This was the second launch of my little unnamed rocket. The motor was again the ER1.75I with a propellant load right at 16 ounces. I used the ARB3D flight computer this time, testing it's functionality. As in the last flight, I set up for "mogue" deployment at apogee with the main charge set to 800' as a "Hail Mary" charge. Although after the flight it appeared both charges went off at the same time, sort of as expected because the charges were so close to each other.
Bill helped me with this flight. And I'm afraid I don't have any video or pictures, the video camera works better with a tape in it... My tracking transmitter was again installed in the nose cone, and turned out to be crucial to locating the rocket later.
It was a bit windy, but with the transmitter installed, and the wind in a favorable direction I decided to go ahead with the flight. We slid the rocket into my rail, installed an igniter and moved the rail upright. Once all was set, I armed the altimeter and Bill and I took our positions at the launch controller.
All clear. 5,4,3,2,1 and ignition. The motor was a little slow to get going, once it got up to pressure the rocket raced up the rail, once off the rail the rocket veered into the wind a fair amount, shortly after we both lost sight of the rocket. I used the RDF receiver to locate the rocket in the sky, but we never did reacquire sight of the rocket.
Once I lost the signal, we quickly loaded up the equipment in the van and set off on the search. I drove around the section, then got out to get a fix on the signal. It was still fairly faint, and we had overshot the rocket, as it was now behind us. So I used a field driveway at the mid mile point and drove into the middle of the section. Bill had the receiver going inside the van, and soon picked up a strong signal. The rocket had landed about 40' from the driveway, so it ended up being an easy recovery.
The nose cone a deep scratch in it, you could see where the nose cone had impacted the upper body tube and left a paint mark on it. I'm sure both charges went off, and the nose cone snapped back and hit the rocket at apogee. I'll have to either seal the second charge so it can't go off with the apogee charge, or just use one charge. I could add some more length to the shock cord as well.
Once home, I downloaded the data into my PC.
Here is the screen capture of the ARB3D data from the flight.
Interestingly enough, this time all the data was clean and the software plotted everything properly. Peak altitude was 4,004.9', looks about right when you consider the wind and the weathercocking. Total impulse of 109 pound seconds is right where static test put it as well. One thing I do think, and this is backed up by the accelerometer data, I didn't have enough spacing between the grains and the motor almost burned as one long grain. The progressive thrust profile seems to indicate this as well.
The only odd thing I see is the flat peak to the barometric altitude. The altitude stuck at 4,004' for about 1.5 seconds. Apogee deployment was about 150' below peak altitude.
It seems both the P6K and the ARB3D are functioning properly, so these last two flights don't shed any light on the early deployment of the A2MD flight. I suppose now I can finish painting this little rocket, and think of a name for it.