Spherical Tanks on S-IVB above J-2 Engine

[jandcando]

Hello, guys I was wondering what the heck these spherical tanks above the J-2 engine on the Saturn V's S-IVB stage are for. Are they helium tanks? Are they valve casings? Are they an attempt from aliens to sabotage the Apollo program using metal-eating microbial growths? Does anyone know what they could be for?

[Kryten]

Helium tanks.

[jandcando]

Helium tanks.

Why are there so many?

[Voidryder]

They are giant jingle bells to help locate the stage when downrange tracking failed.

[Bill Phil]

Why are there so many?

Because helium is a noble gas, so it's used to pressurize things.

[jandcando]

They are giant jingle bells to help locate the stage when downrange tracking failed.

Oh ok that makes sense... What is the sound range on those things?

[Kryten]

Why are there so many?

Easier to fit in the interstage than a few large tanks.

[Motokid600]

What are they pressurizing? RCS? Afaik the j2 needed ulaging. ( spelling? )

[Kryten]

You get problems if you don't at least replace lost volume in the tanks, even in a pump-fed stage.

[Flixxbeatz]

Looks like lymph nodules to me

[Motokid600]

You get problems if you don't at least replace lost volume in the tanks, even in a pump-fed stage.

Now theres a mod for RSS. Lol. What happens otherwise? Is it to avoid creating a vacuum inside the tanks?

[jandcando]

Now theres a mod for RSS. Lol. What happens otherwise? Is it to avoid creating a vacuum inside the tanks?

Ah, that makes more sense than the giant jingle bell theory! That's probably it.

[Tommygun]

Now theres a mod for RSS. Lol. What happens otherwise? Is it to avoid creating a vacuum inside the tanks?

Vacuum implosion:

[Kryten]

Vacuum implosion:

Not much of an issue in space...

No, it just makes the pumping easier and the sloshing behaviour much simpler and thus easier to control. Too much sloshing and you could end up with gas or vacuum in a running turbopump, which would be Very Bad.

[Tommygun]

I was thinking about the first stage imploding while still in the atmosphere, but then again they are not that big and the S-IVB is an upper stage.