lvron@earth.lerc.nasa.gov (Ronald E. Graham) (11/10/90)
I included sci.engr in this follow-up, hoping for some extra technical insight. The original posting was sent to sci.space and sci.astro. In article <1990Nov9.145517.1891@cc.ic.ac.uk>, zmapj36@cc.ic.ac.uk (M. S. Bennett) writes... [From an article entitled "Ariane Returns to Business" by Neville Kidger...] > Arianespace, the company which markets and flies the Ariane launcher, >has resumed operations following the loss of the V36 launcher in February >1990. > The loss of the rocket - with two Japanese commercial satellites >aboard - was found to have been due to the presence of a piece of cloth >in the water supply line to one of the four Viking first stage engines. I've never been part of a failure investigation (thankfully ;-)) since I joined NASA, so I don't know much about the procedure. I hope someone can offer insight on the following questions: (1) the failure was due to a piece of cloth. How could this have been isolated after the failure? (2) what is the mechanism by which a piece of cloth was able to cause the failure? By that I mean - was the cloth of sufficient size/porosity to totally restrict water flow? or did it have to be? - how is a piece of cloth able to be in the water line anyway? - what is the sequence of events leading to the failure, given the presence of the cloth? (3) how can Arianespace ensure no repeat of this mechanism/sequence of events? Please don't give any over-simplified answers like "they screwed up," or "they need to look harder." Unless (3) absolutely requires a very simple answer. I won't assume you know what you're talking about. And, if there are some answers out there, I will gladly summarize. RG - lvron@earth (or mars, or saturn - your choice) .lerc.nasa.gov
henry@zoo.toronto.edu (Henry Spencer) (11/14/90)
In article <1990Nov10.151130.29117@eagle.lerc.nasa.gov> lvron@earth.lerc.nasa.gov writes: >(1) the failure was due to a piece of cloth. How could this have been > isolated after the failure? They pinned down possible causes based on the symptoms, and then went through the recovered debris very carefully, and found the cloth. >(2) what is the mechanism by which a piece of cloth was able to cause the > failure? By that I mean > - was the cloth of sufficient size/porosity to totally restrict water > flow? or did it have to be? I believe it was large enough and solid enough to completely block the line. We're not talking about 30-cm pipes here. > - how is a piece of cloth able to be in the water line anyway? Good question. Nobody knows for sure. The obvious possibility is some minor blunder during manufacturing. If that's the case, there is little hope that the person responsible will ever admit it. > - what is the sequence of events leading to the failure, given the > presence of the cloth? Water flow to one engine chokes off, chamber pressure and thrust in that engine drop, the other engines gimbal farther and farther to compensate, eventually they hit their gimbal limits and the booster starts to turn, and the attempt to fly sideways exceeds its structural limits and it breaks up. >(3) how can Arianespace ensure no repeat of this mechanism/sequence of > events? The usual: more care during manufacturing, more thorough inspections, and some managerial changes to clarify who's responsible for that water line (one company had hold of each end and nobody was in charge of the whole thing). -- "I don't *want* to be normal!" | Henry Spencer at U of Toronto Zoology "Not to worry." | henry@zoo.toronto.edu utzoo!henry
herve@cvl.umd.edu (Jean-Yves Herve') (11/14/90)
In article <1990Nov13.185458.5052@zoo.toronto.edu> henry@zoo.toronto.edu (Henry Spencer) writes: >In article <1990Nov10.151130.29117@eagle.lerc.nasa.gov> lvron@earth.lerc.nasa.gov writes: >>(1) the failure was due to a piece of cloth. How could this have been >> isolated after the failure? >They pinned down possible causes based on the symptoms, and then went through >the recovered debris very carefully, and found the cloth. I seem to remember reading some report stating that the piece of cloth was clean (which meant it hadn't been used for cleaning parts and been forgotten there). Now, how clean can a piece of cloth found among debris be? Or is my memory playing tricks again? Jean-Yves Herve' herve@urdr.umd.edu
mikemr@microsoft.UUCP (Michael MRAZ) (11/15/90)
I'd sure like to know what water is doing in a propulsion system. I don't know anything about the Ariane, but I've never heard of water used for anything other than cooling the pad or quenching astronaut/cosmonaut thirsts. ;-> Can anyone enlighten me, please?