From d3b6a63a38a24a3f45a32ffdbf4998a0a2a06e61 Mon Sep 17 00:00:00 2001 From: Bdale Garbee Date: Thu, 22 Jun 2017 16:28:35 -0600 Subject: [PATCH] more info about our second batch of igniters --- rockets/research/2017-batch-05.mdwn | 27 +++++++++++++++++++++++++++ 1 file changed, 27 insertions(+) diff --git a/rockets/research/2017-batch-05.mdwn b/rockets/research/2017-batch-05.mdwn index c610803..c0e5069 100755 --- a/rockets/research/2017-batch-05.mdwn +++ b/rockets/research/2017-batch-05.mdwn @@ -49,5 +49,32 @@ Mg particle size. It could be that we need to go back to using the finer Mg powder when making smaller igniters, and reserve the "chunky" stuff for large ones? +At NCR's Mile High Mayhem 2017, we used a 12V battery to test one of the +larger igniters, and the bridge wire burned and burned a small amount of +the pyrogen, but then it fizzled out without doing anything really +useful. That made us skittish about trying them on the rail, and we used +up the rest of our commercial igniters and bought a couple more that weekend +instead. + +Once home, we tested the rest of the batch. About 2/3 ignited and burned ok, +but fairly slowly and not very evenly. About 1/3 did what the one we tested +at the launch did, burning slightly then fizzling out. + +The burn time was at least 5 seconds on each igniter, with about 1" length +of pyrogen. That really seems too slow. 1-2 seconds would be better? + ## Observations ## +We think the larger magnesium particles, which make nice "spitty" igniters +when the igniter actually ignites, would probably help start big sugar motor +grains, but we really can't call this batch successful. Our theory is that +the failed igniters hit a big chunk of magnesium that they didn't have enough +energy to ignite before enough of the epoxy-based pyrogen was burning to +sustain combustion. + +Robert noted that large magnesium particles also seem to raise the risk of +starting a grass fire around the launch pad if the motor does light and the +rocket takes off before the igniter completely combusts. + +Next, we'll try going back to the powdered magnesium with bridge wires. + -- 2.30.2