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Grain Specs:
1) 216.2 grams 3.156"
2) 209.0 grams 3.095"
3) 221.5 grams 3.226"
4) 220.5 grams 3.208"
Total Propellant Weight: 863.2 grams/ 1.901 pounds
Total Propellant Length: 12.685"
Kn: 162 initial 181 maximum
Lift Off Weight: 10.2 pounds
Launch day. It was cold, only about 11 degrees (F) and the wind was about 15 mph. Not the ideal day for a launch, but the rocket had been ready to fly so long, I decided it may be now or never. My cousin had been wanting to see a launch, so he and his boy made it out to watch. Bill was on hand to help out as well.
Here Bill loads the rocket on the rail while my cousin and his son watch.
Ignition, and lift off!
Nice straight lift off.
Now the wind hits the rocket and it veers into the wind slightly.
Here is motor burn out.
Click here for a video of the lift off and boost. Bill had the video camera, so the wobble and comments are from him as he slips in the snow trying to keep up with the rocket.
The rocket really leapt off the pad and had a very nice boost and coast to apogee. The yellow paint was very visible, as I had the rocket in sight for the entire flight. All the way from lift off to impact, yip, impact. Unfortunately, there was no deployment. My first thought was the cold, perhaps the battery had lost too much power, or the cold had affected the altimeter. Hopefully when recovered I'd be able to find out the problem.
Finding the rocket was easy, I saw where it had impacted and the snow covered ground was in nice contrast to the black impact crater, if you can call an impact crater nice that is. To my dismay, the rocket was pretty much a complete loss, the altimeter was smashed to pieces, only the parachutes and some motor parts will be salvaged. It was quickly apparent both the drogue and main deployment charges had gone off. So why the non deployment? For starters, if the mid body separation does not occur, it's unlikely the main would deploy because of the high pressure on the nose cone.
When I got home I sat down to think, then it dawned on me. I had thought about it the night before, and forgotten about it. When I had drilled and tapped the holes in the rocket body tube for the nylon shear bolts, I made the mistake of drilling out the holes on the wrong side of the coupler, that is, I drilled out the bolt holes on the glued end of the coupler, not the end that needed the bolts. So I redrilled the holes at the correct end of the coupler without sealing the first three holes. I was going to run three screws into those holes to seal them, I just forgot.
That's the only thing that could have gone wrong, as I used dual initiators and a larger charge than normal. A simple mistake, that cost me a rocket an altimeter and many hours of work.
I have put together a rocket from the parts of the Cosmo rocket project. It's purpose will be to test dual deployment from one tube using the PIRM for main deployment. I'll be using my timers again. Hopefully I'll have better luck with that configuration.