# 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
Rating:57% L-1366Max Pressure:5.5 MPa
Total Impulse:3804 NsSpecific Impulse:131 s
Max Thrust:1706 NVolume Loading:76%
Average Thrust:1366 NFuel Mass:2958 g
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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.