totm nov 2023 SpaceX Discussion Thread

[tater]

44 minutes ago, SunlitZelkova said:

What you said was basically Korolev’s justification for not doing static fires with the N1’s first stage.

OK, that explains it, was not at all clear to me.

45 minutes ago, SunlitZelkova said:

Extensive ground testing is part of why the Saturn V was so successful compared to N1.

Or simply better engineering. Still, like the CCCP, SpaceX has constraints the US Federal Government does not. NASA could simply take land for facilities. Concerns about turtles, etc? EPA regulations? EPA didn't exist until the end of 1970. Money? Musk can afford a lot, but the Apollo budget was huge, and the land issue I just mentioned literally cannot be bought at any price right now. Require eminent domain.

56 minutes ago, SunlitZelkova said:

For one thing, SpaceX is not in a race with anyone, and the US government has also claimed it is not racing anyone (well, China) back to the Moon. Or at least Bridenstine said that. But anyways, there is no imperative to meet a certain date like Apollo or N1 had to, and also importantly, SLS’ own long lead times give Starship plenty of time to mature before Artemis III comes around.

And finally, SpaceX as a whole is pretty onboard with Starship. There isn’t a confidence and funding crisis like Korolev and Mishin faced when the Soviet government began asking questions about the successive failures.

Yeah, the only person who will veto the design based on failures is Musk.

57 minutes ago, SunlitZelkova said:

Of course, that applies to Starship as an SHLV, not HLS. I’m not sure if NASA is concerned with the failures or not (probably no).

NASA is interested, but they are also in constant communication I imagine.

[Exoscientist]

16 hours ago, Cuky said:

I may be wrong but they aren't doing full flight full thrust static fires for Falcon 9 either.

 They might not now be doing full flight duration test firings after the Merlins have been fully qualified for flight, with literally thousands of successful operational firings in flight. But, they did do full thrust, full flight duration testing of the Merlins during its development:

Space Launch Report: SpaceX Falcon 9 Data Sheet.
SpaceX shipped its first Falcon 9 first stage to McGregor in mid-2007. The stage was erected into the company's mass Big Falcon Test Stand during August. During November, 2007 the first Falcon 9 hot fire test, using only one Merlin 1 engine, was performed. This was followed by a two engine test in January 2008 and a three-engine test in early March, Five engine testing occurred in late May, 2008. The first nine engine test was performed on June 31, 2008, in a test tha produced 385.5 tonnes of total thrust. Two more less-than-full-duration 9-engine tests followed. On November 23, 2008, SpaceX performed the first full-duration nine-engine Falcon 9 test at McGregor. Producing tonnes of total thrust while burning nearly 227 tonnes of propellant, the burn lasted 178 seconds. Two of the nine Mer engines shut down as planned after 160 seconds, a sequence that mimicked the planned flight shutdown method. The late-evening test startled Central Texas residents more than miles away.
…
Merlin Vacuum Certification
On March 7, 2009, SpaceX performed a full mission duration firing of the new Merlin Vacuum engine at McGregor. engine fired for six minutes, consumed 45.36 tonnes of propellant, and demonstrated a vacuum specific impulse of 34 seconds, highest ever for a U.S. hydrocarbon rocket engine. The engine produced 41.96 tonnes of thrust in vacuum conditions.
….
November, 2009.
The second stage was test fired in a second, smaller McGregor test stand for 40 seconds during November. On January 2010, the Falcon 9 second stage completed a full duration mission firing, its Merlin Vacuum engine producing 41.96 tonn thrust for 329 seconds. The stage was shipped to the Cape, where it arrived on January 29, 2010. There, it joined the fir stage in the new SpaceX SLC 40 horizontal integration hanger.
…
https://sma.nasa.gov/LaunchVehicle/assets/spacex-falcon-9-data-sheet.pdf

  Two interesting facts about this article. First, “full duration” is meant to be short for “full mission duration”, where the meaning is perfectly clear. Second, the last example specifically makes a distinction between a short mission firing and a “full duration” firing.

