"Pat Flannery" wrote in message
...
On 9/22/2011 2:51 AM, GordonD wrote:

So the question (at last) - on a Saturn IB flight, did the interstage
remain attached to the S-IB or did it separate with the upper stage to
be jettisoned a short time later?

The interstage stayed attached to the first stage in the S-IVB staging
when the Saturn IB launched them.
The interstage incorporated external forward-firing separation motors that
pushed it and the attached first stage backwards as the upper stage fired
its ullage/separation motors and pulled away.
Note that when the video starts it is in darkness, as the stages are still
attached to one another.
The original six RL-10 engined S-IV interstage also stayed with the first
stage on separation: http://www.youtube.com/watch?v=X86LYWyK9_0


I didn't realise the separation motors fired forwards; I assumed they were
posigrade like the ones on the S-II interstage.

I suppose if the Saturn IB interstage had separated along with the S-IVB
then been jettisoned later, it would have been spinning (as in the S-II
shots from Apollo 4) - the pictures as shown are rock-steady.
--
Gordon Davie
Edinburgh, Scotland

"Slipped the surly bonds of Earth...to touch the face of God."