totm nov 2023 SpaceX Discussion Thread

[magnemoe]

15 hours ago, tater said:

 

Almost at the moon and first stage is still burning  Remember an photo of an B-52 in front of the moon also shot with high zoom. Title: an B-52 flying by the moon, 
No the B-52 can not fly by the moon, it can obviously fly in front of it. 

[farmerben]

 

[magnemoe]

4 hours ago, tater said:

JFK's goal was incredibly audacious. No one working on it at the time thought it was a foregone conclusion by a long shot, it's honestly hard to even imagine a more lofty goal.

I agree, it worked, but they spend a lot of money on it. This can be seen in many ways, over optimistic, Musk thinking or making the Soviet spend lots of money on an project the US would end up getting lots of new technology from but the Soviet will have far less of the state and company synergy for stuff like integrated circuits who had some impact 

[tater]

Looks like S25 might be on the move soon.

[SunlitZelkova]

15 hours ago, mikegarrison said:

That's survivor bias.

If you have 1000 people drawing lots, and one wins, you are exhibiting survivor bias if you go ask the winner how he got to be so good at drawing lots.

Likewise, if there are 1000 lofty goals, and 999 fail, that doesn't mean the one that succeeded wasn't lofty. It just means they were the survivor.

If you judge the initial challenges by whether they were ultimately met or not, you are going to end up claiming that all successful attempts were actually easy, and all failures were hard. But that's survivor bias.

I'm not sure if that's the exact definition of survivorship bias.

Is all car travel dangerous because 1 in 1000 people die in a car crash? Or were the trips that succeeded actually quite safe, and one actually dangerous due to some hidden factor?

Vice versa, I would say Apollo in eight years was, with hindsight, and in a technological sense, not lofty. Whereas a Soviet Moon landing in five years was.

But actually I wouldn't say that. I have realized that I never meant Apollo alone was not lofty, but that in comparison to the Soviet attempt or the original Shuttle timeline, it was not lofty.

But anyways, I think that is besides the point. My word use was wrong.

Rather than "lofty goals" I was listing "short, optimistic timelines".

This definition, of course, has some issues too, because depending on the context Apollo could have been a short timeline project too. And of course, Mercury and Vostok were completed in much shorter time than Apollo itself.

So what I was actually listing was basically just "that other Moon landing program that tried to get there within five years" (the Soviet L3 lunar project). The Space Shuttle should be dropped as an example because development of a space plane is very different.

*deep breath before trying to get back on topic*

Thus based on the past example of the Soviet attempt to get to the Moon, Artemis III in 2024 or 2025 was always just a dream even with SpaceX's break-things-and-move-fast development style. Therefore there shouldn't be much worry over being "late". Only if things start to slip past 2029 would it be concerning.

[Royalswissarmyknife]

S25 is on the move!

[CatastrophicFailure]

16 hours ago, Royalswissarmyknife said:

S25 is on the move!

And going up. 

 

 

Edited September 5, 2023 by CatastrophicFailure

[tater]

 

 

[RCgothic]

Full stack!

Also that's some nice heat shielding under S25. Was S24 the same?

Edited September 5, 2023 by RCgothic

[Spaceception]

Predictions for this one? I think it'll make it to stage separation and ignition of Starship. Bit more iffy whether it'll burn the full duration to its semi-orbit, and definitely uncertain if it'll survive reentry. The booster should make boostback, and possibly a soft ocean landing after.

And the pad will survive.

Overall, it'll be a much smoother test than IFT-1, even if I still don't think it'll meet its objectives.

[JoeSchmuckatelli]

1 hour ago, Spaceception said:

ignition of Starship

If they get ignition, I suspect they'll get orbit 

Depends on the number of booster rockets that survived take off - but I think if they have enough to attempt separation, they get orbit 

[tater]

1 hour ago, JoeSchmuckatelli said:

If they get ignition, I suspect they'll get orbit 

Depends on the number of booster rockets that survived take off - but I think if they have enough to attempt separation, they get orbit 

Or "orbital energy" anyway, since I think the actual goal (while not certain to me) is still a "suborbital" flight with an orbital entry velocity (higher apogee, perigee still low over the Pacific to ensure it's not a danger to land areas).

