CatastrophicFailure Posted April 27, 2016 Share Posted April 27, 2016 16 minutes ago, tater said: Historical data is that SpaceX can at most take all commercial launches that are available for American companies to get, which is about 12. Historical data is that if you improve access, that access gets used... Even if the details can't be foreseen at the moment. Link to comment Share on other sites More sharing options...
Damien_The_Unbeliever Posted April 27, 2016 Share Posted April 27, 2016 3 minutes ago, CatastrophicFailure said: Historical data is that if you improve access, that access gets used... Even if the details can't be foreseen at the moment. Also, there's a general pattern to be observed here. We use it all the time. It's why we use caches within our computers. Recent history is generally a good predictor for near-term future. What people sometimes forget is that, at some point, this fails. Whether that's a cache miss or a shift in market forces, at *some* point, recent history will always fail to be a good predictor for the future. It's just bloomin' difficult to predict this before it happens Link to comment Share on other sites More sharing options...
Ten Key Posted April 27, 2016 Share Posted April 27, 2016 1 hour ago, Basto said: I think the analogy is actually pretty apt. If we had to throw away an airliner after every flight and someone came around and said "I have an idea, if we reuse the airplane we could make things cheaper". You would probably have a bunch of people telling them it doesn't make any sense because we only fly 10 planes a year. I'm not sure aircraft and rockets can be compared directly when it comes to reuse. In engineering, most things have what is known as a "factor of safety", which is essentially a rough estimation of how much force they can withstand beyond expected operating conditions. Most things are engineered with a factor of safety of around ten. . .an automobile can survive about ten times as much force as it would normally encounter in day-to-day use. An aircraft with a factor of safety of ten would be too heavy to take off. Airplanes are engineered with a factor of safety of around three. And they are still pretty tough. An airframe that is not overloaded can last for decades with proper maintenance. Rockets have a factor of safety that approaches one. In normal operations the stresses they experience approach their maximum values and could very easily push parts beyond the point of reuse. Just because a part didn't fail doesn't mean it isn't about to, and making sure every piece of a rocket is safe to fly again is not an easy or certain task. Link to comment Share on other sites More sharing options...
Rakaydos Posted April 27, 2016 Share Posted April 27, 2016 6 minutes ago, Ten Key said: I'm not sure aircraft and rockets can be compared directly when it comes to reuse. In engineering, most things have what is known as a "factor of safety", which is essentially a rough estimation of how much force they can withstand beyond expected operating conditions. Most things are engineered with a factor of safety of around ten. . .an automobile can survive about ten times as much force as it would normally encounter in day-to-day use. An aircraft with a factor of safety of ten would be too heavy to take off. Airplanes are engineered with a factor of safety of around three. And they are still pretty tough. An airframe that is not overloaded can last for decades with proper maintenance. Rockets have a factor of safety that approaches one. In normal operations the stresses they experience approach their maximum values and could very easily push parts beyond the point of reuse. Just because a part didn't fail doesn't mean it isn't about to, and making sure every piece of a rocket is safe to fly again is not an easy or certain task. I thought I read somewhere that SpaceX maintains the highest factor of safety of any orbital rocket maufacturer. Link to comment Share on other sites More sharing options...
Elukka Posted April 27, 2016 Share Posted April 27, 2016 (edited) Musk has mentioned a 40% structural safety margin. The first stage also has engine out capability (https://www.youtube.com/watch?v=dvTIh96otDw). For aircraft the FAA apparently mandates a safety factor of 1.5 which the Falcon is rather close to. Edited April 27, 2016 by Elukka Link to comment Share on other sites More sharing options...
Kryten Posted April 27, 2016 Share Posted April 27, 2016 SpaceX have optimised their rockets for lowest dry mass, in order for the reusability modifications to produce lower effects on performance. A side effect of that is they can have more structural margin before they get significant performance hits. Link to comment Share on other sites More sharing options...
