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I had to think that through for a second, but I get it - until now, everyone going to ISS either got there on the US Shuttle or the Russian Soyuz capsule. Dragon represents the first US crew capsule since Apollo, so it has taken nearly 50 years to break that Apollo/Skylab record. I’m really looking forward to seeing other records broken though, like longest stay on the lunar surface, now that I seriously believe it could happen in the relatively near future.
"The problem with quotes on the Internet is that it is hard to verify their authenticity." — Abraham Lincoln
I say there is an invisible elf in my backyard. How do you prove that I am wrong?
The Leif Ericson Cruiser
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Feb. 12 -- Falcon 9 • Starlink V1.0-L19
Launch time: 0525 GMT (12:25 a.m. EST)
Launch site: SLC-40, Cape Canaveral Space Force Station, Florida
A SpaceX Falcon 9 rocket will launch the 20th batch of approximately 60 satellites for SpaceX’s Starlink broadband network, a mission designated Starlink V1.0-L19.
Do good work. —Virgil Ivan "Gus" Grissom
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Starship SN10’s Raptors installed ahead of testing and refined landing attempt. Starship SN11 was moved to the High Bay for nosecone and aero surface installation, with production continuing unabated. At the same time, future vehicles up to at least SN18 are being prepared, along with the first two Super Heavy prototypes.
https://www.nasaspaceflight.com/2021...fined-attempt/
Do good work. —Virgil Ivan "Gus" Grissom
Established Member
I don't understand how it would be easier to start three engines as opposed to starting two.Originally Posted by docmordrid
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I guess it is the probability of getting two is much improved. If the probability of any one igniting is 0.9, arbitrarily, the chance of two is 0.81, but the chance of two out of three is 0.96, (including that all three can start). At least my back of envelope says so.
sicut vis videre esto
When we realize that patterns don't exist in the universe, they are a template that we hold to the universe to make sense of it, it all makes a lot more sense.
Originally Posted by Ken G
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I read that not as easier, but safer.
If you need two engines to land, you try to start three. If all work, you shut down one. If one fails, you can still land safely.
In rocketry, redundancy is your friend.
ETA: Profloater provided a more rigorous explanation while I was typing.
I may have many faults, but being wrong ain't one of them. - Jimmy Hoffa
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And the more unreliable they are, the larger the difference between trying 2 out of 2 versus 2 out of 3. At 0.7 reliability, it's 0.49 versus 0.784. At 0.5 reliability, it's 0.25 versus 0.5.
With sufficient thrust, water towers fly just fine.
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An interesting variation would be if the chance gets better or worse after lighting one up. My guess is the vibration helps but there could be many other factors.
sicut vis videre esto
When we realize that patterns don't exist in the universe, they are a template that we hold to the universe to make sense of it, it all makes a lot more sense.
Originally Posted by Ken G
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Vibration is rarely helpful. There's also the possibility of fluid hammer effects, pressure drop, etc. Redundancy is effective for independent failure modes, but raises the possibility of dependent failures, and won't help with common failures (like SN8's fuel pressure issues).
From how Elon's kicking himself after SN9, I'm guessing it was an independent failure mode and redundancy might have allowed it to land, or at least get closer to it than SN8 did.
Order of Kilopi
Well I can think of systems where some vibration reduces hysteresis, reduces friction, and kickstarts movement, hence the old lunar boot jibe. In fact many systems accumulated hysterisis would make them unworkable without endemic vibration from motors, engines and resonances. But as you say there are flow change possibilities. And more. The negative side of vibration has to be factored in early.
sicut vis videre esto
When we realize that patterns don't exist in the universe, they are a template that we hold to the universe to make sense of it, it all makes a lot more sense.
Originally Posted by Ken G
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Op-ed | In defense of regulation. "Steve Blank’s op-ed of Feb. 5, “The FAA and SpaceX,” demands an informed rebuttal. Public debate over the appropriate level of regulation within any industry is appropriate in our democracy. However, Mr. Blank’s arguments lack grounding in the history and nature of private space activity regulation and he erroneously conflates that mission with the FAA’s primary task of regulating the safest transportation system in human history."
https://spacenews.com/op-ed-in-defense-of-regulation/
Do good work. —Virgil Ivan "Gus" Grissom
Established Member
SN-10 cryoproof looks good
https://twitter.com/NASASpaceflight/...75436529377283
Established Member
All these discussions involve the reason that the second engine did not start properly. I haven't seen any reason given for that failure. If that situation can be overcome then perhaps starting three would be better.
