totm nov 2023 SpaceX Discussion Thread

[JoeSchmuckatelli]

13 hours ago, darthgently said:

What is "kraken-banned"?  Are you having site glitch issues?

Science & Spaceflight (sub) gives me 'Error 500' on every device and every browser whenever I'm signed in.  I can backdoor my way into specific threads where someone has quoted me or liked content - but I have zero access to the main sub.   (Signed out I can see everything) 

Likely has to do with permissions.  

Stranded and Magnemoe have similar problems 

[CatastrophicFailure]

 

 

 

[Spaceception]

And it was probably on the books for a 20th. So disappointing. I hope they can recover enough pieces to preserve it.

[kspbutitscursed]

RIP 1058

[Minmus Taster]

12 hours ago, Spaceception said:

And it was probably on the books for a 20th. So disappointing. I hope they can recover enough pieces to preserve it.

[CatastrophicFailure]

 

 

 

[Deddly]

 

[RCgothic]

1058 was the NASA worm marked booster. A sad loss. 19 flights was a great run.

Still, there are three more boosters already on 17 flights, and a further 5 with more than ten.

[Flavio hc16]

Spacex VP of Launch Kiko Dontchev

Kiko’s full tweet (note OG = Octagrabber):

 

"Super disappointing and sad to lose booster 1058. 

Tippy boosters occur when you get a certain set of landing conditions that lead to the legs having uneven loading. Heavy wind or sea state then cause the booster to teeter and slide which can lead to even worse leg loading. In this state, securing with the OG is super challenging and often only partial successful 

We came up with self leveling legs that immediately equalize leg loads on landing after experiencing a severe tippy booster two years ago on Christmas (first felight of 1069). The fleet is mostly outfitted, but 1058, given its age, was not. It met its fate when it hit intense wind and waves resulting in failure of a partially secured OG less than 100 miles from home. 

One thing is for sure… we will make lemonade out of lemons and learn as much as possible from historic 1058 on our path to aircraft like operations."

https://x.com/turkeybeaver/status/1739640175183945860?s=46&t=u9hd-jMa-pv47GCVD-xH-g

[Minmus Taster]

16 hours ago, CatastrophicFailure said:

 

 

 

[magnemoe]

On 12/25/2023 at 8:29 PM, Vanamonde said:

There's this really weird thing where a couple of people are having trouble accessing this subforum, but only a couple of people, only this sub, and only sometimes. It's really baffling and unfortunately the IT guys haven't found a fix yet. 

Think its depend on computer and browser, at work chrome has this issue. Works with edge, on computer at home and phone. 

[Exoscientist]

I’ve heard from someone who lives near the Starbase site that’s he’s heard scuttlebutt that SpaceX won’t be testing the Raptor at full thrust anymore. Anyone else hear that?

  Robert Clark

[tater]

54 minutes ago, Exoscientist said:

I’ve heard from someone who lives near the Starbase site that’s he’s heard scuttlebutt that SpaceX won’t be testing the Raptor at full thrust anymore. Anyone else hear that?

Nope. Where? They have test stands at McGreggor for Raptor testing, which will certainly include full thrust (they test to failure sometimes).  The Starship testing is always gonna be trouble since it’s not on a proper pad, and static fires replicate little about actual staging. Pressures are wrong, g is wrong, FOD is nonzero vs zero in flight, etc.

[Exoscientist]

57 minutes ago, tater said:

Nope. Where? They have test stands at McGreggor for Raptor testing, which will certainly include full thrust (they test to failure sometimes).  The Starship testing is always gonna be trouble since it’s not on a proper pad, and static fires replicate little about actual staging. Pressures are wrong, g is wrong, FOD is nonzero vs zero in flight, etc.

 Testing to failure might include testing at full power.

   Bob Clark

[tater]

15 minutes ago, Exoscientist said:

 Testing to failure might include testing at full power.

Yes. Or even beyond 100%.

The question was where would they stop testing at full power? At Starbase? Possibly, they only need to know the engines are starting up and reaching steady state nominally once installed on a vehicle. I find it hard to believe they would not test at full power at McGreggor, as they are always iterating, and any changes require testing.

So it's possible that they don't do 100% testing for multiple engine tests (particularly for Starship given the low test stand).

[kerbiloid]

38 minutes ago, tater said:

So it's possible that they don't do 100% testing for multiple engine tests

Lovely N1 style.

[tater]

27 minutes ago, kerbiloid said:

Lovely N1 style.

Launching is the ideal test, they have the hardware.

Did N1 do reduced thrust static fires? I don't think so.

IFT-2 worked perfectly on the booster, boostback issues likely sorted out, or at least understood. Unsure about Starship, but the only realistic tests are in vacuum.

