Mitchz95 Posted February 27, 2016 Share Posted February 27, 2016 Confirmed. Link to comment Share on other sites More sharing options...
Spaceception Posted February 27, 2016 Share Posted February 27, 2016 So, I was a few miles away from the launchpad on Thursday at 4:46-8, and my mom turned on her smartphone to listen to the livestream... Suddenly, I heard they scrubbed the launch. As you know, at the 1:40 mark She jinked it! Good luck to SpaceX on Sunday though, I probably won't be able to make it however Link to comment Share on other sites More sharing options...
KerbonautInTraining Posted February 27, 2016 Share Posted February 27, 2016 Sunday??!? I heard it would be no earlier than March 3! Can't wait! Link to comment Share on other sites More sharing options...
Mitchz95 Posted February 28, 2016 Share Posted February 28, 2016 I certainly hope they make it this time. These constant delays are getting fairly annoying. (I know, it's rocket science, but still...) Link to comment Share on other sites More sharing options...
fredinno Posted February 28, 2016 Share Posted February 28, 2016 On February 27, 2016 at 7:21 PM, sojourner said: And? Nothing there indicates that SpaceX is actually working on making F9 first stage methane based. You're making suppositions. Second stage may get methane but that remains to be seen. How about replacing the merlin 1d with a Merlin 1e, using staged combustion instead of F9 FT? The RD-180 isp is ~30s higher for both Vaccum and surface, you could definitely get enough for the F9 FT performance without deep cryo- SpaceX already has experience on this from Raptor development (which is staged combustion) and Merlin 1e could give experience for MCT/Raptor.It's still not a dead end, like deep-dryo, either. The engine development would still be a pain, but SpaceX has been continually developing and improving the Merlins anyways. The rest of the tooling can also still remain the same. The engine development might be somewhat longer, but SpaceX isreally in no rush,as FT was made to increase performancefor land landings- SpaceX had almost nailed sea landings when V1.1 was retired. Link to comment Share on other sites More sharing options...
KSK Posted February 28, 2016 Share Posted February 28, 2016 Or how about we stop running around like headless chickens worrying that the sky is falling on our heads because *shock* a rocket launch is delayed because of technical issues, stop proposing overcomplicated solutions to a problem that may or may not even exist and see how subcooled LOX works over the next few flights before jumping to any conclusions? Besides, if I remember rightly, Raptor was also going to take advantage of subcooled propellants. This isn't a one-off boondoggle for Falcon. Like propulsive landing, if SpaceX can get this to work properly, it'll have a knock-on effect for everything else they do in future. Link to comment Share on other sites More sharing options...
Hcube Posted February 28, 2016 Share Posted February 28, 2016 4 hours ago, fredinno said: How about replacing the merlin 1d with a Merlin 1e, using staged combustion instead of F9 FT? The RD-180 isp is ~30s higher for both Vaccum and surface, you could definitely get enough for the F9 FT performance without deep cryo- SpaceX already has experience on this from Raptor development (which is staged combustion) and Merlin 1e could give experience for MCT/Raptor.It's still not a dead end, like deep-dryo, either. The engine development would still be a pain, but SpaceX has been continually developing and improving the Merlins anyways. The rest of the tooling can also still remain the same. The engine development might be somewhat longer, but SpaceX isreally in no rush,as FT was made to increase performancefor land landings- SpaceX had almost nailed sea landings when V1.1 was retired. This is interesting but again it's just a bunch of suppositions Link to comment Share on other sites More sharing options...
Falkenherz Posted February 28, 2016 Share Posted February 28, 2016 (edited) As a "totally professional Kerbal Space Program pilot", I wonder why the guys over at SpaceX to not attempt a different concept to land and re-use their rockets: Parachutes? Granted, they might not pull off a point-exact landing with parachutes, but select a big landing region, roughly direct your rocket there, deploy the parachutes and all that matters should be that you have your precious rocket back unharmed and recoverable in one piece, no? Edited February 28, 2016 by Falkenherz Link to comment Share on other sites More sharing options...
DC Posted February 28, 2016 Share Posted February 28, 2016 I can think of a couple of reasons. Firstly those are big rockets, you'd need a lot of parachutes that could be an issue. Secondly I just don't think you'd be able to slow it down enough to avoid damage on hitting the ground. I guess you could use a drogue chute to get it pointed in the right direction but that doesn't seem to be one of their problems. Link to comment Share on other sites More sharing options...
jf0 Posted February 28, 2016 Share Posted February 28, 2016 I'm no expert on parachutes, but I would guess they wouldn't give a soft enough landing on solid terrain. But you could always add some kind of squishy inflatable landing bag. But maybe by this point it is getting just as complicated as doing a powered landing with the rocket. Link to comment Share on other sites More sharing options...
