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S-IVB question
There's a classic piece of footage showing an S-IVB stage separating from
the rest of the stack and lighting up its engine. This appears to be from a Saturn IB flight as there are three ullage motors firing and the Saturn V version only had two. However there's no interstage attached as it pulls away, so either the camera is attached to the interstage itself, or it's on the S-IB stage looking *through* the interstage. Which in turn means that the interstage remained attached to the S-IB at staging. On a Saturn V launch the S-II interstage was there to prevent contact with the engines as the first stage dropped away but the single engine of the S-IVB gives a lot more clearance, so maybe this was not thought necessary. After all the tapered interstage between the S-II and the S-IVB remained attached to the lower stage. 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? -- Gordon Davie Edinburgh, Scotland "Slipped the surly bonds of Earth...to touch the face of God." |
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S-IVB question
"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." |
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S-IVB question
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 Pat |
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S-IVB question
On 9/22/2011 7:58 AM, GordonD wrote:
"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. The ones on the stage you are trying to push back and away from the upper stage always face forward; in the case of the Saturn V, not only did the interstage between the S-II and S-IVB have four forward facing ones, but the S-IC had ones mounted way back in the four fairings over the F-1 engines to pull it away from the S-II/interstage assembly. See number 20 in this cutaway: http://history.nasa.gov/SP-4206/p197.jpg 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. 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. Pat |
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S-IVB question
"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." |
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