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SpaceX just did a full duration test firing of a recovered 1ststage
On 7/30/2016 11:24 PM, JF Mezei wrote:
The other aspect would be the number of times the LOX tank can be loaded and emptied before structural issues surface. I have also pondered that, but those tanks are clearly designed to be loaded/cycled many times. Each Falcon 9 lox tank goes through at least two cycles per launch, and sometimes (with scrubs etc.) several times before it actually launches. Other launch systems historically do the same. Offhand, I don't recall any launch provider ever mentioning concern over multiple lox tank cycles pre-launch. Has anyone else? |
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SpaceX just did a full duration test firing of a recovered 1st stage
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SpaceX just did a full duration test firing of a recovered 1st stage
On Sunday, July 31, 2016 at 10:17:14 AM UTC-4, Vaughn Simon wrote:
On 7/30/2016 11:24 PM, JF Mezei wrote: The other aspect would be the number of times the LOX tank can be loaded and emptied before structural issues surface. I have also pondered that, but those tanks are clearly designed to be loaded/cycled many times. Each Falcon 9 lox tank goes through at least two cycles per launch, and sometimes (with scrubs etc.) several times before it actually launches. Other launch systems historically do the same. Offhand, I don't recall any launch provider ever mentioning concern over multiple lox tank cycles pre-launch. Has anyone else? there were limits on the shuttle external fuel tank, it was mentioned after a bunch of scrubs |
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SpaceX just did a full duration test firing of a recovered 1st stage
On Sunday, July 31, 2016 at 1:48:33 PM UTC-4, JF Mezei wrote:
On 2016-07-31 10:17, Vaughn Simon wrote: I have also pondered that, but those tanks are clearly designed to be loaded/cycled many times. Each Falcon 9 lox tank goes through at least two cycles per launch, and sometimes (with scrubs etc.) several times before it actually launches. I wonder if LOX cycle times will end up being limits on how many times a stage can be re-used. (aka: a scrub would reduce re-usability of that stage because of an extra load/unload cycle.). Some stage1s may end up being re-used more often than others depending on how lucky they are at the pad with launch aborts/scrubs. the tanks could be designed, upgrade to withstand more cycles. at some point it will be cheaper to accept whats available. thats a good thing, the reflown booster s can be used as displays at some point. hopefully indoors out of the weather. how badly the left over saturn 5 boosters were treated still bugs me today. although they were eventually stabilized and fixed up a bit. |
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SpaceX just did a full duration test firing of a recovered 1st stage
Jeff Findley wrote:
From what I've read, this stage will be the "life leader", which would imply that they're going to fill, fire, and inspect it many times to gather hard data to help determine just how many times a Falcon 9 first stage can successfully be reused. I suppose even one "actual" launch of the stage is not too far from crossing the Rubicon, but why wait for a successfully returned stage to do this testing? I suppose "Waste anything but time" doesn't really apply to SpaceX, but it would seem that they could have been rather further along on answering the question of "How many times can we reuse a stage?" via repeated test firings on the ground by just starting that process with a stage many months ago. rick jones -- The glass is neither half-empty nor half-full. The glass has a leak. The real question is "Can it be patched?" these opinions are mine, all mine; HPE might not want them anyway... feel free to post, OR email to rick.jones2 in hpe.com but NOT BOTH... |
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SpaceX just did a full duration test firing of a recovered 1st stage
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SpaceX just did a full duration test firing of a recovered 1st stage
Jeff Findley wrote:
In article , says... I suppose even one "actual" launch of the stage is not too far from crossing the Rubicon, but why wait for a successfully returned stage to do this testing? I suppose "Waste anything but time" doesn't really apply to SpaceX, but it would seem that they could have been rather further along on answering the question of "How many times can we reuse a stage?" via repeated test firings on the ground by just starting that process with a stage many months ago. Except ground testing will never exactly replicate the conditions the stage experiences during hypersonic reentry. Doing this testing with a flown stage gives more confidence that a flown stage can be successfully reflown. But will they really learn that much more from N (greater than one or two as you implied from "life leader") iterations of "fill, fire and inspect" on the ground from a stage which has been launched only once than from one that wasn't launched? That is what I'm trying to get at. Odds of landing success notwithstanding, I'd think they'd want to put a dummy mass on the thing to simulate the second stage and actually launch N times. True, an actual launch and recovery is going to be more expensive than a static fire, but as you say, ground testing will never exactly replicate the conditions the stage experiences during hypersonic re-entry. And it isn't clear to me how much more realistic ground testing becomes after say the first post-recovery static for a stage that has been launched once than those 2-3rd through Nth static fires would be on a stage that hasn't been launched. One or two static fires of an already launched stage seems reasonable, but after the second post-recovery static fire I wonder whether the testing is assymptoticaly (sp) any different than a never flown stage. rick -- a wide gulf separates "what if" from "if only" these opinions are mine, all mine; HPE might not want them anyway... feel free to post, OR email to rick.jones2 in hpe.com but NOT BOTH... |
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SpaceX just did a full duration test firing of a recovered 1st stage
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SpaceX just did a full duration test firing of a recovered 1ststage
On 8/1/2016 7:06 PM, Rick Jones wrote:
But will they really learn that much more from N (greater than one or two as you implied from "life leader") iterations of "fill, fire and inspect" on the ground from a stage which has been launched only once than from one that wasn't launched? I get your point but... Given that they have several recovered boosters now, why would they use a new one? And if they DID use a new one, everyone would ask "why not a recovered one? What are they trying to hide?" Also, I am sure that SpaceX has tested enough Merlin engines on their test stands to have a very educated idea about their MTBF without even bothering to test a recovered booster. IMO, Part of the point of this present testing of a recovered booster surely is to convince customers and underwriters that pre-used boosters can be a safe bet. In other words, it's not just science and engineering that's happening here, it's also a public relations and sales campaign. Which is why I wonder why it took them so long to start it. |
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