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Vertical vs. horizontal integration Q&A by the_other_Doug on 19 Apr, 2015 00:43
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The Russians have always done horizontal integration, putting their rockets together lying on their sides and transporting them to the pads horizontally, then erecting them to vertical at the pad itself. They even did this for the N-1 (though the N-1 required two separate locomotive engines and two sets of rail tracks to pull the rocket and its erector to the pad). SpaceX is using the same integration concept.
In early Apollo planning, while the integration was always planned to be done at a dedicated facility and the vehicle moved to the pad, the concept of horizontal integration was dismissed as presenting too many engineering challenges. Quoting "Apollo" by Murray and Cox, in discussing this issue with Rocco Petrone, they say:
"'With the size of the vehicle we were looking at -- over 360 feet long -- and the umbilical tower it had to have,' Petrone said, 'we just could not see a way to prepare it horizontally and then in its entirety put it up vertically.' There would be bending effects, all kinds of stresses on the vehicle. And they had no choice but to put it up in its entirety, because if they disconnected the umbilicals, then they would lose much of the work they had done in preparing it."
Considering many other rockets -- even ones as large as the N-1 -- were and still are prepared with horizontal integration, were Petrone and the Apollo designers wrong in thinking that bending effects and stresses from horizontal integration would cause massive problems? It would seem that such concerns would not apply just to the Saturn V. If these issues were that difficult to deal with, how do rockets the size of Proton, Angara and Falcon 9 manage it with no problems to speak of?
I've been curious about this for some time... anyone's informed input would be welcome. Heck, even a round of good speculation would be welcome.
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#1 by MattMason on 21 Apr, 2015 19:51
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I am hardly an engineer, but I do watch enough anime and read TV Tropes to consider the likelihood that the square cube law may be a factor to why the 6.2 Saturn V would sag and break if assembled horizontally, while smaller rockets such as the Falcon 9, Antares, Soyuz can withstand and support its own weight horizontally.
That said...we do have a few Saturns resting on their sides in very prominent locations, such as in Florida.
So, if not square cube law, the technologies of the time made it more practical to build the Saturns up, not out. Perhaps the addition of the LM and how it could be supported safely in its adapter horizontally also would have given Tom Kelly and his Grumman team some nightmares. -
#2 by SWGlassPit on 22 Apr, 2015 16:21
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That said...we do have a few Saturns resting on their sides in very prominent locations, such as in Florida.
You are correct, though it's not so much the vehicle being horizontal, it's the process of moving it from horizontal to vertical that presents an engineering nightmare. Imagine what it would take to tilt the Saturn V and the LUT upright... -
#3 by kevin-rf on 22 Apr, 2015 16:44
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I will point one little historical tidbit. The German engineers really liked vertical integration, if you look back at the original V2 basing plans they where underground with vertical integration. Google La Coupole. You will see a fair amount of similarity to the VAB and Saturn... They only changed to mobile basing after the underground bunkers where bombed.
This preference seems to have carried over in the american programs.
Fyi: http://en.wikipedia.org/wiki/La_Coupole
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#4 by edkyle99 on 23 Apr, 2015 15:22
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My thoughts on this are that at the time they were actually building the KSC launch site, the design of Saturn was still in flux. LC 39 design began when Saturn C-3 was the plan, but everyone knew that bigger rockets were likely and that a super big Nova was a future possibility. My guess is that it was easier to plan a vertical integration launch site for an unknown rocket. Looking at the massive, bridge-size "Grasshopper" transporter/erector for N1 shows how closely wedded the transporter design had to be to the rocket design. Kurt Debus was used to designing launch facilities that were oversized to handle future rocket growth (see LC 37 Saturn I images for an example).
- Ed Kyle -
#5 by Jim on 23 Apr, 2015 15:35
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http://forum.nasaspaceflight.com/index.php?topic=27147.0
Here is the thread on Horizontal vs. vertical payload integration
