Classical (Bossart) Atlases and Centaurs had thin walled balloon
cryotanks coated with ice functioning as...*thermal isolation*. When
empty, unless pressurised, balloon tanks become nasty: they crumple.
John
Verzonden vanuit Proximus Mail
Van: roxanna Mason <rocketmaster.ken@xxxxxxxxx>
Verzonden: 1 mei 2023 20:20:53 CEST
Aan: arocket@xxxxxxxxxxxxx
Onderwerp: [AR] Re: Saturns (was Re: APCP ...)
The main issue there on the
Saturns was the manufacturing of very large, very thin ones.
This is partially true,The RL-10 powered Centaur was an order of
magnitude smaller than S-II so scaling up usually presents problems
The other part is the bulkhead had to also be insulated unlike
Atlas which was a simple sheet of stainless steel.
Ken
On Sun, Apr 30, 2023 at 12:08 PM Henry Spencer
<hspencer@xxxxxxxxxxxxx <mailto:hspencer@xxxxxxxxxxxxx> > wrote:
On Fri, 28 Apr 2023, roxanna Mason wrote:
> Other factors which made the LH2 high risk was the requirement for a
> common bulkhead to shorten the SII stagewhich had never been done
> before.
No, Atlas already had a common bulkhead -- in fact, about the most
minimal
common bulkhead imaginable, a single thin sheet of stainless with LOX
above it and kerosene ullage space below it. And the Centaur folks
were
already working on a LOX/LH2 common bulkhead. The main issue there on
the
Saturns was the manufacturing of very large, very thin ones.
> Additionally the insulation was put on the inside immersed in the
LH2.
> This is why there was no ice and thick frost on the outside of the
stage
> like the SI-C stage did on the LOx tank.
> Ditto for the SIV 3rd stage.
Only on the third stage, actually. Douglas's list of advantages for
the
internal insulation quietly failed to mention its one big snag: it
was
heavy, because it needed compressive strength to transmit pressure
loads
(pressurization and hydrostatic) out to the metal wall. It made the
S-IV,
and then the S-IVB, easier... but the S-II was too
performance-critical to
accept the weight penalty, and NAA had to use external insulation.
After
some early difficulties, they eventually settled on using spray-on
foam --
in fact, the original Shuttle ET foam was an improved version of the
S-II
foam.
Henry