UnusualAttitude Posted February 28, 2016 Share Posted February 28, 2016 Almost all western launch sites I can think of launch their rockets over the ocean (mainly for safety reasons, to avoid flying over populated areas), therefore you're gonna have to recover your 1st stage on a boat or platform of some kind in the ocean, and therefore you need to make a precision landing. Parachutes are no good for this. The reason Space X want to land on their barge and not splash-down in the ocean is that landing in sea water makes the refurbishing of the engines much more costly and time-consuming. They have also successfully demonstrated the ability to fly the 1st stage back to a landing pad near the launch site, but this uses much more fuel and limits the payload of the rocket. Link to comment Share on other sites More sharing options...
GluttonyReaper Posted February 28, 2016 Share Posted February 28, 2016 Parachutes, as has been mentioned, don't really allow for a precision landing. (That said, there was apparently a proposal for the Saturn V first stage to be parachuted down and grabbed out the air by a helicopter .... but that's another story.) I'm pretty sure I recall it being mentioned that, on a rocket this big, it's actually lighter to carry the extra fuel and guidance systems for a powered landing than slapping a bunch of parachutes on it. Link to comment Share on other sites More sharing options...
katateochi Posted February 28, 2016 Share Posted February 28, 2016 I thought that it was partly due to the mass of the required parachutes (and possible squishy landing things) to touch down softly would actually outweigh the required fuel for a powered landing (or was very close to it). And also that the various parachutes, chute-fairings etc added greater mechanical complexity. I just found this on stackexchange asking the same thing and the first answer is pretty good I think. http://space.stackexchange.com/questions/7718/why-would-spacex-not-use-parachutes-for-the-final-descent-of-the-first-stage Link to comment Share on other sites More sharing options...
glen.mack Posted February 28, 2016 Share Posted February 28, 2016 KSP has given you a false sense of the usefulness of parachutes. IRL they can't clip through each other, have much more weight per unit of lift they can give and that's without even considering the material science aspects of how much material and tethers you'd need for a rocket that weighs 14 tonnes. Then there's the fact you'd have to do it sideways, because you'd need to distribute that weight along the length as putting it all at the top would require strengthening in a direction opposite to the normal g-forces... Link to comment Share on other sites More sharing options...
technicalfool Posted February 28, 2016 Share Posted February 28, 2016 Quote https://www.reddit.com/r/spacex/wiki/faq/reusability Why doesn't SpaceX save fuel during booster reuse by adding a parachute? SpaceX experimented with using parachutes in the past (mainly for their Falcon 1 vehicles), but parachutes are poorly suited to this application, as extreme speeds and loads cause them to shred. Parachutes large enough to recover the stage are also quite heavy, a weight which could be used for fuel for a propulsive landing and for primary mission assurance. Parachutes also cannot be steered. Essentially, this becomes a problem of people overestimating the amount of fuel required to bring the stage back, underestimating the weight of the parachute system (which would be in the hundreds of kilograms at least), and underestimating the fragility and controllability of a parachute system Disclaimer: SpaceX subreddit is not an official source Basically, chutes weigh more than you think, and the Falcon 9 is already pushing up against the limits of its mass budget. Link to comment Share on other sites More sharing options...
Val Posted February 28, 2016 Share Posted February 28, 2016 Also, I think it's been said, SpaceX wants a lot of experience with powered landings, because that's needed on Mars and almost anywhere else. Link to comment Share on other sites More sharing options...
KSK Posted February 28, 2016 Share Posted February 28, 2016 They tried parachutes and they didn't work. If I remember rightly, aerodynamic stresses caused the booster stages to break up in mid air. Link to comment Share on other sites More sharing options...
magnemoe Posted February 28, 2016 Share Posted February 28, 2016 3 hours ago, katateochi said: I thought that it was partly due to the mass of the required parachutes (and possible squishy landing things) to touch down softly would actually outweigh the required fuel for a powered landing (or was very close to it). And also that the various parachutes, chute-fairings etc added greater mechanical complexity. I just found this on stackexchange asking the same thing and the first answer is pretty good I think. http://space.stackexchange.com/questions/7718/why-would-spacex-not-use-parachutes-for-the-final-descent-of-the-first-stage The parachute would have to be gigantic and empty first stage is 25 ton, fuel use on landing is probably pretty small they just burn for a few seconds., the boostback is more expensive. You are likely to need to use engines anyway to land as parachute would not slow you enough. This is common in KSP too. Accuracy, is second one, even for ground landing they would need an far larger landing area. Wind, no wind in KSP making parashutes more useful, you will have to land with 3-10 m/s vertical speed, higher if its blowing harder, worse this would be pretty impossible to compensate for doing an braking burn and unless you cut parachute on touchdown the wind might tip you over. Link to comment Share on other sites More sharing options...
