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Flash 12-11-2020 02:49 PM

Saturn C-8 / Nova in 1/100 Scale for the Forum to help design
7 Attachment(s)
Saturn C-8 / Nova Direct Ascent to the Moon Rocket

I'm not the best design person that is for sure, thought this might be fun for everyone. Please feel free to download and adjust the rocsim file and reload it for us all. I haven't see this rocket modeled before unless I missed something, which is always possible.

Make no mistake about it, it would be a job, but I believe this rocket could be built from the New Saturn V Skylab kit.

You would need the following extras depending on if you are sticking with the design idea at hand. Extra BT101 and > CPL 101 – 6” BT101 tube couplers to stretch and fill the kits BT 101 for the 1st stage which is 4.8” x 18” diameter unless someone knows where we can get a 4.8” diameter tube that is light weight; BT 58 for command module; Estes LEM plastic Shroud; Estes extra set of F1 plastic Engines to make up the 8 F1 engines for display; BT80 for four 24mm motor clustering layout; BT 50 for motor mount tubes; 3 “E” Engine hooks; ¼” Foam board with cardboard board front and back for making light centering rings; Apollo capsule from vendor of choice or 3d print your own.

I have to say, there really doesn’t appear to be much info out there for the Nova or the Saturn C-8. Nova seems to be a name used for several different rocket ideas, one of which was some 50’ diameter as compared to the Saturn V at 33’. The Nova that looks more like the Saturn C-8 had only one main difference between the Engine choices. They were looking at cutting the Nova down to a more manageable 40’ Diameter monster that would use eight F1 engines in the first stage, two larger “M1” size engines in the 2nd Stage and one J2 engine in the 3rd stage. Here is what one reference had to say about the M1:> “Aerojet's M-1 was the largest and most powerful liquid-hydrogen-fueled liquid-fuel rocket engine to be designed and component-tested. The M-1 offered a baseline thrust of 6.67 MN (1.5 million lbf) and 8 MN (1.8 million lbf) as its immediate growth target. If built, the M-1 would be larger and more efficient than the famed F-1 that powered the first stage of the Saturn V rocket to the Moon.”
The Saturn C-8 was going to use eight J2 engines in the 2nd Stage as compared to the Nova’s two M1’s.

There are some drawings of the Saturn C-8 but they just don’t appear reasonable to me because the 1st Stage is just to short. There was some printed 1st, 2nd and 3rd stage sizes for either rocket that agreed with one another but not with the drawings, so I went with these size specs and I also looked at the Saturn V for what was finally but to put this model together. The Nova/Saturn C-8 First Stage was planed at 40’x 160’; Second Stage was planed at 33’ x 140’ and the 3rd Stage was planed at 21.68’ x 58.30’.

For the First Stage of this design, I used the 160’ total length which includes F1 engines but not the Inter-stage Coupler as was the case when looking at the Saturn V’s first stage size. I also have the rocket the same distance off the ground as the Saturn V. I used the same size Fairings for the bottom flare ring. Doesn’t seem reasonable to have 8 fairings, so this one has a N1 style design as do many modern pictures. Not sure if this rocket would have had 8 fins or not since the F1 engines would have gimbaled as was the case with the Saturn V? I used the Saturn V Air-Frame reinforcement rings and location in laying out this rocket design to. Some was guessing with no real plans to help.

For the Second Stage of this design, I used the 140’ total length which includes the Inter-Stage Ring as was the case with the Saturn V. I again tried to use the Saturn V’s reinforcement ring sizes and locations to help with their placement. Most modern pictures don’t show a middle reinforcement ring on the 2nd Stage airframe of the Saturn C-8 / Nova, but I feel it would have been required as was the case with the Saturn V 2nd Stage. I used the same size as was used on the Saturn V 1st stage at that point.

3rd Stage of the two rockets were almost identical, with the Saturn C-8 / Nova being just a hair shorter at 58.3 as compared to 59’ for the Saturn V, so I went with 59’ and kept the 3rd Stage, LEM and command module the same as what was included on the Saturn V since I haven’t ran across any reliable draws of this part of the rocket. I didn’t include the escape tower in the rocsim design but it will be part of the design at this point.

