[1.12.5] Bluedog Design Bureau - Stockalike Saturn, Apollo, and more! (v1.14.0 "металл" 30/Sep/2024)

[Pappystein]

So, it has been a while... I was so depressed about my failure to finish the Minotaur document due to the lack of unclassified information. I kind of gave up on several articles I had "in the fire."   Well, it has been over a year and that itch is back... Don't worry the Doctors assure me it is not contagious and is just fine  

 

Today I give you a brief article...    Saturn, some of the stages that were not meant to be:

 

Spoiler

This incomplete chronological discussion of stages meant for the Saturn Rocket that were either never designed, never built, or canceled as foolish ideas, but someone still wrote them down!

 

This will not be a complete list as there are a LOT of stages, we don’t have a lot of information on, and some “stages” are hypothetical ones that people not associated with the Saturn Program arm chaired into it because they had media connections…. Lookin' at you, NOVA!

This document will be broken down into Rocket families.

·       The Saturn C series, including Saturn I and Saturn V

·       Saturn A/B series.   Not a lot of engineering was done here

·       Oddballs and un-filed stages

 

Saturn C series C-1 and C-2 stages:

While the Saturn C-1 evolved into the Saturn I and Saturn IB rocket stages… several components were designed but not built.  Before late June 1961, the Saturn C-2 was also being developed.   Its cancelation is the result of focusing Saturn on the moon.

Original S-IV stage.   The Original S-IV was a four-engine LR-119 powered (the RL10B-3 for those who don’t speak US Air Force designations) small-diameter stage.   Its top diameter would have been 3.05m to match with the S-V stage (more to come on that in a bit), and its main tank diameter would have been 4.7m or 185”.   To meet the S-I stage, a combined conic structure on the S-I stage would conjoin with a flared skirt structure with conic-shaped blowout panels.

Here is a picture of the Mockup:

NTRS: 19650020284

Description of the changes:   4, instead of 6 engines, a subtle taper from the cylindrical to the conic tank, almost an ogive curve instead of straight-sided, and the 3d conic instead of half-circle blow-out panels on the aft skirt.   Due to fears of the delay of the LR-119, the enlarged S-IV was ordered and built… and this is one of several “early” mass adds to the Saturn I rocket.

 

Saturn S-V (Centaur) Stage:   Much has been written about this… and much has been obscured.  Before the Centaur's initial launch and failure, the Centaur C series was meant for the Saturn Rocket.   The Centaur was designed to put a large payload into deep space orbit.   Remember, this was before we had even figured out how to calculate planetary slingshot maneuvers or at least test their theory.   The Saturn Rocket was meant to launch a satellite on a direct flight trajectory to any planet in our solar system.   No slingshots, no reserves, no nothing.   Knowing that space was cold, boiloff was mostly not considered…  with tragic results.    Ultimately, The Centaur C series would not be built.    But wait, a Centaur C did fly as part of the return-to-flight test program for Atlas, right?   Well, yes and no.   Yes, a Centaur labeled the #C (as in a numerical designation) did fly.  It, however, was not a Centaur C. It was a Centaur NUMBER C.   Yes, that is confusing as all get out and the Great folks at Glenn Lewis SFC should NOT have re-designated the Centaur Program when they took it over… but they did.  As did Lockheed when they re-asserted control (owning General Dynamics) in the late 1990s.
Centaur C itself was physically about the same size as the Latter Centaur D.1T for the NASA Titan launches of the 1970s.  Like the D.1T it was not supposed to have external insulation unless carried exposed… then Like the D.1A it would carry jettisonable Insulation.   What is the real difference between the Centaur D.1A of Atlas, the Centaur D.1T of Titan, and the Centaur C (S-V) of Saturn?   The skin of Centaur C was almost double the thickness, making the Centaur C, not a balloon-tanked Centaur.    Centaur C and the latter Centaur E were monocoque tank structure stages closer to Agena than Centaur D in tank-wall thickness.  Likewise, the LR-119 engine, AKA the RL10-B-3, which was never actually built, would be used to cater to the higher mass of the stage.

As a follow-up to the Saturn S-V Centaur C, after the issues with space flight and Hydrolox fuels had been “Solved,” Glenn Lewis SFC and Marshal SFC developed but never built or flew the Centaur E.   The Centaur E was a Centaur C with updated 1970s electronics for use with the MLV/INT Saturn Programs.   In the design stages, it was still planned to use the RL10-B-3, but the Centaur E’s tank wall, while still thick, wasn’t as heavy as the Centaur C’s due to the improved design of the tanks and inter-tank structures.  The overall change in mass of the Centaur E vs the Centaur C was a few kilograms.   But it was enough of an engineering change to denote a new designation.

Saturn S-V Big Centaur: Three documents in the USAF archives and the NASA NTRS servers mention a Big Centaur for the Saturn V.   This would have been a stretch of the Centaur E above with further uprated engines.   All references to this are vague and should be considered less as a fact and more as a “hey, can we do” idea.  

 

Saturn S-V Dynasoar.   The Saturn C-1 design, for several months, was the chosen launcher for the USAF’s Dynasoar program, and several features that were to fly on the Saturn I rocket were the result of this.   The Dynasoar would have had a structural, communication, and avionics module to attach to the top of an S-V Centaur (given the time frame Centaur C.)   The “SCA” would replace the centaur avionics and provide USAF-specific ground control features.    Other features built into the Saturn C-1 design that flew on the Saturn I were giant fins.  The Saturn Rocket did not need these fins to fly; instead, they were required to counteract the wing surface of a Dynasoar, and to save time, the stage was not re-engineered to fly without them.   With Dynasoar, these fins were to have hydraulically actuated control surfaces.   In the end, the fins on the rocket were simplified versions without any control actuation or movable surfaces.   With the Advent of the more advanced Saturn IB or Saturn C-1Blk2, the fins, still retained, shed even more mass.  

 

Saturn I S-IVB 220” Diameter.   

Initially ordered as a simple re-engine of the S-IV stage, the S-IVB would have had a tank stretch to increase the fuel.  Switching to the core stage 260” diameter allowed a height reduction of almost 15 feet and increased strength without added mass.  

 

Saturn C-2 S-III stage:

Early on, it was hoped the Saturn C-2 would be ordered about a year and a half behind the C-1 to allow for the development of the S-III stage and its J-2 engine.     The S-III stage would be used on the C-2, C-3, and, for one month, the C-4 rockets.   The S-III stage can best be described as a 2/3rds height S-IVB with 2 J-2 engines.   2x the thrust 2/3rds the fuel capacity.   This is a dramatic over-simplification in terms of accuracy.   While no contract was ever let for this stage, we can surmise that McDonnell would likely produce it.   We know that McDonnell was contracting with Douglas for “Technical considerations” for rocket design.   While this might have been extra engineers to help with Gemini, the author feels it was for the soon-to-be-canceled S-III stage.    S-III was likely canceled to avoid duplication of stages (the S-II stage had a similar role on the C-3 and C-4 rockets) and to free up McDonnell for the Gemini program.   The timing of the cancelation of the S-III coincides with the Silverstein Commission ordering Douglas to make the S-IVB.  

 

Saturn C-2 S-II stage.  

With the cancelation of the S-III listed above, the Saturn C-II needed a new stage.    Thus, the four-engine S-II stage came into existence, which North American Aviation designed to match the 260” diameter of the S-I stage.   The C-2 S-II stage would be approximately the same height as the S-I stage (about 74 ft) and be powered by 4x J-2 engines.   NAA documents call this the S-II-260 as separate from the S-II-396 of the Saturn V.

