totm nov 2023 SpaceX Discussion Thread

[RealKerbal3x]

25 minutes ago, SpaceFace545 said:

Now we get to see if Starship actually works or if it was just a fluke.

If they got the data they wanted from it (which they did, since they were able to recover it), then it's not a fluke. They can see exactly what happened and therefore should be able to repeat it.

Plus, I think reusability has been well and truly proven with Falcon 9. B1051 has flown 10 times and that reusability know-how has undoubtedly transferred to the Starship program.

[SpaceFace545]

1 minute ago, GuessingEveryDay said:

Do you not have any faith? Does anything that SpaceX does impress you? They are doing something that only sci-fi has been able to do, either politics, or competition decided to take break, and not do anything amazing. SpaceX is that force that will motivate humanity to innovate, to dream. This is why I want to move to Mars. To get away from people like this.

well, be my guest to live in a cave your whole life. 

@tater , SN15 was amazing, and it looked like they really got it down after all of those test runs but another failure could just show that SN15's success was just a fluke. So hopefully this flight works to show the feasibility of their grain tank.

 

[tater]

The only reason to fly SN15 and SN16 (17?) is because they have them. They can perhaps get the landing maneuver better characterized, and improve the reliability of it. That's kind of it.

The reality is that meaningful testing for Starship—which is an upper stage, don't forget—means sending it to space. EDL is obviously the next critical testing, and will likely be done destructively for a while (water landings). It seems like a better idea to work out flip/landing reliability on those flights since they are destructive anyway, and test the only actual use case of the maneuver (coming home from space).

[RealKerbal3x]

Just now, SpaceFace545 said:

SN15 was amazing, and it looked like they really got it down after all of those test runs but another failure could just show that SN15's success was just a fluke. So hopefully this flight works to show the feasibility of their grain tank

 A fluke is 'I did that, but I have no idea how, so I can't do it again'. Every one of these test flights gather terabytes of data on what the vehicle is doing from liftoff to touchdown. They know exactly what every component of SN15 was doing throughout the entire flight. It literally can't be a fluke.

[GuessingEveryDay]

2 minutes ago, SpaceFace545 said:

well, be my guest to live in a cave your whole life. 

[Jacke]

9 hours ago, mikegarrison said:

Vostok 1 was definitely in orbit. Without the de-orbit burn, it would have been in orbit for about 20 days (which would have killed Gagarin).

Failing the de-orbit burn would not have killed Gagarin.  As a safety measure, Korolev designed Vostok to have sufficient reserves for the crew to last until its orbit decayed.  It's also why Voskhod had a reserve retro rocket, as with its larger launch vehicle, it was launched into a too-high orbit to use that backup, especially with a larger crew.

[sevenperforce]

48 minutes ago, Jacke said:

Failing the de-orbit burn would not have killed Gagarin.  As a safety measure, Korolev designed Vostok to have sufficient reserves for the crew to last until its orbit decayed.  It's also why Voskhod had a reserve retro rocket, as with its larger launch vehicle, it was launched into a too-high orbit to use that backup, especially with a larger crew.

Vostok had sufficient reserves for up to 13 10 days in orbit (the planned decay lifetime), but the launch failed to place the capsule in the correct orbit and it would have taken 20 days to decay, which was a week more than Gagarin had reserves for.

Edited May 14, 2021 by sevenperforce
correction, updated source

[SpaceFace545]

4 minutes ago, sevenperforce said:

Vostok had sufficient reserves for up to 13 days in orbit (the planned decay lifetime), but the launch failed to place the capsule in the correct orbit and it would have taken 20 days to decay, which was a week more than Gagarin had reserves for.

Dumb question but couldn't the RCS provide some umph to help deorbit?

[tater]

1 minute ago, SpaceFace545 said:

@tater , SN15 was amazing, and it looked like they really got it down after all of those test runs but another failure could just show that SN15's success was just a fluke. So hopefully this flight works to show the feasibility of their grain tank.

It's a second stage. There are no indications SN20 is radically different from 15, 16, etc in build quality, and SN20 is an orbital flight article vehicle.

The success was not a fluke, it validated the concept of the maneuver. So far all the tests have shown the aerodynamic control to work, so that seems figured out. Horizontal relight and flip clearly needs to be better characterized, but it's also pretty complex. The fact that it finally worked means that it's possible for it to work, which tells me eventual reliability is likely.

 

 

27 minutes ago, SpaceFace545 said:

Dumb question but couldn't the RCS provide some umph to help deorbit?

Did Vostok have RCS?

Spoiler

He could get out and push, I have certainly done that in KSP

 

[magnemoe]

39 minutes ago, tater said:

This is a nonsensical statement.

These SN Starships are test articles as part of an iterative process. If they gather data, they worked.

This, note that Musk says SN20 will probably disintegrate. 
Its some stuff who is easy to simulate like the belly flop, people has done that in KSP. 
How cryogenic react to getting shaken is way more unknown,it some knowledge but its very niece, truck driver carrying cryogenic knew that braking hard reduced the pressure because the shaking. But  it looks like they fixed the header tank issues. Getting some fire suppression like co2 under the skirt sounds smart. 
Just install it as standard and trigger on touchdown for now. 

 

[sevenperforce]

21 minutes ago, SpaceFace545 said:

Dumb question but couldn't the RCS provide some umph to help deorbit?

