totm nov 2023 SpaceX Discussion Thread

[sevenperforce]

20 hours ago, tater said:

He's been known to use imprecise terms before, but yeah, certainly possible (though never shown in previous renders of BFR/ITS/SS before).

Well, he often uses imprecise terms, but he doesn't usually use precise terms (like dual-bell) imprecisely.

A dual-bell design would not necessarily be visible in any of the renders. It would show as a very slight inflection point inside the bell and would probably not even be visible in photos unless you had a high-contrast view of the naked engine before it was installed.

20 hours ago, tater said:

Cool link, BTW. Seems like it makes more sense for a sustainer architecture than TSTO, however, as the Vacuum Raptors won't even fire until the thing is around 100km alt anyway.

I think the dual-bell is intended solely for inducing controlled flow separation if the VacRaptors were ignited in a pad abort. In a pad abort, you want all the engines to basically act as if they were SL engines.

19 hours ago, tater said:

19 hours ago, sh1pman said:

Even if Raptors can be used as LES, it won’t help if Starship itself blows up.

That's true for any abort system, though.

Exactly. Dragon 2's LES doesn't help if the pressure vessel goes boom, as it did on the test stand. The escape towers on Orion and Soyuz won't help if the escape tower buckles, folds, and detonates when it impacts the fairing. The pusher escape motors on Starliner won't help if the propellant tanks in the service module explode.

The big distinction is between Starship and the Shuttle. The Shuttle had no abort mechanism whatsoever while the boosters were firing. Starship does.

Even airliner-level reliability won't help an airliner if the wings break apart.

20 hours ago, CatastrophicFailure said:

I shall follow this particular thread with great interest. 

While not untrue, it should be noted that the risk of catastrophic detonation is rather higher for cryo liquids than for hypergolic liquids. For hypergolic liquids, the propellants begin burning at contact, which tends to disperse them all rather rapidly. For cryos, the liquids may have an opportunity to mix before ignition, which makes the fireball much larger. In either case, though, you have plenty of time as long as you trigger LES at first anomaly.

12 hours ago, tater said:

"Cheap." (for you and me, for a rocket... yeah, cheap)

I was trying to estimate costs on a Starship prototype. Say they have 100 people working at $100,000/yr (incl benis, etc) on each.

They don't pay that much.

[tater]

1 hour ago, sevenperforce said:

They don't pay that much.

For such an estimate, I figured I'd slop it well up.

I'd assume the typical wage might really be 50-60k. The goal was a reasonable upper bound on cheap SS manufacture. It's entirely possible that they build both stacks, including the facility upgrades (the tent VABs, etc) for under 100 million (shockingly low).

1 hour ago, sevenperforce said:

They don't pay that much.

That makes sense.

[tater]

The second quote was supposed to be about the use of the dual bell for LES.

[sevenperforce]

4 hours ago, tater said:

The second quote was supposed to be about the use of the dual bell for LES.

Ah, makes sense. _{see what I did there}

Also note the phrasing and response to Scott:

So it sounds like he's saying that if they decide to give early (read: unmanned?) Starships pad abort capability, they would make the vacuum engines dual bell. They are of course already planned to be fixed.

Taking the dual-bell route shaves off efficiency slightly for lunar ops but it's not too bad. They might be able to also use this for single-stage P2P operation, igniting all six-seven engines on the pad for liftoff thrust and then shutting off the core engines as the VacRaptors expand into the bell extension.

His phrasing would suggest that for early manned Starship flights (e.g., #DearMoon), they might launch and fuel Starship first and then use Falcon 9 with Dragon 2 to send up the people, if there is no pad abort

 

Edited September 10, 2019 by sevenperforce

[mikegarrison]

2 hours ago, sevenperforce said:

Even airliner-level reliability won't help an airliner if the wings break apart.

Wings not breaking apart is part of reliability.

[tater]

7 minutes ago, sevenperforce said:

So it sounds like he's saying that if they decide to give early (read: unmanned?) Starships pad abort capability, they would make the vacuum engines dual bell. They are of course already planned to be fixed.

Taking the dual-bell route shaves off efficiency slightly for lunar ops but it's not too bad. They might be able to also use this for single-stage P2P operation, igniting all six-seven engines on the pad for liftoff thrust and then shutting off the core engines as the VacRaptors expand into the bell extension.

His phrasing would suggest that for early manned Starship flights (e.g., #DearMoon), they might launch and fuel Starship first and then use Falcon 9 with Dragon 2 to send up the people, if there is no pad abort

Interesting. Again, I think you're right, that makes sense.

 

[sevenperforce]

3 hours ago, mikegarrison said:

Wings not breaking apart is part of reliability.

Awww geez I have to make the wings reliable too??

[Raven Industries]

37 minutes ago, sevenperforce said:

Awww geez I have to make the wings reliable too??

Best put those things back on the side of the road where you found them, turns out we have to use high quality parts. 

[mikegarrison]

One time when I was a kid, Dad and I were out hunting and we found a strange bit of metal out in the woods. Dad looked at it and saw it had a Boeing part number (he had been a machinist for Boeing when he was in college, so he knew what a Boeing part number looked like). So he turned it in to them. Must have fallen off an airplane at some point.

