway, Crew Dragon is sort of a dead end. Quote Link to comment Share on other sites More sharing options...
Wjolcz Posted June 27, 2018 Share Posted June 27, 2018 24 minutes ago, sh1pman said: Maybe for CRS2 returns as well? You can't poison the crew if there is no crew on board. I wish. Maybe they could try doing that on their demo flight. But the problem is NASA probably wants to see each stage of flight/return to be as if it was an actual mission, so probably no propulsive landing. Does anyone know if the D2's mass/engines/fuel amount changed since the announcement of propulsive landing? If it didn't, it's theoretically possible to still land it. I don't really see anyone wanting their cargo returned that way though. And since the only place you can return (pressurized) cargo from is the ISS then it's NASA who needs to give the permission for that and AFAIK they didn't. Unless Bigelow or some other private company wants to put something in D2 for whatever reason then there's no point in returning anything propulsively. But then the cargo might as well end up being transported to the ISS. Unless it's some hazardous materials I don't see a reason why would anyone want to rent a Dragon and keep it in orbit for a while. But then why put any hazardous materials in it in the first place if you have to deal with them later on the ground? So the only instance in which they could land it like that is just for the sake of it. But since they already know how to land boosters then there's no point in spending money on launching D2 just for the cool return video. Quote Link to comment Share on other sites More sharing options...
sh1pman Posted June 27, 2018 Share Posted June 27, 2018 52 minutes ago, Wjolcz said: So the only instance in which they could land it like that is just for the sake of it. But since they already know how to land boosters then there's no point in spending money on launching D2 just for the cool return video. It's easier to recover the Dragon that's landed on a landing pad vs. fishing it out of the ocean with a ship. Quote Link to comment Share on other sites More sharing options...
tater Posted June 27, 2018 Share Posted June 27, 2018 17 minutes ago, sh1pman said: It's easier to recover the Dragon that's landed on a landing pad vs. fishing it out of the ocean with a ship. Or catching it in a net... Quote Link to comment Share on other sites More sharing options...
Ultimate Steve Posted June 27, 2018 Share Posted June 27, 2018 5 minutes ago, tater said: Or catching it in a net... You know, it still is probably possible that they will try to land crew dragons on Mr. Steven or something else, if it falls slow enough the boat could maneuver to get right under it. Of course I'm probably underestimating how much of a challenge this is, but they could. Quote Link to comment Share on other sites More sharing options...
magnemoe Posted June 27, 2018 Share Posted June 27, 2018 16 minutes ago, Ultimate Steve said: You know, it still is probably possible that they will try to land crew dragons on Mr. Steven or something else, if it falls slow enough the boat could maneuver to get right under it. Of course I'm probably underestimating how much of a challenge this is, but they could. D2 is much heavier than an empty upper stage and you have an problem as in missing the net but hitting the ship or just ahead of an moving ship. Think they also use controllable parachutes on the fairings, that would make it harder to man rate because more can go wrong. Easier to waterproof the capsule, they reuse D1 capsules after all. Quote Link to comment Share on other sites More sharing options...
Cassel Posted June 27, 2018 Share Posted June 27, 2018 4 hours ago, Wjolcz said: The fuel and exhaust products are too toxic. Edit: from Wikipedia: "On 24 July 1975, NTO poisoning affected three U.S. astronauts on the final descent to Earth after the Apollo-Soyuz Test Projectflight. This was due to a switch accidentally left in the wrong position, which allowed the attitude control thrusters to fire after the cabin fresh air intake was opened, allowing NTO fumes to enter the cabin. One crew member lost consciousness during descent. Upon landing, the crew was hospitalized for five days for chemical-induced pneumonia and edema." NTO is what Dragon 2 will be using. I'd imagine it will be for in-space manouvering and LES only. Crew has no protection during landing? It is really shame, I liked this idea :-( Quote Link to comment Share on other sites More sharing options...
CatastrophicFailure Posted June 27, 2018 Share Posted June 27, 2018 Just now, Cassel said: Crew has no protection during landing? It is really shame, I liked this idea :-( They've got four parachutes, of which they only strictly need two. Quote Link to comment Share on other sites More sharing options...