PB666 Posted April 28, 2016 Share Posted April 28, 2016 7 hours ago, tater said: Here's actual news, vs a tweet: https://www.nasaspaceflight.com/2016/04/spacex-debut-red-dragon-2018-mars-mission/ So NASA is presumably coughing up actual money. The outer space treaty needs to just be ignored, it's nonsense. Wow, we are in the rebellious mood today, we are trying to launch nuclear attacks on non-existance lunar colonies, now we are going to ignore the outer space treaty, hey lets get rid of the nuclear non-proliferation treaty, and just have personilzed nuclear weapons. You neighbor walks on your grass, kaboom. Link to comment Share on other sites More sharing options...
PB666 Posted April 28, 2016 Share Posted April 28, 2016 6 hours ago, Elukka said: Musk has mentioned a 40% structural safety margin. The first stage also has engine out capability (https://www.youtube.com/watch?v=dvTIh96otDw). For aircraft the FAA apparently mandates a safety factor of 1.5 which the Falcon is rather close to. Then don't expect repeated recycling, at that margin level they will have a pretty rapid accumulation of stress. The FAA may mandate 1.5, the industry has higher standard on the core structural parts, such as wing and pressure hull, obviously some of the clear air sheer turbulance would have taken out the craft if it was1.5. CRS-8 i have fine captured the data, will present it soon, but a little story in that data, after Max-q, the ride becomes pretty bouncy, I captured momentary fluctuations over 2g on the second stage. Vibrations are not easily countered for, they can fall into black swan territory. Needs lots of emperical observations to determine a adequate safety margin. I wonder how ofter they are going to do xray scan of the frame. Link to comment Share on other sites More sharing options...
StrandedonEarth Posted April 28, 2016 Share Posted April 28, 2016 30 minutes ago, PB666 said: I captured momentary fluctuations over 2g on the second stage Good thing it'll be a new second stage every time! Link to comment Share on other sites More sharing options...
AngelLestat Posted April 28, 2016 Share Posted April 28, 2016 9 hours ago, tater said: Here's actual news, vs a tweet: https://www.nasaspaceflight.com/2016/04/spacex-debut-red-dragon-2018-mars-mission/ So NASA is presumably coughing up actual money. The outer space treaty needs to just be ignored, it's nonsense. The outer space treaty never was an impediment for any private endeavor. Companies can mine asteroids or planets without problem, they can even sell travel tickets, rent habitats or wherever. Countries can do the same thing.. the only difference is that no one can claim a celestial body as their own. They can carry pieces inside its ship or move the whole thing if they can. Next launch? may 3? Link to comment Share on other sites More sharing options...
tater Posted April 28, 2016 Share Posted April 28, 2016 (edited) 1 hour ago, PB666 said: Wow, we are in the rebellious mood today, we are trying to launch nuclear attacks on non-existance lunar colonies, now we are going to ignore the outer space treaty, hey lets get rid of the nuclear non-proliferation treaty, and just have personilzed nuclear weapons. You neighbor walks on your grass, kaboom. Back in the day, private citizens owned warships I was thinking primarily about ownership of planets, frankly, or areas on planets. I don't see it happening, but if some entity established a colony on Mars (or elsewhere) they should own the land they use, and indeed some area around it. Edited April 28, 2016 by tater Link to comment Share on other sites More sharing options...
PB666 Posted April 28, 2016 Share Posted April 28, 2016 Just now, tater said: Back in the day, private citizens owned warships I was thinking primary about ownership of planets, frankly, or areas on planets. I don't see it happening, but if some entity established a colony on Mars (or elsewhere) they should own the land they use, and indeed some area around it. They don't own the land, but trying to move them would be a violation of the outer space treaty. The problem is inch mile, if we say X country can own a bit of celestial Y, then they come and stake the entire Y. We might do that but I can think of at least one country that might. Link to comment Share on other sites More sharing options...
tater Posted April 28, 2016 Share Posted April 28, 2016 Yeah, it was primarily aimed at reigning in totalitarian systems. Link to comment Share on other sites More sharing options...
