3 Trying again using KNSO with our new casting bases. We also have a real
4 eye-dropper now for measuring the surfactant. 4 38mm grains of
5 1.875" length, using formula of
14 The multi-cooker was preheated to about 250F with the lid on. Temp was
15 increased during melting to 275F indicated.
17 Individual casting tubes with fill marks, coring rod inserted after pour,
18 cap installed and grain tapped down.
29 Pour went really smoothly. One grain looked "perfect" with the propellant
30 settled evenly and a couple mm of open gap at the top of the casting
31 tube. We think this one may have been slightly under-filled compared to
32 the others, all of which had some evidence of propellant sticking to the
33 cap and leaving an uneven top surface. This resulted in some quick trim
34 work with a knife, ergo final grain masses not matching all that well.
38 These four grains were assembled in an AT 38/480 case with a random AT
39 delay grain from the pile of left-overs, and flown in Robert's Madcow
40 Little John at Tripoli Colorado Spring Fling 2015. We used a Slim Gem
41 igniter from Quickburst. Great flight! The motor seemed to come up to
42 pressure quickly, and burned brilliantly.
44 The original simulator data:
46 Propellant : propellants/knsb.xml
47 Nozzle diameter : 0.739 cm (0.291") (19/64")
50 Port-to-throat ratio : 2.952
51 Mass Flux : 1.374 lbs/inch^2
53 Propellant length : 18.440 cm (7.260")
54 Web Thickness (max) : 1.026 cm (0.404")
55 Burn rate : 0.773 cm/s (0.304"/s) (a=7.852mm/s; n=-0.013)
57 Total propellant weight: 216.00 g (7.619 oz/0.476 lbs)
58 Average grain weight : 54.00 g (1.905 oz)
59 Theoretical density : 1.841 g/cm3 (0.067 lb/in3)
60 Actual density : 1.582 g/cm3 (0.057 lb/in3)
61 Density ratio : 85.953%
62 Specific impulse (Isp) : 106.342 s (estimated)
63 Initial Thrust : 169.37 N (38.08 lbs)
64 Peak Thrust : 182.21 N (40.96 lbs) at 34.00% (0.45 s)
66 Kn Ini : 309.48 (488.04 psi)
67 Kn Max : 330.39 (520.59 psi)
68 Kn Fin : 248.87 (393.56 psi)
69 Kn Avg : 309.70 (488.40 psi)
71 Total Impulse : 225.104 Ns (40.69% H)
72 Burn Duration : 1.328 s
73 Average Thrust : 169.555 N