Saturn V Third Stage - Not enough room

[benparry]

Morning / Afternoon All.

Another Facebook group argument / debate. Below is a comment from somebody. Is there a website which literally adds up the bits within the Third stage that shows it does all fit





Phase 3 of the Saturn 5 rocket is 61.6 feet tall and 21.7 feet in diameter. If it was a cylinder (which it's not the top has a lander attached to it and it's much smaller and the diameter slowly decreases at the top)
I used a cylinder calculator and came up with 22,781 cubic feet.
Now we look at the list. There were 2 fuel tanks the larger held almost 80,000 gallons the other just over 6,000. The fuel alone takes up 11,417.52 Cubic feet of space. That's not counting the tanks to hold the fuel or the lines and pumps to move it.
Remember it's already more than ½ full even if you just literally poured the fuel in the rocket.

And that's if the entire rocket was shaped like a cylinder, again it's not

We still need room for Insulation so now your available space is even smaller.

Next subtract the cubic feet needed for the rocket's engines.

Don't forget the Lander itself.
We still need an oxygen supply, batteries, computers, and room for 3 Astronauts. It literally doesn't all fit.




cheers guys

Ben

[Peter B]

I used a cylinder calculator and came up with 22,781 cubic feet.

Correct.

Now we look at the list. There were 2 fuel tanks the larger held almost 80,000 gallons the other just over 6,000. The fuel alone takes up 11,417.52 Cubic feet of space.

His figures are fairly off, but his volume is similar to what I calculated.

That's not counting the tanks to hold the fuel or the lines and pumps to move it.

Er, what? Once you put the fuel in, there's no room left for the fuel?

Remember it's already more than ½ full even if you just literally poured the fuel in the rocket.

Um, yes, that's how it works. A bit over half the volume of the stage is taken up by fuel. That leaves a bit less than half the volume for lines and pumps and engines and stuff.

[Allan F]

Are your numbers for the third stage or for the third stage AND the SLA?

[Allan F]

https://en.wikipedia.org/wiki/Apollo_(spacecraft)#Spacecraft%E2%80%93lunar_module_adapter_(SLA)

The confusion stems from your inclusion of the SLA into the 3rd stage. It was a separate entity.

[Allan F]

Also, he thinks the CSM is also inside the 3rd stage.

[Jason Thompson]

Is there a website which literally adds up the bits within the Third stage that shows it does all fit

Not necessary given the massively flawed arguments.

Phase 3 of the Saturn 5 rocket is 61.6 feet tall and 21.7 feet in diameter.

Height measured from where to where?

If it was a cylinder (which it's not the top has a lander attached to it and it's much smaller and the diameter slowly decreases at the top)

That is incorporating both the Instrument Unit (IU) and the Spacecraft/LM Adapter (SLA), neither of which are part of the S-IVB.

I used a cylinder calculator and came up with 22,781 cubic feet.

Remember it's already more than ½ full even if you just literally poured the fuel in the rocket.

Yes, that is literally how most rocket stages work. How much space does he imagine the lines and everything else take up when compared to the volume of fuel?

We still need room for Insulation so now your available space is even smaller.

How thick does he expect the insulation to be? There are many unqualified assumptions being made in his comment that he needs to justify if he claims it supports his conclusions.

Next subtract the cubic feet needed for the rocket's engines.

Go on then? That, again, is his burden of proof. As well as showing that the rocket engine is included in the length of the stage he quotes.

Don't forget the Lander itself.
We still need an oxygen supply, batteries, computers, and room for 3 Astronauts.

None of that was included in the S-IVB stage. The lander sits inside the SLA, and the command/service module sits on top of that. That's a fundamental error in his argument.

That and the fact there are many many diagrams available online that show how everything fitted. Not our burden to go and find the actual answers. His argument fails for being incomplete and making several errors about what needs to be included.

[benparry]

Many thanks Gents for you're answers. As usual the answer is deceptively simple.

[cjameshuff]

Yes, that is literally how most rocket stages work. How much space does he imagine the lines and everything else take up when compared to the volume of fuel?

Reminds me of some of the loudmouths saying that Starship was nothing more than a mockup because "it's just a hollow shell". These people seem to get their ideas of what "real spacecraft" are like from Star Wars, like they're supposed to be full of random bits of machinery and some little fuel tanks stuffed in some corner.

[Dalhousie]

Yes, that is literally how most rocket stages work. How much space does he imagine the lines and everything else take up when compared to the volume of fuel?

Reminds me of some of the loudmouths saying that Starship was nothing more than a mockup because "it's just a hollow shell". These people seem to get their ideas of what "real spacecraft" are like from Star Wars, like they're supposed to be full of random bits of machinery and some little fuel tanks stuffed in some corner.

The first one unveiled was little more than that, a tarted up test article for pressurisation tests

[Peter B]

Yes, that is literally how most rocket stages work. How much space does he imagine the lines and everything else take up when compared to the volume of fuel?

Reminds me of some of the loudmouths saying that Starship was nothing more than a mockup because "it's just a hollow shell". These people seem to get their ideas of what "real spacecraft" are like from Star Wars, like they're supposed to be full of random bits of machinery and some little fuel tanks stuffed in some corner.

Speaking of hollow shells, and veering back to the S-IVB, I'm reminded of when I first read about the wet workshop concept for Skylab. The idea of setting up a space station in a used fuel tank in the third stage seemed crazy to me. I kept thinking of the place reeking of petrol/gasoline fumes...until I realised (a) it was a hydrogen tank, and (b) they'd vent it anyway before filling it with oxygen.

[jfb]

Is there a website which literally adds up the bits within the Third stage that shows it does all fit

You could go to the source: Apollo Saturn V Flight Manual.

Although this site works as well, with some other historical context.  All of the following diagrams are taken from there. 



The Saturn V rocket is everything from the Instrument Unit on down.  The LM is not part of that volume. 

These are the rocket stages, with dimensions:

S-IC (first stage):


S-II (second stage):


S-IVB (third stage):


S-IVB tank construction:


As is clear from the diagrams, engines and pumps took up space in the interstages; some lines were routed through the tanks, some around the tanks, etc.  Other diagrams at the site show how tanks were constructed, how engines were mounted to thrust structures, how fuel flow worked, etc. 

It's not light reading (unless you're a freak), but it shows that yes, Virginia, you could fit everything you needed within the Saturn V's volume (remembering that the spacecraft are not part of that volume).