Mad Rocket Scientist Posted June 27, 2018 Share Posted June 27, 2018 8 hours ago, Wjolcz said: The fuel and exhaust products are too toxic. Edit: from Wikipedia: "On 24 July 1975, NTO poisoning affected three U.S. astronauts on the final descent to Earth after the Apollo-Soyuz Test Projectflight. This was due to a switch accidentally left in the wrong position, which allowed the attitude control thrusters to fire after the cabin fresh air intake was opened, allowing NTO fumes to enter the cabin. One crew member lost consciousness during descent. Upon landing, the crew was hospitalized for five days for chemical-induced pneumonia and edema." NTO is what Dragon 2 will be using. I'd imagine it will be for in-space manouvering and LES only. Do you have any source for this being the reason propulsive landings were canceled? I've always heard that it was because BFR was going to make everything else redundant, and so it wasn't worth the effort to make it work. Plus, if you can get poisoned with capsules just using it for attitude control, I'd imagine it wouldn't be much more dangerous to land with it. After, the capsule is completely sealed so you can just wait for the fumes to blow away. Quote Link to comment Share on other sites More sharing options...
zolotiyeruki Posted June 27, 2018 Share Posted June 27, 2018 Soyuz uses rockets at touchdown, doesn't it? Quote Link to comment Share on other sites More sharing options...
Mad Rocket Scientist Posted June 27, 2018 Share Posted June 27, 2018 (edited) 14 minutes ago, zolotiyeruki said: Soyuz uses rockets at touchdown, doesn't it? I think those are solids. EDIT: Yes, they are. Edited June 27, 2018 by Mad Rocket Scientist Quote Link to comment Share on other sites More sharing options...
CatastrophicFailure Posted June 27, 2018 Share Posted June 27, 2018 38 minutes ago, Mad Rocket Scientist said: Do you have any source for this being the reason propulsive landings were canceled? I've always heard that it was because BFR was going to make everything else redundant, and so it wasn't worth the effort to make it work. Everything I’ve heard was that the challenges for propulsive landing weren’t engineering, but bureaucratic. They could physically make it work, but getting NASA’s OK on ththe system would be more trouble than it was worth, especially with BFR on the (increasingly near) horizon. Like @tater has said, D2 is essentially a dead end for SpaceX, likely to be obsolete within a decade or so, and they aren’t likely to learn that much from making propulsive landing actually work on it. If they can’t get it by NASA anyway, better to just spend that R&D money on BFS. Quote Link to comment Share on other sites More sharing options...
magnemoe Posted June 27, 2018 Share Posted June 27, 2018 2 minutes ago, CatastrophicFailure said: Everything I’ve heard was that the challenges for propulsive landing weren’t engineering, but bureaucratic. They could physically make it work, but getting NASA’s OK on ththe system would be more trouble than it was worth, especially with BFR on the (increasingly near) horizon. Like @tater has said, D2 is essentially a dead end for SpaceX, likely to be obsolete within a decade or so, and they aren’t likely to learn that much from making propulsive landing actually work on it. If they can’t get it by NASA anyway, better to just spend that R&D money on BFS. Pretty much this, add the problem with testing this and the NTO issues on top. And you want to live in an world there technology is obsolete then ready, Quote Link to comment Share on other sites More sharing options...
tater Posted June 28, 2018 Share Posted June 28, 2018 Quote Link to comment Share on other sites More sharing options...
Wjolcz Posted June 28, 2018 Share Posted June 28, 2018 On 6/27/2018 at 4:26 PM, sh1pman said: It's easier to recover the Dragon that's landed on a landing pad vs. fishing it out of the ocean with a ship. I agree. It's just that I feel like people would rather pay for something that's been done and proven (parachutes) than something that's new and possibly risky. Now, I think that nothing bad would happen if they would land it that way. Especially since D2 has so many spare engines. 19 hours ago, Mad Rocket Scientist said: Do you have any source for this being the reason propulsive landings were canceled? I've always heard that it was because BFR was going to make everything else redundant, and so it wasn't worth the effort to make it work. Plus, if you can get poisoned with capsules just using it for attitude control, I'd imagine it wouldn't be much more dangerous to land with it. After, the capsule is completely sealed so you can just wait for the fumes to blow away. Ok, maybe fuel type isn't the reason why it's cancelled. The crew could simply wait for the fumes to go away. I also think I've seen someone mentioning development of the legs being problematic, or something. But there's not much point discussing it since it won't happen anyway. Would be amazing if it did though. Quote Link to comment Share on other sites More sharing options...
cubinator Posted June 28, 2018 Share Posted June 28, 2018 1 hour ago, Wjolcz said: I also think I've seen someone mentioning development of the legs being problematic, or something. Having legs pop out of the heat shield would be problematic because it would entail having a hole in the heat shield. Personally, I would design legs that retract above the heat shield and wrap over the edge when deployed. Quote Link to comment Share on other sites More sharing options...
