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.
+
projects / web / gag.com / blobdiff