  Bob Clark

[Exoscientist]

16 hours ago, tater said:

Because that would be stupid.

<clarification> This would be stupid because they would need to build entirely different facilities, and the testing would involve different—and often worse—risks than flight testing. For all that cost/trouble, there are still test regimes that only actual flight can provide.

 

 

 For the rest of the industry that is just standard industry practice:

Rocket Factory Augsburg
@rfa_space
Jun 2
280 seconds of glorious hot fire! We are incredibly proud to be the 1st private company in #Europe () to hot fire a staged-combustion upper stage for its full duration. This qualifies our upper stage and Helix engine for flight Enjoy the video and read more in our press…
https://x.com/rfa_space/status/1664683388928655374

  Bob Clark

[Codraroll]

1 hour ago, Exoscientist said:

We are incredibly proud to be the 1st private company in #Europe () to hot fire a staged-combustion upper stage for its full duration.

Doesn't sound like "Standard industry practice" to me, if you find 1 (one) example of somebody doing it, and they are the first to do so.

[Deddly]

1 hour ago, Codraroll said:

Doesn't sound like "Standard industry practice" to me, if you find 1 (one) example of somebody doing it, and they are the first to do so.

To be fair, there aren't that many private rocket companies in Europe. 

[Elthy]

14 hours ago, tater said:

 

Those shockwaves on the 33 engine static fire are insane. Seeing that i cant imagine any structure to survive that up close, im even impressed with the drone not falling from the sky...

[tater]

5 hours ago, Exoscientist said:

 

 For the rest of the industry that is just standard industry practice:

Rocket Factory Augsburg
@rfa_space
Jun 2
280 seconds of glorious hot fire! We are incredibly proud to be the 1st private company in #Europe () to hot fire a staged-combustion upper stage for its full duration. This qualifies our upper stage and Helix engine for flight Enjoy the video and read more in our press…
https://x.com/rfa_space/status/1664683388928655374

That's a 2m diameter smallsat launcher.  Building a test stand for a single small engine is not that difficult.

[SunlitZelkova]

10 hours ago, tater said:

Or simply better engineering. Still, like the CCCP, SpaceX has constraints the US Federal Government does not. NASA could simply take land for facilities. Concerns about turtles, etc? EPA regulations? EPA didn't exist until the end of 1970. Money? Musk can afford a lot, but the Apollo budget was huge, and the land issue I just mentioned literally cannot be bought at any price right now. Require eminent domain.

I don’t think easy land grabs or even funding played a role in the fate of each rocket, at least as far as the performance record of the rocket itself goes.

The thing with the N1 wasn’t really its design per se, it was more so severe quality issues, which were endemic to the Soviet industry throughout the USSR’s existence. If the Americans tried to build the N1 and the Soviets the Saturn V, the Saturn V would have exploded dozens of times and the N1 would have flown flawlessly. That’s a dramatic statement, but what I’m trying to say is that a big part of it had to do with the inherent strengths and weaknesses of each country’s manufacturing sector. Heck, the Americans even could have done the artillery style of development and still probably had better success than the Soviets did.

Coming back to Starship, I’ll repeat what I said in the Artemis thread when Exoscientist was bringing up similar gripes. Starship is early in the testing phase. There is no reason to be crying about failures right now. Flight testing instead of ground testing is a valid method of development (not that Starship isn’t ground tested at all), for example the R-7 series was tested this way and it is literally the most reliable rocket in the world equally or at least on par with Falcon 9.

To the naysayers, I say: give it time. It’s been said the N1 might have succeeded on its fifth flight, as it was doing better and better and getting farther and farther each time. Starship will succeed one day too.

[tater]

And again, doesn't matter if you are testing a stage you plan on destroying anyway. No Starships are to be recovered for a while, 100% of them will end up in pieces in the ocean for the foreseeable future.

5 minutes ago, SunlitZelkova said:

I don’t think easy land grabs or even funding played a role in the fate of each rocket, at least as far as the performance record of the rocket itself goes.

