KN/Xylitol Test Stand Results with Polystep B-1 Surfactant (0.15%)
Xylitol exhibits some unusual characteristics, both in its formulation and its burn characteristics under pressure. A 65/35 ratio propellant using surfactant exhibits excellent melt flow properties. The viscosity of the melt is lower than a similar KNSO formulation. As the KNXY formulation cools it can sometimes quickly crystallize or at times will take 3 to 4 days to finally harden. When this final crystallization takes place a significant contraction takes place, often leaving voids in the grain. I found that the best way to get good grains is to pour a large "column" of propellant in a long section of casting tube. Grains were then cut to length using a chop saw. The grains at the lower or bottom end of the poured casting tube were solid where as the upper portions would have the voids. Cores were drilled after grain setting and cutting. Burn rate properties of this propellant under pressure are very interesting. As the grain number of the test increased from 2 to 3 to 4 grains and holding the nozzle throat size very small and constant the burn time increased slightly, along with the pressure. This seems to indicate that the burn rate of this propellant does not change much or may even decrease a bit with increasing pressure. Very unusual. More to come some time in the future......
238 Xylitol w/B-1
Burn time = 7.67 sec
Propellant weight = 123.5g = 0.272 lbs
Nozzle Throat = .00853 in2
Max Thrust = 4.7 lbs
Max pressure = 367 psi
Ave. Thrust = 3.4 lbs = 15 N
Total imp. = 26.1 lb sec = 116 N
ISP = 96
Motor Class = G15
Burn Rate ~ 1.4 mm/sec
338 Xylitol w/B-1
Burn time = 9.13 sec
Propellant wt. = 184.6g = .406 lb
Max Thrust = 6.0 lbs
Nozzle Throat = 0.00853 in2
Ave Thrust = 4.3 lbs = 19.1 N
Max Pressure = 470 psi
Total Imp. = 39.3 lb sec = 175 N sec
ISP = 97
Motor class = H19
Burn rate ~ 1.3 mm/sec
4 gr xylitol w/B-1
Burn time = 9.82 sec
Nozzle throat = 0.00853 in2
Propellant wt. = 239g = 0.526 lb
Max thrust = 8.85 lbs
Max chamber Pressure = 690 psi
Ave Thrust = 5.3 lbs = 23.6 N
Total imp. = 231.6 N sec = 52 lb sec
Isp = 99 sec
Motor class = H24
Burn rate ~ 1.2 mm/sec
