Why did the Saturn V rocket require so many parts?

Answer by Sophia Te Tricht:

TL;DR – Are you kidding me?!  You ask a question about three million moving parts and you want a concise answer?  Can I get you a hot apple pie with that?!  Read the whole answer!  😉 (Just kidding!  I love you guys!)

You came to the right place!  This big, beautiful bird happens to be something I can talk at some length about.  The Saturn V rocket, a collaborative effort between Boeing, North American Aviation and Douglas Aircraft; was a bizarrely complex machine.  It had to be.  Let's go to the map!

HO
LY
CRAP.

Let's break it down a little bit:

This first one, the tall one, is the first stage called the S-IC.  It was powered by 5 F-1 engines (more on those big bastards in a minute), and lifted the entire 6,500,000 pounds off the pad.  And it's mostly tank.  A little bit of pipe, but mostly tank.  The second stage, second to left called S-II, was powered by 5 J-2 engines (we'll discuss them too).  There is what's called an interstage between them, which is just a structure capable of supporting the substantial weight of the second and third stages plus the spacecraft and abort tower without buckling, absorbing and transferring the energy of the S-IC to the rest of the rocket (lest the S-IC just shoot through the rest of the rocket like it ain't no thing), and it holds the separation bolts.  Oh, stage separation, how I love thee…  We'll discuss that too.  The third from the left is the S-IVB.  Another interstage exists between the S-II and S-IVB.  The S-IVB also contained the Instrument Ring.  There was another interstage, in which was stored the lunar module, and atop that interstage sat the Apollo Command and Service Module.

Stage Separation: Let's talk about frangible bolts.  This is a frangible bolt
https://www.youtube.com/watch?v=vBZYk1m4WMIEssentially, it's a standard, run of the mill bolt, but with a chunk of its metal section replaced with explosive.  When a signal is sent to the bolt to fire, well…  The video shows it.  In the Saturn V interstages, there were rings of frangible bolts that detonated, separating the spent stage and the interstage.

Let's talk Instrument ring.  The instrument ring on the Saturn V was in the S-IVB stage, as I mentioned before.  It looked a little something like this:

"Okay," I can hear you saying, "Doesn't look like there's much moving."  Except that this was before the age of digital anything.  They used pitot tubes for real.  Their gyros? 

There's your moving parts…

Speaking of, let's talk about engines.  F-1, submitted for your awe.

probably about half of those parts move in some way or another, not to mention the stuff you don't see, like the rotors in the turbines…  J-2, also pretty freaking awesome:

every valve, turbopump, bypass, flow meter, and generator has dozens if not hundreds of moving parts.

I'm not even going to go into the actual flight systems of the Apollo hardware.  They all add up, when you consider redundancies, which typically were at least double fault tolerant (i.e. a system can suffer two failures without being an irrecoverable loss).

Why did the Saturn V rocket require so many parts?

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