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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

#51

Post by infogulch »

cduzz wrote: post #49
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?

Oh I agree it's not bonkers from the perspective of "wait you want to put people on that bomb and then explode it?" You can make all sorts of rules about what's not allowed to happen, but often those things happen. I'm just ... astonished if they've got a little practice room somewhere in their factory where they give each of their new rockets a nut to process... "Okay kid here's your graduation test!". A "we need sc…

Rockets: "Hey what if we strap people to a giant bomb and explode it juuust slowly enough that they're launched into space alive?"

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

#52

Post by s1artibartfast »

Ajedi32 wrote: post #43
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?

> 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.

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

#53

Post by deprecative »

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…

Watch Elon call it something like Airship and have it be fit for tens to hundreds of people per launch with no need for a pilot (though one may be present). It'd take twenty years to get to market, sure, but hey that's progress.

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

#54

Post by ortusdux »

rob74 wrote: post #46
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...

Actually I'd rather have such "bonkers" tests than the other extreme, like NASA not thinking about what could happen if pieces of foam from the external fuel tank impacted the Space Shuttle on launch until it was too late ( https://en.wikipedia.org/wiki/Space_Shuttle_Columbia_disaste... ).

Or not thinking that an O-ring might experience temperatures below freezing in Florida https://priceonomics.com/the-space-shuttle-challenger-explos...

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

#55

Post by mbostleman »

cubefox wrote: post #13

It's funny that SpaceX is using the term "rapid unscheduled disassembly" unironically, despite it originally being a humourous euphemism.

What about the term “Cato”, is that still used? I think its meaning is limited to take off.

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

#56

Post by njarboe »

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…

I think there is a pretty large market for a trip to space and an hour flight from LA to New Zealand, New York-Sydney, London-Shanghai, etc. for $10-20k. What an amazing combination that would be.

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

#57

Post by foxyv »

guhidalg wrote: post #10
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.

Don’t forget about all the equipment needed to fill the tanks and transport the fuel to the tanks. Probably easier to assume contamination gets introduced somewhere and just slap an in-line filter.

Imagine if the engine failed from FOD. The reaction would be "Why don't they use filters on their fuel pumps?" Whenever you make an engineering decision there are trade offs like this.

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

#58

Post by [deleted] »

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.

[deleted]

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

#59

Post by elteto »

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.

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 turn them… listening for any “clinks”. Pretty funny seeing it done.

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

#60

Post by rbanffy »

njarboe wrote: post #56
Sanzig wrote: post #50

Earlier quoted context omitted.

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…

I think there is a pretty large market for a trip to space and an hour flight from LA to New Zealand, New York-Sydney, London-Shanghai, etc. for $10-20k. What an amazing combination that would be.

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