totm nov 2023 SpaceX Discussion Thread

[sevenperforce]

2 hours ago, Exoscientist said:

3 hours ago, Kartoffelkuchen said:

Not again.

If your cars fuel pump breaks down and the engine stops working, would you say that the engine is unreliable?

I understand the point you’re making but perhaps it’s not the best example to give in regards to a rocket engine. For rocket engines the turbo pumps are part of the engine.

If you understand the point being made, take the point being made instead of taking some other point that isn't being made.

Suppose a truck manufacturer builds a semi-truck, and early tests of the semi by the manufacturer show that the rear wheel assemblies have a tendency to seize up, stop spinning, and frag the axles at highway speed. The truck manufacturer promptly redesigns the wheel assemblies, and they no longer exhibit this problem. Much later, in acceptance testing, the truck manufacturer learns that the transmission is not downshifting properly and is transmitting ten times too much torque to the axles, which causes the axles to fail.

It would be very silly to suggest that this transmission failure in acceptance testing is the same wheel assembly failure exhibited in early testing, simply because both involve the axles.

[RCgothic]

There isn't any evidence the engines were the source of the issues on IFT-2, and even with the previous version of engines some of the failures on SN8 to 11 were not engine related. SN8 had a sudden loss of pressure in the methane header tank and SN10 had helium ingestion.

[tater]

SpaceX is targeting Thursday, December 14 for a Falcon 9 launch of 21 Starlink satellites to low-Earth orbit from Space Launch Complex 4 East (SLC-4E) at Vandenberg Space Force Base in California. Liftoff is targeted for 9:04 p.m. PT

[darthgently]

30 minutes ago, tater said:

SpaceX is targeting Thursday, December 14 for a Falcon 9 launch of 21 Starlink satellites to low-Earth orbit from Space Launch Complex 4 East (SLC-4E) at Vandenberg Space Force Base in California. Liftoff is targeted for 9:04 p.m. PT

I doubt I'll see anything from Reno, NV unless it strangely launches north-northeast, but I'll look that direction as a symbolic act

[AckSed]

Hey, a sparkly new first stage!

[sevenperforce]

3 hours ago, RCgothic said:

SN8 had a sudden loss of pressure in the methane header tank

IIRC that was basically the same failure mechanism as (presumptively) IFT-2 experienced: slosh in the tanks during a rapid flip that dumped vapor into the turbopumps.

[tater]

Going later in the window:

Liftoff is targeted for 12:30 a.m. PT, with backup opportunities available until 12:37 a.m.

[Exoscientist]

7 hours ago, RCgothic said:

There isn't any evidence the engines were the source of the issues on IFT-2, and even with the previous version of engines some of the failures on SN8 to 11 were not engine related. SN8 had a sudden loss of pressure in the methane header tank and SN10 had helium ingestion.

In this slowed down clip by Zack Golden you can see objects spewing out of the engine section. Judging by the 9 meter diameter  of the booster, I would say these objects are 2 to 3 meters long,  6 to 10 feet. That almost certainly means it was an engine explosion: 

https://twitter.com/CSI_Starbase/status/1734783989871763768

  Robert Clark

Edited December 15, 2023 by Exoscientist

[Kartoffelkuchen]

2 hours ago, Exoscientist said:

In this slowed down clip by Zack Golden you can see objects spewing out of the engine section. Judging by the 9 meter diameter  of the booster, I would say these objects are 2 to 3 meters long,  6 to 10 feet. That almost certainly means it was an engine explosion: 

https://twitter.com/CSI_Starbase/status/1734783989871763768

  Robert Clark

You are absolutely right, it almost certainly is an engine explosion we see here.

The question we've been discussing all this time is why it did happen, and the #1 source is likely not that it happened because of faulty engines, but because the engines didn't receive any more fuel. 

See when that turbopump, spinning at dozens of thousands of RPM, is not filled by fuel any more which protects it from runaway, it will spin up even faster and  disintegrate, making the engine fail.

SN8 and SN10 as mentioned above had a similar failure cascade: no fuel /  bubbles in fuel, leading to the engine failure. 

[tater]

Extra stage 0 parts heading from KSC to Starbase

 

[tater]

https://myrgv.com/local-news/2023/12/12/starbase-general-manager-discusses-future-plans-at-invite-only-brownsville-event/

Quote

Following her presentation, Lueders told The Brownsville Herald that the next Starship launch ideally will take place early in 2024.

“We would have love to have multiple flights next year,” she said. “It would be great if we were in the first quarter, definitely. Elon obviously would probably say the end of December, but I don’t think we’ll get there.”

