totm nov 2023 SpaceX Discussion Thread

[Jacke]

35 minutes ago, magnemoe said:

i still feel that the requirements NASA has for an abort system is a bit overkill.

 

32 minutes ago, Nothalogh said:

Especially in light of their adoption of the STS as they did.

 

I think NASA's experience with STS, when they thought they could get away with only covering some failure modes, is the reason now for the stronger current requirement.

[magnemoe]

5 hours ago, Wjolcz said:

Don't build a ship then. Make it an oil rig-like structure instead:

Its still expensive megastructures, the concrete oil platforms are the heaviest structures ever moved, they also rank high on heaviest overall structures build as in heavier than skyscrapers but lighter than dams and a couple of the pyramids. 
It makes sense if you can pump up oil for decades. Not as an niche low capacity airports who might be replaced by other systems in 20 years.  
 

[Nothalogh]

47 minutes ago, magnemoe said:

Its still expensive megastructures, the concrete oil platforms are the heaviest structures ever moved, they also rank high on heaviest overall structures build as in heavier than skyscrapers but lighter than dams and a couple of the pyramids. 
It makes sense if you can pump up oil for decades. Not as an niche low capacity airports who might be replaced by other systems in 20 years.  
 

Easier to just build an island like the Chinese do

[magnemoe]

5 hours ago, ThatGuyWithALongUsername said:

For some reason I went on a minor rant on Starship after reading through some of these. Yes, that is a link to a space blog in my signature, and yes, this probably should just go there, but no, I'm lazy and that thing's been dormant for like a year now.

 

Well... here's what I think about all this. Warning, overall opinion on the system as a whole below:

Starship, whether it will be successful or not, is unlike any other rocket in history. Thus such things like cost, reliability, and flight rate cannot be compared to any other rocket.

The thing is, this is the first vehicle ever designed from the ground up to be rapidly reusable. Yes, I know the space shuttle existed, but it wasn't rapidly reusable, even if it was supposed to be. With Starship, you can just double-check the engines and heat shield, refuel it, and relaunch. If they can't do that, Starship is a failure. so, if we're assuming that Starship is far enough into development to launch people, then we have to assume it was successful at this.

Here's the thing: launching Starship is quick and inexpensive, so they can test it many, many more times than a regular rocket. Elon mentioned in the presentation that the system is capable of multiple fights to orbit PER DAY. They also said they would be basically trying to churn out a bunch of Starships while testing.

So, here's the thing: Even with something more realistic for analyzing test data like 1 flight per weekday, they can test their system and iron out reliability problems hundreds of times in a single year. and this is why it's expected to be reliable- the airline-like reliability would be expected because of airline-like numbers of flights! If a plane only flew, say, 20 times a year, you wouldn't know if it was all that reliable, would you?

This is also why all the other deadlines are so ambitious. Development can go a heck of a lot faster when tests can be done a heck of a lot more often. DearMoon, for example, doesn't even require any orbital refueling, (ok apparently it does but they can test that too) so all they need is the crewed Starship and they can send it on like a dozen trips around the moon before anyone goes anywhere in possibly less than a year.

The other question of course is cost. This is a lot of flights. But that's of course the other place where rapid reuse comes in handy: costs. Costs will be much, much smaller than what we're used to. This is why they need a lot of money for this- not just the development cost, the cost of hundreds f test flights. But fortunately, they have a payload for most of these test flights: Starlink, as well as other commercial missions. So cost will not stop them from doing hundreds of lights, in fact, doing hundreds of flights will stop the cost from stopping them, if that makes any sense.

And of course the argument that Starship is overbuilt for many of the things it does is true, but irrelevant. It doesn't matter how overbuilt it is for the task, it's cheaper and more flexible than anything else. Yes it has fins, but it can still land on the moon for the cost of only like  flights, which isn't that much. Something that is built solely for the moon can't take advantage of this rapid reuse as often, and therefore would have much higher development costs and less flights to offset those, so it isn't as good as it sounds on paper. With Starship, unlike any other launch vehicle ever, it isn't about mass efficiency all the time, but rather operational efficiency/flexibility.

