totm nov 2023 SpaceX Discussion Thread

[CatastrophicFailure]

1 hour ago, RealKerbal3x said:

It would be like ‘passing on the baton’ from Dragon 1 to 2.

I was thinking more like the Dragon crew thumbing their noses thru the window at the empty Starliner... 

1 hour ago, Raven Industries said:

That was a valve failure, I'm thinking more along the lines of a hole in your fuselage. 

Soyuz did that, too... 

[Jacke]

1 hour ago, CatastrophicFailure said:

I was thinking more like the Dragon crew thumbing their noses thru the window at the empty Starliner... 

Starliner looks promising.

EDIT: Still does look promising.  As does...whatever is the name of that big silver rocket SpaceX is working on.

I still wish people would rein in their spiel of achievements SpaceX's new rocket hasn't yet even come close to meeting, especially those at its extremes of predicted performance.  NASA and Roscosmos both have had their own painful lessons in what can happen at the edge of performance that is *all* spaceflight.  SpaceX will eventually have that too.

 

Quote

Soyuz did that [ fuselage failure ] , too... 

Don't know which Soyuz you're referring to.  Soyuz 1 had many faults, but it's not certain what lead to the main 'chute failure and then the drogue and reserve 'chutes tangling.  Other Soyuz failures besides 11's pressure valve were all launch vehicles, I believe.

Edited October 29, 2019 by Jacke

[tater]

2 minutes ago, Jacke said:

Starliner looks promising.  I still wish people would rein in their spiel of achievements it hasn't yet even come close to meeting, especially those at its extremes of predicted performance.  NASA and Roscosmos both have had their own painful lessons in what can happen at the edge of performance that is *all* spaceflight.  SpaceX will eventually have that too.

I haven't seen much in terms of extremes of performance, more people trying to do some Kremlinology and figure out if it can really do what it is supposed to be able to do. So far decent attempts at doing the math have at least corroborated payload numbers, etc (as being possible given the physics).

Getting reuse to be a thing... that's some work, and I fully expect some spectacular explosions.

[CatastrophicFailure]

17 minutes ago, Jacke said:

Starliner looks promising.  I still wish people would rein in their spiel of achievements it hasn't yet even come close to meeting, especially those at its extremes of predicted performance.  NASA and Roscosmos both have had their own painful lessons in what can happen at the edge of performance that is *all* spaceflight.  SpaceX will eventually have that too.

I was referring to Boeing’s CST-100 capsule... which they call the Starliner...

17 minutes ago, Jacke said:

Don't know which Soyuz you're referring to.  Soyuz 1 had many faults, but it's not certain what lead to the main 'chute failure and then the drogue and reserve 'chutes tangling.  Other Soyuz failures besides 11's pressure valve were all launch vehicles, I believe.

Spoiler

 

[Jacke]

42 minutes ago, CatastrophicFailure said:

I was referring to Boeing’s CST-100 capsule... which they call the Starliner...

Thanks for pointing that out.  It's getting hard to keep track of all these without a scorecard.

 

Quote

As what purports to be a joke is made more subtle to the point of obtuseness, at some point it ceases to be a joke at all.  Except perhaps about the failure to get its point across at all.

Edited October 29, 2019 by Jacke

[tater]

 

[kerbiloid]

Spoiler

If the other wing was jettisonnable, it would be much easier to land the F-15.
Also if its T/W > 1, it could land like Falcon.

 

8 hours ago, Jacke said:

Other Soyuz failures besides 11's pressure valve were all launch vehicles, I believe.

Almost every early Soyuz flight had its own... specifics, not related to the LV.
First they totally reworked it on Soyuz-12, then on Soyuz-T-XX. Since that it became flyable.

Edited October 30, 2019 by kerbiloid

[CatastrophicFailure]

Looks like we've got another month or more... 

 

[tater]

 

[tater]

 

[sh1pman]

Don’t know if it was posted here or not, but Robert Zubrin wrote a paper titled “Mars Direct 2.0” describing different Starship Mars mission variants. Very interesting reading, lots of calculations. Starship specs may be just slightly off (from the latest info), but it shouldn’t affect the results.

http://www.pioneerastro.com/wp-content/uploads/2019/10/Mars-Direct-2.0-How-to-Send-Humans-to-Mars-Using-Starships.pdf

[tater]

Zubrin "doesn't get it" IMO.

[mikegarrison]

Zubrin has always been "visionary", which is usually another word for crazy. Of course, the same is true of Musk.

