tater Posted July 20, 2017 Share Posted July 20, 2017 I don't think F9 is tight on payload margins to ISS, so the extra mass doesn't matter at all. Quote Link to comment Share on other sites More sharing options...
DerekL1963 Posted July 20, 2017 Share Posted July 20, 2017 1 hour ago, Kryten said: And there's much more to get hit with nowadays than there was during most of the shuttle era. To some extent, yeah. There's also more awareness of MMOD problem. There's also a great of hype. Quote Link to comment Share on other sites More sharing options...
DeltaDizzy Posted July 20, 2017 Share Posted July 20, 2017 I thought it lost out to spacex. Quote Link to comment Share on other sites More sharing options...
Mitchz95 Posted July 20, 2017 Share Posted July 20, 2017 Wasn't this always the plan? I remember seeing an animation from like five years ago with it launching on an Atlas V. That was the crew version, though. Quote Link to comment Share on other sites More sharing options...
sevenperforce Posted July 20, 2017 Share Posted July 20, 2017 I like a pusher-ring LES. Solid, but reusable when not activated. Stays in the first-stage interstage during nominal flights; fires (and blows the interstage apart) on aborts. Quote Link to comment Share on other sites More sharing options...
ment18 Posted July 20, 2017 Share Posted July 20, 2017 If it stays in the 1st stage insterstage it has to push the entire 2nd stage right? Over 100t on F9 Quote Link to comment Share on other sites More sharing options...
Exploro Posted July 21, 2017 Share Posted July 21, 2017 1 hour ago, DeltaDizzy said: I thought it lost out to spacex. SN did lose out to SpaceX and Boeing for contracts to fly crewed missions to and from the ISS. However there was still plenty to go around for unmanned supply mission contracts; which SN secured in January of last year. Quote Link to comment Share on other sites More sharing options...
tater Posted July 21, 2017 Share Posted July 21, 2017 Commercial crew launch dates updated: Dragon 2 demo NET February '18 Dragon 2 crew flight NET June '18 Quote Link to comment Share on other sites More sharing options...
softweir Posted July 21, 2017 Share Posted July 21, 2017 3 hours ago, ment18 said: If it stays in the 1st stage insterstage it has to push the entire 2nd stage right? Over 100t on F9 Since it has to be robust enough to provide more acceleration during an emergency than it carries during launch, then it would inevitably be at least robust enough to survive. 3 hours ago, sevenperforce said: I like a pusher-ring LES. Solid, but reusable when not activated. Stays in the first-stage interstage during nominal flights; fires (and blows the interstage apart) on aborts. But why put it in the first stage interstage? Why try to save the second stage? The second stage has no facilities that would be useful during a launch emergency, and during an emergency is just dead weight, making a ring LES needlessly heavy to launch every time. Why not have it as part of the second stage interstage, just below the capsule? Quote Link to comment Share on other sites More sharing options...
Brotoro Posted July 21, 2017 Share Posted July 21, 2017 (edited) An LES on the first stage interstage wouldn't have saved the capsule from the two Falcon 9 failures where the second stage exploded. So I'm confused. Edited July 21, 2017 by Brotoro Quote Link to comment Share on other sites More sharing options...
kerbiloid Posted July 21, 2017 Share Posted July 21, 2017 (edited) 4 hours ago, softweir said: Why not have it as part of the second stage interstage, just below the capsule? As it was in the late Clipper project. If the launch were successful, the LES was to add last several hundred m/s to reach the orbit. It was a ring of 8(?) powder rockets right between the last stage and the craft. Edited July 21, 2017 by kerbiloid Quote Link to comment Share on other sites More sharing options...
magnemoe Posted July 21, 2017 Share Posted July 21, 2017 12 hours ago, kerbiloid said: Usually LES weights ~ 1/4..1/2 of the capsule mass and gets dropped after the 1st stage burnout. Delivering a reusable LES to orbit one must deliver: additional mass of hull to hide the LES in; additional fuel to accelerate the LES mass to to 1..2 km/s, but to 8 km/s; additional mass of the last stage to keep the additional fuel in. So, instead of launching a single-use traditional LES weighting, say, 3 t, they would spend 3*5 = 15 t of fuel more to get it to orbit and add ~1 t of tthe rocket fuel tanks to keep this fuel inside. So, a reusable LES means spending 15 t of fuel and hundreds kg of tanks to save 3 t of powder and still several hundred kg of metal. I.e inner LES = burn 10..15 t of liquid fuel to save 3 t of powder. Not a great choice unless suppose that LES option happily appears for the already being planned landing engine (which needs almost the same dV as LES). There is another option, though, which was supposed to be used in Clipper project. 8 solid motors below the ship, on the last stage top. If abort - they separate from the stage and throw up th ship. If success - they were supposed to be ignited before the speed gets orbital, and spend their fuel to give the required delta-V to get into orbit. I.e. LES not spent and not reusable, but used just as an additional stage burning in every flight. Calculation is a bit flawed as they also use the fuel for orbital operations, yes its more than they need but this gives some margin. The Clipper idea is the same but uses less efficient engines and you still have to take it to orbit, the super drako has poor vacuum isp the the drako engines are decent. Also the dragon is launched on falcon 9 who has plenty of margin Quote Link to comment Share on other sites More sharing options...
kerbiloid Posted July 21, 2017 Share Posted July 21, 2017 5 minutes ago, magnemoe said: The Clipper idea is the same but uses less efficient engines and you still have to take it to orbit Clipper way doesn't need to carry the LES engines back to the Earth, making the capsule grow. Yes, solids are less efficient, but rather than, they still work to deliver the craft to orbit, not just are a ballast. 6 minutes ago, magnemoe said: falcon 9 who has plenty of margin This sentence can be paraphrased. "... who is overweighted for its payload mass". If it has a gap, this means that it doesn't work for 100%. Quote Link to comment Share on other sites More sharing options...