Yes, again, rapid reuse is objectively an utterly insane and crazy goal, and perhaps an unrealistic one, but it's kind of the most important thing that Starship has to do to do, well, anything. Cost, reliability, safety, and ability to do interplanetary missions (tank it up quickly) all depend on Starship's seriously rapid reuse capability. If this does not work, Starship does not work. It's obviously not going to be easy, otherwise it would have been done before, but it is necessary, and Elon wants to get to Mars pretty badly, so they're certainly not going to give up on this any time soon. Either they'll fail hard or they'll change everything in the industry. Not much room in between when you commit to such huge risks like this. But Elon wants to go to Mars, and they need this radical change if hey're going to do so. Will they do it? Well, obviously they're doing a lot of things differently with Starship already, but we can't really know if these differences will be successful. Only time will tell. It's going to be some seriously exciting next few years as we figure out which one that's going to be.

Do I think it will work? Well, I don't know. I certainly hope it does, but it's hard to even talk about "hundreds of launches per year" while sounding realistic in any way. So, we'll see.

So yeah, safety is no problem if anything goes anywhere near planned. We just have to worry about how well reuse works, and if that woks, everything else does too IMO.

 

Yes its game changing, and it don't need to be an 50% success to be. If you bring an tank to an knife fight you don't need to be very good to win. 
In short starship wins if not an primadonna hangar queen, and even this can be fixed over time. 
Blue origin can adapt and might come out as good as starship is overbuild. 
China is probably using turbo pumps to pump money into their development. 
In short, you plan for second stage reuse or you are not an player.
Yes it makes sense for countries like Brazil or Israel to have their own launch systems for their military birds, but this is just to keep their independence not to make them economical. 

 

[Nothalogh]

5 minutes ago, magnemoe said:

turbo pumps to pump money into their development

The problem with negative displacement pumps is that they are inefficient for high vacuum monetary transfer.

[tater]

This is being done is a remarkably transparent way, as well. You know that China, and companies like BO are also watching this carefully. If SpaceX pulls off Starship reuse, it's absolutely a game changer. As @mikegarrison said, it has the possibility to create a new market as the 747 did.

My only observation regarding creating new markets is that it requires competition for prices to drop. Blue will certainly follow (they need to be more ferociter, clearly), but until someone can compete on price, SpaceX will have no incentive to massively reduce costs in normal operations. They can undercut everyone else, and pocket the excess cash---and still charge much more than a launch actually costs them. That's the smart move, anyway. I suppose they could charge fairly normal rates, but also participate in start ups with new space business ideas. Asteroid mining, those kinds of things---cut launch costs such that companies can just build and fly stuff without having to have hundreds of millions in funding.

[tater]

 

[kerbiloid]

Spoiler

8 hours ago, sh1pman said:

A million years later we can have the entire galaxy populated. It’s a nice insurance for planetary crises, however unlikely they may be.

Who knows, maybe some other evil alien civilization has already started colonizing Milky Way, and we need to start now to have a fighting chance against them.

So, the nearest fifty years are what is deciding everything. Why wait for proper engines, let's hurry and make a bottle starship on candies.

6 hours ago, mikegarrison said:

6 hours ago, Rakaydos said:

Shelter In Place behind your fireproof steel hull, start draining fuel to get above TWR=1 as a precautionary measure, and let Pad Emergency Services handle the problem.

"draining fuel" with a fire going on just below you? I'm thinking this is not a good plan.

Have a LES pusher plate and start draining the fuel. The explosion will do the rest.

8 hours ago, Wjolcz said:

Don't build a ship then. Make it an oil rig-like structure instead:

This rig definitely deserves four Atlas statues instead of just pillars. In old times they would make them...

 

[sh1pman]

4 hours ago, kerbiloid said:

Why wait for proper engines

Are current engines somehow improper? I don’t understand

Edited October 1, 2019 by sh1pman

[Xd the great]

24 minutes ago, sh1pman said:

Are current engines somehow improper? I don’t understand

They are too expensive to build.

[magnemoe]

35 minutes ago, Xd the great said:

They are too expensive to build.

Cost is not as relevant then you reuse a lot of times. Ease of maintenance and performance get more important. 
The real user of them is superheavy and that is only relevant then they get closer to their first orbital launch. 

[kerbiloid]

1 hour ago, sh1pman said:

Are current engines somehow improper? I don’t understand

For extraplanetary expansion? Absolutely.

Do you fly by multistage planes?
Does a flight take months or even days?

Edited October 1, 2019 by kerbiloid

[Wjolcz]

44 minutes ago, Xd the great said:

They are too expensive to build.

So is pretty much everything in spaceflight.

Do we have any numbers on how much was the first Merlin vs how much they are now?

1 minute ago, kerbiloid said:

Do you fly by multistage planes?
Does a flight take months or even days?

How does any of this make the engines improper?

[sh1pman]

1 minute ago, kerbiloid said:

For extraplanetary expansion? Absolutely.