 

[darthgently]

9 hours ago, Kartoffelkuchen said:

See when that turbopump, spinning at dozens of thousands of RPM, is not filled by fuel any more which protects it from runaway, it will spin up even faster and  disintegrate, making the engine fail.

Not to mention the lack of cooling when the pumps suck nothing

[kerbiloid]

A twin bathtub with 30 60 whirlpools in 30 60 sinkholes.

30 heaters packed in 9 m, when even N-1 had 30 packed into 16 m, and twice lighter than SH Saturn V had 10 m for twice lower heat power.

What could go wrong?

Edited December 15, 2023 by kerbiloid

[Nuke]

we need bigger raptors, t-rex scale at least. then we have fewer points of failure.

[Kartoffelkuchen]

1 hour ago, Nuke said:

we need bigger raptors, t-rex scale at least. then we have fewer points of failure.

We might need to go even bigger to make Starship truly reliable...

Kerbal OG's might remember 

[tater]

As someone who adds googly eyes to things, I approve.

[RUD Everyday]

That is crazy they should do that on IFT-3 that would be hilarious  

[darthgently]

2 hours ago, tater said:

As someone who adds googly eyes to things, I approve.

1m+ dia googly eyes would be optimal.  On Starship 28, maybe the full Monty:

 

Edited December 16, 2023 by darthgently

[StrandedonEarth]

1 minute ago, darthgently said:

1m+ dia googly eyes would be optimal.  On Starship 28, maybe the full Monty:

 

Once they have the Chomper payload bay door operational, that would be ideal, yes

[darthgently]

Success or excitement guaranteed?

Edited December 18, 2023 by darthgently

[SunlitZelkova]

3 hours ago, darthgently said:

Success or excitement guaranteed?

TBH Falcon 1's test flights were the N1's test flights... And as I write this I remember Falcon 1 was successful on its fourth flight, not the fifth, so the comparison I was thinking of doesn't work as well. But given enough time, I think any launch vehicle can become reliable and useful. If you look at Proton's flight record you would wonder why it wasn't cancelled like the N1.

Musk is really lucky to have so many believers though. If not, Starship, if having continued flight test failures long enough, could have fallen victim to internal power politics in the same N1 was (N1 got cancelled more for the reason that Valentin Glushko wanted to erase Korolev and Mishin's legacy and take over the space program, rather than purely for technical reasons, not simply because the Soviets lost the Moon as is often believed).

I think Starship also benefits heavily from not having much of a competitor. If BO had actually been able to deliver on their original HLS proposal instead of asking for more and more government money when there was none, and Starship continued to have flight failures, the NT HLS launching on proven flight vehicles might look like a better option than the exploding Starship as far as getting back to the Moon fast goes.

Oh, and as I write this I realize that's another bad, bad possibility- that even if Starship has one successful flight eventually, it becomes like early Proton and repeatedly has spectacular failures despite also having successes. That could lead to fewer launch opportunities and bad PR. I'd hate to see Starship have all this potential to lower costs of launching stuff to space, but get relegated to only 3-4 launches per year instead of replacing F9 and launching at the same rate.

Although that brings up the question of whether it even makes sense to try and replace F9 at all. But I don't think the ability to cheaply produce satellites, due to not having to use fancy purpose built electronics and what not, is a topic brought up enough. I hope telecom companies and the military are thinking about this, even if it is just "Plan B" and theoretical work.

But then again, would off the shelf components and low grade stuff make sense when you need dependable comms or recon assets? To what extent are satellites highly engineered because they need to be made small for LVs, and to what extent are they highly engineered in order to survive the rigors of space?

[Elthy]

1 hour ago, SunlitZelkova said:

Musk is really lucky to have so many believers though. If not, Starship, if having continued flight test failures long enough, could have fallen victim to internal power politics in the same N1 was

From what i remember Musk has full decivice rights regarding SpaceX, noone would be able to stop Starship without convinging him to do that (or him running out of money).

[kerbiloid]

On 12/15/2023 at 1:54 AM, RCgothic said:

There isn't any evidence the engines were the source of the issues on IFT-2

Except the radial torch.

[Exoscientist]

Two separate, independent methods suggest SpaceX throttled down the booster engines < 75%, while the Starship engines fired at ~90% thrust:

Did SpaceX throttle down the booster engines on the IFT-2 test launch to prevent engine failures?
http://exoscientist.blogspot.com/2023/12/did-spacex-throttle-down-booster.html

 This is important to know because if the engines need to operate at < 75% to be reliable, then I estimate the reusable payload would be lowered from 150 tons to ~100 tons. Then instead of needing perhaps 16 refueling flights for the Artemis landing missions there would need to be perhaps 24.

  Robert Clark

[NFUN]

Oh my god