SpaceX Tuesday...

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Eric Mc

122,010 posts

265 months

Monday 26th February 2018
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Silos are not great places for storing rockets and it does make working on them very difficult. Of course, land based military ICBMs are usually kept in silos for protection but these days these are virtually all solid fuel rockets which don't need to be fueled up just prior to launch.

One US missile which WAS liquid fueled and was kept in underground silos was the Titan II. Its propellants were storable i.e. the rocket could be left fueled for long periods of time rather than having to be fueled in the few hours before launch. However, this was problematic in itself because the fuels did need to be drained and replaced from time to time and that was a very hazardous operation. There were also problems with corrosion and leakage.

In 1980 a massive explosion destroyed a Titan missile in its silo killing one technician and wounding others.

It doesn't really make sense for space rockets to be stored or fueled underground. It's better and safer to work on them above ground.

CraigyMc

16,404 posts

236 months

Monday 26th February 2018
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Eric Mc said:
Silos are not great places for storing rockets and it does make working on them very difficult. Of course, land based military ICBMs are usually kept in silos for protection but these days these are virtually all solid fuel rockets which don't need to be fueled up just prior to launch.

One US missile which WAS liquid fueled and was kept in underground silos was the Titan II. Its propellants were storable i.e. the rocket could be left fueled for long periods of time rather than having to be fueled in the few hours before launch. However, this was problematic in itself because the fuels did need to be drained and replaced from time to time and that was a very hazardous operation. There were also problems with corrosion and leakage.

In 1980 a massive explosion destroyed a Titan missile in its silo killing one technician and wounding others.

It doesn't really make sense for space rockets to be stored or fueled underground. It's better and safer to work on them above ground.
Yup. https://en.wikipedia.org/wiki/1980_Damascus_Titan_...

Rockets underground for protection is a weird strategy in the 21st century.
Rockets on submarines are even more problematic, though that's more their payload than the rocket itself (which, in the case of Trident, is "launched" from underwater with steam).
The worst place for something as poisonous as plutonium is in a sealed tube of people.
It's why nuclear weapons on subs are manufactured with much more refined plutonium than those used in ICBMs (pure Pu actually emits very few gammas).

AJLintern

4,202 posts

263 months

Monday 26th February 2018
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But we're generally talking about liquid fuelled rockets, which are only fuelled once on the pad just prior to launch. So no issue with explosions within the assembly building, whether it's in a conventional building or underground. The suggestion of underground silo was mainly with the idea of making vertical assembly easier when mounting the payload, which could be done at ground level.

Eric Mc

122,010 posts

265 months

Monday 26th February 2018
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That's precisely why an underground facility is not really suitable when you are pumping a rocket full of liquid oxygen and perhaps liquid hydrogen as well. Being out in the open makes far more sense because if something does go wrong (as it did with SpaceX not that long ago), the amount of damage caused is actually less than if the explosion was contained and constrained in the narrow confines of a silo.

If you WANTED to protect the rocket on the pad, you could surround it with a mobile building structure - and that is indeed often done. However, that building is removed from the area BEFORE any fueling is undertaken precisely because of the dangers posed by fueling.

If processing large space boosters underground was a logical and smart thing to do, they would have been doing it decades ago. The fact that they never have and have no plans to do so must mean something.

CraigyMc

16,404 posts

236 months

Monday 26th February 2018
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AJLintern said:
But we're generally talking about liquid fuelled rockets, which are only fuelled once on the pad just prior to launch. So no issue with explosions within the assembly building, whether it's in a conventional building or underground.
Unless someone drops a wrench while it's underground, and is having its payload added to the top. Then if that wrench bounces off the inside wall of the silo and the rocket itself, causing leaks... that's pretty much going to result in an enormous explosion.

Compare with *not* having a silo beside the rocket, where the wrench falls onto the ground.

AJLintern

4,202 posts

263 months

Monday 26th February 2018
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Um, I said it's fuelled on the pad, not in any building...

CraigyMc

16,404 posts

236 months

Monday 26th February 2018
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AJLintern said:
Um, I said it's fuelled on the pad, not in any building...
Do you realise that without fuel in it, the rocket has the structural rigidity of a balloon animal?
The only reason it's strong enough to hold a payload is because it's pressurised: like the strength of a soft drinks can before and after opening is completely different.