Testing. Stennis was simply grabbed by the feds, I can't remember the size, but at least 50,000 acres. Starbase is a couple hundred acres all in. The pad area is ~20. KSC/Cape Canaveral is I think more like 150k acres—and blowing stuff up in the 60s was not an issue that would cause hang-wringing about wildlife habitat.

So say we demand a Stennis like stage test for SH. Can/would the Feds give SpaceX 50k acres around their current facility to test in safely?

5 minutes ago, SunlitZelkova said:

Coming back to Starship, I’ll repeat what I said in the Artemis thread when Exoscientist was bringing up similar gripes. Starship is early in the testing phase. There is no reason to be crying about failures right now. Flight testing instead of ground testing is a valid method of development (not that Starship isn’t ground tested at all), for example the R-7 series was tested this way and it is literally the most reliable rocket in the world equally or at least on par with Falcon 9.

Also, they can do computer simulations no one had in the 1960s.

Edited December 30, 2023 by tater

[SunlitZelkova]

8 minutes ago, tater said:

Testing. Stennis was simply grabbed by the feds, I can't remember the size, but at least 50,000 acres. Starbase is a couple hundred acres all in. The pad area is ~20.

Then we come back to the question of what the point of a full thrust ground static fire is if the stage is going to explode anyways, why not do it in the air.

In the 60s I think the Soviets could be criticized for not doing so because they needed it to work on the first try and perhaps the ability to monitor the characteristics of the flight of the rocket was limited, but with fancy 21st century computers and no deadline, it isn’t necessary.

@Exoscientist, I apologize for asking if you have already said it, but why do you believe a full thrust ground static fire is necessary for Starship? We have pointed out multiple times there is no major benefit to it compared to flight testing.

I ask because you seem to be repeating the same arguments over and over again without addressing our counter arguments.

Edited December 30, 2023 by SunlitZelkova

[RCgothic]

18 hours ago, StrandedonEarth said:

Looks more dirt color to me, but not huge clouds. Was BC experiencing a dry spell at the time? The exhaust blasting over the dirt of the surrounding areas could raise some dust…

The level of reddish colour is fairly constant for the steady state portion of the burn. If it were dirt you'd expect it to decreasing as the dirt was cleared.

Whereas if it were nitrogen dioxide production the colour would be fairly constant at constant throttle, which is what we see. 

I'm not 100% certain, but seems like a much better fit to the evidence to me.

Another source would be iron oxide from constant erosion of the steel, but the deluge is supposed to prevent that .

Edited December 30, 2023 by RCgothic

[Exoscientist]

17 hours ago, Codraroll said:

 It includes repeatedly comparing the Raptor to engines, components, or rockets that do not even exist.

…

  I don’t know what you are referring to. The SLS components have publicly available reliability estimates at 99.9%:

SLS-RPT-077
VERSION: 1
National Aeronautics and Space Administration
RELEASE DATE: MARCH 8, 2013
SPACE LAUNCH SYSTEM PROGRAM (SLSP)
RELIABILITY ALLOCATION REPORT

https://foia.msfc.nasa.gov/sites/foia.msfc.nasa.gov/files/FOIA%20Docs/42/SLS-RPT-077_SLSP-Reliability-Allocation-Report.pdf

 The Merlin engines can be estimated to have better than 99.9% reliability based on the number of successful firings, over 1,000, in actual operational flights. But SpaceX offers no estimates on the reliability of the Raptor. For an engine to be relied upon to power manned flights and for which SpaceX obtained a contract from a tax payer funded agency worth billions of dollars that should be a necessity.

 Based on the number of Raptor’s that leaked fuel and caught fire in the prior Starship tests of the landing procedures I estimated a probability of 1 in 3 that a Raptor would fail in flight, including actually exploding.

 SpaceX claimed the Raptor 2 to be used on the orbital test flight was a more reliable engine. The result? “Only” 1 in 4 of the Raptors on the booster failed in the first orbital test flight, including some exploding.

