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SpaceX discloses cause of Starship anomalies as it clears an FAA hurdle

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Re: SpaceX discloses cause of Starship anomalies as it clears an FAA hurdle

#61

Post by PH95VuimJjqBqy »

dotnet00 wrote: post #25
wiz21c wrote: post #24

Earlier quoted context omitted.

Why can't they just say "exploded" ?

Exploded is a loaded term that has been ruined by media to make it so that people interpret even development testing as a failure. RUD conveys the same idea of the vehicle losing structural integrity, serves as a bit of tongue-in-cheek humor for those who understand it, and limits the number of idiots screaming "look this project is obviously a scam" slightly.

in 10 years RUD will mean exploded, that's how language works.

retarded used to be a medical term to replace loaded terms such as imbecile. You can see how successful that was.

It turns out, dressing up an idea does absolutely nothing since it's the idea that has the negative connotation. And why shouldn't "exploded" be viewed in a negative light?

Re: SpaceX discloses cause of Starship anomalies as it clears an FAA hurdle

#62

Post by mrsilencedogood »

dotnet00 wrote: post #25
wiz21c wrote: post #24

Earlier quoted context omitted.

Why can't they just say "exploded" ?

Exploded is a loaded term that has been ruined by media to make it so that people interpret even development testing as a failure. RUD conveys the same idea of the vehicle losing structural integrity, serves as a bit of tongue-in-cheek humor for those who understand it, and limits the number of idiots screaming "look this project is obviously a scam" slightly.

Same energy as sqlite using etilqs as their file extension for no reason other than to mildly amuse onlookers who "know" and to deter the uninitiated from sending them unearned complaints.

Re: SpaceX discloses cause of Starship anomalies as it clears an FAA hurdle

#63

Post by justinclift »

Tuna-Fish wrote: post #11
Sebb767 wrote: post #9

Earlier quoted context omitted.

Why do those rockets have a fuel filter at all? I get why we have them in cars; we refuel quite often, in dirty environments and with possibly low quality fuel. For space rockets, it seems that it would be (comparatively) easy to ensure that the tanks are clean and the fuel is of high quality. On the other hand, if there wasn't any dirt, the filters would not have clogged, so I guess it does make sense after all.

Most rockets don't have fuel filters, but this requires their tanks to be kept in a much more strict state of cleanliness, and any failure to do so would result in mission failures. SpaceX has long had a very different idea about FOD than most other rocket companies, famously Merlin engine qualification testing contains ingesting stainless steel nuts.

Wonder how many of the nuts it took to fill up that filter? ;)

Re: SpaceX discloses cause of Starship anomalies as it clears an FAA hurdle

#64

Post by AlgorithmicTime »

Sanzig wrote: post #50
misiti3780 wrote: post #44

Earlier quoted context omitted.

Also, wont it theoretically speed up and decrease international shipping + travel. We should be able to go from the US to Japan in an hour or two in the future.

I am pretty skeptical of Starship ever getting used for suborbital transportation, other than maybe for ultra-elite VIP transport or something like a rapid deployment system for military special forces. It seems highly unlikely they will ever get the price down to where it can compete with commercial airliners, and Concorde's commercial failure showed us that people will happily choose cheap subsonic flight over fast…

Half the point of special forces is to be covert, which is made hard when your transportation is a giant rocket streaking through the suborbital zone.

Re: SpaceX discloses cause of Starship anomalies as it clears an FAA hurdle

#65

Post by ceejayoz »

elteto wrote: post #59
Tuna-Fish wrote: post #11

Earlier quoted context omitted.

Most rockets don't have fuel filters, but this requires their tanks to be kept in a much more strict state of cleanliness, and any failure to do so would result in mission failures. SpaceX has long had a very different idea about FOD than most other rocket companies, famously Merlin engine qualification testing contains ingesting stainless steel nuts.

