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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

#101

Post by foobarian »

s1artibartfast wrote: post #52
Ajedi32 wrote: post #43

Earlier quoted context omitted.

> do rocket engines also have injectors Yes[1]. You want the fuel and oxidizer mixed as well as possible to achieve efficient combustion. There are also other small channels fuel has to flow through, like the ones used for regenerative cooling[2]. And not sure how well most turbopumps[3] would tolerate debris either, though that probably depends on the exact design. There are some really simple rocket designs out the…

I posted upthread, but another concern is that stray particulate is an ignition source. Rocket fuel pumps are ~100,000 hp, and that energy is put into kinetic energy of the fluid flow. A stray particulate can cause the metal pump and fuel lines to burn in the presence of O2 at 300 atmospheres.

> Rocket fuel pumps are ~100,000 hp

That is wild. I need to learn more about rocket fuel pumps :-) Thank you all for these comments.

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

#102

Post by DarmokJalad1701 »

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.

> 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.

Things can freeze at cryogenic temperatures. Water ice, dry ice ... or other gases solidifying. There can also be FOD knocked loose by vibrations.

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

#103

Post by ianburrell »

bryanlarsen wrote: post #73
Casteil wrote: post #32

Earlier quoted context omitted.

Starlink V2 sats are bigger, so they definitely won't be sending 400+ up at a time with Starship - probably more like 100-200.. but I don't think they've had any official updates/figures on this in a while.

They just confirmed that 24 V2 minis are 17.5 tons. So ~200 v2 minis would be 150 tons. But v2's are probably bigger than v2 mini's...

The V2 are 1.25 ton according to Wikipedia. Which means 150 tons would be 100-120.

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

#104

Post by foobarian »

TeMPOraL wrote: post #99
robertoandred wrote: post #88

Earlier quoted context omitted.

Didn't SpaceX stop streaming their launches?

I wouldn't notice. I stop watching them, because they got boring . Let me say that again: space launches got boring . I hoped, but never believed, I'll live long enough to see this happen.

Not only that, but freaking first stage landings got routine. Not quite boring yet - I still tear up any time I see one :-)

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

#105

Post by toss1 »

inglor_cz wrote: post #68
toss1 wrote: post #40

Earlier quoted context omitted.

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.

Of course, not for individual rockets on individual flights (but self-repairing would be way cool!).

But Anti-Fragility as you define it definitely should be a goal for their overall organization and system of building and operating the fleet.

Each issue or incident should feedback into the engineering of new units and updating of existing units so that they are improved, stronger, less likely to create issues, more able to handle issues, etc. on each iteration. This actually seems to be the case at SpaceX, including this incident.

Or, am I missing something?

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

#106

Post by inglor_cz »

toss1 wrote: post #105
inglor_cz wrote: post #68

Earlier quoted context omitted.

"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.

Of course, not for individual rockets on individual flights (but self-repairing would be way cool!). But Anti-Fragility as you define it definitely should be a goal for their overall organization and system of building and operating the fleet. Each issue or incident should feedback into the engineering of new units and updating of existing units so that they are improved, stronger, less likely to create issues, more…

Oh yes, that is an excellent observation. The components themselves cannot be antifragile, but the development process certainly can.

Thinking about that, an important feature of that antifragility is not to risk human lives during the process if that risk can be avoided. Even though space exploration is inherently risky, any actual fatality is a huge setback.

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

#107

Post by dotnet00 »

lupusreal wrote: post #89
rbanffy wrote: post #60

Earlier quoted context omitted.

Add a couple hours for the trip between town and pad, security and so on. Still it's 3-4 hours.

I don't think there are many cities that have suitable launch sites near them. It's unlikely they'll ever get approval to launch over populated areas, or even from most populated coastal locations. Also, the issue of getting boosters to all of these destinations seems like a problem. Planes don't split in two and have half return to the launch site but Starships do. So you could land the upper stage in Tokyo, but the…

Yeah the short term approach for crewed Starship seems likely to involve transporting crew to a Starship once it is already in orbit and vice versa for return.

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

#108

Post by inglor_cz »

thegrim22 wrote: post #100
user_7832 wrote: post #86

Earlier quoted context omitted.

I think NASA also has higher public/pr standards they’re held to. A few spacex failures no one cares much about. If nasa fails a few times everyone (particularly more conservative leaning folk) starts complaining about their precious taxpayer money. Hence NASA likely sticks to project that are very low risk. I’m not saying this is good or bad per se, but public opinion is what it is. It’s also a bit of damned if you…

There's also a political angle since NASA represents the US. If anything goes wrong with a NASA project it's a massive propaganda opportunity for agitators and rival countries to mass spam the internet about how horrible America has become, what a laughing stock, etc., etc., doing everything they can to push their anti-US propaganda as hard as they can. There's more repercussions for NASA to fail at something than a…

This is an interesting angle that I haven't thought of.

NASA projects carry a lot more gravitas than "move fast and break things" Musk projects. If something explodes at SpaceX, as long as people aren't hurt, no one really cares. People who dislike Musk will simply point at the debris and say: "We told you he's an idiot" and people who like him will rush to his defense, but the standing of the US as a whole isn't on the line.

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

#109

Post by sebzim4500 »

lupusreal wrote: post #89
rbanffy wrote: post #60

Earlier quoted context omitted.

Add a couple hours for the trip between town and pad, security and so on. Still it's 3-4 hours.

I don't think there are many cities that have suitable launch sites near them. It's unlikely they'll ever get approval to launch over populated areas, or even from most populated coastal locations. Also, the issue of getting boosters to all of these destinations seems like a problem. Planes don't split in two and have half return to the launch site but Starships do. So you could land the upper stage in Tokyo, but the…

You'd probably have to launch from international waters, after taking a boat/helicopter.

>Also, the issue of getting boosters to all of these destinations seems like a problem

You launch them, presumably.

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

#110

Post by inglor_cz »

pantalaimon wrote: post #69
CarVac wrote: post #41

Earlier quoted context omitted.

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'

I still remember the exhaust plume of one of the experimental Starships turning green. "Whoa, it is eating itself!" And verily it was.
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