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[web/gag.com] / rockets / research / 2017-batch-05.mdwn

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+# Batch 2017-batch-05 #
+
+Another try at making our own igniters, using the "epoxy fire" formula from 
+[Scott Berfield](http://www.berfield.com/igniters.html).  Moving from the
+pre-made ematches that "pop" to home-made wire-wound bridge wires with 6
+turns of 30ga nichrome wire, and we'll try the "slow" West Systems 
+hardener.  We'll also try using slightly larger magnesium particles, sifted
+from the "saw chips" bag, not the powder.
+
+Made up a 15g batch with the following formula:
+
+* 68% KNO3, 10.20g, hand ground with mortar and pestle to fine grain size
+* 7% magnesium powder, 1.05g
+* 1% air float charcoal, 0.15g
+* 24% West Systems 105+206 epoxy, 3.60g
+** 3.03g 105 resin
+** 0.57g 206 hardener
+
+Two folded papers were used to weigh out the KNO3 in one, and a mixture of
+the magnesium powder and charcoal in another.  The epoxy was mixed in a small 
+disposable plastic cup with a popsicle stick, then the magnesium and charcoal 
+were poured in and mixed until complete wetted.  Then the KNO3 was added and
+mixed until everything became a homogenous mix.  It was a dry-ish, crumbly
+consistency, but packed into lumps easily.
+
+Two sizes of plastic drinking straws used.  One is about 3/16-7/32" diameter,
+the other about 1/4" in diameter.  Both were cut into 1" lengths.  The 
+procedure was to slide the
+ematch through the straw, pack material into the straw from the "back" end 
+until it was mostly full, then pull the ematch lead until the match head was
+just at the forward end of the straw, then pack more material in the front 
+end of the straw until the match head was just covered.  Using nitrile-gloved
+fingers, it was then easy to mash on both ends simultaneously to make sure
+we had good packing with minimal voids, leaving both ends flush with the 
+straw.  
+
+The matches were left to cure overnight, and then the straws were carefully
+sliced lengthwise with a razor blade and peeled off, revealing what looked
+like very solid cylindrical igniters.  They look a lot like the Quickburst
+ones.
+
+These igniters were made on 2 June 2017.
+
+## Results ##
+
+We got 6 of the larger and 3 of the smaller igniters out of this batch.  It
+was very difficult to pack the smaller straws, probably due to the larger
+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?
+
+## Observations ##
+