On earlier rockets than these the walls were so soft you could deflect them by a foot or more with gentle pressure of your hand.

Beati Dogu

8,889 posts

139 months

Monday 26th February 2018
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Hoop strength. You can see that in Bowling For Columbine, when Michael Moore visits Lockheed Martin's Atlas & Titan ICBM factory.

https://www.youtube.com/watch?v=SaUR-l8OWrk

About 50 seconds in.

AJLintern

4,202 posts

263 months

Monday 26th February 2018
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They seem to manage to transport them to the pad ok currently, and land an empty first stage without it falling to pieces!

Beati Dogu

8,889 posts

139 months

Monday 26th February 2018
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The tanks are pressurised with helium as the kerosene and liquid oxygen is depleted.

They're quite strong, especially vertically, but there's a reason they don't launch during high cross winds.

Eric Mc

122,010 posts

265 months

Monday 26th February 2018
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They don't work on them in silos because it's a dumb idea.

The only reason military missiles are kept underground is for protection from attack.

One of the reasons why the Atlas ICBM had such a short career as an ICBM was because it was totally impractical to keep it under the ground.

MartG

20,675 posts

204 months

Monday 26th February 2018
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wink

Not to mention that you need to build the booster even stronger to withstand the acoustic and pressure effect from launching in a confined space

CraigyMc

16,404 posts

236 months

Monday 26th February 2018
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MartG said:


wink

Not to mention that you need to build the booster even stronger to withstand the acoustic and pressure effect from launching in a confined space
I love signs like that.

It's like the author wasn't aware that everything in the world is made of chemicals.

DHMO FTW.

Eric Mc

122,010 posts

265 months

Tuesday 27th February 2018
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The Titan II launch pad facilities included an emergency shower in case a pad worker had any of the volatile and corrosive fuels splashed on them. It was a highly dangerous rocket in lots of ways.

Ironically, the Titan II WAS designed to be kept in silos because it was primarilly a ballistic missile - so it was an extremely dangerous beast to store permanently underground. I'm amazed they had as few accidents as they had considering it was part of the Strategic Air Command inventory for over 20 years.

MartG

20,675 posts

204 months

Tuesday 27th February 2018
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Block 5 F9 spotted under test at McGregor


Eric Mc

122,010 posts

265 months

Tuesday 27th February 2018
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Do you know what aspects of the Block 5 are upgraded over the earlier versions.

Einion Yrth

19,575 posts

244 months

Tuesday 27th February 2018
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Eric Mc said:
Do you know what aspects of the Block 5 are upgraded over the earlier versions.
This may be of interest.

CraigyMc

16,404 posts

236 months

Tuesday 27th February 2018
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Einion Yrth said:
Eric Mc said:
Do you know what aspects of the Block 5 are upgraded over the earlier versions.
This may be of interest.
Musk has also mentioned that they'd like to remove the landing legs altogether in future, landing directly onto a ground docking collar which would perform that role, in order to reduce flown weight. Unclear if that is only going to be a BFR thing or if it'll apply to F9 too.
They can apparently do this because the landings are getting accurate enough not to need the legs or their ability to cope with any flat level surface.

anonymous-user

54 months

Tuesday 27th February 2018
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CraigyMc said:
Einion Yrth said:
Eric Mc said:
Do you know what aspects of the Block 5 are upgraded over the earlier versions.
This may be of interest.
Musk has also mentioned that they'd like to remove the landing legs altogether in future, landing directly onto a ground docking collar which would perform that role, in order to reduce flown weight. Unclear if that is only going to be a BFR thing or if it'll apply to F9 too.
They can apparently do this because the landings are getting accurate enough not to need the legs or their ability to cope with any flat level surface.
That’s very accurate! Does anyone know what level of accuracy they currently work on?

Toaster

2,939 posts

193 months

Tuesday 27th February 2018
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Eric Mc said:
Yipper said:
SpaceX, Tesla and SolarCity have so far together received somewhere in the region of $10,000,000,000 of free government subsidies worldwide.

And they're still losing money hand over fist.

Have a free graphic.

Shove off Yipper - you only see the negative in everything. In the words of your hero, you're a "loser".

I'm not going to let a grumpy fool like you spoil this for me.

What a great night this is for spaceflight. We are on our way folks.
Yipper, Only just came across the graphic I quite like the way you see the world don't stop...alternative views are always welcomed on the science thread
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