AngelLestat Posted April 28, 2016 Share Posted April 28, 2016 (edited) 1 hour ago, tater said: Back in the day, private citizens owned warships I was thinking primarily about ownership of planets, frankly, or areas on planets. I don't see it happening, but if some entity established a colony on Mars (or elsewhere) they should own the land they use, and indeed some area around it. They dont need to own the land to profit with it. That methodology is not longer needed in the future. 1 hour ago, PB666 said: They don't own the land, but trying to move them would be a violation of the outer space treaty. The problem is inch mile, if we say X country can own a bit of celestial Y, then they come and stake the entire Y. We might do that but I can think of at least one country that might. Lets have this discussion in some of the older outer treaty topics, but the treaty does not mention nothing about that you can not move it. -------------------------------------------------------- Somebody knows the launch date for spacex? Edited April 28, 2016 by AngelLestat Link to comment Share on other sites More sharing options...
Mad Rocket Scientist Posted April 28, 2016 Share Posted April 28, 2016 11 hours ago, tater said: Here's actual news, vs a tweet: https://www.nasaspaceflight.com/2016/04/spacex-debut-red-dragon-2018-mars-mission/ So NASA is presumably coughing up actual money. The outer space treaty needs to just be ignored, it's nonsense. I have to disagree. Treaties prevent entities from overstepping the bounds of decency (Gah, that's not the right word. Oh well). Treaties are a partial answer to the question "Who watches the watchers." Maybe this instance of a treaty is silly, but throwing out the treaty because of a single place where it may be nonsense does not make sense. I'm all for rewriting space treaties to cope with the changes, but the treaties must be there. [/SOAPBOX] Link to comment Share on other sites More sharing options...
CatastrophicFailure Posted April 28, 2016 Share Posted April 28, 2016 10 minutes ago, AngelLestat said: -------------------------------------------------------- Somebody knows the launch date for spacex? May 4 @05:22 GMT Link to comment Share on other sites More sharing options...
Streetwind Posted April 28, 2016 Share Posted April 28, 2016 (edited) In tangentially reusability-related news: SpaceX won a US Airforce launch contract to launch a GPS-3 satellite in 2018. This surprised nobody whatsoever, since United Launch Alliance decided to sit out this round, and thus nobody else submitted a bid. The interesting part is that despite that, the Airfoce still received two proposals... both from SpaceX. Speculation goes that one was a bid with a new launcher, and the other one a bid with a refurbished first stage. After all, in the 2018 timeframe, they should have already reflown multiple boosters. Which proposal was ultimately selected is also only conjecture, but the final price is very close to that of an (unsolicited) example bid that SpaceX gave the Airforce in 2012, before they even started certification. That one I believe was based on a factory-new booster. Edited April 28, 2016 by Streetwind Link to comment Share on other sites More sharing options...
PB666 Posted April 28, 2016 Share Posted April 28, 2016 9 hours ago, StrandedonEarth said: Good thing it'll be a new second stage every time! The stresses on the bottom of the launch will be roughly the same, but at the top of the launch phase at the close to the end of its burn it could see momentary g-forces as high as 5. Link to comment Share on other sites More sharing options...
Elukka Posted April 28, 2016 Share Posted April 28, 2016 As I recall there's quite a bit on in-flight forces in the user's guide: http://www.spacex.com/sites/spacex/files/falcon_9_users_guide_rev_2.0.pdf Makes sense since you have to know the forces your payload must withstand. Link to comment Share on other sites More sharing options...
