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SpaceX’s monstrous, dirt-cheap Starship may transform space travel

economist.com

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Re: SpaceX’s monstrous, dirt-cheap Starship may transform space travel

#381

Post by panick21_ »

qayxc wrote: post #124
jmyeet wrote: post #81

The real problem for Starship (IMHO) is Falcon 9. Falcon 9 is now the most reliable launch vehicle ever created. With reuse the may well be $10m per launch or even less by now and likely to continue to drop. F9 can deliver ~22t to LEO and smaller payloads to geosynchronous orbit. The payloads F9 can't deliver are quite small. What people forget is that payloads are deeply coupled to their launch vehicles. The launch…

While I don't agree that reuse will bring the price down further, I can 100% get behind the other points. Even the argument that demand isn't there because launch costs are high doesn't hold - the bigger the sat, the more expensive it is and the trend goes towards smaller and cheaper sats. Building commercial space stations (plural!) could be done using all-up launches and that would be like what - one launch every c…

> While I don't agree that reuse will bring the price down further

Why? If you have to spend almost 10M$~ on an expensive high tech upper stage you your just gone throw in the ocean its clearly give you a price lower bound.

> it's not as if 100t to LEO is novel or anything

Starship does 150t in its early version while being fully reusable.

> The Soviets and later Roskosmos abandoned the vehicle, because they couldn't find a use for it either

The Soviet union collapsed and they didn't have the money for it.

Re: SpaceX’s monstrous, dirt-cheap Starship may transform space travel

#382

Post by panick21_ »

qayxc wrote: post #150
bmcniel wrote: post #95

Earlier quoted context omitted.

It seems like the thesis is if cost per kg fall enough then the implausible becomes plausible. F9 reduced costs to make starlink possible, what will starship make possible?

"The consequences for SpaceX if we can not get enough reliable Raptors made is that we then can’t fly Starship, which means we then can’t fly Starlink Satellite V2 (Falcon has neither the volume nor the mass to orbit needed for satellite V2). Satellite V1, by itself, is financially weak, while V2 is strong." Seems to me as if Starlink without Starship isn't all that great. Also, OneWeb - despite being smaller in scop…

OneWeb is not even in the same category. Their technology is several generations behind in both their sat and ground terminal tech.

There is a reason they went bankrupt and were mostly solved by government bail-outs. Because its in fact not viable as a business if you have to launch on traditional rockets and have contractor produce your sats.

Re: SpaceX’s monstrous, dirt-cheap Starship may transform space travel

#383

Post by panick21_ »

metadat wrote: post #79
kilroy123 wrote: post #6

If you're ever in the Houston area, I highly recommend going to see NASA Johnson Space Center. They have a full-size replica (?) Saturn V rocket on its side, you can see. You simply can't grasp how big these rockets are until you see it up close. It's like a tall building blasting off into space. They're humongous. I hope to one day see Starship up close in person as it takes off to space.

I loved visiting the Kennedy Space Center at Cape Canaveral in Florida. There is a REAL Saturn-V on display! Not to mention the VAB.. https://en.m.wikipedia.org/wiki/Vehicle_Assembly_Building Pretty much everything about the place makes you feel real small ;)

They are both real.

Re: SpaceX’s monstrous, dirt-cheap Starship may transform space travel

#384

Post by panick21_ »

perilunar wrote: post #242
jiggawatts wrote: post #190

Earlier quoted context omitted.

RP1 deposits too much coke in the engines to allow reuse, or even extensive static test firing. LH2 is stupid dangerous to use, requires physically large rockets due to the low density, and as I mentioned, requires extensive leak detection to be integrated into the design. Super-chilled methane as used by Starship is "just better". You really should read through the Saturn V manuals and documentation. NASA put a lot…

> RP1 deposits too much coke in the engines to allow reuse Falcon 9's Merlin engines use RP1 and are re-used.

Yes but SpaceX is moving on from it because it is not optimal. RocketLab is also moving on from it because its not optimal.

There is a different between 'can' and 'optimal'.

Re: SpaceX’s monstrous, dirt-cheap Starship may transform space travel

#385

Post by panick21_ »

mhh__ wrote: post #9
walrus01 wrote: post #3

For size comparison, interesting that they put a SLS block 1 in there, which has never flown or been to orbit, but didn't include the Soviet N1 which at least has flown a few times (in catastrophic, exploding fashion) but also has never been to orbit. They did include an Energia, which is a defunct program and has zero chances of ever getting manufactured again, same as the N1.

Energia could (could...) Fly again according to some recent chatter. https://www.popularmechanics.com/space/rockets/a22515248/rus...

No, just no. The Russian announced about 20 major space projects every year and about 0.1 of them are ever more then that.

Anybody that has watched the Russian space program knows this is nonsense. They have barley enough money to continue to fly their 50 year old rockets. Their supposed next generation rocket has barley ever flown.

Since that article they have already announced like 3 other rockets as well.

Russian space program is 50 year old soviet tech and a lot of political propaganda.

Re: SpaceX’s monstrous, dirt-cheap Starship may transform space travel

#386

Post by imglorp »

throwaway2037 wrote: post #298
imglorp wrote: post #169

Earlier quoted context omitted.

The last failure in flight was 2015. Since then there were 120 successful launches and no failures. There was one payload lost in 2016 during a static fire test.