 

The Saturn C-3 Rocket family:   

The C-3 has a large diameter, and all new rockets are not derived from the C-I Cluster tank arrangement.   A Clean Sheet design, the C-3, was developed for an Earth-Orbit Rendezvous to build a large ship to fly to the moon and back.   Several C-3 and C-2 launches would be required to construct this space-based ship to go to the moon, perform landings with a lander, and return to Earth.  

S-I (C-3): The first stage of the C-3 rocket was intended to be powered by two new F-1 engines.  This is the rocket the F-1 was first ordered for, not the much later C-5 (Saturn V.). The stage diameter would have been 320 Inches, and the overall length would have been about 113 feet.   The Twin F-1 engines would have been on exposed skeletal mounts, the theory at the time being it would reduce the need for “drag-producing” fins by producing the drag with the engine bells themselves.  Likely, a production version of this would have ended up almost looking like the much later Pyrios Booster for Space Launch System.   The S-I (C-3) stage was also sometimes called S-IB-2.   Given that no other S-I stage for the C-3 was ever designed or designated, I choose to ignore the sources that call it S-IB-2 since they all seem to stem from Astronautix.  

S-II (C-3)   This is the first appearance of the S-II stage for the Saturn Family.   Like the S-I (C-3) Stage above, this S-II stage would have been 320 inches in diameter and had 4 J-2 engines.   The overall length would have been closer to 70 feet, meaning the S-II (C-3) would have slightly more fuel mass than the latter S-II (C-2 would have.)    Again, North American Aviation Documents call this the S-II-320.

S-III (C-3)  A short lived stage for the C-3, the S-III here, identical to that of the C-2 rocket, would have served as a waypoint between the S-II (C-3) and the S-IV (C-3.)  Canceled as the S-IVB was ordered into creation.    On this, the Saturn C-3 rocket, the S-III would have been used for final Orbital insertion in LEO with the S-IV being used for post LEO orbit work only.    There is no indication that the “growth” version of the S-IV would have been used with the C-3 rocket.  It is assumed that the S-IV pictured above is the correct S-IV for all S-III launches.

S-I (C-3B)   Latter in the design process for the Saturn rockets, attention was returned to just the first stage of the Saturn C-3 program and a 33ft (10m) S-I (C-3B) was developed.   This would be a 3 F-1 engine powered stage with significant growth of fuel capacity.    The remaining stages would be the same as on the C-3 before it.    Unlike the Latter S-IC for the Saturn V, the 3 engine C-3B S-I would be approximately 8 meters shorter.

S-N (C-3 or C-3B)  In either case of it’s first stage the Nerva-powered S-N stage for the C-3 would have had a diameter of 320 inches and an approximate length of 65 feet.   Given the secrecy around nuclear reactors, and still today for that matter, there are few realistic drawings of what this stage would look like.   

An interesting drawing shows the C-2 with what appears to be a J-2 powered S-II stage and the C-3 with what seems to be an LR-87-powered S-II stage.      The C-3 pictured here has non-representative F-1 engines, while all the other engines appear correctly represented.  These facts put this graphic as sometime in late 1960 or very early 1961, well before the June 1961 cancelation of C-2.  Also, note the C-1 first stage and the C-2 first stage do not show accurate lengths.  I believe this is artist bias as it was clearly stated they would be a different length (C-1 first stage longer than C-2 by about 10ft.) Lastly, while it is hard to see, both the C-1 and C-2 only show four engines in their first stage.   So, E-1s were still considered at the time the artist drew this.

 

Solid Saturn:

Solid Rocket fans had a proposal to use a Solid Rocket booster to launch a C-3 rocket.  This monolithic SRB would later become the much-loved AJ-260 of Saturn Fame.   It would have been in its 4 million pound-force thrust initial long rocket short burn configuration.  The one that would break the Saturn INT-05 as mentioned in a previous article.   The 2^nd stage would still be the larger 320” diameter, so a conic interstage between 260” and 320.”   One thing noted in several documents is the interstage would have blowout panels in the bottom of the conic structure near the juncture of the AJ-260 and the cone.  

And yes, to the observant of you.  Nova is stupidly stupid big.  And while it uses some of the same engines from Saturn, it is NOT A SATURN!   Also, some of the latter MLV proposals for Saturn used some of the engines from NOVA (M-1, anyone?!)

 

Saturn C series C-4 stages:

 

The Saturn C-4 was the first design to reach the moon in one launch.   It would have had little margin for error, and once Liquid Hydrogen was discovered to not store well in space, this Rocket was thrown out of contention.   The switch from Hydrolox to the storable Hypergolic fuel Aerozine50, or 50/50 as most rocket engine engineers called it, dramatically increased the mass at the top of the rocket.   The change in fuel makes this rocket nearly moot from the get-go.   Two sizes were designed from the start.   After Michoud's dimensions were finalized, a 396” diameter quickly supplanted the 320” diameter.   When Data is present, I will provide it in 320” and then 396” dimensions.   It will be noted if no data is available for one size or the other.

S-I (C-4)   4 F-1 engines, 320” x 113.1ft    396” x 95.01ft.

S-II-320  4x J-2 engines, x69.8ft Length.

S-II-396(C4) 4x J-2 Engines,  x 54.98ft Length.

 

Saturn C-4B:   This is a Saturn V in all but name, utilizing a common bulkhead in the S-IC stage.

S-IC (C-4B): 5 F-4 Engines, 396” x 109.77ft  Common bulkhead.  This stage is approximately 10 feet shorter than the latter flat Bulkhead S-IC for the Saturn V in the MLV programs.

S-II-396:  Identical to Saturn V S-II stage.

Several launch configurations did not use the S-IVB but used a 396” payload fairing attached directly to the S-II stage.

 

Oddball Rockets utilizing the Cluster S-I stage:

Saturn-Atlas: Combining an all-up Atlas F Centaur with the Saturn S-I cluster stage.  This idea was removed as silly early in the thought process.   Without major changes to the Atlas Launcher, there was no way to secure the Atlas on top of the S-I stage.  Also Von Braun did not trust the pressurized “Balloon” tank structures.  Part of the Reason the Centaur C and Centaur E would have a thicker skin wall for the never built S-V stage.

Saturn-Titan:   Separate from the earlier Saturn B series of proposals, a stand-alone un-modified Titan I would be mounted on the Saturn Cluster stage.   The interstage would attach to the Titan’s first stage attachment points.   The USAF’s primary concern was the need for the “cooling” vents that were on all the early Titan I and II rockets.   Something that Martin and Aerojet figured out was not needed two years later when designing the SRM attachment points for the Titan III family.

 

All in all, these are just SOME of the various odds and ends left collecting dust by the wayside of the development of the Saturn Rocket family.

 

[Elro2k]

Having a lot of fun now that I've finally figured out how to do a Venus (Eve) Flyby!

 

[gneoff]

I'm using BDB and System Heat, and in my settings there are multiple options for boiloff.  There's the option under the BDB tab as well as under the system heat tab.  Should I have both active or with that double my boiloff?

[Cheesecake]

On 1/3/2024 at 6:47 PM, GoldForest said:

 

 

It's definitely not interstellar fuel switch, I can tell you that. I don't have that mod and I still get the bug. It's a bug inside BDB, the models or deployable engines. But we need deployable engines for the engines to work, so it's unfixable really... 