 On the second orbital test flight, the Raptors on the booster were able to successfully fire during ascent but there is strong evidence to suggest they were able to do this by throttling down their thrust level to less than 75%. And even then, some did still explode on restart as had been seen repeatedly  on the Starship landing tests.

  Bob Clark

Edited December 30, 2023 by Exoscientist

[tater]

13 minutes ago, Exoscientist said:

  I don’t know what you are referring to. The SLS components have publicly available reliability estimates at 99.9%:

What were the reliability/safety estimates for Shuttle after the first launch?

What was the actual safety risk over the entire program?

What was the retroactively established risk for the first however many launches?

I can answer the second 2. For the whole program it was 2 LOC/LOV/LOM in 135 flights, or a 1:67 chance of catastrophic failure.

For the last one, I have read that retroactively the chance for catastrophe was ~1:9 I think for the first ~20 flights.

 

The plan B lunar lander (I think what the post you replied to was referring to) is the BO lander. Launched by a rocket that doesn't exist, booster powered by an engine that has never flown (that to change Jan 8), and utilizing upper stage engines and landing engines that have never flown, built a company that has never even reached orbit or built a real spacecraft.

Boeing built Starliner by testing all the parts, etc, the old test everything individually so it's dead on perfect the first time, right?

How's that worked out for them?

Edited December 30, 2023 by tater

[CatastrophicFailure]

20 hours ago, Ultimate Steve said:

[another mind-blowing dissertation of rationality]

PLEASE send me a postcard when you get to Mars. 

[tater]

 

 

 

[magnemoe]

12 hours ago, Exoscientist said:

 They might not now be doing full flight duration test firings after the Merlins have been fully qualified for flight, with literally thousands of successful operational firings in flight. But, they did do full thrust, full flight duration testing of the Merlins during its development:

Space Launch Report: SpaceX Falcon 9 Data Sheet.
SpaceX shipped its first Falcon 9 first stage to McGregor in mid-2007. The stage was erected into the company's mass Big Falcon Test Stand during August. During November, 2007 the first Falcon 9 hot fire test, using only one Merlin 1 engine, was performed. This was followed by a two engine test in January 2008 and a three-engine test in early March, Five engine testing occurred in late May, 2008. The first nine engine test was performed on June 31, 2008, in a test tha produced 385.5 tonnes of total thrust. Two more less-than-full-duration 9-engine tests followed. On November 23, 2008, SpaceX performed the first full-duration nine-engine Falcon 9 test at McGregor. Producing tonnes of total thrust while burning nearly 227 tonnes of propellant, the burn lasted 178 seconds. Two of the nine Mer engines shut down as planned after 160 seconds, a sequence that mimicked the planned flight shutdown method. The late-evening test startled Central Texas residents more than miles away.
…
Merlin Vacuum Certification
On March 7, 2009, SpaceX performed a full mission duration firing of the new Merlin Vacuum engine at McGregor. engine fired for six minutes, consumed 45.36 tonnes of propellant, and demonstrated a vacuum specific impulse of 34 seconds, highest ever for a U.S. hydrocarbon rocket engine. The engine produced 41.96 tonnes of thrust in vacuum conditions.
….
November, 2009.
The second stage was test fired in a second, smaller McGregor test stand for 40 seconds during November. On January 2010, the Falcon 9 second stage completed a full duration mission firing, its Merlin Vacuum engine producing 41.96 tonn thrust for 329 seconds. The stage was shipped to the Cape, where it arrived on January 29, 2010. There, it joined the fir stage in the new SpaceX SLC 40 horizontal integration hanger.
…
https://sma.nasa.gov/LaunchVehicle/assets/spacex-falcon-9-data-sheet.pdf

  Two interesting facts about this article. First, “full duration” is meant to be short for “full mission duration”, where the meaning is perfectly clear. Second, the last example specifically makes a distinction between a short mission firing and a “full duration” firing.

  Bob Clark

Yes but it was an couple of full duration first stage tests. Rest was shorter burns, or singe engine ones and single engine long burn is standard for SpaceX. 