I will have to say, that I don’t agree with Rocksim weight estimates. Even on the heavy side it should be no more than 32oz, but if the Saturn V model true weight is around 16oz, then I’m thinking more like 24 or so?

I’ll have to weight the parts as I go, because the CG and CP don’t look good at this point either.

So friends, just wanted to share this project with you and looking for any good ideas and recommendations before this is built. So if anyone has some really good pictures or true plans that would help in changing the rocket’s design, then please feel free to join in, because this project is a plan in motion.

Flash 12-11-2020 02:52 PM

10 Attachment(s)
Here is a copy of some of the info I was looking at about this rocket.

luke strawwalker 01-13-2021 10:50 PM

In the scale section I've done a bunch of "rocket study summaries" using .pdf's I've collected over the years from various sources including NTRS-- NASA Technical Reports Server. This includes a bunch of stuff on uprated Saturn V's, NOVA, and Saturn C-8, as well as Saturn II proposals, and uprated Saturn IB and solid propellant first stage Saturn IB's.

You have to realize, that these were PROPOSALS, and so not a terrible lot of the nuts and bolts technical work had been done. Mostly just "is it even feasible" kind of work, and roughly what kind of performance it could reasonably be expected to have. A lot of the proposal stuff would likely have changed before the final version of the vehicle was produced. For instance on Saturn V, the original proposal was for four engines on the first stage, and no fairings or fins. The fairings and fins came about to shield the engine bells from atmospheric buffeting from the slipstream which made the engines difficult to gimbal at certain angles, since they would be hitting a "wall" of air rushing past the stage. The decision was made fairly early on to add a fifth engine in the center, and so the outer thrust ring of the thrust structure was made wider to accommodate it. The fins were added to ensure stability of the vehicle stack after an engine shut-down prior to the capsule escape rocket tower firing to pull the capsule off a doomed booster. Once the engines were shut down there was no more thrust vector control, so aerodynamic control via the fins was the fallback until the capsule was safely away. A lot of this stuff was discovered in subsequent studies done in the wind tunnel and more intricate design work and analysis of the design. Base heating was also a serious issue with Saturn V, from plume recirculation under the base. This was a major problem with the Soviet N-1 rocket as well due to its large aft diameter and ring of 30 NK-33 engines. They lost the first N-1 because of it, and had to essentially fireproof EVERYTHING in the thrust structure because of it. The added weight caused them to add another six engines to the design in the center ring to reduce the huge vacuum effect and subsequent base heating from plume recirculation.

The reason I mention this about N-1 is, I'm very confident that the NASA engineers would have discovered a similar phenomenon would plague the C-8 design... I've never considered the original "circle of 8" F-1's to be a realistic engine arrangement for those very reasons-- it was already going to be a HUGE stage with a HUGE vacuum behind it as it accelerated through the lower atmosphere; the smaller diameter Saturn V had serious issues with it so it was a sure thing C-8 would have even more so, just as N-1 did. A far more "realistic" engine arrangement for C-8 IMHO would have been to copy the Saturn I/IB engine arrangement-- 4 F-1's in the center, with 4 more arranged in an outer ring , with space between them to help alleviate plume recirculation by drafting part of the slipstream airflow into the base region, as was done on Saturn IB (which had a series of small "scoops" on the bottom edge of the thrust structure to redirect part of the slipstream airflow into the base region to help minimize plume recirculation.) In this arrangement, it would be simple to use 4 of the Saturn V type fairings (if needed) to provide a "windbreak" around the outer engines to prevent slipstream airflow from hampering their gimbaling, as well as placing the fins, which would probably have been necessary for the same reason as they were on Saturn V-- to provide some stability after engine shutdown just before the escape rocket fired in an emergency.

As for the upper stage, there's some interesting proposals there as well... I don't recall reading about the twin M-1 upper stage, perhaps I have and don't recall, it's been awhile since I did those study summaries. The M-1 was to be a hydrogen super-duper version of F-1, burning liquid hydrogen. On some of the uprated Saturn V's I've read about proposals for using a single M-1, since it would have more thrust than the cluster of five J-2's... Basically one M-1 would have been about the equivalent of six J-2's. I've read about six J-2 uprated Saturns (which of course came about after the M-1 engine development was cancelled) and even an 8 J-2 engine S-II stage, which of course would have been lengthened for more propellant. Some of these proposals are more "believable" than others. What I mean by that is, when you consider the rocket equation and the "design requirements" for orbital rockets...

