From 7b01a29d9dab576e34b53db2f0666c95ee6b19c1 Mon Sep 17 00:00:00 2001 From: Bdale Garbee Date: Fri, 2 Jun 2017 13:08:58 -0600 Subject: [PATCH] new stuff --- rockets/research/2017-batch-04.mdwn | 27 ++++++++++----- rockets/research/2017-batch-05.mdwn | 53 +++++++++++++++++++++++++++++ rockets/research/index.mdwn | 1 + 3 files changed, 72 insertions(+), 9 deletions(-) create mode 100755 rockets/research/2017-batch-05.mdwn diff --git a/rockets/research/2017-batch-04.mdwn b/rockets/research/2017-batch-04.mdwn index a0e376f..3d2ca0a 100755 --- a/rockets/research/2017-batch-04.mdwn +++ b/rockets/research/2017-batch-04.mdwn @@ -1,16 +1,25 @@ # Batch 2017-batch-04 # -4 grains of 29mm using sorbitol, intended to be a reloads for the -second-longest GMA 29mm snap-ring case. Grain length 45mm with 1mm spacing -per grain, so we'll make the casting tubes 46mm long. Delrin coring rods of -5/16" diameter. +4 grains of 29mm intended to be a reloads for the second-longest GMA 29mm +snap-ring case, *and* 6 grains of 54mm intended to be 2 3-grain reloads, all +in one sorbitol melt. -Formula for a batch size of 135g: +29mm grain length 45mm with 1mm spacing per grain, so we'll make the casting +tubes 46mm long. Delrin coring rods of 5/16" diameter. -* 65% KNO3, 87.75g, taken from the big bucket -* 35% Sorbitol, 47.25g -* 1% RIO, 1.35g -* PolyStep B1, 2 drops +54mm grain length 76mm with 2mm spacing per grain, so we'll make the casting +tubes 78mm long. Delrin coring rods of 1/2" diameter. + +Formula for a batch size of 1kg: + +* 65% KNO3, 650g, taken from the big bucket +* 35% Sorbitol, 350g +* 1% RIO, 10.0g +* PolyStep B1, 15 drops + +With left-overs from batch-01, this was enough for all but two of the 29mm +grains. We added enough materials for another 100g and were able to finish +up with a bit left over. Presto Multicooker operated at 275F indicated. diff --git a/rockets/research/2017-batch-05.mdwn b/rockets/research/2017-batch-05.mdwn new file mode 100755 index 0000000..e16404b --- /dev/null +++ b/rockets/research/2017-batch-05.mdwn @@ -0,0 +1,53 @@ +# 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 ## + diff --git a/rockets/research/index.mdwn b/rockets/research/index.mdwn index 9f958a6..9f015ee 100755 --- a/rockets/research/index.mdwn +++ b/rockets/research/index.mdwn @@ -11,6 +11,7 @@ ### 2017 ### +* [2017 batch 05](2017-batch-05.html) - 2 June 2017 - 9 epoxy fire igniters * [2017 batch 04](2017-batch-04.html) - 1 June 2017 - 4 29mm KNSB grains * [2017 batch 03](2017-batch-03.html) - 31 May 2017 - 6 29mm KNER grains * [2017 test 04](2017-test-04.html) - 21 May 2017 - 4-grain 54mm KNSB flight -- 2.30.2