tater Posted April 4, 2016 Share Posted April 4, 2016 The pad abort test was for commercial crew... unsure about the tourist capsule. Link to comment Share on other sites More sharing options...
sevenperforce Posted April 4, 2016 Share Posted April 4, 2016 17 hours ago, KerBlammo said: And here is the Slickly Produced Video: [snip] That suicide burn landing is very impressive. Too bad we only get to see the Slickly Produced Video, I'd love to see raw video of that landing from multiple angles. Yes, it was quite impressive. It's falling like a rock until relight and it just...stops. Can anyone guesstimate the gees it pulls on that suicide burn? But despite how impressive that was, the hover at the end was...meh. I've got to say I'm in love with the legs-down-at-engine-off suicide burn used by Falcon 9. Link to comment Share on other sites More sharing options...
tater Posted April 4, 2016 Share Posted April 4, 2016 I really need to drive down there... Assuming I can get close enough to see much. Link to comment Share on other sites More sharing options...
sevenperforce Posted April 4, 2016 Share Posted April 4, 2016 Does anyone know what New Shep uses for attitude control on re-entry? Link to comment Share on other sites More sharing options...
tater Posted April 4, 2016 Share Posted April 4, 2016 No idea. Link to comment Share on other sites More sharing options...
sevenperforce Posted April 4, 2016 Share Posted April 4, 2016 3 minutes ago, tater said: No idea. Hmm. Went back over that video and I spot a quad of air brakes deployed from the cylindrical upper housing at 1:04, so that's probably the primary attitude control. Plus, the weight of the engine likely helps to maintain a retrograde attitude during re-entry. The BE-3 uses a combustion-tapped turbopump so it is probably pretty lightweight..maybe the most lightweight hydrolox engine of its thrust rating. Haven't been able to find even the most tenuous weight or specific impulse numbers, though. I suppose that with LH2 they have more specific impulse than they know what to do with, so they can get away with just dumping the turbopump exhaust overboard. Link to comment Share on other sites More sharing options...
sevenperforce Posted April 4, 2016 Share Posted April 4, 2016 Did a bit more digging, and noticed that the BE-3 is going to be getting a vacuum-optimized bell projected at 670 kN some time next year. That's a great deal more than the 490 kN of the SL version. They can downthrottle to 18%, though, which is odd. How can they get that low without flow separation? Here's a pretty good view of the BE-3's nozzle: It seems more conical than the conventional bell shape of the Merlin 1D: So maybe they are using a differently-shaped bell to allow deeper throttling at the expense of lower specific impulse and some underexpansion? Then again the flow doesn't look terribly under-expanded in videos, so I'm not sure. If we could be sure that the current BE-3 was properly SL optimized then we could get a good idea of specific impulse by comparing the projected vacuum thrust to the SL thrust, but we aren't. Link to comment Share on other sites More sharing options...
fredinno Posted April 4, 2016 Share Posted April 4, 2016 13 hours ago, Shpaget said: I don't follow you reasoning. They are able to abort, hence not ready for manned flight?? How does that follow? The capsule uses retro thrusters to slow down. That's what causes the dust cloud, not the impact. They are not able to abort (during ascent), so they should not launch manned missions. It's much less safe not to have a proper abort system, especially when you carry 100s of people. The Shuttle taught us that you always need to wind a way to bail during ascent if something goes wrong. 8 hours ago, Nibb31 said: I don't think it does have an active abort system at all. Maybe the landing rockets can be used to abort, but then you'd be in for a hard landing. It used its landing rockets on the pad abort. Link to comment Share on other sites More sharing options...
sevenperforce Posted April 4, 2016 Share Posted April 4, 2016 2 minutes ago, fredinno said: It used its landing rockets on the pad abort. Does the capsule have landing legs? If so, BO could make them out of a steel honeycomb that would crumple at faster impact speeds; this way the capsule could use its retrorockets for launch abort and then smash its legs to pieces on the landing. You don't need to worry about reuse in a launch abort. Link to comment Share on other sites More sharing options...