More to come... OL J R :)

luke strawwalker 01-13-2021 10:50 PM


For liftoff, you need tons of pure, raw thrust. F-1 was exceedingly good at that, despite it's rather low specific impulse. Solid rockets are also good at producing tons of pure raw thrust, but they have a lot of drawbacks as well-- can't be throttled (which in fairness basically neither could F-1) but most importantly, once lit CANNOT BE SHUT DOWN in an emergency. Solids are fairly simple, but INCREDIBLY heavy since they must be moved FULLY FUELED, or else stacked on the launch pad (as would have been done with ALL the Saturn V upgrades that involved adding solid rocket boosters to Saturn V). Liquid engines can of course be throttled (if designed to do so) and can be shut down in an emergency, and are more efficient for their propellant and stage mass than solids. ANYWAY, specific impulse, on a first stage, takes a back seat to two other design criteria-- maximum thrust for the size/weight of the stage, and maximum propellant density versus minimum stage empty mass. While solid propellants ARE very dense, their specific impulse is pretty low, and since the motor casing must withstand 700+ PSI of burning propellant gas pressure inside it, the stage then essentially becomes the combustion chamber, and is exceedingly heavy for its size. Liquid propellant tanks on a liquid fueled stage may be larger, but are very thin and lightweight by comparison, giving a much greater mass fraction between propellant mass versus stage empty mass. The key is minimizing dry stage empty weight (mass) versus loaded stage weight (filled with propellants). That is why kerosene and other denser liquid fuels are better for first stages than hydrogen, which is extremely "fluffy" and low-density by comparison. Yes hydrogen burns with higher specific impulse than kerosene, BUT due to its low density it requires absolutely ENORMOUS tanks to hold the necessary propellant to feed the engines for the duration of the first stage burn to get it to the altitude with the expected liftoff mass of the entire rocket. For instance, had M-1 been chosen for the first stage engines of Saturn V, it would have required a first stage at least TWICE AS BIG which would have made Saturn V 1/3 taller or so than it was. Any gains from greater efficiency of burning hydrogen would have been more than lost to the additional weight of the extra long tanks, which would have basically DOUBLED the weight of the first stage. Hence M-1 was never considered, and why the SLS is SO inefficient, and why Delta IV Heavy is SO big for its "medium" lift capability. That's why you want to use dense fuels like kerosene or hydrazine (in storable propellant missiles or rockets like Titan II) for first stages, or solid propellants (but again, storable liquids are more efficient). From this point of view, the first stage of C-8 is pretty reasonable and makes sense.

For upper stages, though, specific impulse becomes the overriding factor in performance, particularly for in-space stages like the S-IVB. This is why virtually ALL "high energy" upper stages use hydrogen as a propellant-- it has the highest chemical propellant specific impulse available without resorting to exotic fuels like hydrogen/fluorine, which was experimented with but never got outside the lab for obvious reasons... (liquid fluorine is about like handling liquid death-- hard enough to keep from destroying the lab or killing everybody; putting hundreds of thousands of gallons of the stuff in a FLYING ROCKET would be virtually suicidal...) ISP trumps all other considerations, with minimizing stage mass right behind it (or hand in hand with it). Minimizing stage empty mass is also a critical consideration. For instance, on Saturn V, every extra pound of stage mass on the S-IVB was a pound of cargo capability lost to the Moon. On the S-II second stage it was almost as bad-- every 1.1 pound of extra mass on the emtpy S-II stage was a pound of usable cargo lost to the Moon. For the first stage S-IC, though, you'd have to shave off ELEVEN POUNDS of empty mass to get an extra pound of cargo to the Moon... So you can see the weight becomes the biggest design driver for upper stages. You can use kerosene or even solid propellants for upper stages (as has been done on Soyuz, Falcon 9, and solids on many upper stages, kick motors, etc. over the years, including the Jupiter C rocket that orbited the first US satellite, but they're TERRIBLY inefficient due to the lower ISP and in the case of solids, empty stage mass for its size. That's why the solid upper stage on the Antares rocket makes so little sense, but then again, Antares is a "one trick pony" made just to loft the Cygnus cargo carrier to ISS to fulfill their COTS contract with NASA, nothing more. SO inefficiency is fine so long as it works. Falcon 9 would get a HUGE performance increase from a hydrogen upper stage, simply due to the increased ISP. So would the Soyuz rocket for that matter. BUT, hydrogen upper stages are a lot more complex and hydrogen is a much harder fuel to deal with... which means more expense. Both Soyuz and Falcon 9 are perfectly capable of doing the assigned job without the extra complexity and expense, so why bother. It's always an upgrade option if needed.

