Author Topic: Rocket parts aren't like LEGO elements  (Read 20924 times)

Offline Jim

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« Last Edit: 07/13/2017 06:02 pm by Lar »

Offline Jim

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Re: Rocket parts aren't like LEGO elements
« Reply #1 on: 07/10/2017 05:28 pm »
Here are examples of bad "LEGO rockets" (rockets pieced together out of other existing elements).
« Last Edit: 07/10/2017 07:25 pm by Lar »

Offline Jim

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Re: Rocket parts aren't like LEGO elements
« Reply #2 on: 07/10/2017 05:31 pm »
Good "LEGO rockets".  (only because the Agena was adaptable (increased tank size) and it also served as a spacecraft bus in addition to being an upper stage)
« Last Edit: 07/10/2017 07:30 pm by Lar »

Offline Jim

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Re: Rocket parts aren't like LEGO elements
« Reply #3 on: 07/10/2017 05:33 pm »
How to make a LEGO rocket  (the parts are never off the shelf, they have to modified between each version)

« Last Edit: 07/10/2017 07:30 pm by Lar »

Offline Kaputnik

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Re: Rocket parts aren't like LEGO elements
« Reply #4 on: 07/10/2017 10:13 pm »
Where would Energia/Zenit fit on the spectrum of good to bad LEGO?
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Offline Joffan

Re: Rocket parts aren't like LEGO elements
« Reply #5 on: 07/10/2017 10:29 pm »
Does (/will) the Falcon Heavy count as a LEGO rocket? As Jim observes, we're never talking about zero modifications to "clip the parts together", but it seems that SpaceX must be relatively close to that situation by using recovered first stages for the side boosters.
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Offline sfxtd

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Re: Rocket parts aren't like LEGO elements
« Reply #6 on: 07/11/2017 12:03 am »
Does (/will) the Falcon Heavy count as a LEGO rocket?
I always thought Jim's LEGO analogy was meant to discourage the idea of taking existing rocket components (stages) that were not originally designed to go together and suggesting that one could use them together relatively easily and at lower cost. Most of the "Good LEGO rockets" had at least some idea that the parts could be combined as part of the design concept for at least one stage.

Falcon Heavy has been a design concept from very early on, so undoubtedly many F9 engineering decisions were made with that goal in mind, so not really LEGOs as originally analogized. Putting an Agena or Centaur US on a FH would be... odd.

Offline Lar

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Re: Rocket parts aren't like LEGO elements
« Reply #7 on: 07/11/2017 12:04 am »
Is SLS a "LEGO rocket"? 
I'd say more of a Mega Bloks one ...  :)

More seriously it does kind of fit the definition, no? Using parts from other projects rather than a clean sheet design...

Does (/will) the Falcon Heavy count as a LEGO rocket?
I always thought Jim's LEGO analogy was meant to discourage the idea of taking existing rocket components (stages) that were not originally designed to go together and suggesting that one could use them together relatively easily and at lower cost. Most of the "Good LEGO rockets" had at least some idea that the parts could be combined as part of the design concept for at least one stage.

Falcon Heavy has been a design concept from very early on, so undoubtedly many F9 engineering decisions were made with that goal in mind, so not really LEGOs as originally analogized. Putting an Agena or Centaur US on a FH would be... odd.

Agreed.
« Last Edit: 07/11/2017 12:05 am by Lar »
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Offline spacenut

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Re: Rocket parts aren't like LEGO elements
« Reply #8 on: 07/11/2017 11:40 am »
What if you used a Centaur upper stage on a Falcon 9.  Would that improve the F9 capabilities?  Maybe not to LEO, but GEO, or GSO? 

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Re: Rocket parts aren't like LEGO elements
« Reply #9 on: 07/11/2017 12:02 pm »
Also instructive in this thread are earlier comments made over the years by NSF posters about adding solid and/or liquid boosters; different load and thrust paths, for which a core would have to be significantly redesigned, to the point of being a new rocket.  Here horizontal processing also introduces new problems, as does any TLE-like interfaces which have to carry more load. Same goes for the core.

