110 pound card stock paper weighs .833 grams per 1" x 6.5".
| Grain # | Length | Weight | Density |
| 1 | 3.23" | 0.4753 | 0.06182 |
| 2 | 3.13" | 0.4388 | 0.05889 |
| 3 | 3.02" | 0.4429 | 0.06161 |
| 4 | 2.91" | 0.4052 | 0.0585 |
| 5 | 3.0" | 0.4244 | 0.05943 |
| 6 | 3.2" | 0.4793 | 0.06292 |
| 7 | 2.83" | 0.3939 | 0.05847 |
| 8 | 2.7" | 0.3943 | 0.06135 |
| 9 | 1.47" | 0.2097 | 0.05993 |
| Total | 25.49" | 3.6638 | 0.06024 |
Grains: (9) 1.91" diameter, .76" core
Nozzle: .5625" diameter throat
Kn: 417, 449, 390
Average Grain Length: 2.832"
Backup Timer: 21.5 seconds
PIRM 2: .36 grams
Apogee: 3.6 grams
Flight Computer: readalt.bs2; scottalt2_0.bs2
Mach Delay: 6 seconds
Main Deploy: 700'
When I was setting up the motor for this launch, I discovered I didn't have the nozzle I had originally made for the motor. I had broken it in a test of an APCP formula. So I found an old nozzle that was in poor condition, and decided to give it a try. The motor has a steel retainer to hold the graphite nozzle, so worst case if the nozzle broke would be a low thrust long burn situation. This was the last flight of the day, after the A2MD launch and the dual outboard flight.
I had terrible problems locating a spot for the magnet on the launch rail to start the back up timer. The four EMT rails make it hard to position the magnet so it clears the fins. Click Here (1.1 MB Divx video) for a short video of an unplanned deployment test, kind of comical actually. So I reloaded the apogee charge and decided to go with my homemade altimeter only. No one got a real good video of the launch, so I'll just add a few captures from the good moments of the video.
Here's liftoff of the Cosmo 2.
Here we are shortly into the flight. As I had sort of expected, the divergent nozzle cone broke off. That gave the rocket lower thrust and perhaps a bit of thrust vectoring as well, as the rocket flew into the wind quite a bit.
Here is a capture from John's camera.
Here we are at the end of thrust.
Notice I said "end of thrust" last frame, propellant continued to burn and acted as tracking smoke. KNER propellant just doesn't burn well with a low Kn, so once the nozzle broke, it opened up the throat and lowered the Kn. Even with a broken nozzle it was a good flight.
Here's a rather distant shot of the apogee charge going off. The larger white spot at the top is the smoke from the apogee charge, the light area below it is the drogue chute opening and the rocket below it.
We watched the rocket drift over us, I got out my tracking receiver and followed it in. Just before the main chute deployed I grabbed my video camera to try to get the PIRM 2 release of the main chute. But I was just a second too late, right on cue the PIRM 2 released the main and the rocket landed behind a small hill.
Here John collects the rocket.
Once home I analyzed the data from the altimeter, 5,432' was the max altitude. Not bad with a broken nozzle...