They’re absolutely fine for places like Moon and Mars, especially if we use orbital refilling and propellant depots.

[kerbiloid]

1 minute ago, Wjolcz said:

How does any of this make the engines improper?

ISP. When it becomes tens km/s, it will be a deal.
Until that - it's building a plane of planks and feathers.

Edited October 1, 2019 by kerbiloid

[Wjolcz]

2 minutes ago, kerbiloid said:

ISP. When it becomes tens km/s, it will be a deal.
Until that - it's building a plane of planks and feathers.

So what you meant to say is that the SL variant is not great for vacuum. Isn't that obvious?

Btw, which rocket achieves tens km/s in vacuum?

[Rakaydos]

7 minutes ago, kerbiloid said:

ISP. When it becomes tens km/s, it will be a deal.
Until that - it's building a plane of planks and feathers.

Carved out logs tied together with vines settled the entire pacific ocean, before recorded history. You dont need a steamboat to colonize Hawaii.

[kerbiloid]

14 minutes ago, Wjolcz said:

How does any of this make the engines improper?

If any engine is proper, why not use ethanol+oxygen, both cheap and green?

10 minutes ago, Wjolcz said:

Btw, which rocket achieves tens km/s in vacuum?

That one which takes hours to reach the Moon, days to reach the Mars, months to reach the Jupiter, and less than human life for Pluto.
And which doesn't need restaging every flight.

So, no at least gas-core nukes - no space expansion.

And building Starships in no degree makes these nukes closer.

5 minutes ago, Rakaydos said:

You dont need a steamboat to colonize Hawaii.

You need air, water, and plants to turn the Mars into them.

[Rakaydos]

5 minutes ago, kerbiloid said:

You need air, water, and plants to turn the Mars into them.

You can make and grow that stuff there. Sure, Hawaii's got flaming volcanoes wiping out half the island every few years, but what's life without a little danger.

[KSK]

7 hours ago, tater said:

 

The ground scatter is a bit lacking and they really need to fix the textures on that big triangular building. Sci-fi rocket looks great though.

What do you mean ‘not a KSP 2 screenshot?’

Edited October 1, 2019 by KSK

[kerbiloid]

14 minutes ago, Rakaydos said:

You can make and grow that stuff there.

On Hawaii - yes, I saw that on TV.

On Mars - never have seen.

[Xd the great]

8 minutes ago, KSK said:

What do you mean ‘not a KSP 2 screenshot?’

It is a KSP screenshot.

[Wjolcz]

19 minutes ago, kerbiloid said:

If any engine is proper, why not use ethanol+oxygen, both cheap and green?

More questions asked than answered.

21 minutes ago, kerbiloid said:

So, no at least gas-core nukes - no space expansion.

The experts have spoken. We will never land a man on the Moon. It's impossible without advanced technologies like the nukes.

23 minutes ago, kerbiloid said:

And building Starships in no degree makes these nukes closer.

Why would it? The whole point of Starship is to make the exploration cheap. Nukes won't make it cheaper than that.

[Kerbart]

8 hours ago, tater said:

This is being done is a remarkably transparent way, as well. You know that China, and companies like BO are also watching this carefully. If SpaceX pulls off Starship reuse, it's absolutely a game changer. As @mikegarrison said, it has the possibility to create a new market as the 747 did.

My only observation regarding creating new markets is that it requires competition for prices to drop. Blue will certainly follow (they need to be more ferociter, clearly), but until someone can compete on price, SpaceX will have no incentive to massively reduce costs in normal operations.

That depends on the definition of “massively.” If SpaceX manages to get this to work the way they envision it, then they want to launch it *a lot*. Supply and demand; if SpaceX floods the market with launch slots, prices need to go down for demand to go up. And I suspect that’s what SpaceX want, to launch their satellite network, maybe even build their own space station. And other things Elon comes up with.

In that scenario the competition is forced to follow quickly as prices will drop rapidly below their current operating cost.

[kerbiloid]

10 minutes ago, Wjolcz said:

The experts have spoken. We will never land a man on the Moon. It's impossible without advanced technologies like the nukes.

Once landed six times.
Any settlers there?

10 minutes ago, Wjolcz said:

Why would it? The whole point of Starship is to make the exploration cheap.

The same aboul sailships. None of them can reach the Moon.

Imagine, it's going to the Moon.

Spoiler

How much fuel from the tank will it spend to Moon and to Europe? 95% vs 5%?
When the ratio gets comparable, things will change.

Edited October 1, 2019 by kerbiloid