Also, the type of ' why not cluster 2-3-4-5-6-7-8 boosters together' - without regard for the same load paths. Or, further away from the 'would it achieve lift-off' kind of questions, introducing impossibilities - or total rework - of all ground processing, erecting of the launcher, GSE / tower redesign, flame trench/ pad rework, etc.

These, and the other examples of a thread, really drive home that a rocket can't be seen apart from it's associated GSE, processing, vertical/horizontal integration, launch pad, even company capabilities (SpaceX and SRB's, hello). It really is a system.

What if you used a Centaur upper stage on a Falcon 9.  Would that improve the F9 capabilities?  Maybe not to LEO, but GEO, or GSO?

To pre-empt this sort of question is exactly why this thread is created. Rockets are not like LEGO elements.

Offline laszlo

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Re: Rocket parts aren't like LEGO elements
« Reply #10 on: 07/11/2017 12:26 pm »
How does the Saturn 1B fit in here? Is it a LEGO rocket, what with the Saturn V bits in the second stage (S-IVB and Saturn V instrument unit, as well as Apollo CSM) and the Redstone and Jupiter tanks in the first stage?

Offline Jim

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Re: Rocket parts aren't like LEGO elements
« Reply #11 on: 07/11/2017 12:49 pm »
Does (/will) the Falcon Heavy count as a LEGO rocket? As Jim observes, we're never talking about zero modifications to "clip the parts together", but it seems that SpaceX must be relatively close to that situation by using recovered first stages for the side boosters.

See Delta IV and Atlas V heavy. They were designed with the intent of making a heavy

Offline Jim

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Re: Rocket parts aren't like LEGO elements
« Reply #12 on: 07/11/2017 01:06 pm »
How does the Saturn 1B fit in here? Is it a LEGO rocket, what with the Saturn V bits in the second stage (S-IVB and Saturn V instrument unit, as well as Apollo CSM) and the Redstone and Jupiter tanks in the first stage?


The Saturn I & IB did not use Redstone and Jupiter tanks in the first stage.  They used tanks that were the same diameter as Redstone and Jupiter vehicles.  The vehicles has 4 bulkheads that created two tanks, one each for LOX and RP-1.  Each tank for Saturn had only two bulkheads and only carried one propellant.   The length of the Saturn tanks were sized so that the combination of 4 Redstone type tanks for RP-1 vs  4 Redstone type tanks and one Jupiter type for LOX were at the proper mixture ratio.  The S-IV was sized for the Saturn I.  To make the Saturn IB, the first stage and engines had to be uprated to handle the S-IVB second stage. 

The  instrument unit and Apollo CSM don't play into this because the IU was just a set of avionics.  And the CSM was just the payload; which, however, was not the same as a Saturn V launched CSM.  Saturn IB launched CSM had to have propellant offloaded since it could not lift a fully loaded one.

Offline nicp

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Re: Rocket parts aren't like LEGO elements
« Reply #13 on: 07/11/2017 03:06 pm »
Also instructive in this thread are earlier comments made over the years by NSF posters about adding solid and/or liquid boosters; different load and thrust paths, for which a core would have to be significantly redesigned, to the point of being a new rocket.  Here horizontal processing also introduces new problems, as does any TLE-like interfaces which have to carry more load. Same goes for the core.

Also, the type of ' why not cluster 2-3-4-5-6-7-8 boosters together' - without regard for the same load paths. Or, further away from the 'would it achieve lift-off' kind of questions, introducing impossibilities - or total rework - of all ground processing, erecting of the launcher, GSE / tower redesign, flame trench/ pad rework, etc.

These, and the other examples of a thread, really drive home that a rocket can't be seen apart from it's associated GSE, processing, vertical/horizontal integration, launch pad, even company capabilities (SpaceX and SRB's, hello). It really is a system.

What if you used a Centaur upper stage on a Falcon 9.  Would that improve the F9 capabilities?  Maybe not to LEO, but GEO, or GSO?

To pre-empt this sort of question is exactly why this thread is created. Rockets are not like LEGO elements.

