Author Topic: Dimensions of Saturn C-4  (Read 2757 times)

Offline MattJL

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Dimensions of Saturn C-4
« on: 11/20/2012 12:39 AM »
I've been learning about the Saturn C-4, and I've been unable to find two sources to agree on what the diameter of the first and second stages were.  Astronautix says 10.1 meters, another source (crude blueprints, I think) gives a diameter of 9.144 m.  Using the drawings from Astronautix, I've come up with a diameter of about 27 feet.

I'm (somewhat) certain that the C-4 was a bit smaller diameter-wise than the C-5/V, but the discrepancy between sources is head-scratching.  Anyone got any more accurate numbers?

The image below shows why I don't trust the Astronautix numbers that much in this situation. (Or should I not trust the drawings)?

[EDIT: I do hope I've put this in the right place].
« Last Edit: 11/20/2012 12:41 AM by MattJL »
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Online Jim Davis

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Re: Dimensions of Saturn C-4
« Reply #1 on: 11/20/2012 01:32 AM »
The image below shows why I don't trust the Astronautix numbers that much in this situation. (Or should I not trust the drawings)?

The C-4 diameter was 320". Astronautix.com, while an ambitious and useful site, is riddled with errors. Mark Wade does the best he can but he is only one guy and there are only 24 hours in a day.

Offline MattJL

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Re: Dimensions of Saturn C-4
« Reply #2 on: 11/20/2012 01:47 AM »
Thanks!  I'm assuming that this drawing is fairly accurate in respect of dimensions, then (excluding the third stage).

[Ignore the file name, it's for a convoluted project of mine]
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Offline TyMoore

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Re: Dimensions of Saturn C-4
« Reply #3 on: 11/20/2012 01:48 AM »
If I remember my Apollo lore correctly the choice of moving from the C-4 to the C-5 configuration was originally made because of concerns over base heating from the 4 F-1 engines---the heat radiated upward onto the central portion of the aft vehicle was becoming problematic. The easiest way to deal with the base heating issue was to "plug the hole" with a fifth engine...and thus the Apollo Saturn C-5 was born.

I don't know if this is an urban legend, I can't remember where I had read that but it sounds reasonably plausible.

Ty Moore

Offline simonbp

Re: Dimensions of Saturn C-4
« Reply #4 on: 11/20/2012 04:34 AM »
That's part of it, and it's in "Stages to Saturn", so it's not a legend.

The other part of it is that the C-4 was scaled to fit a two-launch EOR Direct Landing Apollo. It was a very short-lived configuration that took the C-3 design (2x F-1, 4x J-2) and scaled up the first stage until it fit the two-launch EOR.

Houbolt's original (wildly optimistic) calculations for LOR were then based around using a single C-4. When MSFC was tasked to evaluate LOR, they found that they needed a somewhat larger rocket. So, to make C-5, they took C-4 and scaled up the first and second stages (in both length and diameter), and then added an extra engine to both the first and second stage. The center engine on the S-II was also added with C-5, and the C-4 S-II already had the heat shield on the engines.

C-4, by the way, had a really high liftoff thrust/weight, so it would have really jumped off the pad, and would have had to shut down two of the engines midway through the burn.

Offline Steven Pietrobon

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Re: Dimensions of Saturn C-4
« Reply #5 on: 11/20/2012 04:40 AM »
The C-4 was constantly evolving. This drawing shows the C-4 with a 396" (33' or 10.06 m) diameter on 18 December 1961. This was basically the C-5 with the central engine removed, and was probably the last configuration considered. The article below says the C-5 originally had four engines.

On the issue of 4 or 5 F-1 engines, from pages 192-193 of Stages to Saturn it seems the choice of five engines was mainly for performance reasons, with the additional benefit of solving accumulating explosive gases and base heating problems.

The C-5 configuration, late in 1960, was generally portrayed as a rocket with four F-1 engines in the first stage. Not everyone was happy with this approach, particularly Milton Rosen at NASA, recently tagged by Brainerd Holmes as the new Director of Launch Vehicles and Propulsion in the Office of Manned Space Flight. At the direction of Holmes, Rosen organized a special committee to hammer out conclusions and configurations on launch vehicles (see chapter 3). The group moved into a block of motel rooms in Huntsville for an intensive two-week stint, including, as Rosen recalled, one marathon stretch of five days of almost [193] around-the-clock negotiating. Among other things, the committee's report, delivered to Holmes on 20 March 1961, recommended five, not four, engines in the first stage.

Rosen apparently took the lead in pressing for the fifth engine, consistent with his obstinate push for a "big rocket." The MSFC contingent during the meetings included William Mrazek, Hans Maus, and James Bramlet. Rosen argued long and hard with Mrazek, until Mrazek bought the idea, carried the argument to his colleagues, and together they ultimately swayed von Braun. Adding the extra power plant really did not call for extensive design changes; this was Rosen's most convincing argument. Marshall engineers had drawn up the first stage to mount the original four engines at the ends of two heavy crossbeams at the base of the rocket. The innate conservatism of the von Braun design team was fortunate here, because the crossbeams were much heavier than required. Their inherent strength meant no real problems in mounting the fifth powerplant at the junction of the crossbeams, and the Saturn thus gained the added thrust to handle the increasingly heavy payloads of the later Apollo missions. "Conservative design," Rosen declared, "saved Apollo".

At second glance, MSFC people themselves found no good reason not to add the extra engine, especially with the payload creeping upward all the time. "I had an awfully uneasy feeling, you know," von Braun remembered; "every time we talked to the Houston people, the damn LEM [lunar excursion module] had gotten heavier again." The added F-1 also relieved some of the concern about accumulating exhaust gases, with explosive potential, in the large space between the original four engines, and helped solve a base-heating problem in much the same way. The physical presence and exhaust plume of engine number five filled the void and directed gases and heat away from the base of the first stage. At a Management Council Meeting on 21 December 1961, NASA formalized the five-engine configuration for the S-IC
« Last Edit: 11/20/2012 05:30 AM by Steven Pietrobon »
Akin's Laws of Spacecraft Design #1:  Engineering is done with numbers.  Analysis without numbers is only an opinion.

Offline MattJL

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Re: Dimensions of Saturn C-4
« Reply #6 on: 11/26/2012 03:15 AM »
I'm assuming the payload data as given by Astronautix (99 tonnes LEO, 32 tonnes TLI) is incorrect as well?

That third stage seems a bit too small to be able to have that sort of performance, IMO.
« Last Edit: 11/26/2012 03:21 AM by MattJL »
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Offline Proponent

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Re: Dimensions of Saturn C-4
« Reply #7 on: 12/07/2012 05:37 AM »
Houbolt's original (wildly optimistic) calculations for LOR were then based around using a single C-4.

He expected many of his concepts to fit even the C-3!  (See, e.g., p. 13 of the attachment).
« Last Edit: 12/07/2012 05:38 AM by Proponent »

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