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Starship Update [video]

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Re: Starship Update [video]

#341

Post by pintxo »

midasuni wrote: post #340
pintxo wrote: post #339

Earlier quoted context omitted.

People able to afford first class are mostly time constraint, not money constraint. If you offer something using only 1/10 the time, they will buy it.

But they didn’t with Concorde. There are more first class seats across the Atlantic (well pre covid) than Concorde, but the latter failed to be as profitable, and super sonic business jets aren’t a thing.

Afaik, Concord was run profitable.

But due to noise protection regulation on both sides of the Atlantic, there where not enough profitable routes available to be able to recoup development costs.

Re: Starship Update [video]

#342

Post by verytrivial »

DrBazza wrote: post #209
verytrivial wrote: post #194

Earlier quoted context omitted.

I'm not sure what you mean by this. Can you explain what you are comparing? https://en.m.wikipedia.org/wiki/Thrust-specific_fuel_consump... My understanding is that rockets are good at getting a small mass to move really quickly. They will never win moving a lot of mass within the atmosphere. The fuel costs are radically different. A 747 can lift and land ~80% of Starship's design cargo but uses something like 7 time…

> A 747 can lift and land ~80% of Starship's design cargo but uses something like 7 times less fuel. That's why something like the Sabre engine will always be of interest for a proper space plane. https://en.wikipedia.org/wiki/SABRE_(rocket_engine)

Yeah, I've kept a close but unfortunately deeply skeptical eye on that technology. Seems that all the tolerances are razor thin and all the failure modes catastrophic. Like, water vapour in the pre-cooler tubes? This is waaay out there in engineering terms IMHO.

Reading the recent heat exchanger news [1] the are very careful to talk about Mach 5 airflow temperatures, not velocity. Surely it the product of these two that produce the mind-boggling heat flux that the pre-cooler is tasked with cooling. It feels like they're going to keep carving out smaller and smaller targets until they run out of money.

[1] https://reactionengines.co.uk/reaction-engines-test-programm...

Re: Starship Update [video]

#343

Post by panick21_ »

tim333 wrote: post #332
ewjt wrote: post #124

Earlier quoted context omitted.

I thought 100k HP was either too incredible or a typo. Then I looked it up: “You def don’t want electric pumps on a rocket engine! Raptor turbopumps alone need 100,000 horsepower per engine. That’s not a typo.” —Elon Musk x 32 engines. Amazing! For comparison, this is an internal combustion engine with 100k HP: https://www.zmescience.com/science/biggest-most-poweful-engi...

>You def don’t want electric pumps on a rocket engine The https://en.wikipedia.org/wiki/Rocket_Lab_Electron has them and made it to orbit

Yes, for a tiny rocket and they are not using them for anything larger.

Its doable if you throw batteries out of your second stage when flying.

But no company that makes a rocket payload then maybe a few 100kg would ever use them. And for sure not launch humans or go to Mars.

Even if you assume gigantic improvements in batteries by 400% you wouldn't use if for anything major.

It has potential for in space applications as there you can charge it with sunlight.

Re: Starship Update [video]

#344

Post by panick21_ »

avmich wrote: post #323
panick21_ wrote: post #292

Earlier quoted context omitted.

Space elevator on earth doesn't really make much sense. On Mars maybe, it will happen on Mars way before it happens on earth.

Space elevators conflict with satellites, so not really advisable.

On Mars it would actually clash with one of the moons. But if you coordinate 1000s of pods correctly you can let the elevator wiggle so it never gets hit by the moon. It sounds insane but its doable.

Check out the talk about elevators from Mars Society conference.

Re: Starship Update [video]

#345

Post by panick21_ »

londons_explore wrote: post #217
panick21_ wrote: post #33

The Raptor 2 engine is just an absurd. The original specs were already kind of insane. But Raptor 2 is an monster. They really pushed already significantly into a second generation design before first flight. Raptor 2 is not just a slight upgrade, its a huge upgrade. If it can actually launch multiple times a day without any refurbishment, it will simply totally break space travel as we have known it. This engine mak…

If they are making such big upgrades before even getting to orbit, it suggests the rest of their design is falling short of expectations on mass/performance, and they need more thrust to make up for it.

