"Pat Flannery" wrote in message
dakotatelephone...

That would mean that the S-IV/S-IVB would have to drag the weight of the
interstage along till it was jettisoned, lowering performance; IIRC the
reason the S-II stage carried its interstage along for a while was due to
the fact that there were still some atmospheric effects at the altitude
the first stage separated at and the rocket was more stable with the
interstage attached till more of the atmosphere was cleared.

I've heard that if the S-II interstage had failed to separate on a lunar
mission, it would have been quite a serious problem. And apparently this did
happen on Skylab 1, though with all the other problems they were having on
that one it was the least of their worries.
--
Gordon Davie
Edinburgh, Scotland

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