I can say that I have played more than 1000 hours with BDB and have also made extensive use of the extendable engines. I didn't even come across the error.
If it was a bug in BDB or deployable engines then everyone would have the bug. At least from time to time. But as far as I know this is not the case. And if it's not IFS then it must be a different mod.

[Pappystein]

11 minutes ago, Cheesecake said:

I can say that I have played more than 1000 hours with BDB and have also made extensive use of the extendable engines. I didn't even come across the error.
If it was a bug in BDB or deployable engines then everyone would have the bug. At least from time to time. But as far as I know this is not the case. And if it's not IFS then it must be a different mod.

I am running a pretty lean system... I never paid attention to it, but I, too, have the deploy bug on *SOME* of the engines... EG the SR-119 stage for MX/Peacekeeper/Minotaur IV

Running the Current Dev version
 

[ltajax]

Started a new playthrough, and decided to go for a night launch for Pathfinder 1. However, the weather seems to be against me. 

[Kakub]

I have very very strange bug, when i launched the Apollo mission with Rover attached to the LEM, the whole rocket started loosing apoapsis like it was pushing whole SIV-b stage back. When i decople the rover from the hinge everything went back to normal. Any help with this kraken stuff ?

[septemberWaves]

7 hours ago, Kakub said:

I have very very strange bug, when i launched the Apollo mission with Rover attached to the LEM, the whole rocket started loosing apoapsis like it was pushing whole SIV-b stage back. When i decople the rover from the hinge everything went back to normal. Any help with this kraken stuff ?

Did you lock the robotic parts? You have to lock them during flight to prevent flexing.

Edited January 7 by septemberWaves

[Kakub]

9 hours ago, septemberWaves said:

Did you lock the robotic parts? You have to lock them during flight to prevent flexing.

Yea they are locket and autostrut to the heaviest part

[septemberWaves]

2 hours ago, Kakub said:

Yea they are locket and autostrut to the heaviest part

De-autostrut them. If you have stability issues, I recommend that you use KJR Continued rather than autostruts.

[Kakub]

19 minutes ago, septemberWaves said:

De-autostrut them. If you have stability issues, I recommend that you use KJR Continued rather than autostruts.

I change my KJR to KJR next and it is working now, idk what version of KJR i had but i will try youre proposition maybe it will be better idk. Thanks anyway :3

[bigyihsuan]

I was trying to increase the fuel capacity of the Voyager Mars probe, and apparently the service module doesn't allow fuel crossfeed: (Red line is where the fuel flow graph stops. I've added the fuel line to connect them.)

[septemberWaves]

I've been making some unconventional Saturns.

Juno V-A and V-B, and Saturn A-2 and B-1:

Spoiler

Juno V-A uses a cluster of Juno II first stages as its second stage, and an entire Titan I as its third and fourth stages. This build requires the first stage to be underfueled to about 70% to allow it to get off of the pad, and it can transport something in the range of 2 to 3 tonnes to a trans-lunar trajectory - though you'd have to launch directly to TLI because the Titan I upper stage in reality would likely have been unable to restart in vacuum.

Juno V-B replaces the fourth stage (a Titan I second stage) with a Centaur. The payload capacity is very similar (though seems to be somewhat better), and the first stage once again must be underfueled to 70%.

Saturn A-2 retains the Juno cluster from Juno V, but removes the Titan I stages entirely in favour of a lone Centaur. This one can launch with a full load of fuel (just barely); payload to TLI is approximately the mass of one Gemini spacecraft, which is probably what it would be best at launching. Its limited TWR means that Saturn A-2, like both Juno V variants, is probably not well suited to launching anything to low Earth orbit.

Saturn B-1 (not to be confused with Saturn IB) uses a Titan cluster rather than a Juno cluster. The third and fourth stages are an S-IV and a Centaur, respectively. The tanks of the cluster are Titan 1 first stage tanks, but the engines are the Titan II's LR-87-5, rather than the LR-87-3 used on Titan I.

The first stage is underfueled to 70% once again, and the second stage (the Titan cluster) is underfueled to 80%. Additionally, the second stage engines are reduced to 60% throttle, because otherwise the acceleration is far too high. Payload capacity is somewhere in the range of 4 to 7 tonnes to TLI, so it'd be a good launcher for small station modules or a resupply vehicle, both for a lunar orbit station.

 

Saturn C-3, C-4, and C-8:

Spoiler

Saturn C-3:

The 1959 design for the Saturn C-3 is a five-stage rocket. The S-IB-2 first stage is powered by two F-1 engines. The S-II-C3 second stage has four J-2 engines, and is less wide than the typical S-II. The S-III third stage is similar to the S-IVB, but with four J-2 engines rather than one. The fourth stage is the S-IV, and the fifth stage is the Centaur (otherwise known in this context as the S-V). The payload capacity of this rocket is very high, but TWR at launch is extremely low. Even with uprated first stage engines (F-1A rather than F-1), the first three stages must be underfueled to 70% capacity for the rocket to even take off. With all five stages, the rocket is probably best suited to launching especially massive interplanetary space probes, or (with a large enough fairing) modules for a lunar space station.

The 1961 design for the C-3 omits the S-III stage in favour of a lengthened S-II-C stage. The Centaur is inside the fairing. With this build, the first stage must be underfueled to 60% and the second stage to 80%. Payload capacity is not substantially better than the B-1, but would be drastically improved if the first stage engines had more thrust.

Saturn C-3B:

This is the first of these early Saturns that actually starts to resemble the Saturn V. The diameter of its first two stages should actually be slightly less than the Saturn V, but this is the closest I can get.

The S-IC-C3B first stage is similar to the S-IC of the Saturn V, but is shorter (and ideally would be slightly less wide). While the BDB S-IC-C3B should usually be underfueled to 80% for KSRSS balance, this one is underfueled to 70% to account for the smaller diameter that it should have.

Like the first stage, the S-II-C5B second stage is a shorter (and hypothetically smaller diameter) variant of the S-II of the Saturn V. It is underfueled to 90% in this build to account for the reduced diameter.

The third stage is a smaller diameter version of the S-IVB that actually flew, but is a similar length. The fourth stage is a Centaur.

The C-3B has a payload capacity of around 35 tonnes to LEO, or about half as much to TLI. Due to the very low TWR of the upper stages with high payload mass, it is much better suited for lunar payloads than LEO ones.

Saturn C-4:

The Saturn C-4 uses a shorter, four-engine version of the C-3B first stage, and does the same for the C-3B second stage; both of these are underfueled by the same amount as my C-3B. The third stage is a shorter version of the S-IVB that actually flew, but is otherwise very similar. The C-4 is smaller and cheaper than the C-3B, and has accordingly lower payload capacity: about 26 tonnes to LEO or 10 tonnes to TLI. Unlike the C-3B, the C-4 is well suited to the task of lifting large payloads to low Earth orbit.

Saturn C-4B:

The Saturn C-4B uses the same first and second stages as the C-3B (the first stage should be slightly shorter, but BDB doesn't have a part switch for such a small difference in length). The S-IVB-C5A third stage is a lengthened version of the S-IVB-C3B used on the Saturn C-3B. Payload performance is very similar to the C-3B, but there is no fourth stage.

Saturn C-8:

The Saturn C-8 is a concept developed to study the requirements of a direct ascent lunar landing. The C-8 uses a widened first stage with 8 F-1 engines, a slightly lengthened S-II second stage with 8 J-2 engines, and a substantially lengthened S-IVB third stage. The payload capacity of this build is around 120 tonnes to LEO, or 75 tonnes to TLI.