That said, M-1 would have presented some interesting design challenges and possibilities for upper stage use. It had VERY high thrust-- 1.5 million pounds. BUT you also have to either shut down engines OR deeply throttle your upper stage engines as you are nearing burnout of the upper stage. You have to do this to prevent overstressing your stage, any upper stages above it, and the payload/cargo with excessive g-forces as the fuel mass burns off but the high thrust remains, increasing acceleration exponentially. S-IC did this by shutting down the center F-1, while keeping the outer four burning until stage shutdown. The S-II J-2's were throttleable, so they throttled down to compensate for the empty propellant tanks as the stage neared burnout. So did the single J-2 on the S-IVB. M-1 would to have to be designed to be throttleable, in order to not overstress the rocket and payload near burnout. With 2 M-1's you could theoretically shut one down and just run on the other one as you burned off fuel, to prevent overthrusting the stack, similar to how the SN-8 Starship did in its recent belly flop test... shutting down Raptors one by one as the fuel was burned off in the stage. The rest is just control algorithms, programming, and dynamics. (Sort of how single F-1 powered Saturn IB proposals wouldn't have been that much of an improvement alone-- the 8 H-1's provided about the same level of thrust as the single F-1, so liftoff mass couldn't have been increased by much (therefore payload increase would have been negligible... now if you substituted a 1.8 million pound thrust F-1B in its place, as likely would have happened, then you get some decent increase, but the only other way to do it would be to use TWO F-1 engines on the first stage, but not being throttleable, the final 10-15 seconds of the first stage burn would require shutting one of the two F-1's down and continuing to stage shutdown on the single remaining F-1 to prevent overthrusting the stack and violating your g-load tolerances... you just have to switch the controls over so the single F-1 still provides all the control of the vehicle through stage shutdown... not an insurmountable problem.

ANYWAY, if you want to see the images and stuff I summarized from the studies I've read and gleaned over, search for "NASA study summaries" in the scale section of the forum here, or go over to the Sagitta Cantina forum and Bernie put them all in "Luke's Study" section there for me, as a resource for modelers to use for these little-known or unheard of or unrealized proposals that never actually got built... tons of good stuff in there! I need to get back to doing more of them actually... here's the link...

Later! OL J R :)

georgegassaway 01-14-2021 02:18 AM

Thing is.... the biggest reason for a C-8 / Nova to exist was for either Lunar Direct, or Earth Orbit Rendezvous. With totally different looking spacecraft on top.

See the drawing on this page:

Even Earth Orbit Rendezvous was a bit farfetched to do with a NOVA or C-8, once it became clear that EOR could be done with two Saturn-V launches. Once Lunar Orbit Rendezvous was chosen, it was possible to do it all with one Saturn-V to launch all the Apollo hardware.

So I'm a bit surprised at the C-8 / Nova drawings with normal Apollo-looking spacecraft on top. Or... are those really Apollo with normal shrouds and LM's tucked inside of the shrouds? Note that this Direct Ascent lander pretty much has a early Apollo-like CM/SM, a VERY short adapter shroud, and a 21'8" diameter stage with legs for the lander portion. And yes, it would have had a LES tower for launch. But not the long adapter shroud that was needed for the LOR Lunar Module.

Flash 01-14-2021 01:13 PM

Wow! Love the source of information. I thought this thread was died.

ghrocketman 02-10-2021 11:09 AM

I think all new spacecraft should have to go through actual-flight MANNED Gimbal-Lock test-flights.
If spacecraft and crew survives that "durability" chekk, it should bee GOOD-TA-GO !

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