Potassium/Sodium Nitrate Oxidizers Using Sorbitol Fuel

The following test stand results were obtained using a propellant formulation ingredient weight ratio of 35/30/35 (KNO3/NaNO3/SO).   The ingredients were finely ground, mixed, and then heated to 200C in a small pyrex type glass measuring cup (obtained at WalMart).  A small convection toaster oven was used for the heating.  Once the ingredients became liquid (~30 min.) they were stirred every 10 minutes or so until all the solid nitrates had dissolved.  The dark, runny fluid is then poured into grain casting tubes.  The various engine test results listed below show an interesting burn rate vs. chamber pressure trend.  A significant burn rate increase is observed once Kn levels above 350 are employed.

Caution:  This fluid is very hot.  Take special precaution to avoid any situations where this fluid can spill or come in contact with exposed flesh to avoid burns.  If such hot propellant comes in contact with a combustion source it will burn at a very high rate.  A higher degree of safety precautions should be taken if using this type of propellant.
238 KNaSO
Thrust Duration = 4.07 sec
Propellant Mass = 116.4 g = 0.256 lb
Throat Area = 0.0298 in2
Ave Thrust = 6.8 lbs = 30.0 N
Max Thrust = 13.5 lbs
~ Max Chamber Pressure = 325 psi
Total Impulse = 27.7 lb sec = 123 N Sec
ISP = 108
Initial Kn = 300
Motor Class = G30
238 KnNaSO
Init Kn = ~400
Thrust duration = 2.67 sec
Propellant Mass = 113.7g = 0.250 lb
Throat area = 0.02255 in2
Ave. Thrust = 12.54 lbs = 55.8 N
Max Pressure = 2300 psi
Total impulse = 33.5 lb sec = 149 N sec
Isp = 134 sec
Motor class = G56
238 KNO3/NaNO3 sorbitol
Thrust Duration = 2.67 sec
Propellant Mass = 108.3g = 0.2385 lb
Throat Area = 0.0246 in2
Ave. Thrust = 11.4 lbs = 50.7 N
Max. Chamber Pressure ~ 1200 psi
Total Impulse = 30.4 lb sec = 135 N sec
ISP = 127 sec
Motor class = G51
Initial Kn ~ 365
338 KNaSO
Thrust Duration = 2.87 sec
Propellant Mass = 164.5 g = 0.362 lb
Throat Area = 0.04108 in2
Ave. Thrust = 14.5 lb = 64.5 N
Max Chamber Pressure ~ 350 psi
Total impulse = 41.6 lb sec = 185 N sec
ISP = 115 sec
Motor class = H65
Initial Kn ~ 330
238 KNaSO + RIO
Thrust Duration = 1.60 sec
Nozzle Throat Area = 0.0302 in2
Propellant Mass = 115.5g = 0.254 lb
Ave. Thrust = 17.5 lbs = 77.9 N
Max. Thrust = 53.9 lbs
~Max. Chamber Pressure = 1275 psi
Total Impulse = 28 lb sec = 125 N sec
Specific Impulse = 110 sec
Motor Class ~ G78
Initial Kn = 300
RIO
338 KNaSO + 0.5% RIO
Thrust Duration = 1.63 sec
Propellant Mass = 174 g = 0.383 lb
Throat Area = 0.0519 in2
Max Thrust = 92.6 lbs
Max Chamber Pressure = 1275 psi
Ave Thrust = 27.6 lbs = 123 N
Total Impulse = 200 N sec = 45 lb sec
ISP = 117 sec
Motor class = H123
Initial Kn = 260
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538 KNaSO
Thrust Duration = 1.73 sec
Throat Area = 0.066 in2
Propellant Mass = 271.3 g = 0.597 lb
Max. Thrust =125 lbs
Max. Chamber Pressure = 1300 psi
Ave. Thrust = 40.4 lbs = 180 N
Total Impulse = 311 N sec = 70 lb sec
ISP = 117
Motor Class = H180
Kn = 325