Edited January 8 by septemberWaves

[DaveyJ576]

16 hours ago, septemberWaves said:

I've been making some unconventional Saturns.

Juno V-A and V-B, and Saturn A-2 and B-1:

  Reveal hidden contents

Juno V-A uses a cluster of Juno II first stages as its second stage, and an entire Titan I as its third and fourth stages. This build requires the first stage to be underfueled to about 70% to allow it to get off of the pad, and it can transport something in the range of 2 to 3 tonnes to a trans-lunar trajectory - though you'd have to launch directly to TLI because the Titan I upper stage in reality would likely have been unable to restart in vacuum.

Juno V-B replaces the fourth stage (a Titan I second stage) with a Centaur. The payload capacity is very similar (though seems to be somewhat better), and the first stage once again must be underfueled to 70%.

Saturn A-2 retains the Juno cluster from Juno V, but removes the Titan I stages entirely in favour of a lone Centaur. This one can launch with a full load of fuel (just barely); payload to TLI is approximately the mass of one Gemini spacecraft, which is probably what it would be best at launching. Its limited TWR means that Saturn A-2, like both Juno V variants, is probably not well suited to launching anything to low Earth orbit.

Saturn B-1 (not to be confused with Saturn IB) uses a Titan cluster rather than a Juno cluster. The third and fourth stages are an S-IV and a Centaur, respectively. The tanks of the cluster are Titan 1 first stage tanks, but the engines are the Titan II's LR-87-5, rather than the LR-87-3 used on Titan I.

The first stage is underfueled to 70% once again, and the second stage (the Titan cluster) is underfueled to 80%. Additionally, the second stage engines are reduced to 60% throttle, because otherwise the acceleration is far too high. Payload capacity is somewhere in the range of 4 to 7 tonnes to TLI, so it'd be a good launcher for small station modules or a resupply vehicle, both for a lunar orbit station.

 

Saturn C-3, C-4, and C-8:

  Reveal hidden contents

Saturn C-3:

The 1959 design for the Saturn C-3 is a five-stage rocket. The S-IB-2 first stage is powered by two F-1 engines. The S-II-C3 second stage has four J-2 engines, and is less wide than the typical S-II. The S-III third stage is similar to the S-IVB, but with four J-2 engines rather than one. The fourth stage is the S-IV, and the fifth stage is the Centaur (otherwise known in this context as the S-V). The payload capacity of this rocket is very high, but TWR at launch is extremely low. Even with uprated first stage engines (F-1A rather than F-1), the first three stages must be underfueled to 70% capacity for the rocket to even take off. With all five stages, the rocket is probably best suited to launching especially massive interplanetary space probes, or (with a large enough fairing) modules for a lunar space station.

The 1961 design for the C-3 omits the S-III stage in favour of a lengthened S-II-C stage. The Centaur is inside the fairing. With this build, the first stage must be underfueled to 60% and the second stage to 80%. Payload capacity is not substantially better than the B-1, but would be drastically improved if the first stage engines had more thrust.

Saturn C-3B:

This is the first of these early Saturns that actually starts to resemble the Saturn V. The diameter of its first two stages should actually be slightly less than the Saturn V, but this is the closest I can get.

The S-IC-C3B first stage is similar to the S-IC of the Saturn V, but is shorter (and ideally would be slightly less wide). While the BDB S-IC-C3B should usually be underfueled to 80% for KSRSS balance, this one is underfueled to 70% to account for the smaller diameter that it should have.

Like the first stage, the S-II-C5B second stage is a shorter (and hypothetically smaller diameter) variant of the S-II of the Saturn V. It is underfueled to 90% in this build to account for the reduced diameter.

The third stage is a smaller diameter version of the S-IVB that actually flew, but is a similar length. The fourth stage is a Centaur.

The C-3B has a payload capacity of around 35 tonnes to LEO, or about half as much to TLI. Due to the very low TWR of the upper stages with high payload mass, it is much better suited for lunar payloads than LEO ones.

Saturn C-4:

The Saturn C-4 uses a shorter, four-engine version of the C-3B first stage, and does the same for the C-3B second stage; both of these are underfueled by the same amount as my C-3B. The third stage is a shorter version of the S-IVB that actually flew, but is otherwise very similar. The C-4 is smaller and cheaper than the C-3B, and has accordingly lower payload capacity: about 26 tonnes to LEO or 10 tonnes to TLI. Unlike the C-3B, the C-4 is well suited to the task of lifting large payloads to low Earth orbit.

Saturn C-4B:

The Saturn C-4B uses the same first and second stages as the C-3B (the first stage should be slightly shorter, but BDB doesn't have a part switch for such a small difference in length). The S-IVB-C5A third stage is a lengthened version of the S-IVB-C3B used on the Saturn C-3B. Payload performance is very similar to the C-3B, but there is no fourth stage.

Saturn C-8:

The Saturn C-8 is a concept developed to study the requirements of a direct ascent lunar landing. The C-8 uses a widened first stage with 8 F-1 engines, a slightly lengthened S-II second stage with 8 J-2 engines, and a substantially lengthened S-IVB third stage. The payload capacity of this build is around 120 tonnes to LEO, or 75 tonnes to TLI.

Very nice kitbashing. I have my own versions of the C-2 and C-3. I have wondered about the B-series Saturns. Might try those too! Clustered tanks seem like such an engineering compromise though.

[Pappystein]

16 hours ago, septemberWaves said:

I've been making some unconventional Saturns.

Juno V-A and V-B, and Saturn A-2 and B-1:

  Reveal hidden contents

Juno V-A uses a cluster of Juno II first stages as its second stage, and an entire Titan I as its third and fourth stages. This build requires the first stage to be underfueled to about 70% to allow it to get off of the pad, and it can transport something in the range of 2 to 3 tonnes to a trans-lunar trajectory - though you'd have to launch directly to TLI because the Titan I upper stage in reality would likely have been unable to restart in vacuum.

Juno V-B replaces the fourth stage (a Titan I second stage) with a Centaur. The payload capacity is very similar (though seems to be somewhat better), and the first stage once again must be underfueled to 70%.

Saturn A-2 retains the Juno cluster from Juno V, but removes the Titan I stages entirely in favour of a lone Centaur. This one can launch with a full load of fuel (just barely); payload to TLI is approximately the mass of one Gemini spacecraft, which is probably what it would be best at launching. Its limited TWR means that Saturn A-2, like both Juno V variants, is probably not well suited to launching anything to low Earth orbit.

Saturn B-1 (not to be confused with Saturn IB) uses a Titan cluster rather than a Juno cluster. The third and fourth stages are an S-IV and a Centaur, respectively. The tanks of the cluster are Titan 1 first stage tanks, but the engines are the Titan II's LR-87-5, rather than the LR-87-3 used on Titan I.

The first stage is underfueled to 70% once again, and the second stage (the Titan cluster) is underfueled to 80%. Additionally, the second stage engines are reduced to 60% throttle, because otherwise the acceleration is far too high. Payload capacity is somewhere in the range of 4 to 7 tonnes to TLI, so it'd be a good launcher for small station modules or a resupply vehicle, both for a lunar orbit station.

