18% R45M, 12% Al (325 mesh), 68% AP (200 um), 2% Isonate 143L
This was a 320 gram batch, hand mixed and degassed for one hour prior to adding the curative.
Casting Tubes (4) Weight: 62.4 grams
Number of Grains: 4
Outside Diameter: 1.35"
Core: .5"
Total Grain Length: 9.19" (2.2975" each)
Propellant Weight: .5913 pounds
Density: .05245 pounds per cubic inch
Throat Diameter: .392"
Kn: 201, 231, 213
This is a capture of the motor at full thrust.
Click Here for a short video of the test. (.97 MB Divx file)
Thrust/time curve of the test.
Test Data:
Total Impulse: 116.74 pound seconds
Isp: 197.4
Burn Time: 2.567 seconds
Burn Rate: .1655 "/sec.
Peak Thrust: 58.25 pounds
Peak Chamber Pressure: ~325 psi
Another nice burn in a small motor. The increased Kn also increased the Isp from test 114, as expected. I ran a simulation of this motor In FPRED prior to the test.
Burn Time: FPRED 2.52 sec. Actual 2.567 sec.
Peak psi: FPRED 321 psi Actual 325 psi
Total Impulse: FPRED 128.6 Actual 116.74 pounds
As you can see the burn time and chamber pressure simulations are about dead on with the actual results. The predicted total impulse did not take into account nozzle loss, so going by this test my nozzle loss was about 9.2%. This nozzle was slightly under expanded too, so I'm sure I can get the nozzle loss to a better level as well. I'll increase the Kn again for the next test, I'd like to get about 210 seconds out of this propellant without too short of a burn time.
Reducing the throat diameter to .32", FPRED simulations predicts a 2.01 second burn and an Isp of 222 seconds including the 9.2% nozzle loss. So it looks like I should be able to get my 210 second Isp without any real problems.
For FPRED I'm using: a= .0174, n= 0.4, Gamma= 1.2265, C*= 4976.1 fps,