Does (/will) the Falcon Heavy count as a LEGO rocket?
Is SLS a "LEGO rocket"?
Quote from: Joffan on 07/10/2017 10:29 pmDoes (/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.
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?
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.
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?
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.Quote from: spacenut on 07/11/2017 11:40 amWhat 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.
Quote from: Jim on 07/10/2017 05:28 pmHere 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
Here are examples of bad "LEGO rockets" (rockets pieced together out of other existing elements).
Where would Scout fit in the "Good LEGO" or "Bad LEGO" philosophy?
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.
Quote from: rakaydos on 07/11/2017 09:55 pmThe 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.That's not a "LEGO rocket moment" at all, since the boosters are new builds, designed for SLS.A "LEGO rocket moment" is when an existing stage/component in use is adapted to work with another existing stage/component, in a way that does not match its original intended use.
Quote from: Lars-J on 07/12/2017 05:02 pmQuote from: rakaydos on 07/11/2017 09:55 pmThe 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.That's not a "LEGO rocket moment" at all, since the boosters are new builds, designed for SLS.A "LEGO rocket moment" is when an existing stage/component in use is adapted to work with another existing stage/component, in a way that does not match its original intended use.How about the SLS Block 1 Interim Cryogenic Propulsion Stage (ICPS) actually being a Delta Cryogenic Second Stage (DCSS)?https://www.nasaspaceflight.com/2017/07/sls-upper-stage-residency-former-home-iss-modules/
Atlas-Able was definitely a poor idea, the upper stages were too skinny proportionate to the Atlas which resulted in damage from aerodynamic loads. All three Atlas-Ables launched failed due to this--first one the shroud comes off, second the Able suffers some sort of damage that results in loss of oxidizer pressure, and third one aerodynamic buffeting around the adapter section ruptured the Atlas's LOX tank (before someone claims the Able ignited prematurely, it didn't, this was disproven by GD-A/NASA docs).Mercury-Atlas 1 also of course failed due to buffeting that caused structural failure of the LOX tank and after that happened, a requirement was put out that all Atlas upper stage/payload combinations undergo structural dynamics testing.As for Juno II, some of the failures (including the most well-known and spectacular one) were not caused by the upper stages at all. In that case, the real problem was the lack of qualified, motivated tech personnel since Juno II was a close-ended program with no plans for further development. Vanguard was not very successful either, despite a much smaller size gradient between the first stage and upper stages.The success rate for Agena vehicles in the early years was also about 50%. So we can't blame mismatched upper stages for everything, at this early stage in the space program, getting a LV to fly at all was a challenge.
Success rate was not a factor in selecting Juno II and Atlas Able as bad rockets.
Quote from: Jim on 07/14/2017 04:42 pmSuccess rate was not a factor in selecting Juno II and Atlas Able as bad rockets.Obviously if they were good, well-designed rockets, they wouldn't have failed at the rate they did.
And that is the point, by using existing parts, they can't be well designed.
1. Atlas III combined the Atlas II launcher with the RD-180 engine, replacing the existing MA-5A. It was by no means optimal but surely it was well designed? 2. Titan IIIA was closer to a clean sheet design than the Titan IIIB with the purpose designed Transtage. However, the IIIB ended up being the launcher of choice in this category despite using the existing Agena, both integrated with the payload and in ascent only mode.
Does Shuttle-Centaur qualify as a LEGO rocket?
That one never really worked out. (The tax avoidance credit part apparently worked much better, until tax law got changed.)Ariane 1-4 was quite a bit of mix and match. Or maybe call it extensive carryover from previous versions.
Obviously if they were good, well-designed rockets, they wouldn't have failed at the rate they did.
I think the question is, where do we draw the line between modular, and LEGO rockets? If we define LEGO as "Using a part not specifically intended for a rocket" (which I see the forum has already shunned to some extent) we end with quite a lot of modular rockets left out. If we define it as "Using a part that does not fit with the rocket", that could also be modular. Imagine you have a sattelite and you are going to launch it on a company who uses Modular rockets. You say: "I want the upper stage to be twice as tall, with this engine!" Because the company prides itself on being modular, they will do so. The rocket will fail on launch, yes, but it is not a LEGO rocket, in any sense of the word.