 

Saturn C-3, C-4, and C-8:

  Hide contents

Saturn C-3:

The 1959 design for the Saturn C-3 is a five-stage rocket. The S-IB-2 first stage is powered by two F-1 engines. The S-II-C3 second stage has four J-2 engines, and is less wide than the typical S-II. The S-III third stage is similar to the S-IVB, but with four J-2 engines rather than one. The fourth stage is the S-IV, and the fifth stage is the Centaur (otherwise known in this context as the S-V). The payload capacity of this rocket is very high, but TWR at launch is extremely low. Even with uprated first stage engines (F-1A rather than F-1), the first three stages must be underfueled to 70% capacity for the rocket to even take off. With all five stages, the rocket is probably best suited to launching especially massive interplanetary space probes, or (with a large enough fairing) modules for a lunar space station.

The 1961 design for the C-3 omits the S-III stage in favour of a lengthened S-II-C stage. The Centaur is inside the fairing. With this build, the first stage must be underfueled to 60% and the second stage to 80%. Payload capacity is not substantially better than the B-1, but would be drastically improved if the first stage engines had more thrust.

Saturn C-3B:

This is the first of these early Saturns that actually starts to resemble the Saturn V. The diameter of its first two stages should actually be slightly less than the Saturn V, but this is the closest I can get.

The S-IC-C3B first stage is similar to the S-IC of the Saturn V, but is shorter (and ideally would be slightly less wide). While the BDB S-IC-C3B should usually be underfueled to 80% for KSRSS balance, this one is underfueled to 70% to account for the smaller diameter that it should have.

Like the first stage, the S-II-C5B second stage is a shorter (and hypothetically smaller diameter) variant of the S-II of the Saturn V. It is underfueled to 90% in this build to account for the reduced diameter.

The third stage is a smaller diameter version of the S-IVB that actually flew, but is a similar length. The fourth stage is a Centaur.

The C-3B has a payload capacity of around 35 tonnes to LEO, or about half as much to TLI. Due to the very low TWR of the upper stages with high payload mass, it is much better suited for lunar payloads than LEO ones.

Saturn C-4:

The Saturn C-4 uses a shorter, four-engine version of the C-3B first stage, and does the same for the C-3B second stage; both of these are underfueled by the same amount as my C-3B. The third stage is a shorter version of the S-IVB that actually flew, but is otherwise very similar. The C-4 is smaller and cheaper than the C-3B, and has accordingly lower payload capacity: about 26 tonnes to LEO or 10 tonnes to TLI. Unlike the C-3B, the C-4 is well suited to the task of lifting large payloads to low Earth orbit.

Saturn C-4B:

The Saturn C-4B uses the same first and second stages as the C-3B (the first stage should be slightly shorter, but BDB doesn't have a part switch for such a small difference in length). The S-IVB-C5A third stage is a lengthened version of the S-IVB-C3B used on the Saturn C-3B. Payload performance is very similar to the C-3B, but there is no fourth stage.

Saturn C-8:

The Saturn C-8 is a concept developed to study the requirements of a direct ascent lunar landing. The C-8 uses a widened first stage with 8 F-1 engines, a slightly lengthened S-II second stage with 8 J-2 engines, and a substantially lengthened S-IVB third stage. The payload capacity of this build is around 120 tonnes to LEO, or 75 tonnes to TLI.

Thanks for sharing!   Wonderful pics and interesting ways to kitbash to make some of this work.  Your early Saturns probably should have 4x E-1 engines on them.   Looks like you used 8x H-2s which was not the engine of choice when those were conceptualized.  E-1 was canceled a few months before the cancellation of C-2 and C-3 (and its cancellation is directly responsible for the development of the S-IVB and the S-IVC.)

 

I have a relatively minor nitpick.

So as, *I guess* the local expert on S-III, there were exactly 2 designs for S-III.   1st was a notational stage with no known engine properties... it would have 2 Hydrolox engines.  Either the J-2 or the LR87-LH2   In the case of the LR-87-LH2 (whatever designation it would have received) it was a TWO bell engine... Just like on Titan...    The Notational S-III stage was 220" diameter, or the original diameter of the 4 engine S-IV.      The second and Final design, likely to be built by McDonnell Corp, was 260" in diameter and about 2/3rds of the height of the actually produced S-IVB.   It would have 2 engines...   So 2 Bells with J-2s or 4 bells with the LR-87.    <<<----  This is where the idea that the S-III was a 4 engine stage comes from.   Only 2x engines would be used.     And before someone jumps on me about the LR87... Just because the Hydrolox test engine was a single bell does not meant the production engine was!      Also Somewhere I have a photo of a single bell AZ50/NTO test engine too

S-III stage was deleted long before Lunar Orbital Rendezvous was selected.  So late 1960.

 

[septemberWaves]

20 minutes ago, DaveyJ576 said:

Very nice kitbashing. I have my own versions of the C-2 and C-3. I have wondered about the B-series Saturns. Might try those too! Clustered tanks seem like such an engineering compromise though.

Clustered tanks are absolutely an engineering compromise, and they're an engineering compromise that made it all the way to the Saturn I and IB rockets that actually launched. Being able to reuse existing manufacturing facilities with minimal changes to tooling, or simply being able to reuse surplus older rockets that were never launched, is certainly a good reason to consider clustered tanks. Compared to a single fuel tank with the same volume, a cluster of tanks has higher dry mass and is longer (the latter of which necessitates a taller assembly building, if the rest of the rocket is unchanged). The reason it was done for the first stage, and likely the reason it was considered for upper stages of these early Saturns, is because it is cheaper to manufacture (at least hypothetically).

[Pappystein]

10 minutes ago, septemberWaves said:

Clustered tanks are absolutely an engineering compromise, and they're an engineering compromise that made it all the way to the Saturn I and IB rockets that actually launched. Being able to reuse existing manufacturing facilities with minimal changes to tooling, or simply being able to reuse surplus older rockets that were never launched, is certainly a good reason to consider clustered tanks. Compared to a single fuel tank with the same volume, a cluster of tanks has higher dry mass and is longer (the latter of which necessitates a taller assembly building, if the rest of the rocket is unchanged). The reason it was done for the first stage, and likely the reason it was considered for upper stages of these early Saturns, is because it is cheaper to manufacture (at least hypothetically).

All very true...   Something else... the C-2's Cluster stage needs to be about 10 feet shorter than the C-1/Saturn I's Cluster stage... I just drop it 3 click of fuel and oxidizer (so 85% max capacity)   I find it close enough with a S-III stage (or S-II-260 stage)

 

[ltajax]

Noticed I am getting a lot of errors popping up on launch related to 'RealPlume'. Any idea what might be causing it ? Please fine attached below a screenshot of my mod list, and a link to a copy of my player log file
 

Managed to fix the issue, it was down to what appeared to be a bad install of realplume

Edited January 10 by ltajax

[septemberWaves]

4 hours ago, Pappystein said:

Thanks for sharing!   Wonderful pics and interesting ways to kitbash to make some of this work.  Your early Saturns probably should have 4x E-1 engines on them.   Looks like you used 8x H-2s which was not the engine of choice when those were conceptualized.  E-1 was canceled a few months before the cancellation of C-2 and C-3 (and its cancellation is directly responsible for the development of the S-IVB and the S-IVC.)

 

I have a relatively minor nitpick.