 

[kerbiloid]

7 hours ago, tater said:

Launching is the ideal test, they have the hardware.

Of course, it's much better to catch the telemetry remotely, than to have an full-equipped stand with much better covering of physical parameters.

I just don't understand, why do they do the burn test of the engines, as 

7 hours ago, tater said:

Launching is the ideal test, they have the hardware.

[tater]

9 minutes ago, kerbiloid said:

Of course, it's much better to catch the telemetry remotely, than to have an full-equipped stand with much better covering of physical parameters.

Because then they have to build a special test stand, while incurring 100% of the regulatory and safety issues of a launch. It's needless, and costly.

 

[kerbiloid]

37 minutes ago, tater said:

Because then they have to build a special test stand, while incurring 100% of the regulatory and safety issues of a launch. It's needless, and costly.

 

Yes, the N-1 lacked the stand for same ideas.

Money and bureaucracy.

P.S.
They have allowed him several rockets launchpads in several years.

I can hardly believe that SpX lack the stand for something but saving money.

Edited December 28, 2023 by kerbiloid

[tater]

WRT the booster, they would have learned nothing WRT IFT-2. The booster worked fine until the flip. That is not something a test stand catches, so it looks fine. So a test stand still results in SH blowing up on IFT-2.

Starship? Came within seconds of SECO.  Would a full-duration burn at sea level have given the information required? Maybe. Would said information be that the stage blows up on the ground? Maybe. Which blown up booster creates more schedule risk, one with no mess, or one scattering debris around the (possibly destroyed) test stand?

58 minutes ago, kerbiloid said:

I can hardly believe that SpX lack the stand for something but saving money.

Regulation. Where would they build it? Next to the launch pad? Now a full duration test (much greater chance of failure) can blow up the stand and the pad? They only have what, 20 acres for the launch pad area? Not a lot of room to play with. The longer duration fires also mean the environmental mitigation has to be done for minutes of burns every test, not seconds. Assuming at some level failure is a function of duration (% chance of failure each time interval), longer tests means a great chance of failure—loaded with props, on the ground in this case.

All the red tape they already have would be multiplied—and for nothing. Booster failure was after sep (100% of all other boosters ever made fail every time after sep), not in a regime static testing can mimic.

Stage 2 failure similarly in a non-static fire regime—vacuum.

Edited December 28, 2023 by tater

[RCgothic]

Ah, but what if they built a test stand that could accurately represent dynamic flight conditions /s

[kerbiloid]

7 hours ago, tater said:

Now a full duration test (much greater chance of failure) can blow up the stand and the pad?

The stand is fueled via pipes. The rocket carries many tons of fuel in a tank.
There is nothing to explode in the stand, except the small amount of propellant in the engine pipes.

7 hours ago, tater said:

Where would they build it? Next to the launch pad?

Yes.

7 hours ago, tater said:

They only have what, 20 acres for the launch pad area?

They need 10x10 m to put it vertically. Either up (what an amusing show!), or down (the ugly tower is almost as high, as they need for torches).

7 hours ago, tater said:

The longer duration fires also mean the environmental mitigation has to be done for minutes of burns every test, not seconds.

Did I miss something, or methalox is the most ecofuel?
The ultratoxic shuttle SRB was producing by orders of magnitude more poisons right at ground.

5 hours ago, RCgothic said:

Ah, but what if they built a test stand that could accurately represent dynamic flight conditions /s

Before worrying about the flight conditions, it's good to ensure that it isn't blowing up itself.

[tater]

13 minutes ago, kerbiloid said:

The stand is fueled via pipes. The rocket carries many tons of fuel in a tank.
There is nothing to explode in the stand, except the small amount of propellant in the engine pipes.

Then it's not actually testing the booster. Test like you fly.

13 minutes ago, kerbiloid said:

Did I miss something, or methalox is the most ecofuel?

Tell that to the different regulatory agencies that were concerned about the WATER they were spraying.

13 minutes ago, kerbiloid said:

Before worrying about the flight conditions, it's good to ensure that it isn't blowing up itself.

If the props were piped in from elsewhere, it's not testing the vehicle, just engines next to each other—which they already know work for a full duration burn—see IFT-2.

The booster needs no test at this point, first test had multiple failures a test fire could have seen, second test had none.

 

Edited December 28, 2023 by tater

[tater]

It's important to realize that the regulatory environment in the 1960s was substantially looser than now, and Apollo had the power of the Federal government behind it. They acquired land for a few facilities via eminent domain, for example. Areas of land orders of magnitude larger than the entire Boca Chica facility. Many tens of thousands of acres—some inhabited—grabbed up by the Feds. SpaceX cannot do this, any facilities have to be purchased, and are under strict control.

Also: