(Henry Spencer) wrote in message ...
In article ,
OM om@our_blessed_lady_mary_of_the_holy_NASA_researc h_facility.org wrote:
Cutaway of Saturn I S-IV Stage
http://mix.msfc.nasa.gov/ABSTRACTS/MSFC-9801758.html

..."Blowout Panels (8)"?? Were these part of the actual design in the
end?

Hmm, interesting question. That suggests that they planned "fire in the
hole" staging for the Saturn I -- ignition before separation. But
technical details on the Saturn I are a bit hard to find, and I don't
know offhand just how its staging was done.


According "MARSHALL SPACE FLIGHT CENTER MPR-SAT-FE-64-18,
"RESULTS OF THE SIXTH SATURN I LAUNCH VEHICLE TEST FLIGHT
(SA-6)", the Saturn I first/second stage separation involved
ullage rockets igniting on the S-IV stage, followed by stage
separation about 0.18 second later. At stage separation,
retro-rockets on the S-I stage fired upward. The S-IV engines
ignited about 1.63 seconds after stage separation. The S-IV
ullage rockets were jettisoned about 10 seconds after staging.

And yes, the blowout panels (there were 8 of them) were used
in the Saturn I, Block II vehicles. Keep searching for "S-IV"
stage on NIX and you should find some good photos of this
hardware. The interstage blow ports came into play a bit more
than 8 seconds before stage separation, when the S-IV LOX
Prestart event occured. At this time, the ports were blown
open, presumably to vent LOX gases. The S-IV LH2 prestart
(chilldown) occurred about 42 seconds before staging.

(I recall reading in another reference that Douglas had
struggled with chilldown hydrogen gas venting when developing
the S-IV stage. I think that hydrogen vent pipe "stacks" were
added for this purpose.)

- Ed Kyle