Scotius Posted July 21, 2017 Share Posted July 21, 2017 I have high hopes for Dream Chaser. Ability to control the descent seems very appealing to me, moreso than just dropping the capsule into the atmosphere and hoping for the best. If cargo verion serves successfuly, maybe crew variant will be built. Who knows - maybe one day we'll see Space Shuttle reincarnated Quote Link to comment Share on other sites More sharing options...
Nibb31 Posted July 21, 2017 Share Posted July 21, 2017 11 minutes ago, Scotius said: I have high hopes for Dream Chaser. Ability to control the descent seems very appealing to me, moreso than just dropping the capsule into the atmosphere and hoping for the best. If cargo verion serves successfuly, maybe crew variant will be built. Who knows - maybe one day we'll see Space Shuttle reincarnated Capsules provide lift and crossrange too. DreamChaser is a lifting body, its descent is only slightly more "controlled" than a capsule. A Space Shuttle with actual wings is a huge waste of payload mass. Quote Link to comment Share on other sites More sharing options...
NSEP Posted July 21, 2017 Share Posted July 21, 2017 Quote Link to comment Share on other sites More sharing options...
tater Posted July 21, 2017 Share Posted July 21, 2017 7 hours ago, kerbiloid said: This sentence can be paraphrased. "... who is overweighted for its payload mass". If it has a gap, this means that it doesn't work for 100%. It doesn't mean this at all. F9 has multiple uses, and has evolved a great mass fraction. It has excess capacity that with reuse costs nothing more than fuel. If D2 is 9-10 tons. And reusable payload to that orbit is 13-18 tons (RTLS vs ASDS), then as long as D2 is under one of those values in mass, extra mass is a non-issue. Launch schedule change: CRS-12 is now NET August 14. Quote Link to comment Share on other sites More sharing options...
CatastrophicFailure Posted July 21, 2017 Share Posted July 21, 2017 39 minutes ago, tater said: Launch schedule change: CRS-12 is now NET August 14. That's gonna put it up against NROL-42 and ULA. Which means someone is getting bumped and delayed further. guess which one. Man, and just a little while ago everything seemed to be going so well. Quote Link to comment Share on other sites More sharing options...
tater Posted July 21, 2017 Share Posted July 21, 2017 ULA is flying from VAFB, though. Quote Link to comment Share on other sites More sharing options...
sevenperforce Posted July 21, 2017 Share Posted July 21, 2017 19 hours ago, ment18 said: If it stays in the 1st stage insterstage it has to push the entire 2nd stage right? Over 100t on F9 I was thinking of something like ITS, where you need a high-thrust escape system for the payload-integrated reusable upper stage. Quote Link to comment Share on other sites More sharing options...
tater Posted July 21, 2017 Share Posted July 21, 2017 That's true. If it's 2 stage to orbit, then the whole "spaceship" needs a LES. I wonder if something akin to superdraco would work on the US, and of not used for abort it is used for deorbit, tmi, etc. Quote Link to comment Share on other sites More sharing options...
Ultimate Steve Posted July 21, 2017 Share Posted July 21, 2017 *Gets back from camp* *Sees news* *Screams no* *Realizes that it's hopefully for the greater good* I mean, I guess I know how people older than me feel to have a Mars mission pushed back again and again. I just hope it won't be for five decades... *Packs for immediate vacation eighteen hours after the last one* Quote Link to comment Share on other sites More sharing options...
magnemoe Posted July 22, 2017 Share Posted July 22, 2017 12 hours ago, sevenperforce said: I was thinking of something like ITS, where you need a high-thrust escape system for the payload-integrated reusable upper stage. Think something like ITS would need an escape module with just the crew seating area. Remember you might have to use it during landing too. Quote Link to comment Share on other sites More sharing options...
cubinator Posted July 22, 2017 Share Posted July 22, 2017 4 hours ago, magnemoe said: Think something like ITS would need an escape module with just the crew seating area. Remember you might have to use it during landing too. STS considered something like that but found it would require too much extra infrastructure. I think ITS might find similar issues is they tried that. Quote Link to comment Share on other sites More sharing options...
tater Posted July 22, 2017 Share Posted July 22, 2017 A crew vehicle to be used with NASA as a possible customer would require it meet their LOC requirements and would have to have a LES as a result. The pivot to the Moon is because that;s the way everyone is going. NASA never had takers for a manned mars mission from other agencies like ESA, they simply don't have the resources to play that game. The Moon, OTOH, is far more doable. JAXA has expressed interest in using DSG as a staging point for a lander they might build, for example. Given that NASA is the likely customer, they would need to have it meet their specs. Quote Link to comment Share on other sites More sharing options...
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