# Test 2017-12 #
5 grain 75mm sorbitol motor with pyrodex pellet ignition in 4-inch Wildman
rebuilt airframe at NCR North.
Trimmed CTI 5-grain case (25.75" overall), Loki #42 nozzle, CTI aft closure
ring, forward bulkhead from Terry's pile machined to have 0.5" inside snap
ring plus 0.25" inside liner, with two o-rings, one pushing against liner.
Liner 23.125" long with about 22.25" available for fuel load.
Simulation says this is a 57% L-1366 with 3804 Ns total impulse, 797 psi max,
76% volume loading, and about 2.6 seconds burn time.
CTI mod Sorbitol |
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Rating: | 57% L-1366 | Max Pressure: | 5.5 MPa |
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Total Impulse: | 3804 Ns | Specific Impulse: | 131 s |
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Max Thrust: | 1706 N | Volume Loading: | 76% |
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Average Thrust: | 1366 N | Fuel Mass: | 2958 g |
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![null](http://chart.apis.google.com/chart?chxt=x,x,y,y,r,r&chs=400x200&cht=lxy&chco=3072F3&chds=0,2.78,0,1705.86&chxr=0,0,2.78|2,0,1705.86|4,0,383.49&chd=t:0,0,0,0,0,0,0.01,0.01,0.01,0.01,0.01,0.04,0.09,0.18,0.31,0.49,0.77,1.18,1.4,1.8,2.55,2.77,2.78|0,91.36,178.73,267.59,350.09,424.37,491.87,553.42,609.32,659.92,705.6,1075.86,1095.99,1121.65,1280.52,1398.83,1549.03,1685.96,1705.86,1637.7,490.86,0.61,0.48&chxl=1:|s|3:|N|5:|lbf&chxp=1,50|3,50|5,50) |
Neglected to re-weigh grains after trimming and before epoxying into the
liner. These were the pre-trim masses:
* Grain 2017-7-1, 590g gross, 574g net, trimmed to 4.5" long
* Grain 2017-7-2, 594g gross, 578g net, trimmed to 4.5" long
* Grain 2017-7-3, 592g gross, 576g net, trimmed to 4.5" long
* Grain 2017-7-4, 584g gross, 568g net, trimmed to 4.4375" long
* Grain 2017-7-5, 580g gross, 564g net, cut to 4" long
Total propellant load thus somewhat less than 2860g.
## Results ##
Had to trim grains to fit. Four just required squaring up the ends and
trimming excess casting tube away. Fifth one was cut in miter box with saw.
O-rings made forward closure a *very* snug fit.
Flight data logged as sn 3121, flight 3 on 2017-10-08. 8353 ft apogee, Mach 0.7, 3.4 sec boost.