Anyway, I'm not sure what to think about this. If you carry another spacecraft inside a spacecraft, then you have to duplicate a lot of stuff. However, that's essentially what "staging" is, so sometimes duplicating stuff is the only way to actually do what you want to do.

I think the key here is the tankering concept. If lifting fuel to orbit is as cheap as Musk envisions, then it's probably cheaper to do that than to build a spaceship inside a spaceship. I mean, that's one reason why the Shuttle struggled, right? It's probably easier to just loft Zubrin's Mars ship by itself than to loft it inside a Starship.

On the other hand, if you (like me) have tried tankering in KSP, you have probably found (like me) that it always seems like a better idea than it really is. But KSP is not an accurate simulation, especially of economics, so....

Honestly, I don't think either Starship or anything designed by Zubrin are ever going to Mars. But I could be wrong.

[sh1pman]

22 minutes ago, tater said:

Zubrin "doesn't get it" IMO.

Yeah, I have some criticism of his analysis, but not his calculations, which are the interesting parts.

His TLI and LEO variants require the development of a completely new 100+ ton spacecraft, massively reduce payload to Mars, over exaggerate the problem of needing 2-3 more tanker flights (not a problem with reusable system) and that Mars Starships can’t be reused for at least 2.5 years (also not a problem, as there won’t be that many Mars ‘ships compared to tankers and sat lifters).
 

But the biggest problem with his vision is that Musk’s plan is to have “one ship to rule them all”. A single rocket with few specialized upper stage variants to do everything from LEO sat lifting to Mars colonization.

[mikegarrison]

1 minute ago, sh1pman said:

But the biggest problem with his vision is that Musk’s plan is to have “one ship to rule them all”. A single rocket with few specialized upper stage variants to do everything from LEO sat lifting to Mars colonization.

That vision is either going to make or break the whole enterprise. Probably break it, IMO. But we'll see. It requires a lot of luck and also a lot of real insight in order to come up with a one-size-fits-all aerospace vehicle that actually does fit all (or at least close enough to all).

[sh1pman]

1 minute ago, mikegarrison said:

That vision is either going to make or break the whole enterprise. Probably break it, IMO. But we'll see. It requires a lot of luck and also a lot of real insight in order to come up with a one-size-fits-all aerospace vehicle that actually does fit all (or at least close enough to all).

On the other hand, developing several smaller Starship-derived aerospace vehicles will cost more, take longer, and not necessarily make the whole enterprise easier. We’ll see.

[tater]

26 minutes ago, sh1pman said:

But the biggest problem with his vision is that Musk’s plan is to have “one ship to rule them all”. A single rocket with few specialized upper stage variants to do everything from LEO sat lifting to Mars colonization.

That's kind of the point. A fully refilled Starship (current variant, which is about as small as one could ever be) can do a lunar mission with no ISRU, with something like 20-30t of return payload.

If SS can fly at the F1 price talked about, ~5-6M$/flight, that's ~$35/kg. You can fly a single smallsat to a bespoke orbit for what they'd pay for Electron (they'd not make money), or comanifest 2, and make money. It can deliver a GTO sat to GTO (20-30 tons to GTO) for 10X less than F9.

Bigger is better.

20 minutes ago, mikegarrison said:

That vision is either going to make or break the whole enterprise. Probably break it, IMO. But we'll see. It requires a lot of luck and also a lot of real insight in order to come up with a one-size-fits-all aerospace vehicle that actually does fit all (or at least close enough to all).

I honestly think it's really smart.

One, the goal (aside from Mars, but required for Mars---and I'm not a Mars guy) is grossly cheaper access to space. FedEx sorts of prices to LEO. Two, Jeff Bezos is slow, but he's Jeff Bezos. He's driven to do this, NG is going to happen, and as he says, it's the smallest orbital rocket they will ever build (at 7m diameter). Two, SpaceX has been talking about BFR for what, 3-4 years now? It very likely flies to orbit in 5 years total from when we heard about it. That's the dev time on a next gen rocket. If they wait until NG laps them, 5 years will be too long, IMO.

Remember that BO also used to have a biconic capsule they talked about. They didn't throw that work in the trash, I'd bet money we see it again. NG is out of the box "human ready" (all their press has said that from day one). At some point they'llhave a Blue Moon like reveal, and it'll be, "Oh, yeah, we've been working on a crew vehicle for the last 8 years." SpaceX has to move to stay around.