tater Posted April 4, 2016 Share Posted April 4, 2016 (edited) I do not think it used the landing retros for the pad abort, do you have a source? It looked like there was a motor package below the capsule to me, not to mention that the smoke trail and seeming burn was hugely longer than the ~1 second landing burst. Edited April 4, 2016 by tater Link to comment Share on other sites More sharing options...
sevenperforce Posted April 4, 2016 Share Posted April 4, 2016 3 minutes ago, tater said: I do not think it used the landing retros for the pad abort, do you have a source? It looked like there was a motor package below the capsule to me, not to mention that the smoke trail and seeming burn was hugely longer than the ~1 second landing burst. Yeah, you're right. Watched the launch abort video. In the text at the start they expressly say it uses a "pusher escape motor" for launch, and then on landing there was the same characteristic retrorocket burst. Dunno if these recent tests have been with the pusher escape motor or not...nor whether the pusher escape motor is nominally attached to the booster or to the capsule. Link to comment Share on other sites More sharing options...
fredinno Posted April 4, 2016 Share Posted April 4, 2016 12 minutes ago, sevenperforce said: Does the capsule have landing legs? If so, BO could make them out of a steel honeycomb that would crumple at faster impact speeds; this way the capsule could use its retrorockets for launch abort and then smash its legs to pieces on the landing. You don't need to worry about reuse in a launch abort. It doesn't appear to use landing legs at all. Soyuz doesn't either, so it should be fine. 4 minutes ago, sevenperforce said: Yeah, you're right. Watched the launch abort video. In the text at the start they expressly say it uses a "pusher escape motor" for launch, and then on landing there was the same characteristic retrorocket burst. Dunno if these recent tests have been with the pusher escape motor or not...nor whether the pusher escape motor is nominally attached to the booster or to the capsule. Well, the Dragon V2 uses its landing system as a pusher abort system too. I thought it was the same idea for Blue Origin, since it would save mass. Link to comment Share on other sites More sharing options...
sevenperforce Posted April 4, 2016 Share Posted April 4, 2016 12 minutes ago, fredinno said: Well, the Dragon V2 uses its landing system as a pusher abort system too. I thought it was the same idea for Blue Origin, since it would save mass. I would have thought so too, but apparently not. You know, I bet the pusher abort system remains inside the top of the New Shepard booster during normal flights. Link to comment Share on other sites More sharing options...
fredinno Posted April 4, 2016 Share Posted April 4, 2016 12 minutes ago, sevenperforce said: I would have thought so too, but apparently not. You know, I bet the pusher abort system remains inside the top of the New Shepard booster during normal flights. Source? Link to comment Share on other sites More sharing options...
sevenperforce Posted April 4, 2016 Share Posted April 4, 2016 8 minutes ago, fredinno said: Source? Well, I don't have a source; that's why I said "I bet". But it makes sense. That cylindrical ring up at the top of the New Shepard with the deployable air brakes is just about the same size as the pusher motor shown underneath the capsule in the pad abort test. And you'd want control surfaces in an abort. If you are aborting away from the booster then you are no longer worried about landing the booster. Link to comment Share on other sites More sharing options...
Nibb31 Posted April 4, 2016 Share Posted April 4, 2016 Once they get confident enough in the booster and its RTLS capability, they could probably do away with the separation and try to land with capsule attached. That would simplify operations greatly. It would probably be safe to keep the chutes and abort system though, just in case. Link to comment Share on other sites More sharing options...
tater Posted April 4, 2016 Share Posted April 4, 2016 The big problem with driving down there is where to park... It would make sense to scope it out ahead of time, but I don't feel like a 9 hour trial run. Link to comment Share on other sites More sharing options...
mikegarrison Posted April 5, 2016 Share Posted April 5, 2016 3 hours ago, tater said: The big problem with driving down there is where to park... It would make sense to scope it out ahead of time, but I don't feel like a 9 hour trial run. It's middle-of-nowhere Texas. Can't you just park anywhere you like? Or are you saying the problem is finding a good vantage point to see anything interesting? Link to comment Share on other sites More sharing options...
tater Posted April 5, 2016 Share Posted April 5, 2016 The latter. I checked google maps, and there is a state road nearby, but there is a possibility they are allowed to briefly close roads that might be in danger areas. Link to comment Share on other sites More sharing options...