juanml82 Posted February 28, 2016 Share Posted February 28, 2016 4 hours ago, UnusualAttitude said: Almost all western launch sites I can think of launch their rockets over the ocean (mainly for safety reasons, to avoid flying over populated areas), therefore you're gonna have to recover your 1st stage on a boat or platform of some kind in the ocean, and therefore you need to make a precision landing. Parachutes are no good for this. The reason Space X want to land on their barge and not splash-down in the ocean is that landing in sea water makes the refurbishing of the engines much more costly and time-consuming. They have also successfully demonstrated the ability to fly the 1st stage back to a landing pad near the launch site, but this uses much more fuel and limits the payload of the rocket. I wonder if there is some pair of islands in the Caribbean or the Pacific, near the equator, in which you could launch from a western island and the first stage can fall on the second, presumabily, uninhabited island to the East. That combination should exist somewhere. Of course, that means setting up a launch site elsewhere, with its associated costs and the eastern island is unlikely to be all smooth and plain sand everywhere. But it's still a larger target to hit than a barge Link to comment Share on other sites More sharing options...
samstarman5 Posted February 28, 2016 Share Posted February 28, 2016 2 hours ago, Val said: Also, I think it's been said, SpaceX wants a lot of experience with powered landings, because that's needed on Mars and almost anywhere else. Can you just imagine landing a manned pod the same way Opportunity was landed? Link to comment Share on other sites More sharing options...
Kerbal01 Posted February 28, 2016 Share Posted February 28, 2016 This has been discussed to death and back again on various internet sites for atleast 5 years. Chutes are heavy and inaccurate, and the F9 S1 is heavy. Link to comment Share on other sites More sharing options...
Xyrus Posted February 28, 2016 Share Posted February 28, 2016 Yeah, parachutes won't work well in this situation unless they can find a spot in the ocean that's Kerbin (no wind, no waves). That being said, airbrakes might be plausible. The materials science is there. Using a light enough composite (carbon-fiber) may help reduce the required fuel to land while possibly improving descent control. But that would depend on if the weight of the braking mechanism is less than the fuel it takes to carry it along. The rocket would be "easy" to stage/parachute/recover, even airbag the "critical" components to avoid salt water contamination. But that isn't really the point. They want the whole rocket in one piece so once it lands, they can refuel it and launch with very little turn around time. Link to comment Share on other sites More sharing options...
tater Posted February 28, 2016 Share Posted February 28, 2016 Still a few hours, but this is the technical webcast (no annoying social media idiots, just video and data). Link to comment Share on other sites More sharing options...
fredinno Posted February 28, 2016 Share Posted February 28, 2016 13 hours ago, KSK said: Or how about we stop running around like headless chickens worrying that the sky is falling on our heads because *shock* a rocket launch is delayed because of technical issues, stop proposing overcomplicated solutions to a problem that may or may not even exist and see how subcooled LOX works over the next few flights before jumping to any conclusions? Besides, if I remember rightly, Raptor was also going to take advantage of subcooled propellants. This isn't a one-off boondoggle for Falcon. Like propulsive landing, if SpaceX can get this to work properly, it'll have a knock-on effect for everything else they do in future. Yeah, problem is that if a rocket launch is delayed by a day every time a hold is needed (holds are very common in rocket launches) that poses both a schedule risk (time=money, especially when the launch manifest is packed) and a safety risk (time constraints can cause companies to launch anyways even when unsafe, which led to Challenger.) Nobody has come up with a way Elon might make this situation less problematic, and neither has SpaceX, despite it generally being very open. 12 hours ago, Hcube said: This is interesting but again it's just a bunch of suppositions What's a supposition? Merlins are clearly capable of higher performance, as shown by the RD-180, via staged combustion, are capable of extensive modifications, and Elon himself has stated that staged combustion is going to be used on the Raptor, along with the fact that F9 V1.1 had almost achieved powered landing back in Jason-3. Link to comment Share on other sites More sharing options...
DuoDex Posted February 28, 2016 Share Posted February 28, 2016 Thread punted to Science and Spaceflight. Link to comment Share on other sites More sharing options...
Recommended Posts