Edited October 31, 2019 by tater

[mikegarrison]

I'm extrapolating somewhat from aviation here, which may make parts of the analysis invalid. But the most important make-or-break decision in an aerospace vehicle is usually the very first one: "what is the mission?" Everything else develops from that.

It follows that "one-size-fits-all" tends to have lots of problems because missions themselves are not "one size". Building a ship with too much capability is expensive, but building one with too little capability is a disaster. So the design missions tend to creep up in size. But at some point you just invite someone smaller to come in under you and eat away at your market.

Starship as a sat launcher only works if there are enough sats that need to get launched. There's a reason why A380s don't fly every route for every airline. You can make a vehicle too big. Bigger is not always better. On the other hand, lots of people thought the 747 would be just way too big, and yet it turned out that the market really was there and the planes were successful for decades.

I don't think Starship is too big to be a Mars ship. If anything, I'm worried that it is too small. But hey, old time sailors used to get into tiny wooden boats and sail out into the unknown, so I guess it might work. However, I am questioning the business model that says there will be all this demand for earth sats. Might be true! I frankly don't know. But it seems like SpaceX has put a lot of their eggs into that basket, mainly because they need that basket in order to fly to Mars.

[tater]

20 minutes ago, mikegarrison said:

I'm extrapolating somewhat from aviation here, which may make parts of the analysis invalid. But the most important make-or-break decision in an aerospace vehicle is usually the very first one: "what is the mission?" Everything else develops from that.

It follows that "one-size-fits-all" tends to have lots of problems because missions themselves are not "one size". Building a ship with too much capability is expensive, but building one with too little capability is a disaster. So the design missions tend to creep up in size. But at some point you just invite someone smaller to come in under you and eat away at your market.

Starship as a sat launcher only works if there are enough sats that need to get launched. There's a reason why A380s don't fly every route for every airline. You can make a vehicle too big. Bigger is not always better. On the other hand, lots of people thought the 747 would be just way too big, and yet it turned out that the market really was there and the planes were successful for decades.

I don't think Starship is too big to be a Mars ship. If anything, I'm worried that it is too small. But hey, old time sailors used to get into tiny wooden boats and sail out into the unknown, so I guess it might work. However, I am questioning the business model that says there will be all this demand for earth sats. Might be true! I frankly don't know. But it seems like SpaceX has put a lot of their eggs into that basket, mainly because they need that basket in order to fly to Mars.

This doesn't mesh with the physics, though. Aircraft != spacecraft.

A 747 costs more to make, and costs more to operate than a smaller craft, designed for the mission in question.

Full reuse (rapid reuse, little/no refurb) is aided by larger spacecraft (ballistic coefficient). The rocket equation also shows us that only a small % on the pad will ever get to orbit. It's very, very different than the math for air travel, which is much closer to linear. The onyl way to compare to air is to assume single-use aircraft. Right now, there are single use, mission specific aircraft, they are called missiles. They are expensive, but useful in a specific use case---but aircraft none the less still exist even in the same mission role (military, in this case). Even though we could very well see a huge change here---to UAVs---the UAV is still an aircraft, not a disposable aircraft (missile).

I agree with Starship being too small for Mars, but I tend to think it is just about as small as any fully reusable spacecraft can be for LEO. Like I said, I'm not a Mars person, but I think that low cost comes along for that ride, and is in fact a necessary condition for Mars to even be possible (though not sufficient ).

[Terwin]

13 minutes ago, mikegarrison said:

I'm extrapolating somewhat from aviation here, which may make parts of the analysis invalid. But the most important make-or-break decision in an aerospace vehicle is usually the very first one: "what is the mission?" Everything else develops from that.

It follows that "one-size-fits-all" tends to have lots of problems because missions themselves are not "one size". Building a ship with too much capability is expensive, but building one with too little capability is a disaster. So the design missions tend to creep up in size. But at some point you just invite someone smaller to come in under you and eat away at your market.

Starship as a sat launcher only works if there are enough sats that need to get launched. There's a reason why A380s don't fly every route for every airline. You can make a vehicle too big. Bigger is not always better. On the other hand, lots of people thought the 747 would be just way too big, and yet it turned out that the market really was there and the planes were successful for decades.

I don't think Starship is too big to be a Mars ship. If anything, I'm worried that it is too small. But hey, old time sailors used to get into tiny wooden boats and sail out into the unknown, so I guess it might work. However, I am questioning the business model that says there will be all this demand for earth sats. Might be true! I frankly don't know. But it seems like SpaceX has put a lot of their eggs into that basket, mainly because they need that basket in order to fly to Mars.

