Big Dumb Boosters- and why we're overthinking this whole rocketry business

[Nibb31]

16 minutes ago, Bill Phil said:

If I recall, the idea was to use the already existing ship construction infrastructure for rocket construction, not actually using the techniques associated with it... Although, I do seem to remember that the construction firm they worked with said that it wasn't unlike submarine construction. Then you'd get the added bonus of not having to build a launch pad. Not to say it's practical, though.

http://www.astronautix.com/s/seadragon.html

It still takes longer to build a submarine than to build an SLS core stage, for example (SpaceX can churn out Falcon cores every week or two). A diesel submarine also costs a billion dollars.

Edited September 18, 2016 by Nibb31

[A Fuzzy Velociraptor]

32 minutes ago, Nibb31 said:

That's a pretty bold claim for something that was barely even a paper proposal.

I think what he means was that the system was not intended to be designed that it would have a high rate of failure like Aquarius.

[Tex_NL]

29 minutes ago, Nibb31 said:

It might have seemed that way in the 1950's with the wartime experience of the old Liberty Ships, but with modern shipyards and the cost of a qualified workforce and materials, no way.

Liberty Ships did their job just as well as modern ships of similar size. Modern ships do it faster, cleaner, with more reliability, luxury and style but the old galls got the job done just as well. And herein lies both the problem and the solution. You do not need modern shipyards to build Big Dumb Boosters. You actually CAN slap them together just like the old Liberty Ships. A Big Dumb Booster doesn't need to be fancy. It doesn't need a fancy paint scheme. All it needs to do is get the job done.

[Bill Phil]

17 minutes ago, Nibb31 said:

It still takes longer to build a submarine than to build an SLS core stage, for example. A submarine also costs a couple billion dollars.

Oh, sure.

However, submarines are much more complex than rockets. Especially with that nuclear reactor.

Also, SLS core stages are pretty much just huge cylinders. Yes, there is more going on under the surface, but the most complex part is the engine.

Edited September 18, 2016 by Bill Phil

[Nibb31]

39 minutes ago, Tex_NL said:

Liberty Ships did their job just as well as modern ships of similar size. Modern ships do it faster, cleaner, with more reliability, luxury and style but the old galls got the job done just as well. And herein lies both the problem and the solution. You do not need modern shipyards to build Big Dumb Boosters. You actually CAN slap them together just like the old Liberty Ships. A Big Dumb Booster doesn't need to be fancy. It doesn't need a fancy paint scheme. All it needs to do is get the job done.

A modern workforce requires modern construction techniques. You can't build ships (or rockets) in 2016 (or anything else for that matter) the same way you built stuff in WWII. If Ford reintroduced the Model T today as it was built in 1920, it would cost more than a Mustang. 

The cost of maintaining a workforce is much higher today, there are safety and evironmental regulations, there are laws, quality standards, accounting, procedures, that are much more restrictive, materials are different and more expensive... Sure, you could outsource to India or China where they don't care when a worker falls off a platform, or where you can have near-slave labour, but what kind of progress is that? Even then, ships are work-intensive things to build.

Oh, and I'd like to see the logistics for filling up and launching something that huge. The original plan involved a massive LOX and RP1 plant near the dock and a nuclear aircraft carrier to electrolyse the water into LH2. How is that, in any way, cheap and quick ? And how do you test fire the engine on such a behemoth ?

The whole argument also ignores that modern expendable rockets have become less and less expensive to build. They are optimized for expendability and low cost. They are expensive to design and to operate and to test, but the actual material and manufacturing process is easily automated.
 

Edited September 18, 2016 by Nibb31

[DerekL1963]

1 hour ago, Bill Phil said:

If I recall, the idea was to use the already existing ship construction infrastructure for rocket construction, not actually using the techniques associated with it... Although, I do seem to remember that the construction firm they worked with said that it wasn't unlike submarine construction. Then you'd get the added bonus of not having to build a launch pad. Not to say it's practical, though.

http://www.astronautix.com/s/seadragon.html

Not too unlike a submarine hull.   The hull is the easy and cheap part (relatively speaking) of a submarine, the rest is expensive.   The same is true of rockets, the tank barrels are the easy and cheap part (relatively speaking), the rest gets expensive.

[Bill Phil]

17 minutes ago, DerekL1963 said:

Not too unlike a submarine hull.   The hull is the easy and cheap part (relatively speaking) of a submarine, the rest is expensive.   The same is true of rockets, the tank barrels are the easy and cheap part (relatively speaking), the rest gets expensive.

Yeah... Sounds accurate.

[Tex_NL]

@Nibb31 'Can not' is dead. And 'want not' is buried right next to it.
What you're talking about are all mere mental restrictions, not engineering or physical. Of course it's unethical to work under century old conditions but it is not impossible. You do not have to work under slavery conditions to build a cheaper, simpler design that does the same thing.

[Nibb31]

7 minutes ago, Tex_NL said:

@Nibb31 'Can not' is dead. And 'want not' is buried right next to it.
What you're talking about are all mere mental restrictions, not engineering or physical. Of course it's unethical to work under century old conditions but it is not impossible. You do not have to work under slavery conditions to build a cheaper, simpler design that does the same thing.

There's this thing called 'reality', which is the environment in which we live. It's made of all sorts of economical, political, social, and engineering constraints. Of course, you can handwave them all away, but in 'reality', the chances of bending those constraints are even lower than bending the laws of physics.

My take is that in 'reality', it isn't cheaper to build a 10000-ton rocket out of steel than to build a 1000-ton rocket out of aluminium with modern construction techniques.

[Bill Phil]

11 hours ago, Nibb31 said:

My take is that in 'reality', it isn't cheaper to build a 10000-ton rocket out of steel than to build a 1000-ton rocket out of aluminium with modern construction techniques.

And you are wholly correct. But the question isn't the total cost, but the cost per unit payload.