I can guarantee you that “ingesting a nut” through the engine is not part of the official engine qual program. Maybe it happened once and somehow the engine survived and they were able to ascertain what had happened. But this is not a common thing. Edit: I will say that what actually is a test commonly done (also in industry in general) is doing a “roll test”. They put the stages on these massive rollers and slowly t…

https://www.smithsonianmag.com/air-space-magazine/is-spacex-...

> Part of the Merlin’s qualification testing involves feeding a stainless steel nut into the fuel and oxidizer lines while the engine is running—a test that would destroy most engines but leaves the Merlin running basically unhindered.

They're not running it through the engine, they're verifying that the filter is installed and functional so it doesn't get to the engine.

Re: SpaceX discloses cause of Starship anomalies as it clears an FAA hurdle

#68

Post by inglor_cz »

toss1 wrote: post #40
cduzz wrote: post #16

Earlier quoted context omitted.

That's bonkers. What size nuts do they pass through their engine? Every engine before it goes to space has to have a nut passed through the system? Like a 12mm "go into space" grade nut or a little itty bitty nut like I might find holding down a heat sink assembly in a 1998 vintage motherboard? I'm off to the googles to find videos...

Let us know what you find. I find it not 'bonkers' but a great idea, and hope they are qualifying with the largest nuts found upstream, in 'go to space' grades. Robustness and anti-fragility may not be so critical for an expendable vehicle that operates once for something like 12 minutes, but seems a key attribute for a refuel-able and reusable spacecraft?

"anti-fragility" is probably not a design goal for Merlins and Falcon.

Anti-fragility means more than robustness, it means that the system is getting stronger with each adverse event, and it is not a realistic goal that ingestion of a nut should make the engine better/stronger etc.

It is all "just" about robustness, resilience.

Re: SpaceX discloses cause of Starship anomalies as it clears an FAA hurdle

#69

Post by pantalaimon »

CarVac wrote: post #41
foobarian wrote: post #35

Earlier quoted context omitted.

In my mind a rocket engine would be much more tolerant of debris since you just pipe the fuel into a giant fireball (yes I can practically see the eyes rolling, sorry! :-). For ICEs I can understand clogging tiny injectors or carbs would be a problem, do rocket engines also have injectors or other narrow parts susceptible to clogs?

Yes, rocket engines have many small orifices to atomize and mix the propellant. It's like a showerhead, except if the fuel side clogs, the oxidizer might eat your chamber wall.

> if the fuel side clogs, the oxidizer might eat your chamber wall

Ah, good old 'engine rich combustion'

Re: SpaceX discloses cause of Starship anomalies as it clears an FAA hurdle

#70

Post by nordsieck »

Sebb767 wrote: post #9
tromp wrote: post #3

> "The most likely root cause for the booster RUD (rapid unscheduled disassembly) was determined to be filter blockage where liquid oxygen is supplied to the engines, leading to a loss of inlet pressure in engine oxidizer turbopumps that eventually resulted in one engine failing in a way that resulted in loss of the vehicle," the company stated. "SpaceX has since implemented hardware changes inside future booster oxi…

Why do those rockets have a fuel filter at all? I get why we have them in cars; we refuel quite often, in dirty environments and with possibly low quality fuel. For space rockets, it seems that it would be (comparatively) easy to ensure that the tanks are clean and the fuel is of high quality. On the other hand, if there wasn't any dirt, the filters would not have clogged, so I guess it does make sense after all.

> Why do those rockets have a fuel filter at all?

1. Launch vibration is real. There's a reason why the Merlin 1 engine has to survive a nut being fed into the fuel and oxidizer lines while running.[1]

2. My understanding with this particular issue is that SpaceX uses autogenous pressurization. It pressurizes the LOx tank with the output from the oxygen-rich preburner. Well, that output is mostly oxygen, but it contains various hydrocarbons. Which, when combined with pure oxygen can form ice and dry ice.

It's generally not good to feed solid CO2 and H2O into a high performance turbopump that's designed to accept liquid oxygen.

---

1. https://www.smithsonianmag.com/air-space-magazine/is-spacex-...

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