Author Topic: SpaceX Starship : Texas Prototype(s) Thread 23 : Discussion  (Read 1039997 times)

Offline OTV Booster

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Re: SpaceX Starship : Texas Prototype(s) Thread 23 : Discussion
« Reply #2280 on: 08/07/2022 01:54 pm »
Re: hydraulic failure. In my experience there are three points where a failure can be expected:
- an old system
- a brand new system
- somebody's been messing with it.


It's brand new. A few uses doesn't change this. Knowing SX they may have been messing with it too. Routine sh*t. Don't panic.
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Offline daavery

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Re: SpaceX Starship : Texas Prototype(s) Thread 23 : Discussion
« Reply #2281 on: 08/07/2022 03:04 pm »
From the sound and lack of action, i'd say the hydraulics might be fine, but the rig bound up. Without safeties, that'll blow a line won't it?

No.

I suppose some very tiny hydraulic systems (like a car jack or outboard engine lift/trim) might not be either open loop or have a return but every even slightly complex motorized one has a bypass valve so that if no fluid is flowing through the system it can flow back to the tank.  That's how the pump can be running without anything moving.

actually large  hydraulic systems usually only have a safety overpressure bypass. the systems use variable flow pumps that  modulate to zero flow when the system set pressure is reached. bypass is very rough on the oil as the abrupt pressure drop vaporizes the oil and starts the varnish cycle

Offline Barley

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Re: SpaceX Starship : Texas Prototype(s) Thread 23 : Discussion
« Reply #2282 on: 08/07/2022 03:57 pm »

Does anyone know if the chopsticks have a fully redundant hydraulic drive system?
Each chopstick arm is slewed with a single double acting hydraulic cylinder so there is no redundancy there.  Same for the arms that swing down to clamp the booster.
In my experience hydraulic cylinders rarely fail, but when they do they fail in ways that mechanically interfere with movement so a duplicate cylinder would rarely help.

Cylinders are large lumps of steel that are fairly well understood and can be built with large safety factors.  All the other parts such as valves, hoses, O-rings, pumps and controllers could still be redundant.  (Although on a prototype they may not be, yet.)


Compare this to rocket design where pressure vessels (such as fuel tanks) are not required to be redundant but simply have a safety factor.

Offline Tangilinear Interjar

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Re: SpaceX Starship : Texas Prototype(s) Thread 23 : Discussion
« Reply #2283 on: 08/07/2022 04:25 pm »
Re: hydraulic failure. In my experience there are three points where a failure can be expected:
- an old system
- a brand new system
- somebody's been messing with it.


It's brand new. A few uses doesn't change this. Knowing SX they may have been messing with it too. Routine sh*t. Don't panic.

Somebody's been messing with it = the system has been modified

The whole system is still new, major components of the system have recently been changed, an entirely new hydraulic system has been added (not sure if it is interconnected or not). I personally EXPECT there to be issues.

I think the main mistake that SpaceX made was not spending more time exercising/dry running the system. We should have seen the system go through multiple cycles of operation.

Hydraulic system failures happen, pretty often, so much so that there's companies that will have a custom built hose built to the exact spec's of the one you need in the time it takes to drive to the shop.

As for the mess, it can be pretty bad but that's life. We had a big crane just beginning to lift an 80' concrete beam when it's main line blew and covered a dozen guys and a number of cars and trucks with a few hundred gallons of HOT fluid. Luckily no one was burned. Helluva cleanup tho.

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Re: SpaceX Starship : Texas Prototype(s) Thread 23 : Discussion
« Reply #2284 on: 08/07/2022 04:52 pm »
Going back to the chopsticks discussion, back in the day some dockyard cranes (such as the old Queenís Dock on the River Clyde in Glasgow) used water as their hydraulic fluid, with a central pumping house supplying pressure to rows of them. I wonder if water would be a good idea here?
I'd guess you'd require a glycol-water mixture to prevent freezing. Still, it might make a leak of your hydraulic fluid somewhat less messy?

A better positioned shut-off valve in case of pressure loss might also be a good idea, as well as a double (triple?) redundant system for critical chopstick ops?

Iím not sure you want to glycol spilling into protected wetlands any more than you would any kind of standard hydraulic fluid - it still has to be contained and cleaned up.

But in any case, the better solution is obviously to examine what component(s) failed, figure out why, and then design work-arounds: more or differently-configured hydraulic check-valves, redundant pumps/reservoirs, higher-rated hoses and fittings, etc. This, at least, is not rocket science.

Propylene glycol would be far less damaging than the current fluid, and it has the added advantage of being non-flammable. Iím guessing the concentration required would be quite low too, given the climate there. Iíve no idea about the suitability of it in a hydraulic system, but itís remarkably benign to the environment. Itís in many flavored drinks.

Offline rsnellenberger

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Re: SpaceX Starship : Texas Prototype(s) Thread 23 : Discussion
« Reply #2285 on: 08/07/2022 06:46 pm »

Iím not sure you want to glycol spilling into protected wetlands any more than you would any kind of standard hydraulic fluid - it still has to be contained and cleaned up.