Thanks for the update. Did you get your count from this Wiki page? https://en.wikipedia.org/wiki/List_of_Falcon_9_and_Falcon_He... I'm not sure if that is a reliable source. (Please don't read that comment as a general commentary about Wiki!)

Yes, and me neither. But even if they're +/- several, ie how they count success vs failure, it's still a high number.

Re: SpaceX’s monstrous, dirt-cheap Starship may transform space travel

#387

Post by panick21_ »

WalterBright wrote: post #135
geocrasher wrote: post #14

The thing that's impressive to me, in addition to the sheer size of these machines, is the engines . The Raptor 2 is groundbreaking. And there's 30+ of them between both stages. It's just incredible, and there's nothing like it that's been done.

As I recall, the Soviet moon rocket failed because it had a cluster of engines that they could never get to work together. The Saturn V had a cluster of only 5, and barely were able to get that to work. How did Musk solve this problem?

This is a myth that is often repeated.

The N-1 failed partly because the engine were untested and had high failure rates. The could not be tested on the ground and had a lot of manufacturing issues.

The N-1 failed because the on board computers couldn't handle engine shut downs very well. They basically just shut down the opposite engine.

In some flights that problem lead to complex piping being broken as well, but its by far not the reason the rocket failed.

And SpaceX has already done the Falcon Heavy with 27 engine and its perfectly fine.

What matters is that your engine work well and that if something happens to one engine the computer can figure that out and perfectly adjust all other engines to that new reality.

Re: SpaceX’s monstrous, dirt-cheap Starship may transform space travel

#388

Post by panick21_ »

me_me_me wrote: post #369
WalterBright wrote: post #135

Earlier quoted context omitted.

As I recall, the Soviet moon rocket failed because it had a cluster of engines that they could never get to work together. The Saturn V had a cluster of only 5, and barely were able to get that to work. How did Musk solve this problem?

AFAIK they only tester 3 of them, out off the whole cluster only 3 had been tested. Soviets were desperate by then, no money, no time, and political pressure. > How did Musk solve this problem? Raptor 2 apparently has melting issues, you can only imagine what will happen when you have whole array of them firing.

Raptor 2 has melting issues that prevent many of reuses. It not just gone melt during operation. They have tested Raptor 2 full flight cycles many times.

What they are doing is trying to figure out how much cooling they need to make many reuses possible but still have the highest possible performance.

Re: SpaceX’s monstrous, dirt-cheap Starship may transform space travel

#389

Post by JaimeThompson »

panick21_ wrote: post #373
JaimeThompson wrote: post #55

I think Gwynne Shotwell is the rather unsung hero keeping SpaceX running correctly day by day. https://en.wikipedia.org/wiki/Gwynne_Shotwell

She is not really unsong at all. She is very, very recognized in the industry and everybody that is seriously interested in space travel knows here. She has been on my list of influential woman and given many talks and speeches all over the place. Of course she is not Musk famous, but nobody is. People who hate Musk sometimes try to claim all SpaceX is because of her. That is certainty wrong and she herself would not…

It's most strange to me, and I am not saying this applies to you, that one can have legit concerns about Musk and they are simply dismissed as "hate" by so many.

Why some refuse to hold him responsible for his statements is just weird.

Re: SpaceX’s monstrous, dirt-cheap Starship may transform space travel

#390

Post by panick21_ »

throwawaylinux wrote: post #346
kragen wrote: post #22

Earlier quoted context omitted.

Yes, but it's not just SpaceX; nobody is good at building big rocket engines.

I don't know much about it, but I'm interested to know why the space shuttle solid rocket boosters were so much more powerful than the F1 engine. 2 of them produced about 87% of the thrust of the 5 F1 engines on the Saturn V. I thought combustion chamber instability was the biggest issue with the big engines. Are solid rockets much more stable?

Solid rockets don't really have that problem in the same way. The instability happens in the thrust charmer of a liquid engine resulting from non-uniform burning. The chamber is not very big if you compare it to the size of the tank. Once you press that non-uniform hot gas threw the neck out into the nozzle the expansion happening in the nozzle also expands those imbalances. So you can end up with different pressure pressure in different part of the nozzle leading to vibration and potentially the nozzle ripping itself into pieces.

Solids rocket are like a candle with a hole threw it. They burn inside out, not from the button to the top. So there is not really a thrust chamber in the same way. A channel goes from buttom to the top inside the booster. So the 'thrust chamber' is essentially the hole length of the booster. And all that material gets pushed down in the direction of the nozzle.

I have never heard any rocket engineer explicitly explain this, but my assumption is that on the way down when everything is pushed threw the neck the gas has time to mix enough so that the instabilities are not that large anymore. I also think the pressure is lower in a solid.

Solids have higher thrust but lower efficiency. The thrust comes from the fact that in the solid fuel mix there is lots of other stuff that need to form the solid. Heavier elements that don't participate in burning (thus less efficient) but add thrust.

Solids also have the draw back of being incredibly loud and having massive vibrations.

Solids also can have 'stability' problems as in that if they are not correctly manufactured, they might not burn uniformly and that can lead to a whole lot of problems and additional vibrations too.

Almost no new rocket company uses solids. Its far to expensive and operationally dangerous. At best you can reuse some outer shell, but not the expensive part.

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