Edited September 6, 2023 by tater

[sevenperforce]

2 hours ago, RCgothic said:

Full stack!

Also that's some nice heat shielding under S25. Was S24 the same?

I don't believe so.

[darthgently]

I wonder how much real time control (aside from flight termination trigger) they will have over the craft at various points in the ascent.  There is probably onboard code to automatically attempt a target suborbital apoapsis and eccentricity with a ceiling on reentry speed and reentry geographic location in mind, but can they intervene remotely and raise periapsis at apoapsis instead?  I'd love to know all the details. 

It would be cool, if they find they have the fuel and informed confidence, to raise the PE for true orbit then let it orbit a few times before deorbit burn and reentry.  Big PR, more time and suspense in the news cycles.  As well as testing SS RCS, fuel boil-off rates etc.  Risk would be losing control and having a rather large pointless object in some orbit indefinitely 

 

[tater]

 

 

[Cloakedwand72]

I’ve been thinking would the hot stage method on this coming starship second attempt help it achieve orbit as well as the deluge plate help with minimal engine out?

[RCgothic]

Won't have a lot of impact.

They basically wanted to eliminate a stage separation mechanism which would need to be pretty chunky to push away a 1500t upper stage.

First attempt was flip staging, where the booster main engines induce a spin that causes centrifugal force to separate the stages. They would have attempted this on OFT-1, but didn't get that far. There was some confusion on this point due to the loss of control and tumbling.

Since OFT-1 they've changed their mind and are now doing hot staging. This could save a little DV as there is no coast phase for Starship, and the repulsion of the booster by exhaust gases could save it a little bit of DV on the boostback burn.

The drawback is that the engines, engine bay and interstage take a much harsher beating.

[sevenperforce]

I've been out of pocket. Wenhop?

11 hours ago, darthgently said:

I wonder how much real time control (aside from flight termination trigger) they will have over the craft at various points in the ascent.  There is probably onboard code to automatically attempt a target suborbital apoapsis and eccentricity with a ceiling on reentry speed and reentry geographic location in mind, but can they intervene remotely and raise periapsis at apoapsis instead?  I'd love to know all the details. 

Fairly certain that everything after about T-30 seconds is almost completely automated. They program in all of the parameters and tell it what to do with all contingencies and give it abort modes for anything out of spec.

[tater]

34 minutes ago, sevenperforce said:

I've been out of pocket. Wenhop?

The big question.

The WB-57 calendar has nothing marked so far.

Still waiting on FAA per what I hear.

[tater]

And now I notice that was actually tweeted yesterday:

 

[Geonovast]

Overlapping threads merged.

[Spaceception]

On 9/5/2023 at 6:37 PM, JoeSchmuckatelli said:

If they get ignition, I suspect they'll get orbit 

Depends on the number of booster rockets that survived take off - but I think if they have enough to attempt separation, they get orbit 

Yeah, but I want to temper my expectations, so I'm sandbagging a bit. And while GSE/sensor issues could be the root cause behind the premature engine outs in B9's static fire, we still don't have all the details, so if it was something that may need more of a fix, and other engines face those same issues, then there's no guarantee that IFT-2 will go all the way.

Edited September 8, 2023 by Spaceception

[tater]

25 minutes ago, Spaceception said:

Yeah, but I want to remper my expectations, so I'm sandbagging a bit. And while GSE/sensor issues could be the root cause behind the premature engine outs in B9's static fire, we still don't have all the details, so if it was something that may need more of a fix, and other engines face those same issues, then there's no guarantee that IFT-2 will go all the way.

They didn't swap any engines though, right?

[tater]

 

[magnemoe]

1 hour ago, Spaceception said:

Yeah, but I want to remper my expectations, so I'm sandbagging a bit. And while GSE/sensor issues could be the root cause behind the premature engine outs in B9's static fire, we still don't have all the details, so if it was something that may need more of a fix, and other engines face those same issues, then there's no guarantee that IFT-2 will go all the way.

I think its weird they don't do more static fires while waiting.