CatastrophicFailure Posted June 28, 2018 Share Posted June 28, 2018 1 minute ago, cubinator said: Having legs pop out of the heat shield would be problematic because it would entail having a hole in the heat shield. Personally, I would design legs that retract above the heat shield and wrap over the edge when deployed. You don’t even wanna know how many holes there were in the Shuttle heat shield, then... Both the Soviets and the USAF experimented with putting hatches in the heat shield, too. The VA capsule could even fly multiple times with such. So that much, at least, is fairly well understood engineering. Quote Link to comment Share on other sites More sharing options...
StrandedonEarth Posted June 28, 2018 Share Posted June 28, 2018 The holes in D2’s heat shield weren’t a big problem in themselves, it was the paperwork certifying that it was safe that was the problem Quote Link to comment Share on other sites More sharing options...
RealKerbal3x Posted June 28, 2018 Share Posted June 28, 2018 (edited) 2 hours ago, CatastrophicFailure said: You don’t even wanna know how many holes there were in the Shuttle heat shield, then... Both the Soviets and the USAF experimented with putting hatches in the heat shield, too. The VA capsule could even fly multiple times with such. So that much, at least, is fairly well understood engineering. Yeah, the Shuttle heatshield had three holes for landing gear in it. Actually if you count the tiny gaps between the tiles it had several million holes in it EDIT: Just checked my space launch app, T-14 hours 50 minutes till Block 5 launches CRS-15 to the ISS if it all goes to plan. Shame, I'll be at school when it launches. Edited June 28, 2018 by RealKerbal3x Quote Link to comment Share on other sites More sharing options...
tater Posted June 28, 2018 Share Posted June 28, 2018 Quote Link to comment Share on other sites More sharing options...
CatastrophicFailure Posted June 28, 2018 Share Posted June 28, 2018 17 minutes ago, RealKerbal3x said: Yeah, the Shuttle heatshield had three holes for landing gear in it. Actually if you count the tiny gaps between the tiles it had several million holes in it Try eight. Also had holes for the LH2 and LOX feeds, and all three struts that secured it to the ET. Might have been more. But holey heat shields are a tried and true tech. not to be confused with holy hand grenades... 19 minutes ago, RealKerbal3x said: Just checked my space launch app, T-14 hours 50 minutes till Block 5 launches CRS-15 to the ISS if it all goes to plan. Shame, I'll be at school when it launches. Block 4 still. Tho I saw it confirmed in a tweet somewhere that this will be the last Block 4 launch, and presumably possibly the last expendable F9 launch ever. Quote Link to comment Share on other sites More sharing options...
RealKerbal3x Posted June 28, 2018 Share Posted June 28, 2018 6 minutes ago, CatastrophicFailure said: Try eight. Also had holes for the LH2 and LOX feeds, and all three struts that secured it to the ET. Might have been more. But holey heat shields are a tried and true tech. not to be confused with holy hand grenades... Block 4 still. Tho I saw it confirmed in a tweet somewhere that this will be the last Block 4 launch, and presumably possibly the last expendable F9 launch ever. Oops....well the picture on my phone showed a Block 5....derp... I am looking forward to the fast turnaround times made possible by Block 5. Did they say something like 72 hours? Quote Link to comment Share on other sites More sharing options...
CatastrophicFailure Posted June 28, 2018 Share Posted June 28, 2018 37 minutes ago, RealKerbal3x said: Oops....well the picture on my phone showed a Block 5....derp... I am looking forward to the fast turnaround times made possible by Block 5. Did they say something like 72 hours? 24 hours is the stretch goal, tho I doubt we’ll actually see that except once or twice just as a demonstration that they can. Quote Link to comment Share on other sites More sharing options...
RealKerbal3x Posted June 28, 2018 Share Posted June 28, 2018 1 minute ago, CatastrophicFailure said: 24 hours is the stretch goal, tho I doubt we’ll actually see that except once or twice just as a demonstration that they can. Yeah, I doubt SpaceX technicians will want to work shifts around the clock after every Block 5 launch Quote Link to comment Share on other sites More sharing options...
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