The issue here is that superheavy is significantly larger than falcon 9. Its larger than the Saturn 5 none can be transported by standard roads so you would need to build this static fire stand at the launch site and it has to be significantly more beefy than the standard launch pad and just the deluge water used would be an problem.
And its pretty pointless as both the two tests shows the rocket being able to clear the pad. 
I rather want an second pad if first is taken out. 

[tater]

 

[kerbiloid]

On 12/29/2023 at 10:44 PM, tater said:

Not sure why irrelevant dead guy matters.

Lack of testing, lot of bursting was his practical motto.

[tater]

9 minutes ago, kerbiloid said:

Lack of testing, lot of bursting was his practical motto.

Flying is testing if you do it right.

[Exoscientist]

21 hours ago, Codraroll said:

Doesn't sound like "Standard industry practice" to me, if you find 1 (one) example of somebody doing it, and they are the first to do so.

 

 What I mean to say is it is standard industry practice to do full thrust, full up(all engines), full flight duration(full length of an actual mission) static firings to flight qualify a rocket stage:

 

 SpaceX using the term “full duration” for their 5 second burns misleadingly gives the impression these 5 second burns are sufficient to qualify their stages for flight. The fact their stages keep exploding in flight is clear evidence they are not.

 Bob Clark

[Exoscientist]

17 hours ago, SunlitZelkova said:

..

@Exoscientist, I apologize for asking if you have already said it, but why do you believe a full thrust ground static fire is necessary for Starship? We have pointed out multiple times there is no major benefit to it compared to flight testing.

I ask because you seem to be repeating the same arguments over and over again without addressing our counter arguments.

 

 The fact the SH/SS keeps exploding in flight is evidence the SpaceX little 5 second burns are insufficient to qualify the Raptor for flight. Everyone acknowledges the engines on the N-1 were insufficiently tested. The elephant in the room everyone is ignoring is the same is true of the Raptor.

https://twitter.com/RGregoryClark/status/1700872620604891324/photo/

  Bob Clark

[Deddly]

We can have a serious discussion without it getting heated or personal. I have removed some content from the thread that crossed the line there. 

As a suggestion to everyone involved, if we want people to come over to our way of thinking, we really need to acknowledge the other person's arguments as well. 

Back on topic. 

@Exoscientist, I think I understand your concerns, and the description of "full duration" for those short yet awesome tests is a bit confusing. Having said that, I am a bit confused by your arguments as well. My question is: what difference does it make to test an engine on the ground vs testing it in the air? These are not missions, these are test flights. So what difference does it make? 

[Codraroll]

4 hours ago, Exoscientist said:

 The fact the SH/SS keeps exploding in flight is evidence the SpaceX little 5 second burns are insufficient to qualify the Raptor for flight.

No, it is evidence that the new flight termination system works. The explosions had absolutely nothing to do with the engines, as has been pointed out repeatedly.

[Exoscientist]

2 hours ago, Deddly said:

We can have a serious discussion without it getting heated or personal. I have removed some content from the thread that crossed the line there. 

As a suggestion to everyone involved, if we want people to come over to our way of thinking, we really need to acknowledge the other person's arguments as well. 

Back on topic. 

@Exoscientist, I think I understand your concerns, and the description of "full duration" for those short yet awesome tests is a bit confusing. Having said that, I am a bit confused by your arguments as well. My question is: what difference does it make to test an engine on the ground vs testing it in the air? These are not missions, these are test flights. So what difference does it make? 

The Saturn V development program resulted in spectacular successes. The Soviet N-1 program resulted in spectacular failures.

  Robert Clark

[Ultimate Steve]

It has had two flights. It is not unheard of for new rockets to fail a couple times and then go on to have successful careers, much less possibly the most ambitious rocket in history which was deliberately developed in a way in which more failures than average are expected.

Now, if it still hasn't made orbit by flight 5 or 6, then that is cause for alarm. Even for normal rockets I wouldn't really start worrying until the third failure, although 2 would raise a few eyebrows.