However, my comment (which Jim referenced in the creation of this thread) did ask the question as to _why_ such things are a bad idea. I said "As a new thread I'm sort of thinking of Jim's Raptor upper stage thing (I like), a place where impractical ideas - or even potentially practixal ideas can be discussed. With explanations as to _why_ this or that is ridiculous or physically possible but economically impossible".

I don't know if that's what Jim wants from the thread, but people keep coming up with wacky ideas (many of which are truly wacky) but some are fun to imagine at least, and perhaps would be fun to discuss.
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Offline Jim

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Re: Rocket parts aren't like LEGO elements
« Reply #14 on: 07/11/2017 04:15 pm »
Here are examples of bad "LEGO rockets" (rockets pieced together out of other existing elements).
I respectfully disagree.  Thor-Delta was equally "bad" by this definition, since it consisted of stages cobbled together from Thor and Vanguard.  The difference was simply that Thor-Delta was successful while Juno II and Thor-Able suffered multiple failures. 

Juno II also had its successes.  It gave the U.S. its first heliocentric satellite (Pioneer 4), and orbited three additional Explorer satellites.  I see it as a useful machine for its time.  http://www.spacelaunchreport.com/jupiter5.html

Atlas Able and Juno II are the true definition of bad lego rockets because of the horrible mismatched upper stages*.  Able was way too small for Atlas as well as the SRM tub was for Juno.  Both could support (and Atlas did) much larger and more optimized upper stages.  The Thor Delta was better because of the match in stages.


* A bad lego rocket is where the components make a vehicle less than the sums of the parts.  The components subtract just as they add.

(A+B) + (C+D) > (A+C) + (B+D)

(Atlas+Agena) + (Thor+Able) > (Atlas + Able) + (Thor+Agena)
« Last Edit: 07/11/2017 04:32 pm by Jim »

Offline Jim

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Re: Rocket parts aren't like LEGO elements
« Reply #15 on: 07/11/2017 05:00 pm »
Adding SRMs to Falcon 9 is similar.
All  the minuses are:
redesigned first stage structure
Design and develop SRM
Redesign TEL
Redesign pad
Redesign hangar
Add SRM handling GSE and storage
Resite pad and hangar for solids (or move to another launch site)
Update processes for proximity to SRM's

Offline Thorny

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Re: Rocket parts aren't like LEGO elements
« Reply #16 on: 07/11/2017 06:54 pm »
Where would Scout fit in the "Good LEGO" or "Bad LEGO" philosophy?

Offline Jim

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Re: Rocket parts aren't like LEGO elements
« Reply #17 on: 07/11/2017 07:15 pm »
Where would Scout fit in the "Good LEGO" or "Bad LEGO" philosophy?

Good, and the exception to the rule.  There is/was such a variety of available motors, that vehicle could use properly sized motors.  The Minotaur family of vehicles is similar.  However, some configurations are kludges but that is because of cost and motor availability.

Offline Oersted

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Re: Rocket parts aren't like LEGO elements
« Reply #18 on: 07/11/2017 09:49 pm »
Do we need to involve LEGO in this thread? - With "bad" and"good" *LEGO rockets* it seems there is not even agreement about what it actually is supposed to mean. Also, the LEGO company is a stalwart, great collaborator of NASA, flying figurines on all those unmanned missions, inspiring kids like my own with - for instance - their Saturn V set... - I think they deserve better.

How about "rocket kludges", "frankenstein rockets", or something like that? - Easier to understand and unequivocally negative, which is the purpose of this thread as I understand it.

I'd like to request a title change...

Offline rakaydos

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Re: Rocket parts aren't like LEGO elements
« Reply #19 on: 07/11/2017 09:55 pm »
The SLS block 2 is supposed to use the same core as the block one, but trade out the solid boosters for, as far as I've heard, a Not-yet-defined liquid booster set.

What does this mean for the connecters between the boosters and the core? how overbuilt would they need to be if they need to handle  any plausable booster for the block 2? This seems a classic "Lego rocket" moment.

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