Exoscientist Posted April 5, 2016 Share Posted April 5, 2016 On 4/4/2016 at 11:42 AM, sevenperforce said: Yes, it was quite impressive. It's falling like a rock until relight and it just...stops. Can anyone guesstimate the gees it pulls on that suicide burn? But despite how impressive that was, the hover at the end was...meh. I've got to say I'm in love with the legs-down-at-engine-off suicide burn used by Falcon 9. Suicide-burn is the appropriate description for the Falcon 9 landing technique, not the "hover-slam" term SpaceX has been using. Since the F9 can not hover, it is inappropriate to include the word "hover" in the landing description. A more appropriate name, aside from suicide-burn, would be "land-or-slam", since without hovering ability you only get one chance at it. You stick the landing on the first try or you crash and burn. SpaceX needs to stop trying to reinvent the wheel, and investigate means of giving the F9 hovering capability. Bob Clark Link to comment Share on other sites More sharing options...
fredinno Posted April 5, 2016 Share Posted April 5, 2016 https://www.nasaspaceflight.com/2016/04/new-shepard-hat-trick-blue-origin/ 2 minutes ago, Exoscientist said: Suicide-burn is the appropriate description for the Falcon 9 landing technique, not the "hover-slam" term SpaceX has been using. Since the F9 can not hover, it is inappropriate to include the word "hover" in the landing description. A more appropriate name, aside from suicide-burn, would be "land-or-slam", since without hovering ability you only get one chance at it. You stick the landing on the first try or you crash and burn. SpaceX needs to stop trying to reinvent the wheel, and investigate means of giving the F9 hovering capability. Bob Clark But that would be redesigning the engines to support very low throttling, which reduces efficiency, and incurs high development costs. They do well on land, just not on the sea landings. Link to comment Share on other sites More sharing options...
sevenperforce Posted April 5, 2016 Share Posted April 5, 2016 14 minutes ago, Exoscientist said: Suicide-burn is the appropriate description for the Falcon 9 landing technique, not the "hover-slam" term SpaceX has been using. Since the F9 can not hover, it is inappropriate to include the word "hover" in the landing description. A more appropriate name, aside from suicide-burn, would be "land-or-slam", since without hovering ability you only get one chance at it. You stick the landing on the first try or you crash and burn. SpaceX needs to stop trying to reinvent the wheel, and investigate means of giving the F9 hovering capability. They could put a massively underexpanded Merlin 1D in the center of the cluster, but it would result in a performance hit. And honestly they haven't had trouble with the suicide burns. The first two barge landing failures were tip-over, indicating stability problems. The last attempt, a three-engine suicide burn, had a vanishingly low probability of success from the very beginning, made harder by poor landing conditions. They haven't actually attempted a normal-condition barge landing with the F9FT yet; both tip-overs were on the F9v1.1 model. Link to comment Share on other sites More sharing options...
Exoscientist Posted April 5, 2016 Share Posted April 5, 2016 A landing where you crash and burn is not a successful landing. Bob Clark Link to comment Share on other sites More sharing options...
sevenperforce Posted April 5, 2016 Share Posted April 5, 2016 9 minutes ago, Exoscientist said: A landing where you crash and burn is not a successful landing. No one suggested it was. But alleging that the suicide burns are the source of their difficulty when in fact stability was the source of the two normal-condition landing failures is quite incorrect. Link to comment Share on other sites More sharing options...
Wingman703 Posted April 6, 2016 Share Posted April 6, 2016 No hype for the ISS resupply on the 8th? Link to comment Share on other sites More sharing options...
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