mikegarrison
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Posts posted by mikegarrison
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Might be just the angle the picture is taken at. But there are two test vehicles.
As I understand it, it was initially designed to accommodate two engines, but when the decision was made to only use one engine, they just left it off-center. Maybe for the second one they knew that there would only be one engine, so they relocated it closer to the middle? The 3-view on wikipedia indicates that it is for vehicle #2, and it looks a lot like that second picture.
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14 minutes ago, Meecrob said:
At the risk of sounding like an Elon supporter, if you dig a bit beneath the headlines, you will see that Elon did not go from Tony Stark to some deranged hard-right wing megalomaniac.
Elon Musk is not, and never was, "Tony Stark".
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9 minutes ago, cubinator said:
Isn't it already more economical to launch 24 Falcon 9s for a single lunar mission than one SLS?
There are payloads that a single SLS can launch but no number of F9s can launch.
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1 hour ago, SunlitZelkova said:
Would something like KORD help SH? So if an engine in the innermost ring fails, the engine on the opposite side of the ring can be shut down to avoid uneven thrust, and the rocket can keep flying?
KORD was the engine control computer on the N1 responsible for automatically shutting down engines in the event of failure, in case you don’t know.
That's not the issue. I mean, rockets now have real-time computer control that allows them to land! Dealing with the thrust imbalance is not the difficulty.
The concern is something like a fire or an uncontained turbo-machinery failure that sends shrapnel into the neighboring engines. We've seen in both launches now that engines start dropping out after the engines next to them drop out, which is extremely concerning.
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1 hour ago, Deddly said:
@mikegarrison I remember there was at least one early F9 flight with an engine failure that still completed its mission. Does F9 have armour between the engines?
It all depends on what *kind* of engine failure. There are many failure modes where one engine failing does not particularly risk a cascade, but there are others where it does.
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Seems obvious to me that landing is still the biggest risk item for Starship/SH, but of course landing is optional (for now).
But the risk item that has bothered me from the start that still seems like it my be plaguing them is the large number of engines. More engines = more redundant *unless* their failure modes are not independent. And it has always concerned me that so many engines, so close, without heavy (and space-consuming) armor between them, is a huge risk for fratricidal cascading engine failures. That means more engines = less reliability, rather than more reliability.
We'll see.
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My kerbals are too busy playing Baldur's Gate 3 to celebrate this year.
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17 hours ago, CatastrophicFailure said:
Set an alarm. Download ALL! THE! APPS! Once you’ve seen it you’ll wonder how you ever missed it before, sucker is bright.
Yes, a year or two ago I remember standing outside my house in the cold on the rare clear winter in the Seattle area, waiting for the ISS to pass over. When it did, there was no mistaking it for anything else.
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8 hours ago, Meecrob said:
There is no way SpaceX is going bankrupt. They as a single company, outpace all other launchers combined.
I am not saying SpaceX is going bankrupt.
But that being said, the size of the company is no guarantee against going bankrupt. In fact, it can mean you do so quite quickly. Bigger company means more spending means that you can rack up debts even more quickly.
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36 minutes ago, CatastrophicFailure said:
It’s all about finding that balance point.
Yes, obviously if it increases the percentage chances of success, then delay or slow down the rotation. I was just reacting to the suggestion that the only reason they were doing it quickly was to show off.
36 minutes ago, CatastrophicFailure said:IIRC SS/SH is figured to be cheaper to manufacture than F9
This (almost) can't possibly be true.
The claims that were being tossed around was that the cost per flight would ultimately be lower than F9 due to a substantial increase in reusability. A claim that I found dubious.
Consider, for instance, prop-fans v. high-bypass turbofans. People were predicting things like a 50% increase in efficiency from the prop-fans back in the 1980s, but it's been 40 years and the propfans are still not in service. Meanwhile the efficiency of the high-bypass turbofans has almost increased to the point where the propfans were predicted to be, so now for the prop-fans to succeed they need to be competing against the current turbofans, not those of the 1980s.
As F9 gets more and more reusable and cheaper and cheaper to fly, SH has to compete against the newer, better F9 costs, not the F9 costs that existed when SH was conceived.
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20 minutes ago, Minmus Taster said:
Come to think of that, what is the price of a fully expended vehicle? I assume it's cheaper than a typical rocket of this size but probably not economical to have without it being reusable, especially with all the engines.
There is no "typical rocket of this size".
19 minutes ago, Hotel26 said:From a KSP point of view (knowing nothing and caring little about real life), I think delaying the flip until Starship has gained some decent separation (exhaust-wise) and then performing a much slower flip before full burn-back thrust is applied, ought to be considered. So I can see some motivation to go faster (including being 'flashy'). If it meant beefing up some RCS control on the booster. I can also imagine the usage of small, 'reserve' tanks that are kept full until the flip to avoid ullage problems.
Every second before they boost back makes it harder to return to landing, and the whole premise of the booster is that it must return to landing.
