Launcher vehicle design (modular vs bundling)

[Jestersage]

Researching both the IRL and ETS-timeline, I noticed that the Saturn series actually take a multiple-module approach. Basically, there is a set of stages, and depending on the mission, assembles the required stage as  a single-stack rocket. Eg:  If using a modified Stage 2 of Saturn V, combine with S-IVB, you get Saturn II.

Nowadays, except for SLS (which is more Senate Laundry System), the approach seems to be using a "Core rocket"+Upper VAC Stage, then either strap in Solid Rockets, or 2 (or 3 or 4) "Core Rocket" if extra capacity is needed. IOTL, that will be Delta IV and Atlas V, as well as Angara, the Proposed Irtysh, and Space X Falcon 9. In the ETS, those are represented by Saturn-Multibody and their version of Vulkan.

So my question is: realistically, is there advantage to use the Modular approach, versus the bundling approach?

[RCgothic]

I don't think modular Saturn really works as a concept. The only common stage was S-IVB, an upper stage on both. S-II as a 1st stage would never get off the launch pad. You need a different 1st stage for each configuration.

Core+SRBs is a very cheap way to get variable performance.

Having a common upper and lower core diameter also reduces tooling costs. This is why the "Heavy" configuration of multiple cores also works quite well.

[Jestersage]

1 hour ago, RCgothic said:

I don't think modular Saturn really works as a concept. The only common stage was S-IVB, an upper stage on both. S-II as a 1st stage would never get off the launch pad. You need a different 1st stage for each configuration.

I included the proposals and studies, but what they comes out reflect what you mentioned.

For example, the first planned version of Saturn II, INT-17, utilize a S-II.... modified with 7 HG-3-SL. Then they found out the HF-3-SL is not THAT better. Thus INT-18, which is the exact S-II, but having 4x Titan SRB. Then there's the Multiple variation of Saturn V, which usually is missing 1 stage, and then modify the remaining stages.

That being said, I think that modular structure thinking still require too much modification of a stage to fit the "modular structure" concept to save money

1 hour ago, RCgothic said:

Core+SRBs is a very cheap way to get variable performance.

Having a common upper and lower core diameter also reduces tooling costs. This is why the "Heavy" configuration of multiple cores also works quite well.

Would you say that ETS' launcher progression is a more proper way of progression, once factor into budget and performance? (Saturn IB --> Monolithic Saturn I using 1x F-1B and single "tank" for first stage --> Stretching the first stage and uprate the F-1 as Saturn MB)

Edited December 25, 2020 by Jestersage

[DDE]

9 hours ago, Jestersage said:

Nowadays, except for SLS (which is more Senate Laundry System)

There was another: the N-1, the N-11 and the N-111.

http://www.astronautix.com/n/n1.html

[kerbiloid]

https://en.wikipedia.org/wiki/S-I#Design

Quote

The design of the S-I was based on Jupiter and Redstone tanks to leverage existing chains. A central Jupiter tank^[3] was surrounded by a cluster of eight Redstone tanks. Fours of these Redstone tanks contained LOX and four contained RP-1.

Spoiler

The Saturn family is just a Redstone utilization program used for the Moon.

Saturn was a bunch (literally) of Jupiter and Redstones with customizable upper stage(s).
The Moon was added for hype.

 

[Jestersage]

18 hours ago, DDE said:

There was another: the N-1, the N-11 and the N-111.

http://www.astronautix.com/n/n1.html

That would make it close to Saturn "modular rocket" concept, and place it in the former. (I would not consider them as modern... May be China's CZ-9 would make a better example)

For those that are wondering about N-1 and N-111:

• The N-1 would use the second, third, and fourth stages of the N1. 
•  The N111 would use the third and fourth stages of the N1, and the second stage of Korolev's R-9

In essence, they are not unlike Saturn-II INT-17 (stage 2 and stage 3 of Saturn V) or Saturn-V-INT20 etc

17 hours ago, kerbiloid said:

https://en.wikipedia.org/wiki/S-I#Design

  Reveal hidden contents

The Saturn family is just a Redstone utilization program used for the Moon.

Saturn was a bunch (literally) of Jupiter and Redstones with customizable upper stage(s).
The Moon was added for hype.

 

Right -- I recall the other stages were also suppose to be redstones/Jupiter clustered. In short, S-I (or in fact, the entire series of Saturn) originally is also a bunch of clustered rocket, butr then modification here and there, and then we get our "modular rockets"

In fact, that's basically what happen to UR-500/proton. originally using 4x UR-200 clustered  as first stage and 1x UR200 as upper stage

Edited December 26, 2020 by Jestersage