Edited September 10, 2019 by mikegarrison

[tater]

5 minutes ago, mikegarrison said:

One time when I was a kid, Dad and I were out hunting and we found a strange bit of metal out in the woods. Dad looked at it and saw it had a Boeing part number (he had been a machinist for Boeing when he was in college, so he knew what a Boeing part number looked like). So he turned it in to them. Must have fallen off an airplane at some point.

Wow.

I mean, what are the chances, right?

Also:

 

 

 

[mikegarrison]

1 minute ago, tater said:

I mean, what are the chances, right?

Yeah, I guess.

Another time we found a note in plastic attached to a deflated balloon. Turned out some elementary school in Oregon had released them in the previous spring just to see if anyone ever responded. (It was autumn, the usual deer hunting season.) He sent it back to them, and they said ours was the only one that anyone had sent back. They sent back drawings made by the kids of what they imagined we looked like finding it.

Anyway, back to rockets....

[tater]

Quote

PARIS — SpaceX hopes to launch 24 Starlink missions in 2020 as the company builds out a broadband megaconstellation that could ultimately number close to 12,000 satellites, a company executive said Sept. 10. SpaceX’s Starlink launch cadence will likely average “two a month,” in addition to customer launches, Gwynne Shotwell, SpaceX’s president and chief operating officer, said at the World Satellite Business Week conference here. “Next year I hope we launch 24 Starlinks,” Shotwell said. 

Shotwell said SpaceX may launch more Starlink missions this year, but the final number will depend on customer missions. SpaceX will prioritize launching customers before its own broadband satellites, she said. “If some customers move out, I’ll have some Starlink launches — maybe up to four Starlink launches this year — but we won’t push a customer out for that, so we will wait and see what the end of the year looks like and see what we can fit in.”

 

[mikegarrison]

So SpaceX has a schedule of launches that is independent of their customer payload schedules? That's what it sounds like.

[cubinator]

6 hours ago, sevenperforce said:

His phrasing would suggest that for early manned Starship flights (e.g., #DearMoon), they might launch and fuel Starship first and then use Falcon 9 with Dragon 2 to send up the people, if there is no pad abort

Hmmm, that seems like a fairly good idea in general, as Mars ships would spend a while in orbit getting topped up by other ships anyway.

[Nightside]

10 minutes ago, cubinator said:

Hmmm, that seems like a fairly good idea in general, as Mars ships would spend a while in orbit getting topped up by other ships anyway.

Might be the way to deorbit passengers too, if there is no abort system forthcoming.

Makes a lot of sense, as lifting reentry seems so much riskier.

[cubinator]

22 minutes ago, Nightside said:

Might be the way to deorbit passengers too, if there is no abort system forthcoming.

Makes a lot of sense, as lifting reentry seems so much riskier.

Remember that lifting reentry is still necessary at Mars. But it would reduce risk on return to Earth, and passengers could rest at least a little easier as they come home.

[Nightside]

Just now, cubinator said:

Remember that lifting reentry is still necessary at Mars. But it would reduce risk on return to Earth, and passengers could rest at least a little easier as they come home.

But Mars is still a ways off. A Dragon ferry would allow manned Starship missions in the local Earth-Moon neighborhood while giving them experience.

[Rakaydos]

25 minutes ago, Nightside said:

But Mars is still a ways off. A Dragon ferry would allow manned Starship missions in the local Earth-Moon neighborhood while giving them experience.

Not that far off. The last known plan was 2023 lunar tourisim, 2024-2027 mars gas station construction

[sh1pman]

There’s 21 steel sections lying on the ground. Must be for the booster.

[tater]

51 minutes ago, sh1pman said:

There’s 21 steel sections lying on the ground. Must be for the booster.

A few are marked "Scrap", but some are in the tents, too. I think you are right. Suborbital testing out of TX,and perhaps SH/SS out of FL?

The SH rings are also different. The SS rings are made of multiple panels, the rings on the ground right now are each ONE piece of stainless.

[Mitchz95]

On 9/9/2019 at 10:00 PM, tater said:

Dunno about the travel aspect, I just meant a group of people replicating the Martian (until they realize they need, you know, protein).

IIRC, Mark Watney had plenty of vitamins to take care of his nutritional needs, including protein. The potatoes were just for calories.

[tater]

33 minutes ago, Mitchz95 said:

IIRC, Mark Watney had plenty of vitamins to take care of his nutritional needs, including protein. The potatoes were just for calories.

Protein is food, not a vitamin.

[sh1pman]

Yea, there needs to be a source of essential amino acids. Potatoes have all of them, so you can survive on potatoes forever. You just need vitamin supplements and some minerals (mostly calcium) from some other source.

[CatastrophicFailure]

 

[Scotius]

5 hours ago, sh1pman said:

Yea, there needs to be a source of essential amino acids. Potatoes have all of them, so you can survive on potatoes forever. You just need vitamin supplements and some minerals (mostly calcium) from some other source.

Got milk?

I'm serious. If only our digestive tract could handle such diet, we could live on milk and potatoes indefinitely.