The Vostok capsule had an independent service module, unlike the Mercury capsule, but unlike Gemini service module the Vostok service module only had RCS for attitude control.  The thrusters were placed on the sidewall, pointing radially, so they could rotate the entire vehicle but could not provide translational impulse.

And even if they could, it only had 9 kg of nitrogen at 59 psi which doesn't give you any meaningful dV.

[mikegarrison]

34 minutes ago, SpaceFace545 said:

Dumb question but couldn't the RCS provide some umph to help deorbit?

If this was KSP he could have just gone EVA and used his infinite supply of suit RCS.

[sevenperforce]

9 minutes ago, tater said:

Did Vostok have RCS?

It had 8 thrusters to control pitch and yaw and 8 thrusters to control roll, but they were in two redundant banks. So two identical starboard yaw thrusters to rotate you in one direction and two identical port yaw thrusters to rotate you back, and so on. No means of translation.

[magnemoe]

48 minutes ago, tater said:

The only reason to fly SN15 and SN16 (17?) is because they have them. They can perhaps get the landing maneuver better characterized, and improve the reliability of it. That's kind of it.

The reality is that meaningful testing for Starship—which is an upper stage, don't forget—means sending it to space. EDL is obviously the next critical testing, and will likely be done destructively for a while (water landings). It seems like a better idea to work out flip/landing reliability on those flights since they are destructive anyway, and test the only actual use case of the maneuver (coming home from space).

They can also probe edge cases as they are disposable, Note that SN15 did not light all engines but an sup optimal set, so its still reliability issues in flight. 
But yes the next milestone is sn20. 

[sevenperforce]

16 minutes ago, magnemoe said:

They can also probe edge cases as they are disposable, Note that SN15 did not light all engines but an sup optimal set, so its still reliability issues in flight. 
But yes the next milestone is sn20. 

SN15 lit all three engines on ascent and all three engines at the flip. They did a planned shutdown of one engine once the flip was underway in order to bring down their TWR.

Edited May 14, 2021 by sevenperforce
well this was wrong

[tater]

3 minutes ago, sevenperforce said:

SN15 lit all three engines on ascent and all three engines at the flip. They did a planned shutdown of one engine once the flip was underway in order to bring down their TWR.

Was that clear in the recap video? I remember at the time the telemetry cut out.

I think that they still have some issues to work out on the landing, but I'm pretty confident they start making it look routine in time.

[sevenperforce]

9 minutes ago, tater said:

Was that clear in the recap video? I remember at the time the telemetry cut out.

I think that they still have some issues to work out on the landing, but I'm pretty confident they start making it look routine in time.

Oh yes, very clear.

^{Well apparently my clear memories just suck}

Edited May 14, 2021 by sevenperforce
oops

[tater]

2 minutes ago, sevenperforce said:

Oh yes, very clear.

I just rewatched it. I'm not seeing the engine relights at all.

Real coverage video T +5:39 (~12:10 into coverage) is relight. ~T+5:43 the nearest engine lights, then the one on the right.

 

[sevenperforce]

5 minutes ago, tater said:

I just rewatched it. I'm not seeing the engine relights at all.

Real coverage video T +5:39 (~12:10 into coverage) is relight. ~T+5:43 the nearest engine lights, then the one on the right.

I was sure I had seen all three engines light in the Cosmic Perspective slow-mo but it was just one of the Mach diamonds that made it look like three engines were lit when there were only two.

[tater]

5 minutes ago, sevenperforce said:

I was sure I had seen all three engines light in the Cosmic Perspective slow-mo but it was just one of the Mach diamonds that made it look like three engines were lit when there were only two.

I forgot about that one (cool vid).

The seemed to light sequentially. Perhaps the algorithm is to light 1, then some fraction of a second later the next, and a fraction of a second the next. Once you get 2 showing nominal, don't bother with the third?

[JoeSchmuckatelli]

SpaceX's Starship rocket is set to splash-land into the ocean near Hawaii in its first flight around the Earth, FCC filings show (msn.com)

 

Anyone know if SX is looking for someone with experience chilling out on Navy ships for their recovery efforts?  I'd be happy to have them fly me out to Hawaii so I can stay well back out of the way on some weather-deck and watch them recover this thing!

Edited May 14, 2021 by JoeSchmuckatelli

[wumpus]

1 hour ago, mikegarrison said:

If this was KSP he could have just gone EVA and used his infinite supply of suit RCS.

If this was KSP he could have just waited the 20 days to return to land (infinite air, water, and snacks).  Possibly in 5 days with physics time warp.

I've abused this plenty more times than getting out and pushing.

[mikegarrison]

9 minutes ago, wumpus said:

If this was KSP he could have just waited the 20 days to return to land (infinite air, water, and snacks).  Possibly in 5 days with physics time warp.

I've abused this plenty more times than getting out and pushing.

Except if this were KSP his orbit would have never decayed. He would still be up there patiently waiting, unless you rescued him.

[sevenperforce]

15 minutes ago, wumpus said:

If this was KSP he could have just waited the 20 days to return to land (infinite air, water, and snacks).  Possibly in 5 days with physics time warp.

I've abused this plenty more times than getting out and pushing.

The thing I abuse more than anything is using warp to stop undesired rotation......

[tater]