So as, *I guess* the local expert on S-III, there were exactly 2 designs for S-III.   1st was a notational stage with no known engine properties... it would have 2 Hydrolox engines.  Either the J-2 or the LR87-LH2   In the case of the LR-87-LH2 (whatever designation it would have received) it was a TWO bell engine... Just like on Titan...    The Notational S-III stage was 220" diameter, or the original diameter of the 4 engine S-IV.      The second and Final design, likely to be built by McDonnell Corp, was 260" in diameter and about 2/3rds of the height of the actually produced S-IVB.   It would have 2 engines...   So 2 Bells with J-2s or 4 bells with the LR-87.    <<<----  This is where the idea that the S-III was a 4 engine stage comes from.   Only 2x engines would be used.     And before someone jumps on me about the LR87... Just because the Hydrolox test engine was a single bell does not meant the production engine was!      Also Somewhere I have a photo of a single bell AZ50/NTO test engine too

S-III stage was deleted long before Lunar Orbital Rendezvous was selected.  So late 1960.

 

Regarding these comments: I based these Saturn builds on Friznit's unofficial BDB wiki, so any incorrect design choices come from there.

[Friznit]

Feedback / corrections on the wiki always welcome of course, though where information is scarce or merely speculative, I've just picked something that works/looks reasonable and can be built using existing BDB parts.

[Teslamax]

15 hours ago, Friznit said:

Feedback / corrections on the wiki always welcome of course, though where information is scarce or merely speculative, I've just picked something that works/looks reasonable and can be built using existing BDB parts.

The only thing I don't like is that I use dark mode in GitHub. In that case all your beautiful craft diagrams are black text on very dark grey background. I can't see the text.

I greatly appreciate transparent backgrounds in images like that. But the text is hard to see.

Probably just a "me" problem.

Your Wiki is amazing!

[dave1904]

what avionics unit is supposed to be used on the Minutemann III? Its metioned and even pictured in the wiki but I cannot find it. 

 

[YellowNOFX]

Where should you put the "Craft Files" folder? Just straight in GameData?

[Pappystein]

So given all the "fun" this week regarding stages for the Saturn Rockets... I thought I would repost an old article of mine that is exhaustive in its detail on the stages as well as well cited... the Article I posted last week (at the top of this page) was not well cited and, in fact, is a precursor to the article I have here.

 

Saturn C-2 and C-3, the Unflown and Unloved Rockets in the Saturn Family:

Spoiler

 

 

The Saturn family all started because DARPA, the Defense Advanced Research Projects Agency, was looking to the future of the fledgling space program.    DARPA, often shortened to ARPA to seem less militant, had money and a goal of getting an American Astronaut into space.   DARPA utilized this project to push technology to ensure space dominance by the United States.  DARPA approached the nearly out-of-work ABMA or Army Ballistic Missile Agency and Von Braun to utilize their rocketry know-how to build a cheap large, diameter rocket to get payloads to space.   The Projected growth in the size of satellites is somewhat staggering and astounding.   Mind you all; this was still in the days when a Digital computer was the size of a large school.

Von Braun and team immediately made a significant compromise to keep things cheap and quick.  They would reuse the tooling for both their Redstone and Jupiter missiles.   With this tooling, they could make cylinders any length they wanted at the diameter of these two rockets.   This decision added mass and complexity to the design but likely cut several years off its design process.   Of course, this Cluster stage was called Juno V as we all know.   The Juno V stage would be the basis for several rockets and rocket stages before finally flying as the Saturn S-I stage a few years later.   ABMA and Von Braun proposed to DARPA that the rocket should be as modular as possible so that different parts could be swapped from one rocket to the next to make a new different rocket.   In early 1960 these building block stages were as follows:

·       Juno V (C-1) What would later become the S-I and, after modification, the S-IB

·       Juno V (C-2) Similar to the above but 65" shorter to reduce maximum fuel and oxidizer to 650,000lbs

·       S-I Monohull Replacement monohull for the C-1's Juno V

·       S-I Monohull Replacement for the C-2's Cluster tank with a monohull, shorter than the C-1's Monohull option.

·       S-I New twin F-1 Engine first stage for C-3 of 320" diameter, monohull construction

·       S-II-260 (C-2) 4 engine 260" Diameter stage for C-2

·       S-II-320 (C-3) 4 engine  320" Diameter 2^nd Stage for the C-3

·       S-III (C-2/C-3) 2 J-2 engine 220-260" Diameter stage, usable as the 2^nd stage on C-2 or the 3^rd stage on C-3

·       S-IV 220" (C-1)  Original four RL10B-3 powered stage for the C-1 rocket

·       S-IV 240" (C-1) Finalized six RL10A-3S powered stage for Saturn I Rocket

·       S-IV (C-2) 240" Four RL10B-3 powered upper stage for the C-2 rocket

·       S-IV (C-3) 240" six RL10B-3 powered upper stage for the C-3 rocket, a RL10A-3S powered version would be the final C-2 variant

·       S-IVB (C-1 & C-2) Standard S-IVB-100 from the Saturn IB rocket***

·       S-IVC (C-3) 260" S-IVB design with inline (nose to tail) docking for similar S-IVC stages to allow building in space and refueling of the S-IVC stages.

·       S-V (C-1/C-2/C-3)  Centaur C.   Was an improved Centaur that would carry its insulation to stage ignition and then burn for departure.  Power was by 2x RL10B-3 engines, and the skin was thicker, making it no longer a proper Balloon tank structure.   Extra HTP Peroxide tanks for extended use of the Reaction Control System.

Some notes here:

1.      The S-IV (C-2/C-3) jettisoned much of it's insulation at stage ignition.   Insulation was not discarded before stage ignition to reduce boiloff during any early cruise portions of the flight.   The same is true for the S-V stage.    

2.      The RL-10B-3 is the uprated "XLR-119" that we have heard about for years but never knew much about.   It is unclear how Pratt and Whitney applied any Nomenclature to their engines, so when more information is available, we may be able to share it.  The designed thrust (never reached in testing) was 20,000lbs force.

3.      The RL10-A3S is not an uprated RL10A-3 but rather just an RL10A-3 with Saturn-specific modifications.  Thrust is still 15,000lbs force.

4.      Initially, the H-1 engine topped out at about 188,000lbf thrust.  Latter, Saturn I's would fly at 200,000lbf thrust, and there was room to grow to about 250,000lbf thrust via the H-2 Engine upgrade.   While not much is known about the latter H-2 we do know it was a basic H-1 with a new type of Turbopump that was faster and more efficient, which allowed the pressure in the combustion chamber to be raised, creating more thrust.

5.      Much of this article is based on the Preliminary design for the C-2 from Marshal Space Flight Center (eg ex ABMA.)   These building blocks were not "Solid" and could still change… Just look as the S-IV stage for Saturn I… it grew 20" in diameter and gained 2 engines after said PDR was released!

6.      North American Aviation, the designer and fabricator of the S-II stage, chose to delineate the various S-II stages by their diameter as the stages were unique in each diameter.  So the, Saturn V's S-II stage was called S-II-396 for example, the last number being the average diameter of the stage in inches.  Since only one S-II stage was proposed for each of these rockets at the specified diameter, we will use the same terminology in the document.

7.      KSP scale and BDB are referenced in this document.   KSP being Kerbal Space Program and BDB being the Bluedog Design Bureau mod for Kerbal Space Program.   The intended original audience of this document.

8.      While this document lists the S-IVB-100 as appropriate for the Saturn C-2 the Saturn C-2 was actually canceled about the same time as the development of the lower massed Orbital vs Lunar Saturn S-IVB.  

 

 

Saturn Stage Nomenclature:

NASA and ABMA/MSFC did an abysmal job with stage designations, lots of assumptions were made that you knew what rocket you were talking about when talking about, say the S-I stage.  