But in any case, the better solution is obviously to examine what component(s) failed, figure out why, and then design work-arounds: more or differently-configured hydraulic check-valves, redundant pumps/reservoirs, higher-rated hoses and fittings, etc. This, at least, is not rocket science.

Propylene glycol would be far less damaging than the current fluid, and it has the added advantage of being non-flammable. Iím guessing the concentration required would be quite low too, given the climate there. Iíve no idea about the suitability of it in a hydraulic system, but itís remarkably benign to the environment. Itís in many flavored drinks.
Wikipedia: "Although propylene glycol has low toxicity, it exerts high levels of biochemical oxygen demand (BOD) during degradation in surface waters. This process can adversely affect aquatic life by consuming oxygen needed by aquatic organisms for survival. Large quantities of dissolved oxygen (DO) in the water column are consumed when microbial populations decompose propylene glycol."
« Last Edit: 08/07/2022 06:48 pm by rsnellenberger »

Offline meekGee

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Re: SpaceX Starship : Texas Prototype(s) Thread 23 : Discussion
« Reply #2286 on: 08/07/2022 07:17 pm »



Iím not sure you want to glycol spilling into protected wetlands any more than you would any kind of standard hydraulic fluid - it still has to be contained and cleaned up.

But in any case, the better solution is obviously to examine what component(s) failed, figure out why, and then design work-arounds: more or differently-configured hydraulic check-valves, redundant pumps/reservoirs, higher-rated hoses and fittings, etc. This, at least, is not rocket science.

Propylene glycol would be far less damaging than the current fluid, and it has the added advantage of being non-flammable. Iím guessing the concentration required would be quite low too, given the climate there. Iíve no idea about the suitability of it in a hydraulic system, but itís remarkably benign to the environment. Itís in many flavored drinks.
Wikipedia: "Although propylene glycol has low toxicity, it exerts high levels of biochemical oxygen demand (BOD) during degradation in surface waters. This process can adversely affect aquatic life by consuming oxygen needed by aquatic organisms for survival. Large quantities of dissolved oxygen (DO) in the water column are consumed when microbial populations decompose propylene glycol."

Hmm if we only had a source of readily available oxygen somewhere around..

(Yeah I know it won't work directly, but you could spread water with high DO content over the area, in response to any low DO readings at the site.  Hardly a contaminant.)
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Re: SpaceX Starship : Texas Prototype(s) Thread 23 : Discussion
« Reply #2287 on: 08/07/2022 09:55 pm »
Elon's tweet implicitly referenced napalm. Regarding cleanup, how bad would it be to pour kerosene on the spill and light a match? It's Texas after all. Problem gone?
« Last Edit: 08/07/2022 09:56 pm by sdsds »
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Re: SpaceX Starship : Texas Prototype(s) Thread 23 : Discussion
« Reply #2288 on: 08/07/2022 10:57 pm »
Elon's tweet implicitly referenced napalm. Regarding cleanup, how bad would it be to pour kerosene on the spill and light a match? It's Texas after all. Problem gone?
Even if Texas allowed it, the point is still to mitigate impact on the environment, no?  A bunch of half burned oil and fuel is very impactful.

If they spilled it into the wetlands they need to pick it up to the extent possible, and I am sure that they will.
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Offline ImperfectSense

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Re: SpaceX Starship : Texas Prototype(s) Thread 23 : Discussion
« Reply #2289 on: 08/07/2022 11:22 pm »
I'd be absolutely shocked if Stage 0 doesn't have a completely contained waste water drainage system?  Most airports across the country these days are required to capture all spilled fluids and rainwater runoff and separately treat it before discharging it into the regular municipal wastewater system.  This can be pretty effectively accomplished by how the ground is engineered beneath all of the pavement and structures, and thus is fairly invisible to the naked eye.  Did the environmental reports touch on this at all?  I haven't read them all the way through.

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Re: SpaceX Starship : Texas Prototype(s) Thread 23 : Discussion
« Reply #2290 on: 08/08/2022 01:47 am »
as far as i understand what's there , stage 0 has no water collection,retention, or treatment systems in place or partially installed. at most there are a few small(12 in) concrete storm drains installed along rt4 and draining into the mud flats. in fact there is no water retention or treatment anywhere on the entire starbase site. they are installing storm  drains along esperson, weems, LBJ and parts of rt 4 and remedios but they all end up feeding directly into the mud flats or collection cisterns that then are pumped to the flats
« Last Edit: 08/08/2022 01:52 am by daavery »

Offline Nomadd

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Re: SpaceX Starship : Texas Prototype(s) Thread 23 : Discussion
« Reply #2291 on: 08/08/2022 02:25 am »
Elon's tweet implicitly referenced napalm. Regarding cleanup, how bad would it be to pour kerosene on the spill and light a match? It's Texas after all. Problem gone?
Then they'd not only have the mess the fire left behind, they'd be fined for the air pollution.
 Any kind of petroleum type contamination needs to be scraped up and cleaned at special incinerator type facilities. Oil dripping off a valve can bring the wrath of the EPA down upon you.
 Even in 70s and 80s Texas it was an issue. Back when $100 was a lot of money I worked by showing up at oil field outfits with a hardhat and waiting to be picked up for a days work. A lot of it for the kids like me was handling the messes before inspectors showed up.