wumpus Posted April 28, 2016 Share Posted April 28, 2016 Anybody know if there are plans to recover the center booster on the Falcon Heavy? Some issues: All the data I have is that MEC on Falcon 9 (1.1-full thrust) is ~2km/s. Of course, all I have is the old wiki pages, and confirmation here: http://spaceflight101.com/falcon-9-ses-9/ses-9-launch-success/ (but for all I know they sourced the same wiki). Are they really doing roughly 6km/s on the upper and 2+atmospheric losses on the recoverable first stage? It seems completely backwards, although overbuilding and taking it easy on the recoverable sides seems more logical. It just seems weird that presumably SABRE could hit the speeds of the booster. The problem is just how much delta-v is that upper stage in the heavy. At the powerpoint slide level, it is strongly implied that it is the same old falcon-9 with two extra boosters added on. Digging through the data, that appears impossible: the falcon9 can "only" handle about 13 tons structurally (there are two options, but I think that was the heaviest for 1.0). Without a near-fourfold increase in fuel, the delta-v provided by the top stage would fall to something like 2.0km/s, requiring the center stage to survive a decent roughly four times as fast (presumably a much longer pre-atmosphere boostback burn). I'm sure they plan on a much faster return (for the center), but this seems extreme. I'm expecting another rounds of holes in the barge. Assumptions, marketing, and misunderstandings: Cargo of Falcon Heavy: 50 tons (without crossfeed) Crossfeed is not available (unless you specifically want to fund the R&D) Falcon9 1.1 full thrust MEC (LEO and hopes of landing) 2.0km/s ***THIS IS A BIGGIE, would really help if wrong*** Cargo of Falcon9 1.1 FT ~10 tons Link to comment Share on other sites More sharing options...
sevenperforce Posted April 28, 2016 Share Posted April 28, 2016 49 minutes ago, wumpus said: Cargo of Falcon9 1.1 FT ~10 tons Wrong. LEO payload of F9 was about 10 tonnes; LEO payload of F9v1.1 was over 13 tonnes; payload of F9v1.1FT (we are getting DBZ with these names here) is unpublished but I have previously estimated it at 15-16 tonnes. Link to comment Share on other sites More sharing options...
wumpus Posted April 28, 2016 Share Posted April 28, 2016 9 minutes ago, sevenperforce said: Wrong. LEO payload of F9 was about 10 tonnes; LEO payload of F9v1.1 was over 13 tonnes; payload of F9v1.1FT (we are getting DBZ with these names here) is unpublished but I have previously estimated it at 15-16 tonnes. They would have to upgrade the structure of the upper stage to get much over 13 tons (this was the structural limit of 1.0, and I believe required a separate option). I suspect that F9v1.1FT could send more to GSO (than the warmer edition), but couldn't go much over 13 tons to LEO. Or they could have redesigned the entire structure (they had to redesign the lower bits, it was considerably heavier). But the 13 ton limit was specifically called out as a "structural limit" in the falcon9 handbook and separate from delta-v issues. Link to comment Share on other sites More sharing options...
PB666 Posted April 28, 2016 Share Posted April 28, 2016 http://thetodayevents.com/spacex-just-landed-coveted-83-million-military-contract/ Link to comment Share on other sites More sharing options...
sevenperforce Posted April 28, 2016 Share Posted April 28, 2016 12 minutes ago, wumpus said: They would have to upgrade the structure of the upper stage to get much over 13 tons (this was the structural limit of 1.0, and I believe required a separate option). I suspect that F9v1.1FT could send more to GSO (than the warmer edition), but couldn't go much over 13 tons to LEO. Or they could have redesigned the entire structure (they had to redesign the lower bits, it was considerably heavier). But the 13 ton limit was specifically called out as a "structural limit" in the falcon9 handbook and separate from delta-v issues. The v1.1 upper stage is larger than the v1.0 upper stage, and the v1.1FT upper stage was lengthened and ostensibly strengthened in comparison, so I doubt it has the same structural limits as 9v1.0 did. The SES-9 mission payload was about 110% of the stated v1.1 GTO payload, and that was after circularization in LEO, so presumably the increase would be closer to Gwen's claimed 15% payload increase. I think I calculated it at 15 and some-odd tonnes based on a variety of factors, but don't quote me on that; I may have been thinking of something else. On another note... Does anyone actually know how low SpaceX salaries are? I hear about how they take advantage of status and dreamers to pay less, but I'm trying to get an idea for what that looks like. Link to comment Share on other sites More sharing options...
Streetwind Posted April 29, 2016 Share Posted April 29, 2016 11 hours ago, wumpus said: Anybody know if there are plans to recover the center booster on the Falcon Heavy? From what we currently know, a typical FH scenario would see both side boosters return to landing pads, while the center booster touches down on a droneship. Of course, whether that plan survives actual implementation, we can only speculate. First they need to get this super-delayed thing off the ground for once. Link to comment Share on other sites More sharing options...
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