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4 hours ago, Meecrob said:
time and time again, there has been a part on the drawing board seemingly inhumanely soon after there is a failure. For example. the Water Deluge plates seem to have been almost fully designed at time of IFT-1. It seems they took the data from the flight test, validated their models/made some tweaks, and sent their order to the fabrication shop very shortly after the test completed.
Water deluge has been used for 50 years, at least. The question is not "how did SpaceX design a water deluge system so quickly?", but rather "why did they think they didn't need one before?"
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6 minutes ago, sevenperforce said:
The LGM-30 Minuteman most certainly does not have a maximum velocity of 24,000 km/s, and this was most certainly not the velocity of Starship at cutoff.
I assume he was confusing km/s with km/h.
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7 hours ago, JoeSchmuckatelli said:
Coriolis?
Coriolis has approximately zero effect on such scales.
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On 11/18/2023 at 9:34 AM, JoeSchmuckateli said:
I looked at sea-level weight vs mountain weight a long time ago and the difference is tiny - quick google shows a New York Times article that a person who weighs 150lbs at sea level (New York Hipster Male?) would only weigh 149.92 lbs at 10,000 feet. So not thinking there's a gravity disadvantage to your scenario.
We've also previously discussed the advantages (or not) of dedicated rail / onsite construction at the equatorial Andes vis-a-vis atmosphere pressure & etc. and IIRC, it was a negligible savings.
(Cannot math you an answer - but perhaps good enough?)
Radius of the Earth is more than 6000 km. Even an 8km mountain peak is thus about 0.12% different in height versus sea level. This is why gravity is essentially the same.
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27 minutes ago, JoeSchmuckatelli said:
It looks like the engine compartment is the COG - as it pretty much stays in line with Ship as it begins to flip. (or rather, the COG is just above the rockets) is that correct or likely something from the angle?
With most of the fuel burned, almost certainly the rockets make up the bulk of the remaining mass of the booster.
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The ship was not headed for an orbital trajectory anyway, even if it had completed its burn.
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7 hours ago, Pthigrivi said:
Funny to see all the news stories calling this a big failure for Elon.
If STS had blown up on the first launch in the first stage, and then had blown up again on the second launch in the second stage, absolutely no one would be claiming these were great tests and a great learning experience.
The goalposts are different for SpaceX -- among the SpaceX fans, anyway. But among the general population, don't expect the "whatever happens, we learn something" thing to be a popular viewpoint.
If the third try works, people will no doubt point to the first two and say, "See? Learning by experimentation works." If the third try fails, people will no doubt be saying, "Three times! This rocket is a disaster!"
At least they didn't have the same failures twice.
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42 minutes ago, Minmus Taster said:
Not sure how much would be left though
They are large chunks of metal -- titanium, IIRC. Likely would survive an explosion like that more or less intact.
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I'm surprised they didn't reshow the flight. Is there a way to watch a replay?
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Hmm. I was busy playing BG3 and forgot this was going to happen. I tuned in, and the second stage was burning. But they said the first stage was destroyed? And then, well, they lost contact with the second stage and said it appeared as if the FTS had activated.
That seems like a pretty serious issue -- at that point in the profile shouldn't the FTS be safed?
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11 minutes ago, tater said:
SLS enjoys bipartisan support (and hence Artemis), and this issue is absolutely connected to that program, so maybe it can get some traction. It's also total chump change.
Looks like the total number of employees in the Office of Commercial Space Transportation is ~100 (2019 it was 97). If doubling that number came with a cost of $200k per person (with overhead), that's $20M. This is not something that requires billions, or even hundreds of millions.
Maybe there could be a user fee for these services, and the launch providers can fund the entire thing making it revenue neutral?
The rules against political discussions prevent me from answering most of this.
I will say that EASA charges applicants a fee for them to do the work required to certify an aerospace vehicle. To the best of my knowledge, FAA does not. Both extensively rely on the companies involved spending their own money to do the testing and analyses that the regulators require. They also both allow companies to pay their own employees to act on behalf of the regulators. In such cases the employees are sworn by law to be acting on behalf of the government and not the company that is paying them.
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6 minutes ago, tater said:
At the panel where this was discussed, all the launch providers agreed on this, FWIW.
WIW in the current Congressional environment is precisely nothing at all.
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22 minutes ago, tater said:
The principle complaint regarding current launch license issues was timing. And SpaceX specifically said that FAA (et al) were overworked. SpaceX said they are often competing with themselves to get the paperwork done. Makes sense, FAA's space approval people were created when a launch or two every month was all they had to deal with. Now it's a couple launches a week, next year SpaceX alone is talking about ~3 per week. Plus ULA (32 kuiper launches have to start sometime), plus Rocket Lab (1 per month?), maybe even a test launch by BO. They are gonna need more people.
We could discuss funding levels at the FAA, but that would be political.
Hyperloop
in Science & Spaceflight
Posted · Edited by mikegarrison
Often listed as one of the supposed great innovations from Elon Musk, but it was pretty obviously deeply flawed from the start.
Same with his underground car tunnels idea.
In both cases, he wants to replace mass transit that already works (rail, above or below ground) with individual vehicles. I guess so you don't have to share your personal space with strangers?