The above text is directly from The Saturn C-2 Preliminary Design Phase I document.   Utilizing the S-I stage, the differences between the C-1 and C-2 stages are relatively minor… the C-2's S-I is shorter and carries 200,000 lbs less fuel.   Conversely, the C-3's stage is a new 320" diameter mono hull with 2 of the new F-1 engines.   But they are all called S-I.  Same with S-II and S-IV, each rocket that has one of these stages has a unique, or nearly unique, to its stage variant.      For the purposes of clarity, in this document any stage named will have it's base rocket in parentheses eg S-I(C-3.)    Please note that there are no references to a S-IB-2 as listed on Astronautix or Wikipedia (quoting Astronautix.)    That appears to be a fictitious name to separate it from the Saturn IB's S-IB stage on Astronautix.    As stated above, we will use North American Aviation's designation for their various S-II stages because they A) make sense and B) give you the size of the thing, in one simple package.

 

Building Block S-I:

The S-I stage on the C-2 rocket differed only slightly for the Block 1 Saturn I Rocket that first flew on 10/27/1961.   The major structural changes were in shortening the stage by 65" to reduce fuel capacity to a maximum of 650,000lbs between the fuel and oxidizer.   There were no drawings with the S-I stage carrying fins on the C-2 rocket that the author could find.

Like the Saturn I rocket, the S-I stage for this rocket was large, kludgey, and the only thing it had going for it was low cost to begin manufacture due to the reuse of many of the Redstone/Jupiter tools.

 

 

Building Block S-I Monohull:

No NASA designation was listed for this unique Saturn C-2 development.   Designed as a production standard for the C-2's S-I stage, the Mono-hull used 8 H-1 engines in a single ring around the outer edge of the stage.  None of the engines were particularly submerged like the original Cluster S-I as described above.   Because of the nature of the simplified construction, there was no provision in the stage at the time of the source material, for Fins to be attached.   The total tank and engine length is 496" long. Compared to the S-I Cluster stage at 1915" long a significant size shrinkage can be seen.  This led to improvements in payload to orbit and total rocket size, which can lead to reduced launch costs.  Suggested designation is S-IM(C-2) M for monohull in this case.

 

 

With a modest estimated 30" stretch, the S-IM(C-2) could become the S-IM(C-1) for Saturn I rockets.   No document found to date covers the Saturn I usage, however.     Stretched size is estimated based on adding 200,000 of fuel and oxidizer back onto the first stage.

While no Solid first stage was ever designed for the C-2 rocket, any of the Saturn I Solid first stages would likely have worked in situ.  

 

               Building Block: S-I (C-3)

Here, we see the first vestiges of what would become the Saturn V moon Rocket emerge.   The F-1 engine is, for the first time, planned on a rocket stage; a large monohull stage of 320" diameter is planned.    Two versions of this stage are designed based mainly on the positioning of the engines.   The wider stance of engines allows enough room for a 3^rd engine in the center of the rocket should it be needed (and this is the drawing we have.)   The more economical version, smaller in it's maximum diameter, has the two engines 45" closer together.      The gross dimensions are 320" main diameter by 1092" long from the bottom of the F-1s to the top of the upper tank lip.

 

 

If you think the Above booster looks a lot like the now long canceled "Pyrios" Booster for Artemis, you would not be too far off!

For the thrust structure, three different options were studied.   From the standpoint of reliability and cost, the main drawing is the most efficient, but it is the second tallest option, and height adds weight in this case.   Included is an illustration of the three thrust structure choices.

Thrust Structure options and descriptions:

·       Option A) Gains 10" in excess height off the baseline drawing.    Engines are moved 45" closer to the center, this reduces instant yaw/pitch if an engine out situation arises but does not effectively provide any sort of efficiency or drag reduction.  

·       Option BASELINE)  standardized stage structure.   Base structure design can be reused in future rocket stages.   Not the most efficient for weight or height

·       Option C)  Reduces total height of stage by a staggering 100." While this shortening of the stage potentially reduces overall mass, it significantly increases complexity.  Likely a 2^nd set of turbopumps would be required.

 

 

               Building Block S-IS (C-3)

In a departure from the norm at the time, the C-3 was planned with an alternative "low cost," Solid rocket stage to repace S-I (C-3.)    In drawings, the rockets used appear to be 4 segment UA-1204s but they lack the Liquid TVC injection tanks.   Likely instead of 7x 4segment Rockets, it would be 6x 5 or 6 segment rockets to deliver a similar thrust.  This leaves enough room for TVC liquid injection tanks.   The drawing is missing all scale references, and it appears to have a diameter of greater than 354" 354/3 is approximately 118" lending credence to the thought of a 120" SRM utilized in this stage.

Then there is everyone's favorite, the Giant, Monohull AJ-260 Saturn C-3 first stage:

  

The Other two rockets in this picture are both All solid Nova Rocket proposals.

 

Building Block S-II-260 (C-2):

Between 1959 and June 1960, it was determined that the proposed S-III stage for the C-2 rocket would be too small.  Further, the 220" diameter of the tank caused issues with bending moments when combined with the 260" first stage diameter.   The decision was made to move the S-III to the C-3 rocket at this juncture and then build a smaller 220" Diameter S-II stage for the C-2 rocket with four engines.   Quickly, this again fell by the wayside as the 220" diameter did not work without severe compromise on the C-2 rocket.   The final stage, a 260" by approximately 700" tank and engine stage, would provide enough thrust for the largest then planned payloads to orbit. 

 

 

               Building Block S-II-320 (C-3):

When conceptualizing the need for a bigger rocket than the C-2, the engineers at MSFS quickly conceptualized the new monohull S-II stage for the C-3.   Designed here first at 320" diameter, before being shrunk down to fit on the C-2 rocket as an S-III replacement, the C-3's S-II-320 design was the most complete before canceling.   While drawings for the C-2 S-II-260 sometimes show an individual hydrogen feed to each engine, the author believes that the combined twin feed as depicted here would continue production as it did on the S-II-396 stage Saturn V.

 

 

Building Block S-III (C-2 and C-3):

In the face of the growing payload requirements, the 220" S-III stage was deleted from the C-2 Program.  The S-II-260" stage replaced the S-III stage.  The S-III stage would evolve into a 260" stage very briefly but was never assigned to a Rocket in that size.   Instead, the S-III was removed from consideration for the C-3 rocket at the time S-II-320 was expanded from 260 to 320" diameter.   There was no attempt at designing a 320" diameter version of the S-III.

 

This image is from a different source and predates the 260" size increase.