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As I said, rarely. One example is the throttle valves for the Merlin 1D, they added dithering (intentional variation in position) to address stiction issues that caused one booster to crash. However, I would not expect ignition of a third Raptor to improve anything in a vehicle's operation unless there's a design flaw of some kind that should have a real fix implemented.
Established Member
I have for a long time though it is funny how most things Space X is doing was suggested back in the 80s, 90s and early noughties on the Usenet space news groups. It does suggest that some of the ideas are not as ground breaking as some people want to make them out to be (still very impressive to see them put to practice). There where some really knowledgeable people and good discussions around those groups until eternal September killed them.
https://groups.google.com/g/sci.spac...m/7v6YgUeslasJ
"If they hand you a lemon, make lemonade." If ignition failures (the most
likely form of engine failure) are considered a significant issue, attempt
to light more engines than you need, and then shut down or throttle back
the unnecessary ones. There is a fuel cost for this, but no fundamental
technical problem. A variety of related schemes are conceivable, notably
the popular engine-out-during-launch idea of throttling the remaining
engines up to emergency maximum when one fails.
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The supercharger as a means of improving the internal combustion engine was invented on paper before any working internal combustion engine had actually ever been built. The timeline between inventing something with the mind and putting it in practice is sometimes astonishing. There are many reasons for this, but not in the least:
-the devil being in the details between paper and reality
-some development in technology for materials or manufacturing is needed to put the idea into practice. The jet engine comes to mind; initially there was no compressor of sufficient performance available.
-some great minds loose interest as soon as they have the problem figured out and can't be bothered to further develop it, often because they lack the means (skills, money, network) to do so. Ask my wife if she knows such a person.
But it is a victory of the human mind that there are people able to invent stuff purely in thought without the need for practical trials.
What we see SpaceX do is not so much completely new inventions. Musk's strengh is far more in making happen what has already been conceived but never put into a "commercial product"; he knowns to stay on the achievable side of progress unlike too many people who want to develop seven generations into the future at once and then be surprised they fail. Using new developments in manufacturing, software control and other fields his companies turn old ideas into new technology. And that is a massive step, because as we all know the paper is very willing but reality is overly generous in telling you you're doing it wrong.
With sufficient thrust, water towers fly just fine.
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As a sidenote, I have my own company that develops innovative tools and so much is similar whether you're the smallest or largest innovative company. We too have reality serve us daily doses of "see, you did not take that into account" with a preference of getting the message across by means of spectacular failure. We too have 100 things that work on paper, especially other people's paper, turn into 20 things that work in a test setup, turn into 1 thing that finally works in reality. We too see how we can achieve things now thanks to recent developments which would have been next to impossible 20 or even 10 years ago, sometimes even 2 years ago. We notice how new technologies sometimes allow us to do things with such ease that we wonder why nobody else is doing it. And, we too have a mixed relationship with regulations. They are a powerfull guideline towards clear goals, they are a welcome benchmark to keep the "cowboys" out of the market, but at the same time they often stand firmly in the way of new developments.
With sufficient thrust, water towers fly just fine.
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Most of the people I know, critics and "cheerleaders' alike, who follow SpaceX are very clear that Musk is taking old - sometime quite old - ideas and actually making them work. Or willing to spend money on the risk to find out. What you seem to be suggesting is that anything that's been developed since the 1930s with rockets is just riffing off Goddard and not impressive. Or that developments in controlled flight are all useful and stuff, but it's all just stolen from the Wright Brothers (or whomever THEY stole it from, right?).
CJSF
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About angels, unicorns and elves
Now I like those stories
As much as anybody else
But when I'm seeking knowledge
Either simple or abstract
The facts are with science"
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lonelybirder.org
Banned
I hope the rogallo wing if not lifting bodies make a come-back...perhaps as escape pods. Portree's "No Shortage Of Dreams/Beyond Apollo" site had an article with a lifting-body immersed in a nosecone/tub deal...solids could be applied pointing both back and "down" so escape could be had with Starship either horizontal or vertical. Maybe a lengthwise wing on top on a pivot that can swing out.
