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- Feb 3, 2012
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Ok, here's a puzzler...
I had an AT Hobbyline 29/40-120 F52 toast the inside of my Madcow GX3 about 1/2 second after ignition yesterday. There was no BP in the well, as it was flying DD, and the well was taped over to prevent the delay grain burn from getting into the body tube (presumably well after burnout). Took apart the motor afterwards...
o Everything was there, and in the right order (i.e. the delay grain o-ring was against the housing)
o Both closures were tight
o The delay grain was definitely facing the o-ring
o The delay o-ring was toasted, so propellant gases definitely breached the delay grain/o-ring seal
o Both of the propellant grain o-rings were intact
o The washer was essentially intact (as much as could be expected from the burn...)
o The kink in the igniter where I bent it and taped it to the nozzle coincided with the top of the grain... it butted up against the taped-over slot (since it was a single-grain "F" load)
o The motor had been thoroughly cleaned and all o-rings greased prior to assembly the night before
I don't see any reason why this should have happened. I've probably flown at least 100 HL loads, and this is the first time I've ever had this happen. Any ideas? Thanks!
I had an AT Hobbyline 29/40-120 F52 toast the inside of my Madcow GX3 about 1/2 second after ignition yesterday. There was no BP in the well, as it was flying DD, and the well was taped over to prevent the delay grain burn from getting into the body tube (presumably well after burnout). Took apart the motor afterwards...
o Everything was there, and in the right order (i.e. the delay grain o-ring was against the housing)
o Both closures were tight
o The delay grain was definitely facing the o-ring
o The delay o-ring was toasted, so propellant gases definitely breached the delay grain/o-ring seal
o Both of the propellant grain o-rings were intact
o The washer was essentially intact (as much as could be expected from the burn...)
o The kink in the igniter where I bent it and taped it to the nozzle coincided with the top of the grain... it butted up against the taped-over slot (since it was a single-grain "F" load)
o The motor had been thoroughly cleaned and all o-rings greased prior to assembly the night before
I don't see any reason why this should have happened. I've probably flown at least 100 HL loads, and this is the first time I've ever had this happen. Any ideas? Thanks!