No, they are always evolving everything as fast as they possible can. They don't have a 'target performance' that they need to hit because the military or somebody told them.

They are just iterating each individual part pushing towards ever higher performance.

Re: Starship Update [video]

#346

Post by panick21_ »

verytrivial wrote: post #342
DrBazza wrote: post #209

Earlier quoted context omitted.

> A 747 can lift and land ~80% of Starship's design cargo but uses something like 7 times less fuel. That's why something like the Sabre engine will always be of interest for a proper space plane. https://en.wikipedia.org/wiki/SABRE_(rocket_engine)

Yeah, I've kept a close but unfortunately deeply skeptical eye on that technology. Seems that all the tolerances are razor thin and all the failure modes catastrophic. Like, water vapour in the pre-cooler tubes? This is waaay out there in engineering terms IMHO. Reading the recent heat exchanger news [1] the are very careful to talk about Mach 5 airflow temperatures , not velocity. Surely it the product of these two…

If you look at the cost the calculated originally for the Skylon, it doesn't actually beat Falcon 9 even.

And when I listened to some presentation with the people involved, it seem they had no real understanding of some of the complexity involved. Their history is mostly in academic and British space industry, and all the project they worked on before are canceled paper studies that were kicked around in Britain.

When asked about the structure of Skylon the answer was vague hand waving about some new materials that might exist. Nothing at all concrete that has even begun being tested for high complexity air frames and high requirements.

Elon himself was asked about this when he presented in Britain. And he answered by saying that investing massive amount of complexity in the easiest part of your flight was counter productive.

Pushing the thrust of your traditional rocket engine a little bit higher, is far, far easier then engines.

And if you are really optimizing to that kind of extreme, doing even more advanced version of second stage engines and structural optimization on the second stage would likely always have a higher pay off per complexity invested.

Re: Starship Update [video]

#347

Post by panick21_ »

sfblah wrote: post #83
panick21_ wrote: post #28

Earlier quoted context omitted.

We have enough land on earth already. Land is not actually the solution to any problem on earth. But Mars is the solution to a potentially big problem on earth. And the technology to manufacture fuel from solar and nuclear energy, building advanced life support system, advancing the state of rocket technology, allowing much more use of sat technology, massively advancing science planetary/biology/(and more), controll…

Let's say someone argued instead that we should figure out a way to establish a human settlement inside of a volcano, or at the bottom of the deep ocean. Couldn't you make all the arguments you just made in favor of doing that as well? What makes Mars any different? Why is this specific Quixotic activity more valid than the ones I just mentioned?

Because Mars could be self sustainable. It has water and the temperatures in the right areas are not that hostile. Mars soil can be used for agriculture. There is sun light.

From Mars its effective to launch to Orbit. Its easy to transport and move around on Mars, Supersonic electric flight is very doable for example.

Low density makes super fast trains very doable as well, massive movement of resources on Mars is orders of magnitude easier on Mars then even in deep water.

Re: Starship Update [video]

#348

Post by DrBazza »

panick21_ wrote: post #346
verytrivial wrote: post #342

Earlier quoted context omitted.

Yeah, I've kept a close but unfortunately deeply skeptical eye on that technology. Seems that all the tolerances are razor thin and all the failure modes catastrophic. Like, water vapour in the pre-cooler tubes? This is waaay out there in engineering terms IMHO. Reading the recent heat exchanger news [1] the are very careful to talk about Mach 5 airflow temperatures , not velocity. Surely it the product of these two…

If you look at the cost the calculated originally for the Skylon, it doesn't actually beat Falcon 9 even. And when I listened to some presentation with the people involved, it seem they had no real understanding of some of the complexity involved. Their history is mostly in academic and British space industry, and all the project they worked on before are canceled paper studies that were kicked around in Britain. Whe…

SpaceX vs Skylon/Sabre, feels a bit like the Henry Ford quote about "faster horses". I do appreciate the scale of the engineering problems and neither is easy, but SpaceX and rocketry just seems like another "faster horse", whereas Skylon/Sabre is something totally new. But I don't have much hope given how long it's taken to get to where we are now. It's the space equivalent of tech - get to market first with something that works, not something that's a tech tour-de-force.
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