The difference here, is that SpaceX is trying for full-reuse when no one else has more than attempted re-use of specific parts.

For anyone to under-cut him, they will also need full reuse, and the smaller your vessel the harder it is to manage full reuse.

While Starship my have huge cargo to orbit(150t), it may not be feasible to substantially under-cut his costs even with full re-use.  Remember: the smaller the rocket, the less efficient, and at a certain point you can't even get full reuse, let alone useful cargo with full reuse.

Even Electron saw where things were going and announced partial reuse plans in hopes of not having their small-sat launch market stolen by SpaceX.

If SpaceX succeeds in getting Starship launching for 5-6M per launch, that puts them in direct cost-competition with Electron($6M for almost 0.5t to sun synchronous orbit) and under-cutting everyone else currently in the market(including themselves) by an order of magnitude or more(6M to lunch SS vs 60-90M to launch Falcon and Falcon is dirt-cheap compared to pretty much everyone else)

[tater]

57 minutes ago, Terwin said:

Even Electron saw where things were going and announced partial reuse plans in hopes of not having their small-sat launch market stolen by SpaceX.

They say at least that this has a lot to do with production rate. Beck said that reuse even once effectively doubles their production rate (booster is 80% of the time to make a new rocket he said).

[Nothalogh]

23 hours ago, kerbiloid said:

Also if its T/W > 1, it could land like Falcon.

Well, an F-15 can break the sound barrier in a vertical climb, with a full weapon and fuel load.

So, I think it has that nailed.

The issue would be controllability in that retrograde descent.

Many moons ago, the USAF and USN played around with tailsitter VTOLs, and found them to be nightmarish creatures.

2 hours ago, mikegarrison said:

I don't think Starship is too big to be a Mars ship. If anything, I'm worried that it is too small.

My suspicion is that BFR and SS are going to be a lot bigger by the time one gets sent to mars.

 

[tater]

9 minutes ago, Nothalogh said:

My suspicion is that BFR and SS are going to be a lot bigger by the time one gets sent to mars.

Yeah I think if "colonists" go to Mars on the current 9m Starship... I'll volunteer to eat one. (a SS, not a colonist).

[magnemoe]

2 hours ago, tater said:

That's kind of the point. A fully refilled Starship (current variant, which is about as small as one could ever be) can do a lunar mission with no ISRU, with something like 20-30t of return payload.

If SS can fly at the F1 price talked about, ~5-6M$/flight, that's ~$35/kg. You can fly a single smallsat to a bespoke orbit for what they'd pay for Electron (they'd not make money), or comanifest 2, and make money. It can deliver a GTO sat to GTO (20-30 tons to GTO) for 10X less than F9.

Bigger is better.

I honestly think it's really smart.

One, the goal (aside from Mars, but required for Mars---and I'm not a Mars guy) is grossly cheaper access to space. FedEx sorts of prices to LEO. Two, Jeff Bezos is slow, but he's Jeff Bezos. He's driven to do this, NG is going to happen, and as he says, it's the smallest orbital rocket they will ever build (at 7m diameter). Two, SpaceX has been talking about BFR for what, 3-4 years now? It very likely flies to orbit in 5 years total from when we heard about it. That's the dev time on a next gen rocket. If they wait until NG laps them, 5 years will be too long, IMO.

Remember that BO also used to have a biconic capsule they talked about. They didn't throw that work in the trash, I'd bet money we see it again. NG is out of the box "human ready" (all their press has said that from day one). At some point they'llhave a Blue Moon like reveal, and it'll be, "Oh, yeah, we've been working on a crew vehicle for the last 8 years." SpaceX has to move to stay around.

You could make an smaller fully reusable rocket. However it would not be tiny, Falcon 9 is kind of small here only leaving a couple of ton for payload. New Glen looks like it would work nice with an reusable upper stage. 

So starship is a bit to large for an optimal satellite delivery rocket, yes as its designed for Mars and deep space. 
And its large enough for mars missions. For colonies they would want something larger but that is far down the line. 

One main benefit of the large starship is that you can take lots of extra dry mass and still have an effective rocket. 150 ton try mass, Still works well for orbital operations. 

[Xd the great]

37 minutes ago, tater said:

Yeah I think if "colonists" go to Mars on the current 9m Starship... I'll volunteer to eat one. (a SS, not a colonist).

I don't know if cannibalism is better than chewing steel.