dwv@ihuxz.ATT.COM (Bazooka Joe) (10/04/88)
Since we all have been talking about this backflow theory on the SRBs, I was wondering if the same didn't happen on the Saturn V first stage. I seem to remember all the long camera shots looking like the last 30 seconds of stage 1 burn was going up the sides of the bird? Anyone else remember this? -- "What we have here is | Dave Vollman (HASA "F" Division) FAILURE TO COMMUNICATE" | AT&T Bell Laboratories - Struther Martin in | Naperville, IL "Cool Hand Luke" | ..!att!ihuxz!dwv
kluksdah@enuxha.UUCP (Norman C. Kluksdahl) (10/04/88)
In article <3447@ihuxz.ATT.COM>, dwv@ihuxz.ATT.COM (Bazooka Joe) writes: > > Since we all have been talking about this backflow theory on the SRBs, > I was wondering if the same didn't happen on the Saturn V first stage. > I seem to remember all the long camera shots looking like the last 30 > seconds of stage 1 burn was going up the sides of the bird? Anyone else > remember this? > (Disclaimer--I am quoting this from memory, without my sources in front of me. Although the essential facts are correct, there may be some small error. Please bear this in mind before flaming.) IF memory serves me correctly, I seem to recall a few rather strange facts relating to the development of the Saturn V. There were a few designs, such as the Saturn III and Saturn IV, which were to use 3 and 4 of the F-1 engines respectively. The Saturn IV was to have these engines arranged in a square pattern at the base of the stage. The reason this idea was NOT carried through is that a SEVERE backflow of the exhaust gasses in the center of the engines. The effect was supposedly somewhat akin to blasting the base of the stage with a very high powered torch, which was leading to structural failure. The solution was to strengthen the framework at the base of the stage, and put a fifth engine in the center. Exhaust from the fifth engine would alleviate the backflow problem. Voila, we have the Saturn V. Now, this raises some interesting questions regarding the shuttle. If the backflow problem can be this severe, what is the effect of the backflow from the SRB's and the three SSME's?? It seems to me that the critial area for backflow would be at the base of the external tank. If this is the case, then I hope that the ET has very good insulation in that area. Norman Kluksdahl Arizona State University ..ncar!noao!asuvax!enuxha!kluksdah This represents in no way, shape, or form the opinions of ASU (unless I have made a mistake, in which they are the convenient scapegoat!!!!).
henry@utzoo.uucp (Henry Spencer) (10/05/88)
>> Since we all have been talking about this backflow theory on the SRBs, >> I was wondering if the same didn't happen on the Saturn V first stage. >> I seem to remember all the long camera shots looking like the last 30 >> seconds of stage 1 burn was going up the sides of the bird? Anyone else >> remember this? As outside atmospheric pressure drops off, the plume does extend itself upward. At very high altitude, a typical launcher will be enveloped completely in its plume, which is a real nuisance if you're got a payload that really cares about contamination. (Or if you're trying to build a missile-interception system and you want an infrared sensor to find the missile, not the plume.) >IF memory serves me correctly, I seem to recall a few rather strange facts >relating to the development of the Saturn V. There were a few designs, such >as the Saturn III and Saturn IV, which were to use 3 and 4 of the F-1 >engines respectively. The Saturn IV was to have these engines arranged >in a square pattern at the base of the stage. The reason this idea was >NOT carried through is that a SEVERE backflow... Well, not quite. The Saturn 3 and Saturn 4 were indeed paper designs with three and four F-1s respectively. However, the main reason for adding the fifth engine in the center of the Saturn 4 was simply that it was fairly trivial to do -- the structure was X-shaped so there was already ample support for the center engine -- and it made for a much larger performance margin. It did have the useful side effect of reducing the problem with hot-gas stagnation in the center, but that wasn't the main motive. (See "Stages to Saturn", one of the NASA History books, for the details.) -- The meek can have the Earth; | Henry Spencer at U of Toronto Zoology the rest of us have other plans.|uunet!attcan!utzoo!henry henry@zoo.toronto.edu
johnson@ncrcce.StPaul.NCR.COM (Wayne D. T. Johnson) (10/05/88)
In article <141@enuxha.UUCP> kluksdah@enuxha.UUCP (Norman C. Kluksdahl) writes: >Now, this raises some interesting questions regarding the shuttle. If the >backflow problem can be this severe, what is the effect of the backflow from >the SRB's and the three SSME's?? It seems to me that the critial area for >backflow would be at the base of the external tank. If this is the case, >then I hope that the ET has very good insulation in that area. > It depends, since the LOX and hydrogen are extreamly cold, is it possible that this backflow heating of the ET simply supplies additional pressure to empty the tank? Actualy, I don't think this is much of a problem, if they discovered the problem on the Saturns, they should have enough engineering knowhow to predict it on the Shuttle. The flame I saw seemed to move around a lot, unlike the challenger, and was usualy going away from the ET. -- Wayne Johnson (Voice) 612-638-7665 NCR Comten, Inc. (E-MAIL) W.Johnson@StPaul.NCR.COM or Roseville MN 55113 johnson@c10sd1.StPaul.NCR.COM These opinions (or spelling) do not necessarily reflect those of NCR Comten.
dave@viper.Lynx.MN.Org (David Messer) (10/05/88)
In article <3447@ihuxz.ATT.COM> dwv@ihuxz.ATT.COM (Bazooka Joe) writes: > >Since we all have been talking about this backflow theory on the SRBs, >I was wondering if the same didn't happen on the Saturn V first stage. >I seem to remember all the long camera shots looking like the last 30 >seconds of stage 1 burn was going up the sides of the bird? Anyone else >remember this? Yah, I remember seeing this. I thought at the time that it was an effect of the camera angle. Now I think it was a real effect. -- If you can't convince | David Messer - (dave@Lynx.MN.Org) them, confuse them. | Lynx Data Systems -- Harry S Truman | | amdahl --!bungia!viper!dave | hpda / Copyright 1988 David Messer -- All Rights Reserved This work may be freely copied. Any restrictions on redistribution of this work are prohibited.
knudsen@ihlpl.ATT.COM (Knudsen) (10/06/88)
In article <141@enuxha.UUCP>, kluksdah@enuxha.UUCP (Norman C. Kluksdahl) writes: > In article <3447@ihuxz.ATT.COM>, dwv@ihuxz.ATT.COM (Bazooka Joe) writes: > Now, this raises some interesting questions regarding the shuttle. If the > backflow problem can be this severe, what is the effect of the backflow from > the SRB's and the three SSME's?? It seems to me that the critial area for > backflow would be at the base of the external tank. If this is the case, > then I hope that the ET has very good insulation in that area. My sentiments exactly. Note the Russians have solved the problem just like the Saturn V -- put the main engines under the tank! (Now if they'd just put the bird on top so it looked like a rocket instead of an "American joke"...) And thanks for the Saturn history.