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Speaking about the ideas SpaceX is putting into practice: I've seen loads of flyback booster conceps throughout the years, but does anyone have a reference to the "skydiver" bellyflop method of controlling atmospheric return attitute while maximizing cross-sectional area before SpaceX did it? SS1 did something like it but entirely passive with a design that would be very tricky to scale up to large craft, especially orbital.
With sufficient thrust, water towers fly just fine.
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Well the converse is that having an idea does not mean you can carry through. Like Edison said 1% inspiration and 99% perspiration. Similarly you cannot patent a business idea, although people try, you have to actually do it.
sicut vis videre esto
When we realize that patterns don't exist in the universe, they are a template that we hold to the universe to make sense of it, it all makes a lot more sense.
Originally Posted by Ken G
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My experience of especially mechanical systems is that the essential role of small impacts and hard to avoid vibration in keeping things going, is underestimated. Deliberate dithering is thus rare, because oscillation is almost universal in energetic systems. It is true that vibration is regarded as a nuisance, as indeed it is, but it is a design and management issue, like a dose .
sicut vis videre esto
When we realize that patterns don't exist in the universe, they are a template that we hold to the universe to make sense of it, it all makes a lot more sense.
Originally Posted by Ken G
Banned
Here, it is sloshing that is more of the issue? Does Starship have to be in one craft? Imagine a split nosecone-two lifting bodies flat-to-flat. Mustard style. Payload in fairing..fuel and cockpit in the other. Lunar starship a one off.
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It occurred to me the other day that high frequency vibrations could be an aid in loosening stuck screws. It'd be a --- well, you know!
Cum catapultae proscriptae erunt tum soli proscript catapultas habebunt.
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The frequency would be resonance, either the whole screw or a bar frequency that set it ringing like a tuning fork. Of course an impact includes all those frequencies!
sicut vis videre esto
When we realize that patterns don't exist in the universe, they are a template that we hold to the universe to make sense of it, it all makes a lot more sense.
Originally Posted by Ken G
Order of Kilopi
I worked on some very low friction assemblies using ball bearings. They were glued into housings to avoid distortion. The measured friction in service was less than calculated or measured statically because of tiny inevitable vibration in an airframe.
sicut vis videre esto
When we realize that patterns don't exist in the universe, they are a template that we hold to the universe to make sense of it, it all makes a lot more sense.
Originally Posted by Ken G
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SpaceX is seeing strong demand for its dedicated smallsat rideshare missions, a program that is putting pricing pressure on small launch vehicle developers. During a panel discussion at the 2021 SmallSat Symposium Feb. 9, a SpaceX official said the company has two more dedicated rideshare missions scheduled this year after its Falcon 9 Transporter-1 launch Jan. 24 that placed a world-record 143 satellites into orbit. “Customer demand has been extremely strong. Demand is growing, so we’re certainly going to have some very full rockets coming up,” said Jarrod McLachlan, senior manager of rideshare sales at SpaceX.
https://spacenews.com/spacex-sees-st...unch-services/
Do good work. —Virgil Ivan "Gus" Grissom
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I'd like to know how much revenue they got from the 133 third-party satellites on Transporter-1. There is a minimum of 1 million for a 200kg lot, but if a single customer can squeeze more than 1 satellite in 200kg I can't know how much revenue they had just from that number. Similar if some satellites were heavier than 200kg.
With sufficient thrust, water towers fly just fine.
Established Member
As posted in the Lunar Gateway Outpost thread, the Gateway's Power & Propulsion Element and HALO habitat will be launched joined by Falcon Heavy in 2024.
Order of Kilopi
I’m wondering if the “bellyflop” is really much different from previous work with lifting bodies. NASA has done a lot of work testing various lifting body configurations. The flip and vertical powered landing strikes me as more of a new twist.
My impression is that a lot of SpaceX’s technical innovations are ones that aren’t so obvious, for instance automated manufacturing where in the old days there would have been far more manual work with manual evaluation and rework if bits didn’t pass quality control checks.
"The problem with quotes on the Internet is that it is hard to verify their authenticity." — Abraham Lincoln
I say there is an invisible elf in my backyard. How do you prove that I am wrong?
The Leif Ericson Cruiser
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