A rough calculation utilizing everyone's favorite cylindrical volume formula gives us a 260" by 43ft tank size for the 260" S-III.  This is between the same size as the S-IVB tankage or just slightly longer.    The S-III stage was intended for Orbital insertion with Orbital circulation completely by the S-IV stage.     Likely a smaller bell would have been used on these J-2s

 

Building Block: S-IV(C-1, C-2, and C-3)

As initially conceived, the S-IV stage would be the same between the C-1, C-2 and C-3 rockets.  It would be a 220" diameter Hydrolox stage powered by 4x of the still-to-be-built LR119, a.k.a. RL10B-3 engines.   Quickly, it was realized that the C-3 could take advantage of a larger S-IV stage and it was expanded to 240" with 6x of the RL10B-3 engines.  As progress was made on the other stages, the decision to eliminate the 220" diameter for the S-II(any) and S-III(any) stages had an impact on the S-IV.  Why make it with two diameters if 220" is bad?  The S-IV became 240" across all three rockets.   Differences being limited to tank profile and overall tank length between each of the Rockets, engines excluded.  The S-IV(C-1) and S-IV(C-2) are similar except for insulation.  The S-IV(C-3) is slightly longer than the S-IV(C-2) as well.  The engine mounts and interfaces to lower stages remaining consistent for each of the 3 iterations of the S-IV stage.   Due to a looming cancelation of the RL10B-3, it was decided to convert the S-IV stage for the C-1 and C-2 Rocket to a 6 engine design.   The six-engine mount already planned for the S-IV (C-3) would be utilized with the lower power RL10A-3.    In the case of the S-IV(C-3) the design was altered to a single J-2 engine.  This set of engine switches would eventually lead to the optimized S-IVB that flew to space on the Saturn I and V rockets.   Only a few minor changes were required with the decision to utilize the RL10A-3 from the Centaur.  These new engines, designated RL10A-3S, only have modifications to allow the centaur engine to interface with the Saturn S-IV rocket stage.  One other significant change existed between the C-1 S-IV and the C-2's S-IV.  The S-IV(C-2) utilized an add-on,  jettisonable insulation blanket outside the standard S-IV tankage to reduce boiloff before engine ignition during the coast phase.  These panels surround the conic and cylindrical portions of the tankage up to the LOX portion of the tank.  There are also extra thermal blankets between the top of the S-IV(C-2) stage and the Instrument Unit (IU).   Internally, additional insulation is added between the Hydrogen and Oxygen tanks.    The Larger S-IV(C-3) with its longer tank utilized the same discardable insulation for use up to engine ignition.   The S-IV stage had the most in common structurally from one Saturn rocket variant to the next.   During the creation of this document, I could find zero drawings of a C-2 S-IV at 240".   The C-3's S-IV disappeared simultaneously as the decision to fly Saturn with the S-IVB stage.  

 

C-I S-IV-220" Mockup note 4x RL10-B-3 engines.  Note the "blown out" scallops to inter-mesh with the 220" interface on the S-I to S-IV interstage.  These would become almost smoothly cylindrical on the 240" version of this stage.

Saturn C-2 S-IV-220" drawing (note the similar length vs the Saturn C-1/S-1's S-IV?)  

 

               Building Block Interlude, the Saturn S-IVB and S-IVC (no, not the ETS one!):

While not designed or fully fleshed out at the point of the C-2 rocket preliminary design, we can not afford to ignore the S-IVB and it's S-IVC sibling.    The S-IVB stage replaced a fair but overly complex S-IV stage with a higher thrust but similar total Delta-V and a much simpler stage.   With the S-IVB we can have a larger payload fairing.  This means the S-V stage can carry less external insulation.    The S-IVC introduced slush fuel LH2 and end-to-end docking ports.  All of the changes were planned to bring about the orbital construction of a Lunar rocket.  The S-IVC stage was proposed to fly the Command/lander module of a Saturn C-3 to a Lunar landing.  An Un-crewed Lunar lander C-3 would launch with 1x S-IVC,  A second C-3 drone ship equipped with a PLF to protect the S-IVC would then launch rendezvous with the on-orbit C-3 stack and dock nose to the tail of the on-orbit C-3 stack.  Then a 3^rd S-IVC would launch with a small tug attached.   From here, several refueling flights and a crew delivery flight would be flown before sending the stack off to the Moon.

 

 

Building Block S-V, not your daddy's Centaur:

The S-V stage is loosely based upon the Centaur that flew on Atlas and Titan rockets.  However, it is not the same stage beyond initial concepts and broad shapes.   Initially called Centaur C by Convair and the newly named Marshal Space Flight Center, the S-V stage would support greater payloads and longer coast times than pre-SOFI Centaurs.   The tanks' skin thickness was almost tripled to support these longer flight times and greater payloads, making them self-supporting or monocoque.   These improvements had the benefit of reducing boiloff as the tank's maximum pressure level was significantly higher.   Additional propellant bottles for the cold gas RCS system were added.   Finally, the detachable insulation was thickened.  All these changes translate into a rocket stage that has the overall performance of a Centaur but can last longer in space and or carry a heavier payload.     Of course, the additional mass of all these changes needed new engines; as mentioned in the S-IV section above, Pratt and Whitney were working on the LR119/RL10B-3 for the USAF, and they would power the S-V stage.  

Two factors prevented Centaur C from ever flying on Saturn.

1.      Cancelation of the RL10B-3 Hydrolox engine and its increased performance

2.      The failure of the early Centaur test flights on Atlas-Centaur

When NASA took over the development of the failing Centaur, they changed the designation scheme that Convair had in place.   The Atlas Centaur's stage, which was initially Centaur B, was moved to Centaur D, with each successive version of the Centaur D being designated as D.1, D.5 etc.   The then non-existent but on paper S-V Centaur C became the S-V Centaur E simultaneously.   The initial flight version would be Centaur E.1.  This causes some fractures in the documentation of the Centaur program.   Something that is a severe mess even today as the modern incarnation of Convair, Lockheed Martin has their own new 3^rd designation systems for the Centaur stage.

 

 

The S-V Centaur C (latter Centaur E) stage

 

NASA's whole 1970s space program would have been vastly different had Centaur S-V proceeded.  Titan IIIE and IIIF would not exist, and a different launcher would be used to place a myriad of satellites in orbit.

 

Utilizing Building block designs to make a Rocket:

Von Braun et al at what is now known as Marshal Space Flight Center, and then known as the Army Ballistic Missile Administration out of the Redstone Arsenal, were quite adept and slapping two rocket parts together and getting a third functional rocket out of the mess.   Of all rocket design centers at the time, they were the leaders of this "cost-effective" process.  

With these blocks as designated above, a myriad of rockets can be constructed.    My favorite combination of the S-I(C-1) with the S-III(C-3 260") to launch A Full up Apollo CSM and LEM is a prime example of this.  

 

If you have played around with these building blocks yourself, I am curious about what you have built.

 

Sources: (Primary)

NTRS 19740076058

NTRS 19630045066

Sources: (Secondary)

Stages to Saturn

En.wikipedia.org articles on Saturn Rocket family

 

[Pappystein]

So decided to build a C-2(1960) and test out the best Orbital setup..

As you can see S-I is DEFULED to bring it in line with C-2 fuel loads.   This is 10% reduction.   Utilizing BASE H-1 engines on this launch
Payload is a small Ore tank with 300 units of Ore.

Spoiler

Right after S-I separation... Utilizing standard size S-IVB tank with the ES-IVC (ETS not RL) engine mount with 2x Sea-level J-2 engines.   This is pretty close to what the S-III stage was meant to be

In space still climbing... the Fairing is left intact for Boiloff prevention/reduction

S-III separation and the S-IV-240-4 is running with its RL10B-3 engines
Only 4 engines, not 6 of the Latter RL10A-3S engines

Orbit but way LOW and almost out of gas in the S-IV stage

Go S-V go!
 

On orbit!

 

So suggestions about MechJeb and launching this stack.   

1) higher altitude launches are easier than lower altitude launches.  the S-IV stage should be partially defueled if you want to go to low orbit (below 250kmeters on a 2.5/2.7 scale system like JSNQ that I am currently using)

2) If you use Classic Ascent profiles:  I suggest the following for a Saturn I or Saturn C-2 launch:

RL10B-3 engine is a subvariant that is in the Pafftek folder of BDB extras... it "attaches" onto the RL10A-1 inon engine part so you use the same engines, but a different variant.

 

 

also  Screenshot Tax Season  

Edited January 13 by Pappystein