 In any case, I'm not sure what they have to worry about. The biggest items are probably truck and generator related, same as any industrial site has. The berms are enough for hydraulic leaks.
« Last Edit: 08/08/2022 02:27 am by Nomadd »
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Crews are currently making sure the base of the orbital launch mount is clear of debris. 😱

And hopefully clear of anything liable to ignite spontaneously when exposed to high concentrations of LOX. :)
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Re: SpaceX Starship : Texas Prototype(s) Thread 23 : Discussion
« Reply #2293 on: 08/08/2022 06:53 pm »
Doesn't the hydrolic failure mean we'll need a re-design of the chopsticks?  Any mission other than Starlink launches, Starship will require multiple launches for refueling in quick succession.  Such a failure could have big impacts on the mission.
No. Starbase is the prototyping place for the chopsticks. Such failures are not an uncommon occurrence for prototype high performance hydraulics systems, just look at the behind the scenes video about Boston Dynamicsí Atlas, at the 2:00 mark and 3:09 mark:

Just fix and and go again. Donít cry or cower about it. ďThe first one through the wall always gets bloody...Ē
« Last Edit: 08/09/2022 12:50 am by Robotbeat »
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Re: SpaceX Starship : Texas Prototype(s) Thread 23 : Discussion
« Reply #2294 on: 08/09/2022 11:05 am »
https://twitter.com/nextspaceflight/status/1556702945822982144

Quote
Crews are currently making sure the base of the orbital launch mount is clear of debris. 😱

And hopefully clear of anything liable to ignite spontaneously when exposed to high concentrations of LOX. :)

Why did it seem to me that last night's test was only one engine?  I expected a cloud to extend downward around the entire circumference instead of just one specific area. 
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Crews are currently making sure the base of the orbital launch mount is clear of debris.

And hopefully clear of anything liable to ignite spontaneously when exposed to high concentrations of LOX. :)

Why did it seem to me that last night's test was only one engine?  I expected a cloud to extend downward around the entire circumference instead of just one specific area.
I kind of remember them removing only one outer engine. Did they remove any more, and if not is that maybe the engine they tested?

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Why did it seem to me that last night's test was only one engine?  I expected a cloud to extend downward around the entire circumference instead of just one specific area. 

Because apparently it was. For B7, there were what looked like two single-engine tests, though it wasnít clear to me that it was the same engine each time.
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Re: SpaceX Starship : Texas Prototype(s) Thread 23 : Discussion
« Reply #2297 on: 08/09/2022 12:28 pm »

Why did it seem to me that last night's test was only one engine?  I expected a cloud to extend downward around the entire circumference instead of just one specific area. 

Because apparently it was. For B7, there were what looked like two single-engine tests, though it wasnít clear to me that it was the same engine each time.

After the incident last time doesnít it make sense to run through the spin test steps initially for the booster for just one engine, confirm that things donít blow up and then go on to multiple engines ?

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Why did it seem to me that last night's test was only one engine?  I expected a cloud to extend downward around the entire circumference instead of just one specific area. 

Because apparently it was. For B7, there were what looked like two single-engine tests, though it wasnít clear to me that it was the same engine each time.

After the incident last time doesnít it make sense to run through the spin test steps initially for the booster for just one engine, confirm that things donít blow up and then go on to multiple engines ?

A lot things ďmake senseĒ to lay people when we donít have any insights into the thought processes, rationales, or testing objectives. I personally prefer not to speculate about stuff like last night with so little data. Remember, SpaceX hasnít done a whole lot of real engine testing with a Booster at all yet. We donít know what exactly they were testing last night, nor what the limitations were/are. Proving out GSE? Testing a single engine and measuring for residual methane or LOX concentrations in the local wind conditions? Etc.

Absent that info, I will suspend personal judgment on what seems to make sense. FWIW, there are possible closures listed for today and Wednesday as well, from 10:00am - 10:00pm. So hopefully we will see more Booster testing and ge some more insight into how SpaceX is running this test program.
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Offline OTV Booster

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Re: SpaceX Starship : Texas Prototype(s) Thread 23 : Discussion
« Reply #2299 on: 08/09/2022 03:58 pm »
There are rings and subassemblies for multiple boosters at BC. It doesn't look exactly like a linear process. It's not as if one is 30% complete and the start the next following the same production path, modifications excepted.


Are there certain assembly steps that are more efficient if batched for multiple steps?  The dome flip comes to mind. It calls for specific jigs and equipment arrayed in a specific way. It seems that flipping domes for several ships at once would call for fewer labor hours, and a dome subassembly takes up half the space of a dome and it's ring assembly.


Has anybody been tracking this formally or noticed any patterns?
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