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   1 # Batch 2017-batch-04 #
   2
   3 4 grains of 29mm intended to be a reloads for the second-longest GMA 29mm
   4 snap-ring case, *and* 6 grains of 54mm intended to be 2 3-grain reloads, all
   5 in one sorbitol melt.
   6
   7 29mm grain length 45mm with 1mm spacing per grain, so we'll make the casting
   8 tubes 46mm long.  Delrin coring rods of 5/16" diameter.
   9
  10 54mm grain length 76mm with 2mm spacing per grain, so we'll make the casting
  11 tubes 78mm long.  Delrin coring rods of 1/2" diameter.
  12
  13 Formula for a batch size of 1kg:
  14
  15 * 65% KNO3, 650g, taken from the big bucket
  16 * 35% Sorbitol, 350g
  17 * 1% RIO, 10.0g
  18 * PolyStep B1, 15 drops
  19
  20 With left-overs from batch-01, this was enough for all but two of the 29mm
  21 grains.  We added enough materials for another 100g and were able to finish
  22 up with a bit left over.
  23
  24 Presto Multicooker operated at 275F indicated.
  25
  26 These grains were cast on 1 June 2017.
  27
  28 Simulation says:
  29
  30 <p>
  31 <!--Begin motor 29mm 4-grain Sorbitol #14 HTML export from MotorSim-->
  32 <table class='motor' style='text-align: left; border: 1px solid black'><tr><th colspan='6' class='title'>29mm 4-grain Sorbitol #14</th></tr><tr class='summary'><th>Rating:</th><td>99% G-180</td><th>Max Pressure:</th><td>6.47 MPa (939 psi)</td></tr><tr class='summary'><th>Total Impulse:</th><td>159 Ns</td><th>Specific Impulse:</th><td>133 s</td></tr><tr class='summary'><th>Max Thrust:</th><td>228 N</td><th>Volume Loading:</th><td>69%</td></tr><tr class='summary'><th>Average Thrust:</th><td>180 N</td><th>Fuel Mass:</th><td>122 g</td></tr><tr><td colspan='4' class='thrust'><img src='http://chart.apis.google.com/chart?chxt=x,x,y,y,r,r&chs=400x200&cht=lxy&chco=3072F3&chds=0,0.89,0,227.96&chxr=0,0,0.89|2,0,227.96|4,0,51.25&chd=t:0,0,0,0,0,0,0,0,0,0,0.02,0.04,0.07,0.12,0.19,0.29,0.44,0.52,0.65,0.78,0.8,0.88,0.89|0,10.15,19.94,29.95,39.31,47.83,55.66,62.85,69.45,75.47,134.47,149.05,157.98,170.21,186.92,207.36,225.35,227.96,219.77,198.86,37.95,0.12,0.06&chxl=1:|s|3:|N|5:|lbf&chxp=1,50|3,50|5,50' width='400' height='200' alt='null' /></td></tr></table>
  33 <!--End motor 29mm 4-grain Sorbitol #14-->
  34 </p>
  35
  36 ## Results ##
  37
  38 Average 29mm casting tube mass 1.25g.
  39
  40 29mm grains
  41
  42 * Grain 1, 29.3g gross, 28.05g net
  43 * Grain 2, 29.1g gross, 27.85g net
  44 * Grain 3, 28.9g gross, 27.65g net
  45 * Grain 4, 28.5g gross, 27.25g net
  46
  47 Total of 110.8g propellant, vs 122g simulated.
  48
  49 With a 7.40" liner, 14/64" nozzle throat, buna-n o-rings, simulation says
  50 this reload will be a 99% G-180, 159 Ns, with about an 0.8 sec burn.
  51
  52 54mm grains
  53
  54 * Grain 5, 184.6g gross, ?g net
  55 * Grain 6, 183.3g gross, ?g net
  56 * Grain 7, 186.2g gross, ?g net
  57 * Grain 8, 182.6g gross, ?g net (canted - casting tube tilted at pour time)
  58 * Grain 9, 184.0g gross, ?g net
  59 * Grain 10, 180.5g gross, ?g net
  60